View Full Version : Operating Temperature Question
Not too long ago I replaced both thermostats using a pair of Stant T-stats that look just like the OE ones and things improved... heat worked good, it ran better, better MPG, etc. Temperature was a little high from what I was gathering was the normal operating temperature for the 6.5TD. It was between 1/2 and 1/4 on the gauge (the line in between). So I got a pair of AC/Delco thermostats a few weeks ago which also look nearly identical to the Stants that I got, and put those in and changed the coolant at the same time using Prestone green stuff as green was already in it. Old coolant was not really dirty. Temp is still about the same. When I really get on it from a stop or going up hill, temp climbs just a hair below 1/2 on the gauge which is 210. I do know that the turbo is not working to the best of its ability because of a worn vacuum pump, but I can hear it whistle a little sometimes (I have a pump and will replace it soon) and the crossover pipe is the original GM type but it has a 3" exhaust and a cat delete. Would any of these cause this problem? I am not getting excess coolant pressure, so I am ruling out a head gasket, besides I am not losing coolant. My other option is to get a new coolant temperature sensor for the gauge. Last resort is to put 180ºF thermostats in it. I just do not want to cook it if I am going to tow or drive in the mountains like I usually do. Any advice or input is greatly appreciated!
What is the real problem your trying to fix?? Low temp/climbing temps?? You mentioned head gasket??
I run mine with 190 stat...and it will climb to 210 when pulling a big New Hampshire hill, however I'm running a single stat.
I would verify mechanically your temps...temp a gage into the cab and get a real read...these gages can be off quite a bit.
There are a lot of approcahes to getting the cooling in these units working correctly...use the search feature and read, read, read.
What is the real problem your trying to fix?? Low temp/climbing temps?? You mentioned head gasket??
I run mine with 190 stat...and it will climb to 210 when pulling a big New Hampshire hill, however I'm running a single stat.
I would verify mechanically your temps...temp a gage into the cab and get a real read...these gages can be off quite a bit.
There are a lot of approcahes to getting the cooling in these units working correctly...use the search feature and read, read, read.
The climbing temp is what I am trying to fix, also I was told it should never really go above 1/4 on the gauge scale, but maybe that is bad advice. I just want to know why it does this and if it is normal and if the fact that it needs a vacuum pump and has the original crossover is not helping things... if it is something else, I want to decide where to put my money first. I ruled out a head gasket long ago. I already have HO cooling as it is a 96 3500 (dual t-stats) and I have done tons of reading and research but have not really found answers to my questions of if it is normal and if what I have is a problem and what is the root cause. If it is something I should not worry about, that is great. I know diesels temperatures can fluctuate, but is mine going to high.
Ok well I guess you answered your own question in a way...
a funked turbo will not allow the engine to breath and could very well cause a temperature build-up..
You say you have a dual stat set-up with the HO pump??
Check your to clutch fan make sure its doing the right thing or buy a fan set up from Kennedy Diesel thats a better, more responsive unit.
Flow your radiator...take it out and have it checked...cleaned.
Get all the garbage out between the radiator and condenser.
Verify your temps with another gage.
Of course you can get crazy and add an intercooler...modify the snorkel for more airflow, and add electric fans to the radiator...
Honestly after you go thru all I mentioned, you should be in terrific shape.
Oh dont forget to get all th eair out of the system via the bleeder...helps alot.
Lemme know how you make out.
I don't understand.:confused:
If you ran at the 1/4 dash you would be running at only 180-185*F. That seems pretty cool. I have the dual thermostats, "HO" pump, flushed radiator, duramax fan, and 18:1 pistons, my temps sit right at 195*F all the time. It doesn't sound like it is a problem.
I echo rogers...
why do you think it could be a head gasket??? doesnt add up.
I echo rogers...
why do you think it could be a head gasket??? doesnt add up.
I don't... anymore. The reason it was one of the suspects was because in working on other diesels (mainly VW/Audi diesels), if the head gasket was even remotely blown, compression would seep between cylinders or into the coolant with no major signs (no coolant loss, no coolant in the oil or oil in the coolant, or excessive pressure) and it would run hot. I ruled that out as an issue early on.
Have you checked temp with another guage or a heat gun. I wouldn't put to much faith in the dash guage. Your sig doesn't say how many miles on your rig. I had overheating problems on my 93. Guage would go right to the red when towing uphill. After cooling mods(check my sig) I still run a single stat and have never even come close to overheating. I have run like this for over 3 years towing a 5th wheel and boat in tandem on 4,000 mi. trips. I was going to upgrade to dual T stats & HO pump but I haven't found a grade steep enough to warrant the expense.
I might be wrong about this but as far as I know I am the only one who runs a 5 core rad with single T stat. Get your rad checked out. Mine was plugged solid. Good luck.
Have you checked temp with another guage or a heat gun. I wouldn't put to much faith in the dash guage. Your sig doesn't say how many miles on your rig. I had overheating problems on my 93. Guage would go right to the red when towing uphill. After cooling mods(check my sig) I still run a single stat and have never even come close to overheating. I have run like this for over 3 years towing a 5th wheel and boat in tandem on 4,000 mi. trips. I was going to upgrade to dual T stats & HO pump but I haven't found a grade steep enough to warrant the expense.
I might be wrong about this but as far as I know I am the only one who runs a 5 core rad with single T stat. Get your rad checked out. Mine was plugged solid. Good luck.
Sorry, I have 195K. Bought it with about 191K a few months ago and I suspect it has a reman motor in it, but I cannot confirm this. Just from what I see.
Get a scanner and read the temps as the PCM sees them. Also, if the vacuum pump is throwing the boost off, fix it.
The dash gauge is good for trends only. GM's stance is that if it isn't in the red it's OK...
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