'96 K2500 6.5 overheating

[Kbrooks8516]

Newbie here, to diesels as well as this forum.

Firstly I have a '96 K2500 with 6.5. I started experiencing overheating problems shortly after getting this truck about 4-5 months ago. It ONLY overheats when I am pulling my 6x10 utility trailer with a zero-turn mower. After MUCH research on this forum as well as others, I have recently done the following modifications:

S&B cold air intake
All aluminum Mishimoto radiator
SSDiesel fan clutch and water pump combo

I used my truck today for the first time since those mods were installed and the truck ran perfectly until I went up a steep grade on the interstate. I got about halfway up the grade and (pardon the sloppy description) it felt like the truck lost power all of a sudden. As I continued to the top of the hill my RPM and speedometer just slowly kept going down and down even with the gas all the way to the floor. The temperature climbed to about 3/4 on the gauge and it went down as I descended the hill after a few minutes.

I feel like this damn truck is a patient on an episode of House....500 different possibilities of the cause of the problem but no definite answers. I've heard everything from the upgrades I have already completed to it being the injection pump to cracked heads (I'm losing 0 fluid). I am at a loss. I want to keep my truck but right now it seems like it's a money pit. I have already sunk $2,000 just in THOSE upgrades alone, not to mention others I have done that have nothing to do with the overheating problem.

I am no mechanic by any means, I only know enough to get myself in trouble, but one thing I do know for sure is that this truck should be able to pull a friggin' mower on a trailer with little to no effort. So if anyone could give me some more insight that would be much appreciated. I am kind of wondering if it's maybe transmission related because when going up the hill when it dropped to lower gear it's almost like it just held the truck back instead of helping it climb. I don't know. Any help is appreciated.

[svcattle]

Head gaskets maybe

[Kbrooks8516]

Even with it losing no fluid?

[Robyn]

Any SES light coming on ??

When was the fuel filter last changed ??

A dirty fuel filter will cause exactly what you describe.

If the rig runs OK under light load, then the filter is a good starting spot.

When changing the filter

Do not start the engine to refill the filter housing after the change.

Remove the old filter and clean out the housing well and remove any crud in the bottom of the unit.

Install the new filter, then open the bleeder on top of the unit and then run the lift pump only to refill and bleed the filter of any air.

When clean air free fuel comes out of the bleeder on top of the filter your good to go.

This will very likely solve the power loss on the hard pull.


The heating issue.

Does the fan clutch hook up well when the temp comes up ???

At an engine temp of around 220 (no more) that fan should be howling.

What Tstats are in the thing ??

Good luck

Keep us posted


Just sayin

A cracked head or bad gasket and you will see coolant blowing out of the fill jug all over the inner fender.

No coolant loss is a good thing.

[Kbrooks8516]

Any SES light coming on ??

When was the fuel filter last changed ??

A dirty fuel filter will cause exactly what you describe.

If the rig runs OK under light load, then the filter is a good starting spot.

When changing the filter

Do not start the engine to refill the filter housing after the change.

Remove the old filter and clean out the housing well and remove any crud in the bottom of the unit.

Install the new filter, then open the bleeder on top of the unit and then run the lift pump only to refill and bleed the filter of any air.

When clean air free fuel comes out of the bleeder on top of the filter your good to go.

This will very likely solve the power loss on the hard pull.


The heating issue.

Does the fan clutch hook up well when the temp comes up ???

At an engine temp of around 220 (no more) that fan should be howling.

What Tstats are in the thing ??

Good luck

Keep us posted


Just sayin

A cracked head or bad gasket and you will see coolant blowing out of the fill jug all over the inner fender.

No coolant loss is a good thing.

I do have an SES light on BUT it is because the wastegate solenoid went out for the 2nd time so my mechanic bypassed it so I guess the computer is throwing the code because it isn't connected (?)

The fuel filter was just changed roughly 2 months ago with a Wix filter. I bled all the air out and all that. I have a 180 thermostat in but the water pump was replaced with the higher output one from SSDiesel.
The fan and clutch also was replaced with the 9 blade that is supposed to engage at lower temperatures.
Honestly though, I don't ever hear this "loud roar" that I hear on here that is supposed to be the fan kicking in. I don't know if it is because my truck is loud to begin with or what. Is there anyway I can test that while idling?

Also, to put this to rest, is there ANY possibility of the injection pump being the cause of any of these issues??

[N9Phil]

Do you have the duel thermostat housing installed?

[Kbrooks8516]

Do you have the duel thermostat housing installed?

Yes. And that may be an issue there because my mechanic may not even have added the second or installed a 195 or something along with my 180

[a5150nut]

Minus one thermostat would cause heating problems and one of the easiest to correct.

[JohnC]

You need to deal with the boost issue. The engine will run hot and not produce full power if the boost is low. Too much boost also means high intake air temps and high running temps as well. When the check engine light comes on the PCM is limiting engine power due to the fact that it cannot otherwise control boost.

I don't think it's likely your mechanic didn't install both thermostats. The single stat won't fit in the dual housing, either.

How do you define overheating? (GM says if the gauge isn't in the red it's "normal".:rolleyes:) How hot is the ambient temperature? How steep and long is the grade?

I used to pull a two horse trailer with to fat a$$ horses, lots of drag and about 7,000 lbs, across western MA with my '95. My cooling system was completely stock. On the steepest grades the temp would climb to about 220 and the fan would lock up. You couldn't miss the sudden increase in fan noise and the temperature quickly dropped.

[arveetek]

You need to deal with the boost issue. The engine will run hot and not produce full power if the boost is low. Too much boost also means high intake air temps and high running temps as well. When the check engine light comes on the PCM is limiting engine power due to the fact that it cannot otherwise control boost.




Ditto what John just said. On the DS4 engines, the computer does not like not being able to control boost, and will put the engine into "limp mode." After swapping to a manual boost controller on my '95, I had to have a custom chip made for my ECM so that the computer would quit "pulling fuel" on me. Now I can keep the pedal to the medal, and the power and boost stays up.

I believe you have two different problems that need addressed: engine heating up, and engine defueling. They are not necessarily related.

Casey

[Kbrooks8516]

Thanks for the feedback! I agree on the boost issue. I don't know that it's even related but yesterday for example I pulled out of my driveway and I could hear the turbo whine real good. When I got about 15-20 miles out to town with stop and go traffic I couldn't hear it at all.

The truck will heat up to about 3/4 on the gauge (whatever temp that is?)
It has been my understanding that any temperature over 210 is detrimental to the engine.

As far as the "mechanic" who worked on my truck goes...there is no telling what he did. The idiot didn't even know if the upgrade had a dual thermostat or not. I drove it last night too and noticed it was shifting oddly and checked the trans fluid and it was BONE. DRY. The sorry SOB didn't even put fluid back in where he changed the rad out. ugh.

[JohnC]

The idiot didn't even know if the upgrade had a dual thermostat or not.

How could that be? Did he install it with his eyes closed?

[Robyn]

The plot thickens.

Do you have a boost gauge and a pyro on the engine ???

If not at least get a boost gauge on it and see wasssssup.

Boost on a stock system should peak at about 8 psi.

If the boost goes over the factory setting the ECM will get unhappy and set fuel to limp mode.

AS mentioned.

I you are going to run BIT HIGHER BOOST you need a reprogramed ECM

About 10-12 psi is max boost on a 6.5

You need a pyro as well.

1000 F temp at the outlet of the LH exhaust manifold ( Just into the XOVER PIPE is a great place for the probe) This is a good safe max EGT

Get much beyond this range and there is a little town called "MELTVILLE" that you will visit :eek: not a nice place.


The previous mention of the defueling causing the loss of power is spot on.

Get the boost controller issues handled by either repairing the vacuum solenoid system or installing a "Turbo master" or similar device.

With a mechanical boost controller you will need an ECM reprogram to stop the defuel and power loss.


Get this issue handled and boost/EGT in order and then we can address the overheating.

[Scholtus74]

So I've got a 95 2500 overheating, some days it runs great others it overheats, larely even at an idle the temp gauget gets up to 260 I'll run it a little and it'll cool off so that makes me think fan or thermostat but when it's hot it seems like steem is coming out of the motor oil dipstick wich makes me question heads? I've had to add water to it on days she gets warm, the truck recently had the heads done, new gaskets amd studder right before we got it from a close freind, so could it just be the head gasket is torn I've got alot of white smoke sometimes to?
Any help is appreciated first 6.5 I've dealt with I'll admit I'm a 5.9 cummins guy

[Slippery Smitt]

With the cap off on the resivior bottle (take cap off when cold) do you have bubbles in the tank or a washed off spot on the right side inner part of fender?

Smitty