cooling issues and fixes

[B&J 88]

2006 GMC ccsb Z71 155,000 miles
5.3 auto/od, 4.10 gear
2005 Springdale 242FRL
Pullrite Super Glide hitch

3rd time out with this camper. We love it. It's roomy and comfortable.
The truck I hope to keep for a long while.
On the two other trips the engine temp did go up to about 210 while climbing a couple of hills but came right back down once we leveled out again. I think that is normal. On this most recent trip the temp climbed to 225-230 or so on a bit steeper hill while the outside air temp was low 80s. Once again it did cool right back down once we leveled out. I think in the hotter summer temps it will be a problem. The engine has aluminum heads.
This truck has dual electric fans OE. I'm thinking about maybe adding a pusher fan set to temps above 215 or so for these hard pull times.
I'd appreciate your thoughts.

[sourdough]

What is the condition of the radiator? With that many miles and you wanting to keep it for a long time I'd replace it if it hasn't been. How new is the coolant and what mix is it? Is it the OE water pump? If so, that could be an issue. Again, with those items and that many miles I would replace them. It sounds like you have a problem that's getting about ready to get you and it's trying to let you know. I would also have all new hoses, radiator cap etc.

When all of those items are determined to be up to snuff you might think about a pusher fan, but, on a truck as new as yours that would more likely just be covering up an underlying problem unless something is wrong with the OE dual fan setup.

[jsmith948]

This ^^^^^. PLUS, why let the temp get that high? If your engine is overheating, or just running hotter than normal, why not back out of it a bit and drop a gear. Put your 4-ways on and drive a little easier over the hill?
Maybe you have already done that. If so, then you do have a problem, as stated above, with your cooling system.:)

[Desert185]

Sometimes debris gets trapped between the AC condenser and the radiator. Check that.

Change coolant, if it is due, and consider going to a cooler thermostat like a 170 or 180. Make sure to burp any air out of the system. If air gets trapped, the cooling system won't cool properly. Also, wire the fan(s) with a switch to turn them on early.

Install a trans fluid cooler in addition to the one in the radiator. A cooler trans is a cooler radiator and engine.

As a last resort, turn off the AC before you begin a long pull up a grade. A cooler condenser is a cooler radiator.

[sourdough]

The replies above point out some additional great thoughts. In AR there are a lot of bugs. If you run much at highway speeds your radiator may be clogged with them...it has to be clean; a pressure washer works great.

If you have a towing package on the truck you may already have an aux transmission cooler; if not you should install one. Not very costly and easy to do. If it does have an OE you may want to just change it out "because".

Changing the radiator cap will usually help, and is cheap, but don't do that until you know all the rest is in good shape. It can still cover up issues. A new cap can't overcome poor circulation or bad coolant. I think your truck, if equipped properly (cooling components) should pull the trailer without big heating issues. I will say that after replacing EVERY cooling component on my Jeep CJ7 (and the engine) that I still had to go to a lower thermostat to deal with 100+ temps. Downside is that I keep it in the mountains and when fall comes I have to pull it out and put the normal 190(195?) degree in.

[ls1mike]

2006 GMC ccsb Z71 155,000 miles
5.3 auto/od, 4.10 gear
2005 Springdale 242FRL
Pullrite Super Glide hitch

3rd time out with this camper. We love it. It's roomy and comfortable.
The truck I hope to keep for a long while.
On the two other trips the engine temp did go up to about 210 while climbing a couple of hills but came right back down once we leveled out again. I think that is normal. On this most recent trip the temp climbed to 225-230 or so on a bit steeper hill while the outside air temp was low 80s. Once again it did cool right back down once we leveled out. I think in the hotter summer temps it will be a problem. The engine has aluminum heads.
This truck has dual electric fans OE. I'm thinking about maybe adding a pusher fan set to temps above 215 or so for these hard pull times.

I'd appreciate your thoughts.

The PCM commands the low speed cooling fans ON under the following conditions:
1. Engine coolant temperature exceeds approximately 94.5°C (202°F).
2. A/C refrigerant pressure exceeds 1447 kPa (210 psi).
3. After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.



The PCM commands the high speed fans ON under the following conditions:
1. Engine coolant temperature exceeds approximately 104.25°C (220°F).
2. A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
3. When certain DTCs set.



At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.

Are you using the dash gauge? You need a scanner, the dash one is not accurate.

C5 Corvettes, the Trans Am and similar cars, which use an all aluminum version of the LS motor in your truck don't come on unit 226 and 235.
If the fans are coming and you are cooling down, no worries. Get a scanner you are probably not over 220.

[B&J 88]

I didn't know if I was expecting too much of the truck or not. But it's not even hot weather yet. I do realize the temp should go up on a hard pull. I am pleased to say it does cool right on down after we level off. I've not had a truck with electric fans only before so I'm learning.
I do not know the grade of those hills I climbed but I did slow down and pull them in 2nd gear. It was maybe 1/4 of a mile on the steeper one.
But towing down the highway at 55 and rpms about 2600 in drive it cools just fine. I do use the tow/haul mode.
This 5er is about twice the weight of the last bumper pull camper so I expected more tug on the truck for sure but this 5er sure pulls nice.
I'll spray the condenser and radiator fins out just in case. The coolant is less than a year old as well as the radiator cap.
So you guys believe my truck should pull this 5er just fine as is without getting too hot? How hot is too hot?

[ls1mike]

I didn't know if I was expecting too much of the truck or not. But it's not even hot weather yet. I do realize the temp should go up on a hard pull. I am pleased to say it does cool right on down after we level off. I've not had a truck with electric fans only before so I'm learning.
I do not know the grade of those hills I climbed but I did slow down and pull them in 2nd gear. It was maybe 1/4 of a mile on the steeper one.
But towing down the highway at 55 and rpms about 2600 in drive it cools just fine. I do use the tow/haul mode.
This 5er is about twice the weight of the last bumper pull camper so I expected more tug on the truck for sure but this 5er sure pulls nice.
I'll spray the condenser and radiator fins out just in case. The coolant is less than a year old as well as the radiator cap.
So you guys believe my truck should pull this 5er just fine as is without getting too hot? How hot is too hot?

I can't tell you until you put a scanner on it. If you are getting over 240 in an LS based motor, your 5.3, you should back off. Do you have a tranny temp gauge? I would be more concerned about that. 230-235 in an LS motor pulling a hill is no big deal.
What is it about 6000 lbs?

[B&J 88]

Mike I am only able to read the dash gauge. I believe a single fan runs most all the time if the a/c is on. If it sits and idles for long the 2nd fan comes on somewhere just over 210 or so according to the gauge. I guess I need to pay it more attention when I have the hood open and mark when each fan turns on just so I'll know.
These are single speed fans correct?

[ls1mike]

Mike I am only able to read the dash gauge. I believe a single fan runs most all the time if the a/c is on. If it sits and idles for long the 2nd fan comes on somewhere just over 210 or so according to the gauge. I guess I need to pay it more attention when I have the hood open and mark when each fan turns on just so I'll know.
These are single speed fans correct?

One low speed, one high speed I forget which is which.

Get yourself a cheap OBDII scanner that displays real time data. It will help you sleep at night. :)


The dash gauge on these is miserable. They are not accurate. You can google it and read about it.

[B&J 88]

I thought most all late models use a 195* stat. If so the gauge reads right at 200* at normal temp.
I have an Innova brand had held scanner. I'm not sure if it works real time or not. I'll have to try to find some papers on it.
This is a real good engine and I don't want to cook it.

The camper is around 6700#.

[bsmith0404]

Yep, the dash gauge is likely off by anywhere from 10 to 20 degrees, get an OBDII port scanner such as an edge cts. If your coolant is good (check to make sure it's a good 50/50 mix, good to -30 degrees) and the radiator is clean inside and out then you should be good to go. Based on the fact that it cools back down quickly tells me you don't have a leak anywhere and your cap is good. If you were actually hitting 235 and the cap wasn't holding pressure you'd be boiling water. At slower speeds the fan has to work harder to push the air through, it's not going to cool as well. IMO, changing the thermostat isn't going to help you, your fans are still set to come on at a certain temp, a lower stat will just give you a lower starting point. High mileage radiators do tend to get crud in the bottom, if it hasn't been flushed in a while, that could help. Get the scanner so you know for sure wh at you really have. My dash guage reads about 20 degrees higher than my scanner

[notanlines]

I liked the advice of all who said to increase your cooling in your transmission. I also like the idea of maybe junking your radiator and starting fresh. A radiator online is maybe 150 plus a new thermostat, cap and coolant you're at about $250 or so. No reason not to add a couple new hoses also. I realize this makes me a parts replacer rather than a mechanic, but you have an older, high mileage truck and it would be a good investment that is relatively easy to do in your driveway. Plus, if you're a good shopper you can easily beat my $250 mark. Keep us up on your progress.

[bsmith0404]

As long as the radiator is clean and doesn't have any leaks there isn't a reason to replace it, all it does is flow water and transfer heat. You can use a flush kit to clean them out, but I prefer to pull them and flush them. If you pull it, you can normally take it somewhere and have it flushed and pressure tested for about $35. You can add a little more to that and they will straighten all of your cooling fins as well. If you flush it yourself, you can buy a radiator comb for about $5 and straighten all of the fins yourself. Of course you could take the truck somewhere and have the entire system flushed which would help to remove any sediment in the engine cooling jackets. Flushing the cooling system every 100k miles or so is not a bad practice.

The cap is cheap and easy to replace, but if the water isn't boiling the cap is holding pressure and is still doing it's job. A good 50/50 mixture of antifreeze would still boil at about 220. The radiator cap raises that about 2.5 degrees per psi. You most likely have a cap somewhere between 12-15 psi. so say another 30-35 degrees worth of boiling point protection. So if you're water is not boiling when you get up to 225/230, you have a sealed system which means no leaks and a good cap.

Your truck is a Z71, if I remember correctly, that comes with the towing package which includes the trans cooler.

If your water pump isn't leaking any water it is most likely still good.

I'm not a parts swapper, I believe in finding the problem and fixing it. While I'm at it, I may decide to change some related parts just because I'm partially there and it's easier/cheaper at that point. For example, if I pulled the radiator to flush it, I would most likely change the belt, hoses (including heater hoses), and water pump at that time since the radiator has to be pulled or drained to do all of that (except the belt) anyway. Also a good time to check/replace the belt tensioner.

You can most likely cure your problem and change your hoses for less than $100. That would also give you a little peace of mind that your cooling system is in better shape and not going to let you down on your next trip.

[BOWWOW]

I also would advise putting an additional trans cooler with a fan, I leave mine on all the while I am towing . It does help the engine temps to recover much faster. One other thing is that while pulling a steep grade try to keep the engine RPMs up a bit no matter what gear it takes to keep the fluids circulating quicker will also help cool it faster. I use a piece of screen in front of the radiator to keep the debris out , it slips in and out easily to clean it.

[Ken / Claudia]

My experience with a aftermarket electric fan forcing air into the transmission cooler. I had the factory cooler replaced by one that is 2x as large and centered it in the grill. The factory placed them behind and below the bumper. At highway speeds the fan does not change the temp. On hills or driving in hot weather at low speed it keeps the tranny cooler, up to around 30-40 degrees cooler. I have had it that way for around 10- 11 years. The shop that did the work wanted to put the cooler and fan under the truck between the frame rails. That they said is the best location. But, for me 1 elk hunt or bad snow day and I think the cooler and fan would be packed with snow or mud.

[ls1mike]

While I agree a larger than stock tranny cooler in that truck is a must, he has not exceeded what the stock tune or engine setup was designed for. He has not ever put a scanner on the thing yet. My 2002 6.0 reads 210 on the gauge in reality according to HP tuners that is anywhere from 190 to 218. The newer gauges are even worse. :)

The 5.3 is an LS based motor, iron block, iron heads. The difference between that motor and the one is my Trans Am is iron block VS aluminum block, 5.3 higher compression heads, updated oiling in 2006 and 5.3 vs 5.7. The difference between my 2002 6.0 is the 5.3 has higher compression heads, updated oiling and 5.3 vs 6.0. I have seen my 6.0 hit 220 to 235. This is not an issue in these engines. I do like to keep the tranny fluid under 200 and with a larger cooler I have not seen over that yet.

Scanner and pull a bit before you start spending money. Do a flush if it makes you feel better. Don't just start swapping out parts.

Based off what he says the only thing is his truck is working harder to move a larger trailer.

[T3/T4 Hybrid]

This is my thoughts.

The stock radiator has normally one row of cooling. Heavy duty will upgrade to 2 rows of cooling. The newer style radiator tanks are now sealed with a rubber style gasket and usually fail in this area. Which is my guess and what I would be looking at.

If you are going to keep the truck then I would be paying some love to the cooling system. Its giving you a hint that something is not right. Have the system checked and if its good then have it cleaned out.

If a new radiator is needed then upgrade with a 2 or 3 core radiator. That will keep it cooler than the stocker and work a lot better than a pusher fan. The extra fluid that the thicker radiator holds will help cool your engine. I would stick with a new stock style water pump. Personally I don't like high flow pumps. It pushes the fluid to fast through the radiator where the heat exchange with air cant occur properly. "I know that's a completely different argument. :D" If you are going this far then a cap, thermostat and fluid flush should get it back to better than stock day one operating level.


Good luck