Poor ventilation/truck overheating?

[Beastmaster]

After a mere 1 month of ownership and 1200 miles on the wife's H3, I've noticed an interesting trend of the vehicle running continuously hot. Most of the time, the temps are sitting at 3/4, and when climbing hills, will run up to the red zone to where the A/C will shut off.

The clutch fan has been replaced, and the dealer is now throwing their hands up in the air. Has anyone noticed any bad thermostats coming out of the factory? Or does the H3 have really bad airflow to where I have to add a pusher fan to the outside radiator area?

TIA,
Steve

[PARAGON]

Originally Posted by Beastmaster

After a mere 1 month of ownership and 1200 miles on the wife's H3, I've noticed an interesting trend of the vehicle running continuously hot. Most of the time, the temps are sitting at 3/4, and when climbing hills, will run up to the red zone to where the A/C will shut off.

The clutch fan has been replaced, and the dealer is now throwing their hands up in the air. Has anyone noticed any bad thermostats coming out of the factory? Or does the H3 have really bad airflow to where I have to add a pusher fan to the outside radiator area?

TIA,
Steve

The T-stat shouldn't have anything to do with it running hot under the circumstances you described unless it's very restrictive. It doesn't sound like a "sticky T-stat" situation. Meaning, you could probably remove the T-stat completely and still experience your overheating, as described.

Auto or stick? Any aftermarket add-ons that could cause airflow restriction?

Doesn't the H3 have an oil cooler? Where is it and what does the oil look like now?

[Michael1]

Have you removed the radiator cap (WHEN COLD!), to be sure the coolant level is all the way to the top. Also, is your coolant reservoir full. After the system gets hot, be sure the coolant reservoir is topped off, so that when it cools, and draws in coolant, the reservoir doesn't become empty and just draw in air.

It could also be that you have a defective radiator with blocked tubes, or there was material left over from manufacturing that has blocked some of the tubes. After running the engine, turn it off (remove the keys so someone doesn't accidentely start it), place your hand in between the fan blades, and feel the radiator fins for uniform temperature. It should be very hot and uniformily hot, so be careful not to burn yourself. If there are cool bands, the tubes are blocked.

In cool weather, does the temperature stabilize? If so, then it also could be a thermostat that works, except not opening all the way. If you see wide changes on coolant temperature, near "C" when going down hill, and near "H" when going up, your thermostat may be stuck partially open.

I have noticed that the H3 does run hot in slow traffic on hot days. It never quite overheats, though, and the temperature comes down quickly when the engine speed comes up (increases fan speed).

Michael

[HummBebe]

It is regularly 90+ here in the summer. Never had this issue.

Sounds like a Q for f5fstop.

Call Hummer, they will keep the dealer so busy he can't "throw-up his hands"

It's probably going to be something simple. My guess, could be a relay?

[BABHUMV]

While towing about 4500lbs in traffic, I got he temp gage to go high, never to hot though. I am tending that the radiator is defective, you should not need to put on an extra fan.

[ketcat]

I live in Phoenix and mine runs in about the middle of the gauge most all of the time. The only exceptions are when it's over 100 and I'm moving slowly (4 wheeling) or stopped (idling in parking lot). At those times mine has gone all the way to the bottom of the H on the gauge and I'm pretty sure if I kept letting it idle it would have continued to get hotter. The last time it happened I was in a store and my wife and kids were sitting in it idling with the A/C on for about 20 min. It was 113 and she was sitting in a parking lot in direct sun. When I got in the needle was all the way to the bottom of the H. After driving for about 5 miles the needle was back to the middle of the gauge. About 30 minutes after I got back in the H3 we went through two drive thru?s which took about 10 to 12 min and by the time we got moving again the gauge was back almost as high as before.

Note: While the gauge on mine has gone very high it has never puked any coolant or overheated and the A/C has never stopped working. So unless your are in 110 PLUS temps for a couple of months at a time I would not be too worried about the gauge moving. If the A/C stop?s I would go straight to the dealer.


From what I understand it is a common problem in this area and Jay at Lund Hummer is working on a larger aluminum radiator for the H3.

As a side note he has completed a tune for the PCM and is getting some very good HP and TQ improvements from what I understand.
You can contact him at:
www.lundhummer.com

[Beastmaster]

Originally Posted by PARAGON

The T-stat shouldn't have anything to do with it running hot under the circumstances you described unless it's very restrictive. It doesn't sound like a "sticky T-stat" situation. Meaning, you could probably remove the T-stat completely and still experience your overheating, as described.

Auto or stick? Any aftermarket add-ons that could cause airflow restriction?

Doesn't the H3 have an oil cooler? Where is it and what does the oil look like now?

Oil's fine. I looked at that the first time it's happened.

It's an Auto. No aftermarket stuff yet since I'm waiting for more hardcore stuff to come out from RubberDuck (Travis), like better/beefier rock sliders and a full end to end UCP.

The first thing on the aftermarket bin will likely be a winch. But not until this gets resolved.

[Beastmaster]

Originally Posted by ketcat

I live in Phoenix and mine runs in about the middle of the gauge most all of the time. The only exceptions are when it's over 100 and I'm moving slowly (4 wheeling) or stopped (idling in parking lot). At those times mine has gone all the way to the bottom of the H on the gauge and I'm pretty sure if I kept letting it idle it would have continued to get hotter. The last time it happened I was in a store and my wife and kids were sitting in it idling with the A/C on for about 20 min. It was 113 and she was sitting in a parking lot in direct sun. When I got in the needle was all the way to the bottom of the H. After driving for about 5 miles the needle was back to the middle of the gauge. About 30 minutes after I got back in the H3 we went through two drive thru?s which took about 10 to 12 min and by the time we got moving again the gauge was back almost as high as before.

Note: While the gauge on mine has gone very high it has never puked any coolant or overheated and the A/C has never stopped working. So unless your are in 110 PLUS temps for a couple of months at a time I would not be too worried about the gauge moving. If the A/C stop?s I would go straight to the dealer.


From what I understand it is a common problem in this area and Jay at Lund Hummer is working on a larger aluminum radiator for the H3.

As a side note he has completed a tune for the PCM and is getting some very good HP and TQ improvements from what I understand.
You can contact him at:
www.lundhummer.com

I'm familiar with Jay....he and I have been talking quite a bit about H2 upgrades over the past few years. I live down the street from Lund.

Funny thing - I ended up getting my truck from Legends. Their Internet Service Manager didn't try and push anything strange onto me and when she couldn't find what I wanted, handed me an order checklist.

[Michael1]

Originally Posted by ketcat

From what I understand it is a common problem in this area and Jay at Lund Hummer is working on a larger aluminum radiator for the H3.

No need for a larger radiator. It's not overheating under load. The problem is at low speeds, when there is low air flow. Best solution would be an electric pusher fan. I've noticed the A/C isn't the greatest at low speeds on hot days, too, so an electric fan would help there, too. It is too bad GM didn't include one, because then it could be programmed to turn off with higher vehicle speeds.

A larger (deeper radiator) will reduce A/C performance, because of the additional air restriction, unless they reduce the fin count, which would negate the extra depth.

Michael

[Ipedog]

This sounds like a problem in the cooling system, not a normal condition.

The last time at Paragon we had all been spashing through mud for days and the trucks were completely coated. I know that my radiator had lots of crap in it. We were running a long crawler of a trail and it was HOT (see pic below) and the truck never got to the H. Both HIHUMMER and I were on the same trail and noticed the same conditions.

It sounds like your dealer isn't trying hard enough to figure out what the issue is.

It was a wee bit warm...

[ChevyHighPerformance]

Did the dealer independently check the engine temps (i.e., separate thermometer)? Could your engine coolant temperature sensor be bad?

[f5fstop]

As Chevy High Performance states...is it the coolant, or is it the gage, but more importantly, is it the sensor. If the gage is bad, the A/C should not shut off, but if the sensor is bad, the signal from the PCM to the BCM will trigger the BCM to shut down the A/C. In addition, the PCM, controls the coolant gage, and if the sensor is showing hot, the PCM shows hot on the gage.
They can check the coolant temp via a thermometer and verify the sensor via the Tech 2.

Has the dealer checked the fins in the radiator, checked the passages?


If this fails, request the dealer do a complete drain and then perform a vac-and-fill procedure. On some engines (especially inline), there has been problems with large air bubbles causing overheating problems, usually localized to that are of the engine. The vac-and-fill method prevents air bubbles from forming. This condition can come from the plant if during fill the storage tank was switched for the coolant/water mixture.

If this is not the problem, I would say you have a restriction. Airflow is ok through the compartment at speeds, and the mechanical fan does a good job of drawing air, and believe it or not, weighs in less than a electrical fan setup. (Weighed one versus an electrical setup for the infamous H3Lady last year ).

What you describe is not normal. Mine in up to 90 degree weather has remained just below the 1/2 mark.

[ketcat]

Originally Posted by Beastmaster

I'm familiar with Jay....he and I have been talking quite a bit about H2 upgrades over the past few years. I live down the street from Lund.

Funny thing - I ended up getting my truck from Legends. Their Internet Service Manager didn't try and push anything strange onto me and when she couldn't find what I wanted, handed me an order checklist.

Jay's a great guy, I have worked with him on several different projects and he has always been helpful.

Glad to hear a dealer treated you right. Even though I have a good relationship with Jay and Lund I bought my from Edmark Hummer in Idaho. My brother works for them, they give very good deals without all the hassle and since he is my brother I figure I should send the $$$ his way.

Does yours get hot when it's 101? Mine does not it really needs to be about 110 before mine will run up to the red.

If you ever want to do some local wheeling (back way to Crown King?) Pm me and we'll see if we can find the time.

[ketcat]

Originally Posted by Michael1

No need for a larger radiator. It's not overheating under load. The problem is at low speeds, when there is low air flow. Best solution would be an electric pusher fan. I've noticed the A/C isn't the greatest at low speeds on hot days, too, so an electric fan would help there, too. It is too bad GM didn't include one, because then it could be programmed to turn off with higher vehicle speeds.

A larger (deeper radiator) will reduce A/C performance, because of the additional air restriction, unless they reduce the fin count, which would negate the extra depth.

Michael

As I'm sure you know (sounds like you are mechanically inclined) if you ask three different engineers about cooling system theory you will get three different answers. Bigger radiator, offset rows, different fin designs, different coolant, coolant flow direction, fans etc..... Lot's of race teams are using the SMALLEST radiator they can run without overheating on the track.

The fact is any stock car should be able to idle in 110 (even 120) all day with the A/C on and never overheat or getting hot.

Because it appears to be a problem with most H3's in this area I thought it would be important for people to know someone is looking at one possible solution.

Personally mine has not overheated but if it did I would make the dealer fix it and if they didn't I would get GM involved.

[Michael1]

Originally Posted by ketcat

As I'm sure you know (sounds like you are mechanically inclined) if you ask three different engineers about cooling system theory you will get three different answers. Bigger radiator, offset rows, different fin designs, different coolant, coolant flow direction, fans etc..... Lot's of race teams are using the SMALLEST radiator they can run without overheating on the track.

The fact is any stock car should be able to idle in 110 (even 120) all day with the A/C on and never overheat or getting hot.

Because it appears to be a problem with most H3's in this area I thought it would be important for people to know someone is looking at one possible solution.

Personally mine has not overheated but if it did I would make the dealer fix it and if they didn't I would get GM involved.

You are absolutely right about this. Cooling system design is a bit of balancing act, and black art. You want a big, deep radiator with a lot of fins, plenty of tubes, but not too deep and not too many fins and tubes such that it restricts air flow. You can change the pitch and number of fan blades. You can change the clutch cut-in temperature, and fan rpm. GM runs a lot of tests on cooling systems to try to strike the best balance, including cooling system performance, A/C performance, fan noise, and fan load. I am a little surprised the cooling system seems a bit marginal at low speeds and high temperatures on a vehicle designed for rock crawling, but I wasn't there when they came up with the compromises stated above. I wouldn't mind hearing what people's trailer towing experiences have been in hot weather. That is one of the most difficult tests to pass.

I was only suggesting the pusher fan, because it would probably be less expensive than a custom radiator, and so far the problems have been reported at low engine and vehicle speeds. I also thought the A/C performance was marginal at low engine and vehicle speeds, and an electric fan would help that condition, too. My experience is the H3 cools down quickly as soon as engine speeds are brought up.

Michael

[deserth3]

One item I haven't seen mentioned here is the lower radiator hose. It should have a spring in it to keep it from colapsing. Easily checked by squeasing the hose.

[ketcat]

Michael

We are on the same page, especially about the fan and the a/c performance. Wasn't R12 a wonderful thing? Ice cold A/C no matter what.

PS: It's 109 outside, my H3 has been idling on asphalt int he sun for about 45 minutes with the a/c on and the gauge is at 3/4. The day that mine got hot I think it was 114. I have a Tech II in the shop but don't have a candi module so I can't track temps. If I can use a friends candi module I will track the temps and see what happens. If I really get ambitious I will hook up the data logger.........we'll see.

Excellent cooling system chat by the way, thanks.

Ken

[Michael1]

Originally Posted by ketcat

Michael

We are on the same page, especially about the fan and the a/c performance. Wasn't R12 a wonderful thing? Ice cold A/C no matter what.

PS: It's 109 outside, my H3 has been idling on asphalt int he sun for about 45 minutes with the a/c on and the gauge is at 3/4. The day that mine got hot I think it was 114. I have a Tech II in the shop but don't have a candi module so I can't track temps. If I can use a friends candi module I will track the temps and see what happens. If I really get ambitious I will hook up the data logger.........we'll see.

Excellent cooling system chat by the way, thanks.

Ken

Ken,

How about R12, and a GM swash plate 6 cylinder non-cycling compressor? Comfy!

109F, idling, and gauge at 3/4 doesn't sound too bad. Which direction was the nose pointed relative to the wind? It would be interesting to pin down the conditions where these things are getting hot. I was at the Hummer Happening near Los Angeles in the Santa Monica Mountains, and temps were low 90's. I was watching the guage closely, because of the overheating reports. One minute the guage was just below the red zone, and the next it was mid-point, even when just idling with the air on. Seems like something isn't quite right.

Michael

[ketcat]

Originally Posted by Michael1

Ken,

How about R12, and a GM swash plate 6 cylinder non-cycling compressor? Comfy!

109F, idling, and gauge at 3/4 doesn't sound too bad. Which direction was the nose pointed relative to the wind? It would be interesting to pin down the conditions where these things are getting hot. I was at the Hummer Happening near Los Angeles in the Santa Monica Mountains, and temps were low 90's. I was watching the guage closely, because of the overheating reports. One minute the guage was just below the red zone, and the next it was mid-point, even when just idling with the air on. Seems like something isn't quite right.

Michael

The "good old days" when you could hang a side of beef in your car.... Oh well I guess DuPont made out on the R12 to 134 switch.... Just joking I know why the EPA made us switch and A/C in newer cars actually works pretty well, in fact one of the things I like about the H3 is how well the A/C works. I'm sure the relatively low heat load due to the small glass area helps.
Interesting question about the wind direction.
The other day when it was 109 and the gauge stopped at about 3/4 (I agree 3/4 on the gauge is not a concern) the wind was blowing about 5 to 10 mph and was hitting the vehicle on the drivers front (i.e. if the H3 was facing north the wind was coming from the north west). Today the temp was about 107 and there was no wind. After idling for about 10 min the gauge was past 3/4 which was surprising until I read your e mail. Just for fun I'm going to have the guys in the shop throw a 14" Spal fan on it and see what happens.