Problems keeping cool

[GreasySub]

As an un-techie, I need a little advice. I run a 1990 6.2L SUBURBAN 4x4 with 193K. When I first bought it about 30K miles ago, the engine temp was pretty consistently around 160 (dash gauge). Over time, the temp slowly averaged higher until now it runs around 210 average. When I tow a 5K lb trailer, I come dangerously close to 230 and have to back off the throttle. Someone suggested I take out the thermostat to see if that was the problem. I did, and the engine barely got to 100. So I put in a new thermostat - right back to 210. Then someone suggested I replace the fan clutch which I did - no difference. I am correct in assuming that since the radiator cooled fine without the thermostat that it is okay? Are there other things I should be looking at?

Does running without a thermostat or a much cooler thermostat damage the engine?

Any help would be greatly appreciated.

[darkroad]

If you have put 30K on it since you had it I would check and see if the radiator or the AC condensor fins are caked full of bug debris and other yucky stuff. Since this has been a gradual thing its very likley. pull of you grill so you can get a good look at it. You can also unbolt you shroud and lay it back toward the engine to see better. Dont forget and look between the condensor and radiator. Check to see if you have a lot of bent over fins.
Use a water hose and try and spray directly into the fins, some use a pressure washer but if you don't know what you are doing you can do more harm than good. Try your local heating and cooling store and see what kind of fin cleaners they have. Most carry several from mild all the way up to acid base cleaners. Stick to something milder, wet down the radiator ( better if cool) and spray away. They break up the sirface tension that holds the dirt in place so you can flush it away. I was amazed the first time I had a home heating and cooling guy flush my home unit, the water ran brown for 5 minutes...

Next look down into your radiator cap for mineral deposits. We have extreamly hard water here and if you fill it with 50/50 mix of tap water you will get mineral deposits quickly. Always use distilled water or buy it already mixed. If its real bad take it to a radiator shop and get them to look at it for you. They may be able to rod it out . If its close to home just drive it with the cap clicked one notch so it won't build up pressure and scald the repair man trying to help you. Around here its getting harder and harder to find a radiator repair shop, they are all closing down. There are some brands of radiator flush, some work better and some don't seem to work at all. If you want to try it your self stick with a brand name and follow the directions.


On removing your thermostat, I only do it if it is stuck. Some people don't realize that in addition to heating up you truck the thermostat also slows down the water flow thru the radiator so the fan and air pushing thru it has time to pull heat away from it. Too fast a water flow and you get less heat removal.

Darkroad

[HammerWerf]

GreasySub,

A couple of items come to mind.

Have you checked to see how much bug and plant litter is stuck in and between your radiator and A/C condensor? A good back wash with the hose and a nozzle will remove most of the stuff. You should be able to remove the upper radiator mounts and push the top of the radiator toward the engine to get a good look between the rad and A/C condensor.

Another spot to check is inside the radiator itself. If your radiator is brass, look at the tube ends. if there is what looks like a whiteish crusty covering there, you could have solder bloom or scale from hard water. Either way, the radiator is nearing or at end of life.

I had solder bloom in my 83CC radiator when I was asked to tow a 95 big block suburban back home. Lovely day in July in the Central Valley of Calif. The low temp that day was 103*F. Ran 210 - 230 the whole day. When the radiator was replaced about 2 weeks later, I inspected the old core and found 60% of the tubes covered over.

HammerWerf

[GreasySub]

Thanks guys. It apprears I have both problems. There seems to be a fair amount of junk stuck to the radiator and some junk in the radiator. Since I have to tow tomorrow, I'm hoping a good cleaning will get me buy especially with the cold front blowing through. I think I see a new radiator looming in my future, though.

Thanks for the help

[mrbornery21]

Hey man I just went through the same process with my 6.2l turbo 1989 G.M.C Jimmy 700r4, started slowly running hotter over time, Then finaly I couldnt go up any Hill without babying the throttle, Checked fan ok, checked thermostat ok, Checked for bugs ands stuff stuck to front of radiator ok, Drained raidiator coolant enough to see down the raidiator Bad Very Bad hard water mineral deposits, Tried every radiator cleaner & Flush I could get my hands on nothing worked, dont bother. Dad suggested I Take it to a Radiator shop and get it rodded out and cleaned, I figuered the radiator with 148k has seen its last days. Boy was I right the radiator began leaking everywhere farbeyond any repair, No problem Ill just buy a new one:eek: $470, Napa, Autozone & Checker $350. What the hell. Found a better way www.discountradiators.com Part#850 $262.32 Shipped:cool: I live in Arizona recieved my radiator the next day Must have came from one of there warehouses in Phoenix sweet!. Pulled old radiator out and put new on In, Oil cooler lines screwed right in, transmission lines screwed in, put upper & lower radiator hoses on, along with a new thermostat and gasket, went to put heater hose on damn! needed a screw in type hose fitting, went to napa bought one, damn! wrong size!, kicked the box that the radiator came in over. Whats this? a plastic bag full of transmission line adapters, oil line adapters, heater adapter, coolant sensor adapter!!! Started feeling real stupid! but happy cause that coolent sensor adapter came in real handy! Only problem I had with the kit besides being stupid is coolant sensor adapter had the right threads but my sensor was just a hair to big to fit down the hole to get the threads started:mad: easy fix drilled out the inside of the non threaded part of adapter, sensor fit right in. Filled radiator with coolant and distilled water, and off I went. Truck started runing hot when i would get on the gas "what the hell" bad water pump? was i stupid enough to put thermostat in backwords? no not the problem, Took new thermostat out and inspected it, nothing looked wrong with it as it was brand new! Pulled a thermostat off a 6.2L engine that over heated and seized in the garage exact same Thermostat, looked at the Thermostat that originaly came out of the truck Hummm? looked different. Filled a pot of water put it on the stove, when water was almost to boiling point I started testing the thermostats one by one, The thermostat that came from the seized 6.2 & the new napa thermostat opened the same, But the original thermostat opened up way more and you could tell that it could out flow the other two thermostats, so i put the original thermostat back in my truck and engine runs at normal operating tempature now and has no problems staying cool. Hope this helps someone!

[jerry598]

Bought a 95 k3500 4 years ago. First summer trip ran into severe overheating problems with no clue as to problem. Thinking radiator was clogged or there was a thermostat or water pump problem, I pulled them all. I found more than half the volume of the space (the 1-2 inch gap) between the AC cooler and the radiator was clogged with debris. Looked like a packrat had been living in there. Couldn't see any of it until I pulled the cover over the top of the radiator. I've had relatively stable cooling system temps since then (according to dash guage), but now I'm installing a dual thermostat HO system. Hoping for the best, but wondering why I'm going to the trouble considering the price of fuel nowadays.

[trbankii]

Ok, looks like I'm in the market for a radiator... This morning there was a puddle under the driver's side front corner. Pulling the upper shroud this evening showed copper patina colored corrosion down both ends of the core where it meets the side caps and putting a pressure tester on showed at least one actual hole on the driver's side.

Looking at RockAuto and Discount Radiator, I'm a bit confused by the options. The more expensive ones are the ones that say WITH engine oil cooler... Does that mean with an engine oil cooler built into the radiator? I have an engine oil cooler, but it is separate. If they are talking about trucks with the SEPARATE oil cooler, why is that model more expensive?

Also, Discount Radiator doesn't make any mention of transmission oil coolers - with a manual, I don't need one... At RockAuto three of them have transmission oil coolers and two of them make no mention either way...

Just want to make sure I order the correct part... Many thanks!

[ccatlett1984]

DUDE, why couldnt you have posted that link a week ago, I just had a custom aluminium radiator made for mine.

[trbankii]

Posted which link? The message with the link to DiscountRadiator was posted back in April if you check the date... :)

My apologies for my post. I was searching for radiator information and didn't realize that this was in the 6.2 forum - reposted in the 6.5TD forum...