1966 Plymouth VIP with a 400 engine running hotter than I think it should. What could be the reason.

[rsh1966vip]

My 66 Plymouth VIP 283 was replaced by the previous owner with a 400. It is probably 1970-72?? but that not the point of the post. The point is this engine runs hot and I have had every thing replaced new. It has a 26 " new orginaial radiator etc. However it runs abut 200 degrees after about 10 miles of driving. I have read most of the posts concerning engines running hot on the forum.
Here is what I have done to try and analyze the problem.
1. Checked the in car gauge against my infrared hand held device and the gauge is correct it's running hot.
2. One thing that I found while shooting the valve covers with the infrared was that in the center of the values cover it was checking above 200 degrees. I was surprised at the difference shooting across the valve covers.
3. The next thing that I am going to try (I have a 67 Newport with 45k) is to drive the 67 get it good and hot and let it idle in the shop for 10 to 20 minutes and reshoot and compare. As you know the 67 is a 383 with 4 barrels and runs perfect.
Your comments will be appreciated.
rsh

 

[1970FuryConv]

How is the flow at top tank of radiator?
Is your thermostat opening all the way?

 

[Big_John]

My 66 Plymouth VIP 283 was replaced by the previous owner with a 400. It is probably 1970-72?? but that not the point of the post. The point is this engine runs hot and I have had every thing replaced new. It has a 26 " new orginaial radiator etc. However it runs abut 200 degrees after about 10 miles of driving. I have read most of the posts concerning engines running hot on the forum.
Here is what I have done to try and analyze the problem.
1. Checked the in car gauge against my infrared hand held device and the gauge is correct it's running hot.
2. One thing that I found while shooting the valve covers with the infrared was that in the center of the values cover it was checking above 200 degrees. I was surprised at the difference shooting across the valve covers.
3. The next thing that I am going to try (I have a 67 Newport with 45k) is to drive the 67 get it good and hot and let it idle in the shop for 10 to 20 minutes and reshoot and compare. As you know the 67 is a 383 with 4 barrels and runs perfect.
Your comments will be appreciated.
rsh

First thing that jumps out at me is that you are taking the temp on the valve covers. That's going to be heated from the exhaust manifolds and really doesn't mean too much in engine temp.

So assuming that your water temperature is 200 degrees F... 200 degrees sounds ok to me.

It's probably got a 195 degree thermostat in it. That would be worth checking... A 180 or even 160 degree thermostat might drop the temperature a little if you want, but it might not too.

Good idea to check the timing. A little more advance might help. Is the vacuum advance hooked up and working right?

One other thing that is often missing in older cars, is all the rubber shrouding below the radiator. Another place to look is the fan clutch as they often fail.

And sometimes it's a combo of all above....

 

[rsh1966vip]

excellent comments and I will follow up. thanks rsh

 

[65Coronet7165]

I've tried chasing down a similar problem with my 67 300 for. Years. When I was having the engine overhauled in 2007, the shop lost my original fan. It was a 4 blade fixed fan, no clutch but it does have a should. I also replaced the original rad with a Glen-Ray 26" 3 row core unit (my original was leaking.. Anyway I put a 6 blade Bouchillon Performance unit with a Hayden fan clutch on it to replace the "lost" 4 blade unit.

As long as temp outside is less than 82 degrees outside and car is moving, temp always stayed 180 degrees. Get stuck in traffic or at a light on hot days and you can just watch guage rise. I usually start getting nervous when temp reaches 200 degrees. If seen the temp get as high as 215 on a 95 degree day but never higher.
I bought a 4 blade used fan off eBay during the winter. I'm going to take off the 6 blade and clutch and try the 4 blade by itself. Hopefully THIS will make it run as originally intended.

 

[413]

just put in a 180 thermostat and recheck.

Check the temp on the water pump housing and front of cylinder heads.

The valve cover temp isn’t an accurate measure of the coolant Temp.

 

[CBODY67]

FWIW, the 400 debuted in 1972 with a 8.2CR and a 185 degree F thermostat. My parents bought one new. It had no overheat or "hot" issues at all. There was a TSB to add the ThermostaticIgnitionControl system, such that after the water temp got to a certain point, the thermovacuum switch would switch the distributor to manifold vacuum to speed the idle speed up a bit. ALSO in that TSB was the installation of thinner masticated die-cut rubber panels to ensure that all air that went through the radiator came THROUGH the grille, rather than from the sides or recycled from under the engine. The whole thrust of that TSB was to keep a/c gas pressure under control so a/c hoses would not blow up in hot weather from high a/c gas pressure. Being a recall, we got it done, but to no real benefit to us.

One other thing about the 8.2CR 400 is the heat of the exhaust (at the rear tail pipe exit) is a good bit higher than for our '66 Newport 383 2bbl 9.2CR engine.

As Chrysler CAP systems probably had 195 degree F thermostats in them, the car is designed for such and will operate there without issue. Which means the instrument panel gauge "middle line" is probably 200 degrees F, or thereabouts.

I understand these things, but whenever the heat gauge needle starts to ease past that middle mark, I start to get a little concerned, especially if it heads toward the "3/4" mark. BUT also consider that the "H" is usually at 260 degrees F, which is the boiling point for the pressurized cooling system. I suspect a 180 degree F thermostat should keep things a needle-width or so below the center mark on the gauge?

To your concern about "running hot", 200 degrees F is NOT too hot. It might be hotter than some might like, but NOT hot enough to cause issues with engine and/or automatic transmission longevity or durability.

As you have an IR heat gun, also aim down to the side of the cyl block on eash side. Check the temps THERE to look for variations from front to back. More heat at the back indicated the possibility of sediment from the cooling system having collected back there (settled-out) resulting in localized "not cooling well" due to decreased coolant flow. Which MIGHT be causing elevated cooling system temps. The fix, knock our the core plugs and flush everything out, install new core plugs and new coolant (9 qts of pure antifreeze with the balance being clean water).

Might add 2.5 degrees BTDC into the base timing, for general principles.

Just some thoughts and experiences,
CBODY67

 

[65Coronet7165]

Just keep in mind that any mods you make to any of the systems on the car can have unintended consequences. Just changing the fan can change the way the whole cooling system operates. Everything was engineered a certain way at the factory. One change can through the whole balance off. And that's my 2 cents

 

[metaldad]

My 66 Plymouth VIP 283
was replaced by the previous owner with a 400. . It has a 26 " new orginaial radiator etc. However it runs

Everything was engineered a certain way at the factory. One change can through the whole balance off. And that's my 2 cents

my 2 cents......... seems if my reading comprehension is working, car has original radiator, to the 283. car now has a 400. can that rad cool a bigger engine?

 

[herbdog]

Remember, to a certain extent with today's crappy fuel they will run a little bit hotter. 200 wouldn't bother me. It's funny back in the day with idiot lights we really never knew. Put a number gauge in and we get paranoid. My 68 runs 185-190 on the hiway. In town 200-205. Have not boiled over or had a gasket blow yet. Been that way last few years I've owned it.

 

[300rag]

my 2 cents......... seems if my reading comprehension is working, car has original radiator, to the 283. car now has a 400. can that rad cool a bigger engine?

I'm sure that 283 is a typo. Should read 383, which is really the same as the 400.

 

[1966newport]

200 IS not overheating

 

[USSMOPAR]

200 is NORMAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Stop the old man nonsense - Typical hot air cooling thread
1972 factory cars did not come with 185T Stats. CAP emissions did not have a different thermostat - prove the nonsense.
Do not use a 160/180 thermostat, 195!
200 is not hot, try normal, today's fuel requires it to burn properly and it keeps the oil cleaner/longer, cold temps form sludge.
240 is hot
What are the temps after a hot soak with the hood closed?
Under the hood temps may be hotter than the operating temp - always overlooked by all the experts.
How hot at the base of the carb, right after being driven?
Exhaust manifolds?
Timing!!!!! 15 degress btdc
Carb requires the proper set up
Coolant mixture 40% AF 60% water, bottle of water conditioner
Good radiator? - core needs to be checked with the IR gun
Correct radiator cap...what is the best cap? I know, but i want to see what the answer is.

 

[65Coronet7165]

USSMOPAR, the rad cap was16 psi.

 

[Verse]

The thermostat is not a temperature control device. Once you are at operating temp, it opens and it has no more influence. The coolant temp would more determined by the rad cap pressure, in that it raises the boiling temperature.

 

[CBODY67]

A thermostat IS a temperature control device, as in cold engine operation. Past that, once it opens, it is still a temperature control device due to the fact that the restriction in coolant flow then determines the general temperature range of the coolant. The size of "the hole" is the restriction and "temperature control device", for the upper coolant temperature range.

Many circle track racers do no run thermostats, BUT do run washers with particular hole sizes in their place, to control coolant temperature by the flow rate of the particular washer's hole. A trial and error situation, many times.

So the temperature-controlled flap shortens the "warm-up" time as the flow restriction of the item determines the ultimate flow rate of the cooling system. TWO functions.

Respectfully,
CBODY67

 

[Verse]

Cooling system design has many moving parts. When an engineer designs a cooling system, he has to know how much heat is generated under varying loads, what the heat transfer fluid is, system pressure, and the ambient conditions. He also has to know the system configuration, such as parallel flows. He then has to balance the pump flow capacity against the pressure drops in the system. These pressure drops include the flow of coolant through the block, heater core, heads, radiator, and the thermostat; wide open or partly open. If the pressure at the inlet of the pump is too low when at higher than design flow rates, the fluid will boil in the pump and eventually destroy it (cavitation damage). Operating under pressure (16 PSI) helps to alleviate this.
The higher the flow, the more pressure drop through the system; and the difference in temperature between the radiator outlet and inlet is lower too.
The lower flow will result in a higher temperate difference but less pump outlet pressure is needed to move the fluid. This temperature may then be too high to cool the heads sufficiently for example.
A higher difference in temperature between the engine and coolant results in higher heat flow.
If the cooling jacket temperature is too low then the combustion efficiency is lowered.
50% antifreeze under 16 PSI boils at 265 deg F
Whenever a thermostat is removed, water pump capacity is changed, or radiator is upgraded, the cooling system may not respond in a predictable way.

 

[CBODY67]

Cooling system design is a big balancing act. Having sufficient flow and volume for good heat dissipation into the coolant and then cooling the heated coolant to a sufficient level in the heat exchanger(s). Plus having enough reserve capacity to handle periods of high power demands and/or higher altitudes. Part of that reserve also relates to the radiator itself, in flow rate and heat dissipation efficiency. Higher efficiencies can mean smaller radiators to do the same job as a big one, for example.

As OEM electronic engine controls have possibly helped to diminish cooling system radiator requirements due to more consistent control of fuel delivery and spark timing of modern engines, I suspect. Additionally, most people have become aware that HD2500 pickup trucks make much better total tow vehicles than cars do/did.

Enjoy!
CBODY67