Diagnostic question - engine is extremely slow to get up to operating temp - 5.2L

[tallhair]

Not a C body but thought I'd ask where I know some very knowledgeable folks hang out - hope no one minds.

99 Durango, 5.2L, 4 x 5, with towing package I've had since new.

Has about 85K on it.

Seems like the engine cooling package is just toooooo effective. Will not get up to operating temp i.e. 195F even if idling for 20+ minutes in cold (frost/icy weather) until being driven for at least 10 minutes after.

Has been doing this for several years and I'm getting tired of it. Once up to 195F everything is fine and heater/defrost works. Before up to close to 195F temp the defrost / heater doesn't work much. The heater core may be partially blocked due to age but it really seems like the main issue is getting it up to operating temp takes way to long.

I've read a ton today on dodge.com and durango/dakota forums and everyone's issues seems to be about no heat and/or clogged heater cores. But when it is up to 195F it will heat fine. It just takes for freaking ever to get there and starting/warming it up before driving has almost no effect or no normal effect. Ideally I'd like to start it and let it warm up before I drive so I don't have to scrape windows every morning in the winter (parked outside) but it just won't warm up while idling !

I've had the vehicle in IL - cold winters since 2009. Prior to that it was in TX or England where it wasn't an issue. Seems to be getting worse the last few years. A week or so ago we had some frost and I let it run for 20 min and it wouldn't defrost the window hardly at all. Once I got to driving heater/defrost seemed to work great after about 10 min when temp came up to 195F. When icy last year - Forget about it.

Anyone experience this with the 1st gen Durango's, Dakota's or even similar year Rams? If so what was the fix?

The only repeated suggestions I've seen in articles I've read is blocking part of the rad from airflow in the winter - rest were all focused on clogged heater core (which is fine once it hits op temp).

 

[Johnny Mac]

Few things.

1. fluid level...there may be enough coolant in it to cool the engine, and register the gauge, but at idle, it's not pumping it through the core. had a jeep with a slow WP leak that would register completely fine, but never warm up the heater core...rev the engine...and boom...warm heat. so thats how i found out my fluid was low...which led to the wp leak being discovered.

2. your core is plugged...not too many easy fixes for that other than replacing, or flushing.

3. thermostat is stuck OPEN...so it's moving the water before the block even heats it. (or thermostat has disintegrated...which is the same as open).lol

4. WP blades have disintegrated...so you're not moving much fluid at low Rpm.

i'm guessing 1,2,or 3. with #4 you'd probably overheat eventually.

 

[tallhair]

Few things.

1. fluid level...there may be enough coolant in it to cool the engine, and register the gauge, but at idle, it's not pumping it through the core. had a jeep with a slow WP leak that would register completely fine, but never warm up the heater core...rev the engine...and boom...warm heat. so thats how i found out my fluid was low...which led to the wp leak being discovered.

2. your core is plugged...not too many easy fixes for that other than replacing, or flushing.

3. thermostat is stuck OPEN...so it's moving the water before the block even heats it. (or thermostat has disintegrated...which is the same as open).lol

4. WP blades have disintegrated...so you're not moving much fluid at low Rpm.

i'm guessing 1,2,or 3. with #4 you'd probably overheat eventually.

Thanks for all the suggestions! I thought of or read most of them today but it NEVER EVER overheats and matter of fact it never moves past 195 on the temp gauge. I will check fluid level and see where it's at but it's been full and had the same issue - I'll make sure full now.

Seems 3 and 4 would result in over heating but as said it never ever over heats nor does it ever get above 195.

regarding number 2. could that have an effect on it not getting up to operating temperature at idle?

P.S. I'm going to get an infra red thermometer so any feedback on a good one w/o breaking the bank that works are appreciated. I'll use it to validate the actual engine temps

 

[Johnny Mac]

a plugged core has almost no effect on engine temp. (lots of hotrods running around with no heater cores out there, and the ports simply plugged)

#3 (stuck OPEN t-stat) would not result in overheating at all... How a thermostat works is it remains closed until it gets hot. this helps cars heat up in colt weather. It its stuck open...or the spring has rotted off and the diaphram is just hanging open, it'd be like not having a thermostat almost...the cold water just keeps sloshing around, never hanging in the block enough to actually warm up. until you put a load on it by driving. then you appear to get a little heat. which makes sense.

infrared would be a fine idea, but nothing your hands (carefully) can't tell you. if the heater core hoses are cold...or the OUTLET side is cold...then its clogged...or not getting enough fluid (level)

 

[MarPar]

im thinkin yer thermostat is stuck open (or non-existent), Bry.

I purchased a milwaukee infra red temp gun from Northern tool a while back for like $25. I think it was a closeout as i just searched for it, and it is not available.

 

[MarPar]

in lieu the t-stat, just stick a brick on the pedal for like 15 min.

 

[tallhair]

in lieu the t-stat, just stick a brick on the pedal for like 15 min.

Haha

 

[tallhair]

im thinkin yer thermostat is stuck open (or non-existent), Bry.

I purchased a milwaukee infra red temp gun from Northern tool a while back for like $25. I think it was a closeout as i just searched for it, and it is not available.

Thanks Mar. I think you are wrong on the t-stat but won't rule it out. It is the original but it never overheats

 

[stubs300]

Hey buddy, I got the same problem with a 94 Caravan w/3.3 v6. I've had it since 99, was a Ameritech service van with 83K when I got it, 147K now. It just sucks for heat, spent foolish money on it complaining no heat. It seems modern Mopars have this problem, they must use a heater core about the size of a cell phone now, it's awful! If your not already, just surf for some Durango or other Mopar forums and just lurk and search the problem at hand, you'll be surprised what you find. Those first winters in Chicago sucked, still bad out here in Ca. I'm going to have to toughen up with the move next month over the hill! Good Luck

 

[tallhair]

I will check fluid level and see where it's at but it's been full and had the same issue - I'll make sure full now

Turns out it's low on coolant so I'll address that first and hope it solves the problem

 

[tallhair]

in lieu the t-stat, just stick a brick on the pedal for like 15 min.

Actually I'm contemplating the cardboard over the rad instead of the brick if the coolant isn't the issue.

 

[MarPar]

Actually I'm contemplating the cardboard over the rad instead of the brick if the coolant isn't the issue.

old school baby. it works though!

 

[sixtyf]

I was just going to say JP was probably on the money with the low coolant, with the air going the the highest point in the system. Not sure with the durango's but you need to be in the right mood to change the stat on the rams - not as straight forward as the older cars

 

[tallhair]

you need to be in the right mood to change the stat on the rams

seems nothing is ever easy LOL

 

[stubs300]

It's like you have to overfill the system in order for it to work, how do you do that?

 

[Johnny Mac]

It's like you have to overfill the system in order for it to work, how do you do that?

while cold.with the cap off..You grab all the hoses and squeeze them hard and fast to try to burp the system. With the the rad cap still off, start it. Once your assumed to be functioning t-stat opens, you will see the fluid move rapidly. You then top it off. Let it run a bit, and cap it, while running. We now hope all the air bubbles are out.
Oh...and...you are welcome OP ;)

 

[stubs300]

Been there, done that, still sucks. I just deal with it, but hate it!

 

[cantflip]

1- Sounds like a classic stuck open T-stat...
2- With a functioning pressure cap on the cooling system, it should eventually purge itself of excess air. Which does not mean it couldn't overheat if not properly burped after service.
3- In really cold conditions, a sheet of card board behind the grille will cut airflow and increase temperatures... and easily cause overheating. (Murphy's law, it will happen while on the highway or when the wife is driving and cost you bigger repairs.)
4-If the engine temperature is good and heat is weak...TRY THIS... if your control looks like this...

Then you may be able to adjust or repair the cable for the "blend door"

I don't recall anything with the few Durangos I worked on in 97... and have nothing in the "library". Cable operated systems can get the cable dislodged, some are adjustable and the plastic parts do sometimes break... by 98 I was into another brand due to financial concerns (I'm a *****, it's a job... follow the money...). The engine MUST be able to reach operating temperatures before this makes sense, that is the job of the thermostat. Failing open is a common enough issue, generally the bracket that holds it together is broken... I have done them in FL to fix heat issues and older stuff in PA to fix emissions concerns.

 

[65sporty]

Since the coolant is already low, drain it the rest of the way, change the thermostat, flush out the heater core, check the protection on the coolant( we don't want it to freeze). Depending on the age you may want to change it any way. It may look good but it can become acidic over time. Most shops have test strips to check the acidity of coolant.

 

[tallhair]

Since the coolant is already low, drain it the rest of the way, change the thermostat, flush out the heater core, check the protection on the coolant( we don't want it to freeze). Depending on the age you may want to change it any way. It may look good but it can become acidic over time. Most shops have test strips to check the acidity of coolant.

I'll be flushing the entire cooling system, reverse flushing the heater core, and replacing the t-stat today