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2004 Avalanche overheating issue

Toqwik

Full Member
Joined
May 10, 2019
Messages
17
Greetings all. About 5 months ago the old girl started loosing water. Discovered the weep hole was draining so I had a new water pump put in it. Don?t know if they did a thermostat at that time. All has been fine until this week. I live in Florida and the temp has always been rock solid at 210. No mater how hot or whatever I am towing. Anyway this week I noticed the gauge climbing. That night I added some water and figured all would be good. Drove to work in the morning and all was good but it was cool out. On the ride home it was 93 and began heating up. It never got to the 235 mark but close. By the time I got home it had split the seam on the overflow tank, but never puked out the overflow hose. I stopped and bought a radiator cap hoping that was it. Next morning fine again. Yesterday evening was a nightmare again. Doesn?t do to bad as long as you are moving but stop and go get warm quick. Fan seems to be working correctly. I can let it run in the driveway for an hour with the ac running and it?s fine. When you drive it in the heat of the day is when it has issues. So the truck is 2003 1500 4x4. 185k, rebuilt trans and transfer case a year ago. Original motor with no major work ever performed. Never wrecked. Never seen the temp gauge change no matter what. Where should I start?
 
Given the truck is a 2003, the very first thing I would do is replace the old engine fan clutch with a new severe duty replacement.

This is a fairly easy and fairly cheap repair and can be done as a DIY project, for most people.

I have replaced the fan clutch in my 2004 twice since I have owned the truck.

Each time to maximize the a/c performance before a busy summer driving season.

Even though the fan may "appear" to be working OK, a good fan clutch will go a long way toward keeping the engine cooler at idle and in stop and go traffic.

A new fan clutch will also make your a/c system much colder at low speeds and idle.

A worn out fan clutch will obviously allow the engine fan to spin, but does not allow it to spin with greater force when it is needed, like at idle, slow speeds and when the outside temperature is high.

A brand new, severe duty fan clutch will made more of a fan "roar" when the engine is cold and when the need for more cooling is required.

Do not worry that you get more noise when you first start out for the day.

That is normal and the fan will quiet down as the clutch and engine reach normal operating temperatures.

Others may chime in and suggest converting over to electric engine cooling fans.

Not a bad idea if you are so inclined and capable of doing the modifications required.

Easiest thing to do is just replace the old worn out fan clutch with a new severe duty fan clutch and be done.

And my truck holds a solid 195 degrees in the heat of summer with the a/c running, all day long, regardless of the speed.

Standing still or running at highway speeds.

The temp may climb 10 degrees or so if I am towing my 25' party barge in the middle of summer down the freeway with the a/c running.

The engine in my truck is the LQ9 6.0 liter HO engine with all wheel drive with 227K miles.

The new severe duty fan clutch will make all the difference in the world.
 
Did you really put water in it. ???
 
Yes I put water in it. No use to put coolant in it to just puke out a few minutes later. I think I have it fixed. I found that the thermostat was sticking. I have the heavy duty clutch fan and I guess it was helping to cool it with the thermostat partially open. That?s a crazy design putting the housing down low on the engine so sediments can get in it. Anyway put a new thermostat and housing and replaced the overflow tank. Flushed out the radiator and added coolant. Low 90s yesterday and it ran fine. I need a couple more warm days to confirm it?s fixed but as of now it?s doing what it is suppose to. Off to the next task, tackling some oil leaks.
 
That's good to see, water is the last thing you want to add
 
Well I guess I celebrated too soon. Just to update it had a new water pump put on about 5 months ago. This past few weeks I have put a new water neck, thermostat, and clutch fan. Heavy duty. Full of coolant. Also replaced the cap and overflow tank. Does ok as long as you are moving but in stop and go it still is heating up. Even if you drive it for a while and all is good, you can park and let it run and it will slowly climb. So I?m down to either a radiator, a clog, or something else weird. But there is one thing. The truck is missing the air deflector on the top of the radiator. Some call it the radiator support cover. Could this possibly be the root issue?  Going on a trip soon and need to get this fixed. Thanks!
 
Toqwik said:
... The truck is missing the air deflector on the top of the radiator. Some call it the radiator support cover. Could this possibly be the root issue?  ...

I had a 1985 Trans Am many years ago and I knocked off the lower air dam, by accident.

That car immediately began over heating whether it was sitting still or rolling, even with the electric fans running wide open.

I replaced the missing air dam and the overheating problem went away instantly.

So, I guess those things are there for a reason.

Replace the fan cowling and see what happens.

Looks like you have covered everything else.

Your symptoms sure sound to me like a bad fan clutch, but you say you have already taken care of that.

So, there must be another problem with air flow.

Let's go with the fan shroud.

(y)
 
The only thing that puzzles me is I have owned this truck for 3 years and I?m fairly sure it has never been there. The only other thing I can think of but I?m tired of throwing parts at it and getting the same results.
 
Are the little flapper things at the bottom of the radiator on(Behind the bumper). They direct air thru the radiator also.

Fans have very little effect above 45 MPH, above 45 mph they will be turned off if you have electric fans.

A few years back my electric fans burned out on my car while I was down at the Derby of course it was Sunday so I could not get them fixed, drove all the way back to Michigan like that as long as I stayed above 50 it was fine.
 
I?m tempted to grab some cardboard and duct tape and make a makeshift cover to see what happens. It seems to be fine as long as you are moving over 45, it just gets warm in traffic. That makes me think more of this is related to this shroud piece. I would think if the radiator was bad it would act up all the time.  But I am not a professional mechanic. Need your advice.
 
OK I'm curious when you changed the thermostat how did you refill the engine block. burp
 
To be honest I took it to my usual repair shop. I work too many hours and just don?t have time to mess with it during the week and it?s my only vehicle. Think it might be trapped air?  I have put a few hundred miles on it since then.
 
Yeah I was looking at all angles of what it could be, you would have had to open up something on the cylinder head to get all the air out.
 
You don?t think after a few hundred miles it would have forced the air to the overflow tank?
 
Yes, driving 200 miles should have bled the system.

Yes, you need the air box/dam/guide that directs the air flow through the radiator. Without that piece it's like trying to suck through a straw but your lips can't aren't allowed to touch the straw. You just can't make any pressure without the seal. However, I cannot explain why it wasn't a problem 5 months ago, except 5 months ago (December) ambient temperatures were lower. Good luck toqwik
 
Can you post a pic of the how it looks without air deflector?
TO ensure we are all on board with part is missing.

If you are missing anything that goes around fan then that is your issue and should be called FAN SHROUD.
THis is what makes a fan efficient at moving air. without it air is sucked from above and below and not from in front of radiator.
 
It?s not the fan shroud, it is the piece you first see when you raise the hood. The plastic piece that goes from fender to fender and keeps you from seeing the radiator. It would be the first piece you would remove when pulling the radiator. This piece has the decals with emission decals and fan belt routing decals.
 
Even tough the fan clutch is new, are you sure it's working properly?  It could be a defective product.
 
frito said:
Even tough the fan clutch is new, are you sure it's working properly?  It could be a defective product.

That's what I keep thinking.

Does the fan make a pretty good roaring sound when you first start for the day?

A good severe duty fan clutch can be pretty loud at times.

When the engine is off and cold, if you try to spin the fan by hand, it will not turn very far if the fan clutch is working properly.
 
New clutch is HD and is noisier than the other and it is more noticeable than the old one, especially between starts throughout the day. I drove it about an hour this afternoon and it did fine, but not many stoplights. Stopped at a drive thru with 2 cars in front of me and it started to rise. I have about an hours drive home this evening so I am interested to see what happens. Not much traffic or lights and it is in the high 90?s right now. I ordered the radiator deflector and it is suppose to be here today. Hope that is it but not counting on it. Are there any plastic pieces between the bumper and radiator on the lower side?  If so mine is missing that as well. If I look down the front between the radiator and bumper I can see the ground. Truck appears to have some new parts on the front, possible crash in its past. But I have owned it for 3 years and never had an issue. Considering adding an electric fan to see what happens.
 
My fan shroud is just two pieces.

Upper and lower.

Both fit snug up against the radiator.
 
This is not the fan shroud I am talking about. I am talking about from the radiator to the grille. The fan shroud is intact and complete. How do you post pictures?
 
Still no success. Ordered and installed the air deflector but no luck, still getting warm. The mechanic thinks it might be a bad clutch fan so he is going to replace it again. It?s getting old having to turn the ac off and it is 100 degrees outside. I guess they are also going to do a thermal scan on the radiator tomorrow again to verify it is working correctly. Any other ideas?
 
Ask them about a air bubble idea.
 
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