Overheating Problem

[66PolaraRag]

Thank you all for the suggestions! I really do appreciate the help!
The thermostat has been replaced, the filler pan/front valance is there and the lower hose is new with the spring in it. The radiator is a new all aluminum replacement that was supposedly sized for the car. It has a new cap with a temp gauge in it. When the gauge in the car says it's hot, so does the gauge on the cap. I've also installed a overflow reservoir to keep it from puking all over the place when I stop. I thought about trying a high flow water pump next. I'm pretty convinced that it's a water flow problem and not an air flow issue.
After reading cbarge's comment, I may pass on the high flow water pump.

 

[CBODY67]

Something's not "right" in this deal, from what I've read . . .

There are basically two sizes of C-body radiators, width-wise. The '66 and back had the round top, newer ones had the square top tank, but still the same width and size. So, how was it determined that you got the "correct size"? Dimensions or otherwise?

The cars came with a 180 degree thermostat. The 195 degree thermostat came in the later 1960s, but in '72, it was a 185 degree OEM thermostat. NO significant differences in how "hot" they ran due to this.

What type of fan? Direct drive, thermal, flex fan, size, number of blades? My theory is that the thermal clutch 7-blade fan is best. A flex fan might be lighter, but might block air flow through the radiator at higher fan rpms, as it feathers-out. Fan shroud should match and is needed.

Getting all of the air through the radiator is important, which is why Chrysler had their "yoke seal" on the bottom of the hood, to go between the radiator tank and the top of the core support when the hood is closed. Decreasing gaps between the side of the radiator might help too, but Chryslers were not nearly as bad as GMs were about gaps on the sides of the radiators.

Hopefully, the water pump pulley is the correct one to have the correct drive ratio for the water pump and a/c or non-a/c water pump. The a/c pump has fewer vanes, but it runs about 40% faster due to the different drive ratio. "Drive ratio" is in comparison to the crankshaft pulley size.

I've run my '66 Newport 383 a/c car with a defective vacuum advance and all it did was to consume more gas. No overheating issue due to the "retarded" spark as it was on only mechanical advance when the vacuum adv wasn't working. It would take a very lean mixture to result in overheating, although many diagnostic lists mention carb mixture as a "cause". IF it's THAT lean, you'll know by how it's NOT running well. The original Lean Burns were spec'd for a 16:1 mixture, rather than the normal 14.7:1, with no larger radiators or other changes to the cooling system.

Using the heat gun, what are the temps you're finding? At the thermostat, at the water pump, at the radiator top core, and at the radiator bottom of the core? Even with the OEM parts, Chrysler C-body cars (and others) usually did NOT have any overheat problems when new. Much less than Fords and GMs back then. That has been my observations over the years . . . unless something's mechanically wrong. Bad fan clutch, internally restricted radiator core, lower hose issues, etc. What engine, rear axle, tire size combination?

To me, stay away from the "high flow" noted items. As noted, there is an optimum speed of the coolant through the block for best heat transfer. Other than the water pump, that flow is regulated by the restrictions in the head gaskets. If the gaskets are original and the coolant hasn't been serviced as it should have been, flow over the many miles and poor maintenance can erode these hole and enlarge them. An outside chance, but I don't know that THAT would cause overheating.

Too much new stuff with no improvement. Doesn't all add up.

CBODY67

 

[Wile E Coyote]

What's your tire pressure in the right rear tire? In historical case studies of overheating issues, it has been factual determined that (INSERT sound of record player needle being dragged over the entire 33 album HERE) - I got nothing to add over the smart people here. They'll help you figure it out!

 

[66PolaraRag]

Something's not "right" in this deal, from what I've read . . .

There are basically two sizes of C-body radiators, width-wise. The '66 and back had the round top, newer ones had the square top tank, but still the same width and size. So, how was it determined that you got the "correct size"? Dimensions or otherwise?

The cars came with a 180 degree thermostat. The 195 degree thermostat came in the later 1960s, but in '72, it was a 185 degree OEM thermostat. NO significant differences in how "hot" they ran due to this.

What type of fan? Direct drive, thermal, flex fan, size, number of blades? My theory is that the thermal clutch 7-blade fan is best. A flex fan might be lighter, but might block air flow through the radiator at higher fan rpms, as it feathers-out. Fan shroud should match and is needed.

Getting all of the air through the radiator is important, which is why Chrysler had their "yoke seal" on the bottom of the hood, to go between the radiator tank and the top of the core support when the hood is closed. Decreasing gaps between the side of the radiator might help too, but Chryslers were not nearly as bad as GMs were about gaps on the sides of the radiators.

Hopefully, the water pump pulley is the correct one to have the correct drive ratio for the water pump and a/c or non-a/c water pump. The a/c pump has fewer vanes, but it runs about 40% faster due to the different drive ratio. "Drive ratio" is in comparison to the crankshaft pulley size.

I've run my '66 Newport 383 a/c car with a defective vacuum advance and all it did was to consume more gas. No overheating issue due to the "retarded" spark as it was on only mechanical advance when the vacuum adv wasn't working. It would take a very lean mixture to result in overheating, although many diagnostic lists mention carb mixture as a "cause". IF it's THAT lean, you'll know by how it's NOT running well. The original Lean Burns were spec'd for a 16:1 mixture, rather than the normal 14.7:1, with no larger radiators or other changes to the cooling system.

Using the heat gun, what are the temps you're finding? At the thermostat, at the water pump, at the radiator top core, and at the radiator bottom of the core? Even with the OEM parts, Chrysler C-body cars (and others) usually did NOT have any overheat problems when new. Much less than Fords and GMs back then. That has been my observations over the years . . . unless something's mechanically wrong. Bad fan clutch, internally restricted radiator core, lower hose issues, etc. What engine, rear axle, tire size combination?

To me, stay away from the "high flow" noted items. As noted, there is an optimum speed of the coolant through the block for best heat transfer. Other than the water pump, that flow is regulated by the restrictions in the head gaskets. If the gaskets are original and the coolant hasn't been serviced as it should have been, flow over the many miles and poor maintenance can erode these hole and enlarge them. An outside chance, but I don't know that THAT would cause overheating.

Too much new stuff with no improvement. Doesn't all add up.

CBODY67

I agree, hence my confusion. This car has always run a little warmer than I thought it should, but I've been told that Mopar big blocks are notorious for that. Other than the new radiator, (which is the exact same width, height, depth & capacity as the original), this car is bone stock. The fan has been replaced, but it's identical to the one that was on the car. It's a direct drive fan, (no clutch). I've never been a fan of flex fans. When this problem started, I thought it was the thermostat, so I replaced it. (180°) Didn't seem to make a difference. Then I noticed that the lower radiator hose was collapsing, so I replaced the hoses. Making sure they had the spring. That helped, but didn't cure the problem. Next came the radiator. The system was flushed when that was done. I thought that solved the problem. I drove the car all over (except on the interstate) with no issue, even in traffic. When I took it to an out of town cruise-in, I noticed that as soon as I started running around 70 it started heating up. Within a few miles the gauge was pegged. After I pulled off onto a side road, the temp started to drop down. Cruising at 55-60 the temp stayed consistent. As I got closer to 70, it started heating up again. It doesn't make sense.

 

[Yatzee]

I'm having a problem with my Polara overheating on the highway. I can drive it around town with no issue and even on State Routes at 55-60, but on the interstate running at 70+ it will overheat every time. It's a 383 4 barrel without air. I have replaced the temperature sensor, radiator, fan & hoses. The water pump is less than a year old. The heads have been checked. I've even tried an auxiliary electric fan. I'm not sure what else to look for. Any suggestions?

This situation is one of those mystery occurrences that defies explanation. If everything that has to do with efficient cooling has been replaced or upgraded then you need to look back to see what changed since the OE equipment was more than sufficient to 70 mph. It is obvious that the engine is producing more heat than the cooling system can dissipate and everyone has provided possibilities for this situation. You say everything is original but there exists the possibility that the engine was over bored and rebuilt. You do not mention this as a possibility. Regardless, it would appear that the cooling system has not got enough capacity, in it's given state, to cope with the amount of engine heat. Try the same run with the heater on full (fan included) and note if there is a temperature drop. Also if the heat is not moving out of the engine compartment this will just antagonize the situation. I suspect that new rad is not up to the job of transferring the heat produced by the engine. You will have to experiment a bit more.I don't know what rpm translates to 70 mph but if the car is sitting stationary with a couple of box fans up front it should still be able to cool at this given rpm. The fans will replicate the air stream as if you were going down the highway except that there is no real load on the engine. If it over heats under these circumstances I would say the rads the issue or the coolant flow is too great or not sufficient or the cooling system is not large enough. Good luck.

 

[saforwardlook]

This situation is one of those mystery occurrences that defies explanation. If everything that has to do with efficient cooling has been replaced or upgraded then you need to look back to see what changed since the OE equipment was more than sufficient to 70 mph. It is obvious that the engine is producing more heat than the cooling system can dissipate and everyone has provided possibilities for this situation. You say everything is original but there exists the possibility that the engine was over bored and rebuilt. You do not mention this as a possibility. Regardless, it would appear that the cooling system has not got enough capacity, in it's given state, to cope with the amount of engine heat. Try the same run with the heater on full (fan included) and note if there is a temperature drop. Also if the heat is not moving out of the engine compartment this will just antagonize the situation. I suspect that new rad is not up to the job of transferring the heat produced by the engine. You will have to experiment a bit more.I don't know what rpm translates to 70 mph but if the car is sitting stationary with a couple of box fans up front it should still be able to cool at this given rpm. The fans will replicate the air stream as if you were going down the highway except that there is no real load on the engine. If it over heats under these circumstances I would say the rads the issue or the coolant flow is too great or not sufficient or the cooling system is not large enough. Good luck.

I agree with Yatzee, your radiator isn't up to the task for higher speed driving, which means it isn't deep (thick enough with enough rows of tubes or the tubes are too narrow) and doesn't have the flow capacity that is needed at higher rpms. It must be efficient enough (i.e. the fin spacing is adequte for heat transfer for what is flowing through them) if it is performing well under low engine speed conditions where radiator width is a determining measure keeping the engine cool, so it must be a higher flow capability issue. Not enough depth to flow the volume of coolant needed. One measure of that variable is how much you paid for the radiator. If it was pretty cheap, like maybe only 2 rowws of narrow tubes or around $200, you probably have your culprit.

 

[PontiacJim]

Seems you have done all the "right" things. However, an investment in a hand held laser heat gun would go a long way. You can spot check many areas of the radiator, cooling system, engine, and exhaust to see if there is any hot spots that stand out. My '73 Fury showed hot to overheating on the gauge and I replaced a few things for good measure and got no difference. Bought the hand held and my radiator was well below hot, but my gauge read hot - so something is amiss in the temp gauge system, not the cooling system.

My brother has a 360CI (.040" over) I built up. I asked my machinist if the overbore would cause additional heating as I had heard this would. He said no it would not. He told me if it runs hot it is not because the block is .040" over. I had a new 2 core factory style radiator when I pulled the 318CI. Never any cooling issues with it and it was .030" over, but the 360 ran hot and would over heat when I first got it running. Used the A/C water pump which has more blades (I believe 8 vs 6) for added flow. Added 160 degree thermostat - took longer to get hot/over heat, so not a cure. Added a flex fan - this improved temps to a more tolerable overall level, but stop/go driving still got it too hot for my liking.

Next was an aluminum radiator - stock style replacement with 2 rows. I did a lot of research and all aluminum radiators are not created equal. The number of rows and the size of the tubes are most important. Some of the 3 rows can actually inhibit airflow due to smaller tubes and tighter packing and only slight improvements might be seen. The company we selected said the 2 core he offered was more than enough and we did not need the 3 core. Many are listed to support "X" amount of horsepower as horsepower means more heat. The radiator as I recall was in the $200 plus range and had the larger cooling tubes. Installed the radiator, and the engine typically never gets past the 1/4 hot line on his temp gauge and on a 95 degree day in stop go traffic it might top the 1/2 mark on the gauge and then drop right down once moving and steady air is passing through the radiator. No issues at higher RPM's & steady cruising speeds up to 80 MPH with 3.55 gearing trying to keep up with traffic (which I told him was going to kill his engine cruising distance at that speed/RPM's).

So here are my suggestions. You have not addressed anything on engine timing. RETARDED timing WILL cause an engine to run HOT. It seems that you are OK up to a certain speed and then it gets hot. It is very possible that your distributor timing, ie the advance weights could be: sticking, have a broken spring, may have been swapped out for an aftermarket set, or the advance curve is not correctly adjusted for your engine/todays fuel. Do not know if your original compression is over 9.0 which is best for pump gas, but the trick of retarding your timing to prevent "pinging," "spark knock," or "run-on" could cause the engine to heat up. Have you by chance tried an octane additive or running some racing gas mix just to see if this makes any changes?

It may also be possible that the timing chain is loose and having an effect on the timing at higher speeds/RPM's.

With that, I would check my timing advance curve to see at what RPM's my mechanical advance is coming in at and then at what RPM my total advance is all in.

You can test the timing chain play by pulling the distributor cap and watching the rotor. Turn the engine by hand in its normal rotation to take up any chain slack and watch the rotor move. Make a mark on the balancer for reference. Then rotate the engine in the opposite direction and stop the minute you see the rotor move. Note how far your mark on the balancer has moved. You can repeat this just to be sure of your results. The mark on the balancer should not have moved (from what I have sourced off the internet) any more than 5-7 degrees. More than that and the chain should be replaced. You Tube has a couple video's on doing this test.

A LEAN condition will cause an engine to heat up and higher RPM's requires more fuel. So fuel related things like fuel filter dirty, air cleaner dirty, fuel pump going bad and not producing enough pressure, sucking air from a loose, kinked, collapsed, cracked, or split rubber hose - especially if they have never been replaced for use with ethanol fuel, float setting too low, needle & seat going bad, vent plugged in gas tank, wrong gas cap. Ethanol laced fuel is said to run a bit leaner, so you might want to try opening up the idle screws a couple more turns to richen up the mixture a bit just to check/see if it makes a difference. If it does, you might need to go a couple steps more on the jets.

Do you know you have the correct spark plugs/heat range for your engine? You need the "typical" US brands of spark plugs as some of the modern plugs used in newer cars are not meant to be used in older engines and can cause higher cylinder temps.

Exhaust is not flowing as it should. Collapsed pipe internally, collapsed muffler, don't know if Mopar's have a heater "butterfly" built into the cast iron exhaust manifold like GM cars. If stuck closed or only partially open, this can cause an engine to run hot.

Have you run a vacuum gauge on the engine? Might be a valve hanging open or stuck closed effecting the engines running condition at the higher speeds. Could have a vacuum leak introducing additional oxygen at higher RPM's causing a lean condition.

PCV system might not be operating correctly. This should be checked.

And, I will add that I have had bad "new" thermostats - poor quality Chinese parts. They last about 2-3 weeks and stop working, either partially opening and/or flat out failing. Used up 3 in an older '97 Toyota I used to have after the original went 160,000 miles. Finally just cut out the center and used the outer ring ala stock car style. Mopar's used a specific style of thermostats. If using a store bought generic type, it may be the problem. I always drill a couple 1/8" holes in the outer ring to allow air to pass through as well as some fluid/pressure should the t-stat stick shut. It'll still overheat, but you get a little more time/warning as it does not build up the boiling pressures in the block as quick and puke out the radiator cap all in one big burst. Some aftermarket t-stats have this feature built in.

 

[MOVE N UP]

Dumb question....when the work to install the new radiator was performed, did the fan get installed backwards?

 

[CBODY67]

I know that sounds like an impossibility, but it has happened. When the '68 Coronets were still used cars, my barber bought a '68 Coronet R/T for his son and daughter to drive. A non-a/c car (for some reason!). He said one day that it had always run warmer then it should, but everything checked out good. One day, he was doing something to it and was standing in front of the grille and felt warm air blowing on his legs. THAT should not have been happening, but it was. He investigated further and the fan was flowing away from the engine, rather than toward it. He took off the ran and noted that the "FRONT" stamping was not facing "front". He put it on correctly and all was well and as expected. That's how it came from the factory.

As mentioned, there are several varieties of "aluminum radiators" Fin count, number of tubes, etc. I've found that the number of tubes might not be the most absolute measure of possible radiator performance.

On my '80 Newport 360, the stock a/c radiator (on the car) was a two-row item. I found a pair of '79 Gran Fury 360 police cars in the salvage yard. I noticed that the one with the radiator still in it was a two-row, too, BUT wider rows compared to my "normal" two-row. So I got the good one and had it redone by a good radiator shop. Worked fine!

Having too fine of a "fin count" can be similar to having an oil filter with the filter media that gets all of the small micron stuff out of the oil. It'll flow well up to a point, then the bypass valve will open and let the pressurized non-filtered oil go back into the oil pan.

The best gauge of fin count is to look at current production LX Hemi cars with a/c. I've had great luck with the aluminum-composite radiators. Some people don't like them, but I've not had any problems with the OEM-level replacements. Cool much better than a 3-row copper Modine (in the same car and engine).

The infrared "heat guns" are reasonably priced. Whether from Amazon or Harbor Freight (or similar). The basic one goes to 500 degrees F, with the upgrade one going to 1000 degrees F. They can be great diagnostic tools! Just don't try to measure temp of something "white" as it freaks it out and can ruin it. Been there, done that!

The issue of "big block Chryslers run hotter" hasn't been proven from my experiences with stock 383s, all a/c cars. No issues with 180 degree thermostats being too hot, either. Factory fan clutch fans work as designed and do need the factory shroud around them.

Get the heat gun, do the checks, and as mentioned, look for temp variations on the block, the heads, thermostat housing, radiator hoses, and several places on the radiator core. Also note the thermostat housing temp as the engine warms up (with the heat gun) and where the needle is on the temp gauge (if it has one) in the instrument panel.

Be aware, too, that a "coolant flush", even with the flush chemical additive, you're usually getting only the loose stuff that will wash out. The only real "best" way is to put the car on a lift, drain the coolant (after it cools some!), remove the freeze plugs, and mechanically remove any accumulation of sediment from the water jackets. As the rear of the motor sits lower, more will be in the rear of the block. It's messy and wet, but the only way to get things really clean. In another forum, many noted how much cooler their cars ran after doing this (after chasing over-heat issues for a while).

One other thought . . . when the gauge reads "HOT", when you turn off the motor does hot coolant come out of the overflow line after it sits for a while? What is the coolant level in the radiator tank, below the radiator cap filler neck and/or above the radiator core? Does this level stay consistent?

Keep us posted on your progress,
CBODY67

 

[jct]

Oddly enough my car is doing this same exact thing, rebuilt the top end and timing chain, replaced the thermostat and temperature sending unit and the new style of MP steel head gaskets(the engine was unmolested with the original timing chain and all)
(Tested at idle after a 10 mile drive)
Used a infrared thermometer on said spots around 220° at the thermostat housing about the same at the upper radiator house neck about 190°ish on the lower radiator neck

Made sure my radiator fan is blowing the in the correct direction

 

[ayilar]

The 195 degree thermostat came in the later 1960s, but in '72, it was a 185 degree OEM thermostat. NO significant differences in how "hot" they ran due to this.

Last year, I replaced the thermostat on my '71 Monaco (440-4 T-code) with a Stant 180-degree 45478 thermostat and the matching 27140 gasket. I bought the units from Summit. The t-stat has worked fine for almost 800 hundred miles in various conditions since then, so I wanted to get the same unit for my '70 Polara 'vert (383-4 N-code) and my '73 NYB (440 T-code). In the Polara's case, there is a leak there and I hope the gasket is the issue; in the NYB's case, it'd be preventative maintenance as I bring the car on the road after she stayed 9+ years in a collection without driving much (if at all).

Summit says that the 45478 is fine for the Polara but not for the NYB. In the latter's case, it recommends the 195-degree 45479 unit. The gasket is the same in both cases. Rock Auto says both the 78 and the 79 are fine, and I'd personally prefer a 180-degree thermostat. Any reason why I should stick to the 195-degree one for the NYB, or should the 180-degree work just fine?

 

[MoPar Maniac]

Here is a thought...
I had a 92 Spirit with the 2.5 4 popper.
On a trip if I kept the speed down the temp was fine. If I went faster the gauge would go to the top of the normal range.
Got home and could find nothing wrong. Then I heard bubbling. Removed the rad cap and it got louder. Took it to the mechanic and they found a blown head gasket. No coolant loss, no oil in water.
Replaced the gasket and all was well.

 

[ayilar]

Here is a thought...
I had a 92 Spirit with the 2.5 4 popper.
On a trip if I kept the speed down the temp was fine. If I went faster the gauge would go to the top of the normal range.
Got home and could find nothing wrong. Then I heard bubbling. Removed the rad cap and it got louder. Took it to the mechanic and they found a blown head gasket. No coolant loss, no oil in water.
Replaced the gasket and all was well.

I had a similar experience with Poppy, my '70 Polara convertible, last year.

I bought her in 2018. in Spring that year, I had the original radiator recored and all hoses replaced, and the car worked great for the first year / 1000 miles after I'd brought her back on the road. She did tend to get hot in stop-and-go traffic when the weather was humid, but not otherwise. Then, on the way back from Carlisle last year, she overheated in the fast lane on the highway. Caught it on time, stopped, and in the next few weeks the diagnostic was made. In addition to a problematic head gasket, there was plenty of accumulated "crud" in the 318 -- likely because of lots of short trips taken by the previous owner in the 1970's and early 1980's (the car only had 31k miles when I bought her and had sat for 32 years). Rebuilt the head, car now runs great.

 

[saforwardlook]

Last year, I replaced the thermostat on my '71 Monaco (440-4 T-code) with a Stant 180-degree 45478 thermostat and the matching 27140 gasket. I bought the units from Summit. The t-stat has worked fine for almost 800 hundred miles in various conditions since then, so I wanted to get the same unit for my '70 Polara 'vert (383-4 N-code) and my '73 NYB (440 T-code). In the Polara's case, there is a leak there and I hope the gasket is the issue; in the NYB's case, it'd be preventative maintenance as I bring the car on the road after she stayed 9+ years in a collection without driving much (if at all).

Summit says that the 45478 is fine for the Polara but not for the NYB. In the latter's case, it recommends the 195-degree 45479 unit. The gasket is the same in both cases. Rock Auto says both the 78 and the 79 are fine, and I'd personally prefer a 180-degree thermostat. Any reason why I should stick to the 195-degree one for the NYB, or should the 180-degree work just fine?

I would leave the 180 t-stat in place and not the 195. Unless you are really struggling with not enough heat when temperatures are very low outside, there is no reason to go with a higher temperature. Maybe it was specified for vehicle emissions issues in 1973, but all the higher temperature ones do is place added stress on the cooling system components such as the radiator and heater core for no real good reason in my view.

 

[mr. fix it]

Cheater. LOL

Lol!

 

[ricks_RR]

is the radiator the original i ask because my road runner did the same thing at 70 it was a two core radiator so a bought a three core and put ( water wetter in the radiator ) i small bottle and i have had no problems at all . when she gets hot ( how hot ) 200/210 ok but if it it 230, 240 not good.
i hope this helps

 

[Mike66Chryslers]

I would leave the 180 t-stat in place and not the 195. Unless you are really struggling with not enough heat when temperatures are very low outside, there is no reason to go with a higher temperature. Maybe it was specified for vehicle emissions issues in 1973, but all the higher temperature ones do is place added stress on the cooling system components such as the radiator and heater core for no real good reason in my view.

The engine temp will also affect the thermal expansion of the block. I seem to recall reading that running either a colder or hotter thermostat (I think it was colder) will contribute to accelerated cylinder bore wear over time, especially at the top where there is both less coolant flow in the water jacket and less lubrication from oil splash in the crankcase. A 180* thermostat is the best compromise between cylinder bore wear and stress on the cooling system / margin against overheating.

 

[marty koirtyohann]

Thank you all for the suggestions! I really do appreciate the help!
The thermostat has been replaced, the filler pan/front valance is there and the lower hose is new with the spring in it. The radiator is a new all aluminum replacement that was supposedly sized for the car. It has a new cap with a temp gauge in it. When the gauge in the car says it's hot, so does the gauge on the cap. I've also installed a overflow reservoir to keep it from puking all over the place when I stop. I thought about trying a high flow water pump next. I'm pretty convinced that it's a water flow problem and not an air flow issue.
After reading cbarge's comment, I may pass on the high flow water pump.

do u have a shroud on it? & a fan clutch?if it is still over heating u have a blockage someplace if i was u i would toss the casp with the temp gauge in iyt & get a oem cap most csps today r not wj=hat they r cracked uo to. a bad week cap or one they dose not ope k=like it should will cause it to yrun hot aklso get a 180 or maybe a 160 high flow i=one from mr gakt'

 

[livininharrow]

do u have a shroud on it? & a fan clutch?if it is still over heating u have a blockage someplace if i was u i would toss the casp with the temp gauge in iyt & get a oem cap most csps today r not wj=hat they r cracked uo to. a bad week cap or one they dose not ope k=like it should will cause it to yrun hot aklso get a 180 or maybe a 160 high flow i=one from mr gakt'

smoke another one.

 

[marty koirtyohann]

smoke another one.

what do u mean by the comment of smoke another one? mr gasket makes a high flow thermostat that is a exact copy of the mopar high flow race one i had to use the mopar oe on my 440 i bought the last one it was a nos direct connection . but with the aluminum radaitor he shouldnt be haveing over heating issues there is something else going on there