Hello,
I have a 1998 GMC 1500 p/u ext cab with the 6.5 turbo. From what i have read, the 98's were not supposed to have the overheating problems becuase of the dual thermostats. Pulling a 3000 lb 17' boler trailer up hills, i get right up to 100 deg c, then it cools off as soon as we are on level grade or go down a hill. Anybody have inexpensive sugguestions to fix this problem?
Mike

What speed are you trying to maintain while pulling the hill?
I was amazed this past weekend while driving my truck unloaded at 75 MPH that my truck ran about 210 on the temp gauge BUT if i backed down just 5 MPH my temps dropped to about 195 degrees. Oh course it was 100 out side temps that day. It really drove home the fact that I need to get my dual stats installed ASAP

Mine did that this weekend too, my trailer is 5000lbs.

Is the rad clean? DO you downshift?
I would go from 5 th to 4 th on the big hills.
I only got that to 100 c twice , 2 big hills, but my rad was quite dirty too.

Hope that helps
later

Have you ever pulled the shroud and grill and clean all the junk out of your radaitor and coolers? ;)

Carey

Hello,
I have a 1998 GMC 1500 p/u ext cab with the 6.5 turbo. From what i have read, the 98's were not supposed to have the overheating problems becuase of the dual thermostats. Pulling a 3000 lb 17' boler trailer up hills, i get right up to 100 deg c, then it cools off as soon as we are on level grade or go down a hill. Anybody have inexpensive sugguestions to fix this problem?
Mike

I assume you are bone stock, 1st check & make sure rad is clean as others have detailed, 97+ has improved cooling but oveheat can still be a problem, next 1st is open exhaust/downpipe and start saving for a set of gauges you will not want to change anything that gives more fuel/boost without them more boost will help lower temps, a retuned fan clutch would be a good bolt on mod. What kind of smoke you making when pulling grade, inoperative WG can cause high temps from no turbo assist.

Depending on depth of your wallet many mods can be added to enhance your rides performance, go to FAQs for power building tips, which also lower operating temps.

hello, i was pulling at 100-110km/h about 60-65mph. I am only towing about 3500lbs at the most. i already have the dual thermostats,so i'm not sure what the problem is. i found a place called diesel performance systems in town here that i am going to check out.

What are the normal operating temperatures of the 6.5's. When I first bought mine the dealer told me that it was normal for it to operate at 210. It has always run at that even when I wasn't pulling anything. It was is normal temp 210 or a little below.

that seems hot, my truck usually runs at 95 deg c (about 200 def f) when i do not have a trailer on it. i spoke with a diesel specialist today and he said that the 98's shouldn't have a overheating problem with only pulling a 3500 lb trailer. he suggested just checking my fan clutch which i have yet to do. he stated that some of his clients pull much more than that without a problem. on my last trip when the temp reached 100 deg c (212 deg f), my cruise control cut out and would not work after that, also the truck was running loud and rough. Once we got to where we were going the truck started fine and the cruise worked again. Anybody know what could cause this?

What are the normal operating temperatures of the 6.5's. When I first bought mine the dealer told me that it was normal for it to operate at 210. It has always run at that even when I wasn't pulling anything. It was is normal temp 210 or a little below.
Part of it depends thermostats, I am running 195 RS's from J/K and I see under 200 until I pull unless it's real steep and I'm push real hard. But the factory gauges are not accurate on all trucks.

I only tow 3,000 lbs. or less, usually, but with 8 people in the truck, with all their crap, the AC on high and a 2,000 lb. trailer I only saw 210 once or twice on the way to nova scotia 2 years ago. Rt. 9 along the route in maine has some fairly steep (but not too brutal)and frequent hills.

Just a thought but the overheating problem could be due to having the stainless bug screen in the front. You would be surprised how much air flow you lose having that. I would rather wash my rad more often then try pulling with a restriction from the get go. Experiment a little, that's what I did and I will not put my stainless fronts on until winter.

hello,
on our truck it only had a screen bug deflector, which i also took off. that did not help either, next week i am going to go to the diesel specialist and see what they have to say. I still cannot figure out why my cruise stopped working temporarily, strange.
Later,Mike

When I had a problem with a shorted wire coming from IP to ECM my cruise would kick off everytime a code was kicked by ECM. THen after a restart the cruise would work again. Have you checked for any codes, ones that may not necassarily trip the SES light? If not visit your local Autozone or other parts stores to have the codes pulled.

Has anyone tried water-wetter(not sure of spelling)in ther diesel.I have heard of some guy's using it in there gas engines and they claim it works.

And where can you get this stuff ?

Not sure state side but Canadian Tire has it on the shelf here.

pep boys has it too and my motorcycle racing buddies swear by it. I've never used it myself however. Redline makes it and their reputation is outstanding.

Find a local radiator specialist and get a quote on having your radiator cored. When mine recently split the driver's side tank I found a place near me that would core, clean, and replace both tanks for $187 total. It would be much less if you did not need to replace the tanks, obviously. On cross flow radiators if there is any sludge it starts to clog the lower cores slowly reducing the effective cooling surfaces. I instead chose to replace the entire rad with a conventional brass tank, copper/brass core radiator I found at autozone for $250 because I have learned to hate plastic. Apparently I have needed a rad for a couple of years at least because since the swap it runs so cool that I am considering going back to the 195deg tstat.---My $.02

Autozone recently started carrying it. I have it in my burb and seems to help.

Thank's CR canadian tire does carry it and it is the Red Line product too.Just picked-up a bottle.

Does your truck have the original high output waterpump? It's possible that if the waterpump was replaced, the earlier and cheaper version was installed. Also, you can add a 9 blade duramax fan for around $50. Let us know how you make out.