I went and talked to a tech I know at the GMC dealer today....I have two more things to check now. He told me to check and make sure that everything is sealed up so all of the air the fans pull goes through the radiator and not around it, and I'm also gonna try pulling the tranny coolers I have mounted to the radiator off and see if it makes a difference. I have one mounted in front of each fan, and I'm thinking that maybe when towing uphill the coolers heat up enough to be passing hot air through the radiator, decreasing its ability to cool the engine. Do you have tranny coolers on your radiator?

 

Nope, I have come up with about three possible "problems"

1. Sending unit is bad "telling PCM it is overheating but really not"

2. Cooloing system has crap in it and causes a clog until it just builds up enough pressure it blow buy.

3. Water pump has some kind of a problem but I have know idea why it would work sometimes and not others.

Like I said before I have put in New T-stat, New e-fans, (on all the time) New hoses, and checked all holes in radiator for blockage. So the only things I have NOT done are New radiator, New Water pump.

 

Since I do not run the stock radiator that has the air to water cooler...which has the best heat transfer ratio...I decided a long time ago to also run a dual remote trans and engine oil cooler with fan...I also run the factory cooler up front....if you are going to run two filters in series make sure it flows more liquid that the stock cooler as it could restrict the oil flow to the trans...no a good thing! Reason I went with the biggest dia tubing Hayden made...right now I run with with a manual switch but will soon also have it setup with a sensor like the radiator has.

Between the front air dam and the frame...had to loose the plastic skid plate...high enough to not get hit by rocks, etc.



At work I use an infrared scanner to check actual radiator temps...would rule out a bad sensor or guage unit...also make sure that the radiator core is free of bugs as it can get plugged up in just a few days in bad areas...also suggestion to check air flow seal is a good idea...On mine since I have more air flow restriction with the huge intercooler up front which is larger than the radiator I had to seal off both sides of the headlamps with flat alum. inserts to actual help force the air through the system when above 30mph otherwise some of it would just go around everything.

Ken

 

Where do you get these?

 

That style T-Stat will not work on the gen III motors.

 

Right, he's got a SBC....

Why are stats for other vehicles $8-$11, and ours are $25-$50?

I want a 180 but can't find one under $49

 

99-03 will be about 54 bucks
04-05 will be about 26 bucks

 

Ours come with the whole thermostat housing and everything, can't get just the stat by itself. That's why it's more expensive.

I pulled one of the two tranny coolers off the radiator today and pulled the same hill again, this time instead of 240 I barely got over 210, so I think I found the culprit. I need to get the other tranny cooler off of the radiator and I think I will have the problem solved. Tranny gets to 200-210 or so pulling the hill, can't be good to be passing 200 degree air through the radiator. Ken - I will probably end up doing a remote mount with a fan like you did, thanks for the pics. I will keep the thread updated when I get everything finished. Thanks for the comments.

 

That's cool man...I've been following your situation wondering what the final result would be. Seems like you found the culprit. Quick question, do you have the stacked plate style trans coolers or the traditional finned ones? I've heard that the stacked plate ones may have a tendency to restrict air flow while the finned style doesn't. (One of the reasons that I went with the PermaCool as opposed to the ever popular B&M)

 

sweet, glad you figured it out.