Roadtrek 190 Chevy 6.0 overheating?

[Kon]

Hi and thanks in advance for everyone’s input.
I have a “new to us” 2004 Chevy chassis with the 6.0 V8. I’m not familiar and couldn’t find good answers so far on what the normal engine coolant temps should be. I’m hoping I can get some tips on what is normal.
*Please note that I have recently just replaced the fan clutch and belt (OEM Delco)
I had the mechanic flush the coolant but I’m not sure if they flushed it properly as I recently found out that this Chevy system doesn’t have a traditional drain plug.

Here’s what I’ve observed so far in mines.
194- 195.6 during regular cruising speeds (flat roads)
195- 197 during short idles (1-3mins)
197- 202 during longer (5-10 mins)
200- 220 on long slow incline roads (10-15 mins)
I haven’t climbed any major inclines yet and that’s frankly what I’m concerned about.

These temperature data were recorded using the obd2 reader.
Based on the dial gauge in the van, it usually reads a tad below the middle point.

What would be temps that I should be worried about before overheating?
Are mines normals or are they running high?
Thank you again everyone for your help. It’s greatly appreciated.

[rowiebowie]

I think you're ok. But I can't find he post I saw here (or imagined I saw here) where someone reported temps like you report above 200 were not a problem for the Chevy motor.

[booster]

Originally Posted by Kon

Hi and thanks in advance for everyone’s input.
I have a “new to us” 2004 Chevy chassis with the 6.0 V8. I’m not familiar and couldn’t find good answers so far on what the normal engine coolant temps should be. I’m hoping I can get some tips on what is normal.
*Please note that I have recently just replaced the fan clutch and belt (OEM Delco)
I had the mechanic flush the coolant but I’m not sure if they flushed it properly as I recently found out that this Chevy system doesn’t have a traditional drain plug.

Here’s what I’ve observed so far in mines.
194- 195.6 during regular cruising speeds (flat roads)
195- 197 during short idles (1-3mins)
197- 202 during longer (5-10 mins)
200- 220 on long slow incline roads (10-15 mins)
I haven’t climbed any major inclines yet and that’s frankly what I’m concerned about.

These temperature data were recorded using the obd2 reader.
Based on the dial gauge in the van, it usually reads a tad below the middle point.

What would be temps that I should be worried about before overheating?
Are mines normals or are they running high?
Thank you again everyone for your help. It’s greatly appreciated.

Those are very typical temps for the that vintage of Chevy. We have a 2007 and it was very similar.


The bad is that it will be higher than that even on steeper climbs.



What is a major concern is that not only is the engine running warm, and 220* is quite warm but not horrible, the transmission is also getting hotter than it should and it a big part of the reason the water get hot because the transmission cooling is in the radiator also.


Depending on which OBD scanner you have, we use a Scangauge, you should be able to see the transmission temps also. We saw times of 240* on the trans in ours in Rocky Mountain Nat Park and it did a power reduction of the engine.


There are quite a few threads on the subject on the forum, and will find some of them and link them later as I need to leave home for while soon, or you can find them with the search.


Bottom line is that addon fans, trans coolers, bigger radiator improved airflow, all helped but didn't eliminate the completely the temp increases, particularly in the transmission. What I finally wound up doing was getting a tuner and changing some of the programmed settings in the transmission which is pretty serious to do, but it fixed our issues.


The main issue for temp is that the transmission is setup for max power under heavy loads, not max heat removal, so long pulls keep moving well, but things get hot. They do this by keeping the torque converter unlocked much of the time to gain torque and that generates heat. I changed the lockup parameters for the torque converter in the PCM computer of the van.


Some of the issue can be worked around by staying in a lower gear than might appear to be necessary as running high rpms will get the transmission to lock the converter more of the time. There are speed charts for lockup posted in the other threads so you can see what the speeds are.


There is also a programming quirk in the vans that are in the earlier range, and our 2007 had it. In low gear setting (1 on the shifter) it will still still shift into second gear at times. What happened to us a few times that pointed it out was we were climbing a very steep and winding grade in low gear at a reasonable rpm without major issue. On a very sharp curve I had to let off the throttle to slow a bit and it shifted to second even though the shifter was still in 1. Second gear would not pull us back up to speed and we had to nearly stop before it would go back into low gear again. The tuner manufacturer has since come up with programming access point to change the program to eliminate the issue which we have done and now it works well. Rare occurrence but really scary when it happens as you just lose all ability to move.


Many people never get much into the high temp situations, but quite a few do. I think may more get higher than desirable transmission temps but don't know it because there is no gauge.


A 2004 came with Dexron III or IV trans fluid in it, so it is a good idea to get it changed to Dexron VI to get the much better high temp handling it has.

[booster]

Here is one link to the transmission discussion that will allow you to see what it is all about.


https://www.classbforum.com/forums/f...icks-7158.html


A link to the oversize radiator install in the above thread and this it also


https://www.classbforum.com/forums/f...vies-7131.html


Here is on on our trans cooler install. They are know both used for trans and the oil cooling is in the radiator.


https://www.classbforum.com/forums/f...hevy-6402.html

[JohnnyFry]

With those temps you should be fine. The system is pressurized to about 15 PSI raising the boiling point to about 245°F. The system is designed to operate at 215°-230°

[Deano]

I won't mention the potential for disaster I experienced after the local Chevy dealer replaced the coolant in mine.
I'll just say, check your coolant in the radiator, not just in the overflow bottle. Only AFTER it has cooled down.

[Kon]

So much thanks to everyone’s input And tips. You guys are all the best and I love this forum.
I’m learning a lot here and it’s definitely helping us out on our RV experiences.
Thanks again!

[Kon]

For future reference, would you happen to know what’s the proper way to “burp” the system?
Thanks

[booster]

Originally Posted by JohnnyFry

With those temps you should be fine. The system is pressurized to about 15 PSI raising the boiling point to about 245°F. The system is designed to operate at 215°-230°

In general, I would not want to run that hot for several reasons, with around 220 the tops for me. First off is that the temp gauge is not generally in the hottest spot of engine so there are areas that will be hotter. Even under normal conditions of moderate load many engines generate some steam that gets out with water to the radiator. Higher head temps can also be an issue in detonation from preignition which is the harsh damaging variety many times. But I think the biggest issue is that if you are running above about 210* the thermostat should be pretty much wide open as it tries to control the temperature, that also means the radiator is getting maxed out trying to get rid of the heat. Once the stat is wide open and radiator maxed, the temp can raise much, much faster than it did getting there. If it took 5-10 minutes to get to 210* you might get to 230* in a minute or two, which is what we saw. Depending on the temp drop across the radiator, the exit temp will likely be very high and on the exit side is where the transmission cooler is located. If a lot of the heat being put in from the system is from the transmission, which it appears to be in the Chevies in question, the trans oil is going to come out of the radiator without much cooling at all. When ours would heat up before the fixes, the water and trans tracked up together and the trans would put the engine in reduced power mode and it would lock the torque converter reducing power even more, at about 240* trans temp in ours, with water 10-15* cooler than that.


If the budget and desire aren't there to address the high heat issues with changes to hardware and software, then the previously mentioned driving method changes may help, but IMO it should be a pull over and cool down if trans temp hits 230* or water about 225* or you may wind up in reduced power on big mountain where it isn't enough push to let you pull over. That happened to us and it was not a pleasant thing.


Max temps for water, oil, and transmissions always make for lots of opinions that run all the way from "everything should run on thermostat" to some very high numbers for all. The older transmission fluid temp charts actually showed no higher than 170* or trans life would get severely shortened (this is pan oil temp which is somewhat cooler than the temp sensor temp seen on an OBD scanner). The Chevy vans almost never that cool when climbing a long hill. I think this in itself is enough reason to get the Dex VI fluid in all the older GM transmissions as it will survive high temp episodes much better.

[Kon]

Originally Posted by booster

Here is one link to the transmission discussion that will allow you to see what it is all about.


https://www.classbforum.com/forums/f...icks-7158.html


A link to the oversize radiator install in the above thread and this it also


https://www.classbforum.com/forums/f...vies-7131.html


Here is on on our trans cooler install. They are know both used for trans and the oil cooling is in the radiator.


https://www.classbforum.com/forums/f...hevy-6402.html

WOWOWOW.. awesome mods on your van! Thanks for posting and sharing

[Kon]

Hi, What would be the steps or process to change over to the DEX V! coolant?
Thanks

[booster]

Originally Posted by Kon

For future reference, would you happen to know what’s the proper way to “burp” the system?
Thanks

There is a very specific coolant filling procedure for the 6.0 LS engines as they do tend to trap air. They have a bleed hose coming from the top of the engine that needs to be open, and then a fill a specific way. IIRC filling though the upper radiator hose works the best. The thermostat is located at the radiator return hose instead of top of the engine so air can get trapped in the lower radiator hose until the thermostat opens, also. They can be tough to get to burp once full. Sometimes it will work to let them get running and somewhat warm and then rev them fairly high for just a second and let off, all with the radiator cap loose (you may puke some coolant, though).


I will try to find the factory service manual procedure to confirm what they say about it, as it has been a while since I have done ours (it is getting do for coolant change) and I not certain of exactly how the said things.


Here it is and sounds right to what our 07 FSM said also, but I haven't looked yet.


https://www.gmupfitter.com/files/med...ulletin_50.pdf

[booster]

Originally Posted by Kon

Hi, What would be the steps or process to change over to the DEX V! coolant?
Thanks

Dexron VI (Dex 6) is the newest transmission fluid. I like to use the Valvoline version as it is full synthetic rather than blend.


Dexcool is the engine coolant.


To change the trans fluid usually will take about 3-4 cycles of changing the fluid that is in the transmission pan, as that is all can get out at a time unless you have a flushing machine. Unfortunately, many of the shops with flushing machines have universal fluid in them which IMO is not a good idea to use in much of anything. A GM dealer would be the best idea to ask if they have Dex 6 in their flush machine, as that way it gets done all in one shot.

[Kon]

Thanks.. have you heard of a common situation that people say changing or flushing the system might cause new transmission issues?
My mileage is at 75k … what are your thoughts on this?

[booster]

Originally Posted by Kon

Thanks.. have you heard of a common situation that people say changing or flushing the system might cause new transmission issues?
My mileage is at 75k … what are your thoughts on this?

That is a very common statement and certainly can be true if there is a lot of debris moving around in the trans because of poor maintenance with regular fluid changes. If the fluid is still pink and doesn't smell burnt plus the unit is still shifting ok, I don't think there would be any issue but if it has never been done, you may want to start with the pan removal partial fluid change as the flush machines have been said to be more likely to dislodge stuff and cause issues.

[dicktill]

Originally Posted by booster

There is a very specific coolant filling procedure for the 6.0 LS engines as they do tend to trap air. They have a bleed hose coming from the top of the engine that needs to be open, and then a fill a specific way. IIRC filling though the upper radiator hose works the best. The thermostat is located at the radiator return hose instead of top of the engine so air can get trapped in the lower radiator hose until the thermostat opens, also. They can be tough to get to burp once full. Sometimes it will work to let them get running and somewhat warm and then rev them fairly high for just a second and let off, all with the radiator cap loose (you may puke some coolant, though).


I will try to find the factory service manual procedure to confirm what they say about it, as it has been a while since I have done ours (it is getting do for coolant change) and I not certain of exactly how the said things.


Here it is and sounds right to what our 07 FSM said also, but I haven't looked yet.


https://www.gmupfitter.com/files/med...ulletin_50.pdf

If I'm not having a senior moment, I seem to recall that there is a drain plug on the lower left(?) of the block that you need to remove if you want all the old coolant to drain. It requires a short 17mm hex wrench to remove (also IIRC).

[Kon]

Hi, newbie question. What's IIRC ?

[booster]

Originally Posted by dicktill

If I'm not having a senior moment, I seem to recall that there is a drain plug on the lower left(?) of the block that you need to remove if you want all the old coolant to drain. It requires a short 17mm hex wrench to remove (also IIRC).

Dick is exactly correct on that, and it does require a special allen wrench or removing the oil cooler line adapter to get it out of the way. I cut off a metric allen wrench quite short and fit it into a socket and used a flex handle breaker bar as that is all that would fit and clear the obstructions. It will be VERY tight, and it will make a mess when you take it out.


Of course the front will make a mess also as there is no radiator drain. You have to remove the lower radiator hose with it's hard to use quick connect fitting.


IIRC is "if I remember correctly".

[MagicBox]

These transmissions are a bit tricky to service on the 6.0 because the pan won’t come off without loosening/removing the exhaust y pipe and the dipstick tube is longer than most fluid remover hoses like on a MityVac.
Either tip the pan and suck out as much as you can or try to source an appropriate, longer suck hose.

[booster]

Originally Posted by Kon

Hi and thanks in advance for everyone’s input.
I have a “new to us” 2004 Chevy chassis with the 6.0 V8. I’m not familiar and couldn’t find good answers so far on what the normal engine coolant temps should be. I’m hoping I can get some tips on what is normal.
*Please note that I have recently just replaced the fan clutch and belt (OEM Delco)
I had the mechanic flush the coolant but I’m not sure if they flushed it properly as I recently found out that this Chevy system doesn’t have a traditional drain plug.

Here’s what I’ve observed so far in mines.
194- 195.6 during regular cruising speeds (flat roads)
195- 197 during short idles (1-3mins)
197- 202 during longer (5-10 mins)
200- 220 on long slow incline roads (10-15 mins)
I haven’t climbed any major inclines yet and that’s frankly what I’m concerned about.

These temperature data were recorded using the obd2 reader.
Based on the dial gauge in the van, it usually reads a tad below the middle point.

What would be temps that I should be worried about before overheating?
Are mines normals or are they running high?
Thank you again everyone for your help. It’s greatly appreciated.

Those are pretty typical temps for the pre 6 speed 6.0 Roadtreks, allow IMO they are too high and you will get hot in the mountains.


There are some very detailed discussions on the forum about what works, and lots about what doesn't help much but you think it would. We have been through all of them with our van and we know can climb mountains and not get over 200* on the water or the transmission. You may want to read through them.



I would suggest that the first thing you might wan to do is get a Scangauge and put it in place, which is pretty easy to do. That way you will get more accurate water temps and also the transmission temp, which usually is a bigger issue and much of the cause of the high water temps.