Over-heating Alpha when towing. Need some advice.

[Hans3T]

Another shot.

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[H3nightrod]

Can Cruz control have anything to do with it?

 

[Hunner]

Pull your front skid and check and see if this here thingy is all stoppeded up.

and check these for pinched lines.

Next, get a Scan Gauge II so you can speak in degrees of temperature and then you can see what temp the dash gauge is indicating.
Have you checked or just replaced the radiator cap just to see it that changes things?

 

[Mr_Rich]

I wouldn't be towing in OD, for one thing. I would've run in 3 as it's marked on your dash. I'm sure that running in OD added to a lot of heat build-up in the trans. I always stay out of OD unless I'm cruising down the highway. When I hit the base of the hills I kick it down and move the lever to D (3) in my Chevy. The 700R4 made it 235K miles before I rebuilt it using habits like that. In my 3T I shift I shift out of 5th and let the engine rev. My temp gauge stays at the same place all the time and made it up El Cajon in summertime loaded with gear; no problem.

 

[MaxPF]

Wildly fluctuating temps are usually a thermostat. And despite what GM says, Dexcool is not good for 5 years or 150k miles. It's barely adequate for 5/150k, but not good. I'd dump it every 2-3 years regardless of mileage.

A scanner than can read trans temps can indicate if there is a trans heating issue, but usually a trans that is getting hot enough to cause an engine overheating issue will throw a code and go into hot mode. Your issue sounds more like a stat to me.... but I've been wrong once or twice in my life :giggle:

 

[ReconH3]

Thermostats that get stuck can get unstuck giving an impression that it's no that. Because it got unstuck it doesn't mean it's fixed. It's still prone to doing it again. I would suggest, like others have, getting it changed out. It's not a complicated task.


"Ex Umbris Venimus"

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[LagunaH1]

This doesn't solve the problem but it might help you get to where you are going:

If you run hot, pull over and put the truck in P or N and then rev the engine to about 1300 RPM. You should hear the fan make a lot of noise and see the temps drop within a few minutes. I have used this technique several times when I had my '3 and it always worked beautifully. -It's even described in the owner's manual

 

[bebe]

Like Mikkel says - engage the fan clutch and see if it goes down - you can hear it when it's engaged. That could also be an issue along with towing in OD, flat or not, it could be running hot because of it.

 

[Scarsman]

I wonder if your fan is not engaging, maybe?

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[Kurt]

I'd do what others stated and try not using overdrive on mountains when towing and see if that has an impact. It would probably help to have a more accurate means of getting temperature such as an OBD-II scanner or a laser probe, It's hard to tell what the H means, does it mean the truck is creeping up to 220? Or 240?

 

[Hans3T]

Great stuff everyone, thank you all.

Just moved to my new place and cell reception is awful so internet via the phone is hard to get. No internet in the house until next week. I hope to answer all of your questions/statements soon.

Un-hitched the U-Haul today and got the truck up to 70 for a few miles and the temp guage seemed right as rain. Needle pointed right at about half way.

Who can say for sure. A trip to the dealer is more than likely in order, but still have some things to do around the house first.

Thanks again all...I'll keep this updated as it develops.

PS: Hunner, my phone internet couldn't load your pix, but I will check asap!

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[Hans3T]

PPS: As for overdrive - is there a way to disengage it? Or is simply shifting out of "D" the only way?

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[MaxPF]

Shift to "3" to inhibit OD. If the shift schedule is like any other GM vehicle, it should drop out of OD on hills anyway. Does it hunt between 3rd and 4th? Can you tell if the TCC is disengaging? A slipping or non-engaged TCC will make a lot of heat.

 

[Mr_Rich]

PPS: As for overdrive - is there a way to disengage it? Or is simply shifting out of "D" the only way?

Use "3" instead of "D". GM used to use a 1, 2, D, and D with a circle around it to indicate overdrive. My work truck was a 2500HD and it had a tow/ haul button on the column shift and no OD indicator on the dash. It was strictly 1, 2, and 3 as indicating forward gears.

I'd recommend using "3" all the time instead of "D" You have the advantage of keeping the engine in the powerband when driving around town. When you get on the highway shift to "D". I don't think you'd notice any mileage difference driving around town.

 

[SC_Hummer_Guy]

Hans if you need a Scan Gauge I have one in my garage! I can bring it up next time I'm in NC to see the gf's dad now that I know where your at. Freaking trying to keep that a secret, what a silly thought! Lol

 

[Hans3T]

So they truck has been doing fine the past few quick jaunts around town and drives of up to 60 miles. However, today in 95 degree temps driving for about 35 mins with the a/c on I almost hit "H" again.

I guess I'll be calling the dealer in Wilmington tomorrow to schedule an appointment. Sheesh.

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[Hans3T]

Hans if you need a Scan Gauge I have one in my garage! I can bring it up next time I'm in NC to see the gf's dad now that I know where your at. Freaking trying to keep that a secret, what a silly thought! Lol

Hahaha! That'd be great. By all means, I would appreciate that a lot.

I think my Flashpaq is supposed to read codes, but I can't figure it out.

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[4speedfunk]

Get a coolant test kit (hydrometer) and check the coolant/water ratio (specific gravity). Coolant actually de-rates the cooling capacity of the water, and running too much coolant will make the motor run hot. You should only run enough coolant in your water to satisfy the winter freeze protection in your area. I run mine to meet a -5F degree wintertime temperature. Adding more is just wasting coolant and further de-rating your water's ability to transfer heat. I mention this because sometimes people "top off" their cooling systems with straight coolant, and over time...you can end up way past the optimum ratio. I've seen people try to run straight coolant, and they usually don't get three miles down the road before they overheat. Most auto parts stores now sell pre-mixed 50/50 coolant...which IMO is still way too much (unless you live in Alaska). It should be closer to 70/30 for us guys here in the midwest.

Dextron provides boiling and freezing protection, corrosion protection, and lubrication for your water pump. Water does the cooling.

 

[alrock]

I've thought about using a higher water to coolant ratio but have been concerned that it would likewise de-rate the corrosion protection benefits of the 50/50 mix.

 

[Hans3T]

Looks like I'm going to be dropping the truck off at Rippy Caddy/Hummer tomorrow. I called them this morning and said they'd be happy to take a look at it. The truck hit "H" again today just sitting in traffic, so hopefully they'll fix whatever is going on.

 

[Mr_Rich]

So far my 3T stays at the second hash mark and doesn't go any further. When the weather is unbearably hot my Chevy pickup would run hot in traffic or when climbing grades. It would cool down as soon as I was able to get back on the highway or in moving traffic. I thought this was the case with your truck, but it sounds like it is getting way too hot like there is a blockage or the fan clutch stopped pulling air through the radiator. I wouldn't want to speculate on any worse case than this. It will be interesting to hear what happens....

 

[MaxPF]

Get a coolant test kit (hydrometer) and check the coolant/water ratio (specific gravity). Coolant actually de-rates the cooling capacity of the water, and running too much coolant will make the motor run hot. You should only run enough coolant in your water to satisfy the winter freeze protection in your area. I run mine to meet a -5F degree wintertime temperature. Adding more is just wasting coolant and further de-rating your water's ability to transfer heat. I mention this because sometimes people "top off" their cooling systems with straight coolant, and over time...you can end up way past the optimum ratio. I've seen people try to run straight coolant, and they usually don't get three miles down the road before they overheat. Most auto parts stores now sell pre-mixed 50/50 coolant...which IMO is still way too much (unless you live in Alaska). It should be closer to 70/30 for us guys here in the midwest.

Dextron provides boiling and freezing protection, corrosion protection, and lubrication for your water pump. Water does the cooling.

You want at least 50% antifreeze in your coolant. It does a lot more than prevent freezing. As Alex mentioned, it also gives corrosion protection.

What is often overlooked is that it also raises the boiling point of the coolant. This is more important than preventing boil-over. As the coolant flows around the engine, it encounters areas in the cylinder head and upper cylinder areas that are much hotter than the bulk of the engine. If there isn't enough "antifreeze" in the coolant, it will boil on contact with these surfaces. Just like when water boils in a pan on your stove, bubbles of steam adhere to the metal surface. Steam doesn't conduct heat worth a crap, so the surfaces get hotter, making more steam bubbles, and so on and so forth. Next thing you know, you need a new head gasket.

Cliff notes: Never run less than 50% antifreeze.

 

[Hans3T]

:hans: Thank you for the Cliff Notes!! :wink:

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[LagunaH1]

*bump*

Any updates?

 

[Hans3T]

Yes and no -

The truck is in at Rippy Cadillac-Hummer and will be ready either tomorrow or Monday. I dropped the T off this afternoon and figured I would pick it up after an interview I had at 330. Well, the interview was 2.5 hours so when I got the loaner back to Rippy the service dept was closed of course.
All they could tell me was its having work done and not much else. Rippy has a certified Hummer tech, so I'm very happy about that and I know Barney is in good hands.

More as it develops...

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