'94 Runs Warm

[Big T]

'94 K2500 Suburban runs at near 200 F.

Follow is what has been done or replaced.

Single T-stat crossover with 190 t-stat
HO Water Pump with spin on fan
Duramax fan
New Hayden fan clutch
New OEM style radiator (plastic side tanks)

Not sure what else we can do, short of installing another AC Delco HO Water Pump and Champion Radiator???

 

[MrMarty51]

Are You sure that the fan clutch is engaging ?
My Kennedy Diesel fan clutch was not engaging as it should and was causing the engine in my truck to warm beyond a comfortable range.
Will L suggested running a sheet metal screw through the clutch to lock it up solid, on a day the temps was over 110 and the engine got to 200 IIRC. After I locked the clutch solid.
That destroyed the clutch but I figured out right away that it was no other components causing the problem.
Oh yeah, I did have the FC that was original to the truck when I bought the truck so that wass the FC that I used. Saved the KD fan clutch but he would not do a thing about it as it was a munth or so out of warranty.

 

[dbrannon79]

could it possibly be a failing t-stat? since I have installed the cooling upgrade (2000+ Wp w/ spin-on pulley, thermal-electric clutch, d-max fan) still has factory radiator with plastic tanks and single 180 t-stat. I have the fan controller set to come on at 200deg and I barley get to 180. my fan hasn't kicked on at all. the gauge does fluctuate a bit under load but not enough to turn the fan clutch on.

of course I drive it like a passenger car not towing anything lol

 

[Big T]

Are You sure that the fan clutch is engaging ?
My Kennedy Diesel fan clutch was not engaging as it should and was causing the engine in my truck to warm beyond a comfortable range.
Will L suggested running a sheet metal screw through the clutch to lock it up solid, on a day the temps was over 110 and the engine got to 200 IIRC. After I locked the clutch solid.
That destroyed the clutch but I figured out right away that it was no other components causing the problem.
Oh yeah, I did have the FC that was original to the truck when I bought the truck so that wass the FC that I used. Saved the KD fan clutch but he would not do a thing about it as it was a munth or so out of warranty.

Fan clutch is engaging. It was the last thing added to address the cooling issue.

 

[NVW]

That tells me gauge or sender. No reason it should overheat if everything else is good.

 

[Will L.]

FIRST: IS this a block off style thermostat?

I don’t see it is way off. You are staying stable under 200 with 190 stat- that means the fan is not coming in soon enough. I know it is a new fan- but you just need to do the fan clutch mod so it start cooling a hair sooner. Or get a 180-185 stat.

If you are just driving and if you are towing and it is this constant temperature- it is cooling enough, you just need to adjust the point it runs at. Those are the two items which do it.

If you stay under 200 empty but when you tow it gets hotter, then you are overloading the radiator at that point. Order the better radiator.

I know a lot of people want that magic 195° operating temp. The most gain I ever saw was 1/10 of 1mpg. I know others say they got more. Maybe in Montana you want a super butt kickin heater- but imo it just isn’t worth it.


Buy try a 180 stat for $20 and see how it does. If it fails you are not out a lot of money or time. I have had this work many times in 6.5 and other rigs. Then the added bonus of more headroom away from over heating.
If the radiator is overtaxed or close to it- the temps will stay up. If the temperature goes up and down from 180-200-180-200 and the fan is kicking in and out, only adjusting the fan clutch will address it.

The fan clutch mod is free, just labor. Kind of. If you have a fan running a lot to keep down the temperature, you will notice the noise and the power loss. Then come tank fill up day you will notice lower mpg as well. That big fan is a power sucking monster, and you have to burn fuel for that. So of you can run the lower stat I am all for it. You can modify the fan clutch and you can “un-modify” it if you don’t like the results. But then you are done, you cant go back and forth trying a bunch of different bends- the tab will break.

 

[WarWagon]

IR temp gun aimed at a lot of things as @NVW is my first concern. Not the first engine/transmission/etc. removed and replaced over a bad gauge or temp sender.

Don't care about accuracy as much as temp differential and what's hot and not.

200 isn't much over the "full open" of a 190 degree T-Stat. This is why the lower T-Stat and the lower temp KD fan calibration worked well.

 

[MrMarty51]

I do like that extra temp gauge installed in the rear of the right side cylinder head.
I have not checked, if there is a threaded port in each end of the chlinder heads, I’ll install a gauge in the rear of the head on tje left bank too.

 

[dbrannon79]

Honestly if there was a way to have a manual temp gauge and be able to relocate the PCM sender back there to the hottest part of the engine it would be great.

 

[93detroit]

Make sure your a/c condenser, oil cooler, and transmission cooler fins are clean too.

 

[Big T]

Put the GM Tech 2 scan on it and the gauge does run a little high:

 

[Twisted Steel Performance]

I for one don't think 200* is high enough to even look at, I would worry if 230* is seen consistently ...

 

[dbrannon79]

run it with the tech 2 connected, put it under a load for a bit and watch the gauge and tech 2. what I have done is since some person had previously been in the cluster, I opened up the cluster pulling the clear glass cover. set the cluster back in the dash. ran it to temp watching the scanner (GMTD) once it settled at a temp that wasn't changing I used a plastic fork and gently pried off the needle from the gauge and reset it according to the temp the scanner was showing.

I had to do this to all the gauges. the only one I have not verified is the oil pressure. I figured it was within range since it stays around 40 on the road and drops to 25 sitting still.