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Discussion Starter · #1 ·
Hi,
I just got a 1990 Suburban and notice that within 5 minutes of first driving it the temp. gauge goes past halfway towards 220, then immediately drops down to below the halfway mark and pretty much stays there. When it first happened I put the truck in park and let it idle...and it remained cool. I checked under the hood and I have plenty of coolant.
Is this something I need to worry about?
 

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RE: Temperature Gauge Help

How is the thermostat? If it does not overheat who cares. If your driving that 5 minutes and it goes past the 1/2 way mark turn your heater on. Now don't go sueing me I no motor head, But
If it's not broken you may fix it until it is. I'm just a dumb real estate investor/ want a be motorhead. Thats my story and I'm sticking to it.
 

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RE: Temperature Gauge Help

Sounds like your thermostat is sticking when it's cold. I would replace the t-stat, and see if that makes a difference.
 

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RE: Temperature Gauge Help

Definitely sounds like the T-Stat is sticking. Keep your eye on it, but I'd definitely get it replaced before the really cold weather hits.

Kevin
 

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My dad's 94 does the same thing. I think it is that the system is so big that when the thermostat opens it cools the coolant down below what it took to open the thermostat so the temp drops just a bit.
 

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Discussion Starter · #6 ·
Thanks for giving me a place to start! I have a feeling that this truck and this forum will teach me about auto mechanics!
 

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I've seen my share of sticking thermostats, so that's my first place to start as well.
 

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Discussion Starter · #8 ·
Please forgive my newbieness, can someone please tell me how to change the thermostat? Is it as easy as changing a headlight? I really want to learn how to work on this truck myself.
 

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Welcome

jerseyfred said:
Please forgive my newbieness, can someone please tell me how to change the thermostat? Is it as easy as changing a headlight? I really want to learn how to work on this truck myself.
If you can change a headlight, (sealed beam) you can change a t-stat.

1. You may want to drain off a little of the coolant before you start. You can do this by opening the petcock at the bottom end of the radiator or loosen the lower radiator hose.
2. Pull the top radiator hose by loosening the clamps.
3. Remove the two bolts holding the thermostat housing. The tstat housing is the metal assembly that the upper radiator hose is clamped to.
4. Pull the thermostat.
5. Reverse the process to complete the project.

Notes: Consider buying the best tstat you can afford. The better quality seem to be made in Israel these days. Avoid the made in Mexico versions, I have had trouble with those. Use anti seize compound on the tstat housing bolts to avoid future corrosion/binding. Use a gasket and silicone sealant to seal the tstat housing to the block. Clean the gasket surfaces on the housing and the engine. Consider replacing the housing if the gasket surface shows heavy corrosion.

Good luck!
 

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RE: Welcome

Consider buying the best tstat you can afford.
That's great advice. Considering the tstat is extremely inexpensive by comparison to other parts, it seems silly when someone opts for the $1.69 model from the local parts shack, which is likely to fail far sooner, just to save a couple bucks.
 

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Discussion Starter · #11 ·
RE: Welcome

Thanks for the advice. Quick question. When I got the truck, the radiator was leaking pretty good. I had the radiator replaced. Would they have done the thermostat also since the thermostat housing is connected to the radiator?

Thanks
 

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RE: Welcome

No they do what they are paid to do and no more unless asked to.

My temp guage does the same thing, goes to 220 and then drops and runs at half way but I just replaced mine when I did the head gaskets this summer so I know mine is good.

The only time it ever runs close to 220 after it warms up is when I am stuck in traffic on a hot day.
 

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RE: Welcome

220 is not hot, my Fiero is made to run at that speed.

195 thermastat (sp) is a low stat now days, and don't forget the guage may be off just a little. Put a candy thermomiter on the thermastat housing and let the truck idle, then keep an eye on the guage.

As soon as you see it hit 220 on the dash guage look at the thermomiter just to be sure.
 

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Re: RE: Welcome

jerseyfred said:
Thanks for the advice. Quick question. When I got the truck, the radiator was leaking pretty good. I had the radiator replaced. Would they have done the thermostat also since the thermostat housing is connected to the radiator?

Thanks
Now that you mention the radiator being replaced, maybe there's an air pocket in the system? That would cause the temp gauge to act a little nuts...

Kevin
 

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RE: Re: RE: Welcome

Another good point. Always get the air out of there.
 

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Discussion Starter · #16 ·
RE: Re: RE: Welcome

Yah,
When I got this Burb it was pretty sick. I should have known by the low price. I've always driven Caprice wagons and have never had any problem despite age, high mileage and abuse. I should have checked it out more carefully. It looked good and ran well and a cursory check of the undercarriage (I did not know what I was looking for) showed only surface rust on the frame. I was very excited about the purchase since I really always wanted a Suburban, especially that body style.
To make a long story short, it turned out ALL the body mounts were gone due to rust and the body was only sitting on the frame without being secured. A few days after that, the radiator began leaking, then I discovered metal chunks embedded in the tires, and then it failed inspection. I was so depressed.
I was ready to walk away from Suburbans forever and made arrangements to buy another Caprice wagon (gave my LT1 Caprice wagon to my wife after her Dodge Caravan died). Then I ran into a friend whose neighbor owns a body shop. Four days later, for the price of labor only, they lifted the body of the frame, attached/welded in new body mounts and supports, 4 new tires, a clean inspection sticker and a new radiator.
However, it still has a few issues, as you can see. I definitely want to learn to work on it myself. So I really appreciate the advice and support.
How do I diagnose/get rid of an air pocket?
 

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RE: Re: RE: Welcome

Well, what I do and what I recommend are two different things. :) When I do it, I hit the radiator with a hose of cold water for about 10 minutes, cool that sucker down and open the cap. Make certain that the radiator is cool before you open the cap, otherwise you'll get 3rd degree burns. OUCH. Then I let it heat back up quickly and start to fill it back with the correct amount of water and fluid.

To be safe, I suppose you could let it cycle a couple of time and fill it back up when it's cool. But you may habe to do that a couple of times. Either way, check it when it's cool and see if it's low on liquid in the radiator.
 

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RE: Re: RE: Welcome

Air pockets typically expel themselves, as the engine runs. The air is going to rise any chance it gets, since the pump draws from the bottom of the radiator, and the block expels coolant back up through the tstat into the radiator, and air is going to be pushed into the radiator, where it will show as a low level. The cooling system is designed to prohibit air pockets from staying in the engine. The only way you could maintain an air pocket is if the engine were very low on coolant, in which case you would see a very high temp 280+ deg.

Steve's advice is very good for topping off your coolant system. I would suggest you follow his directions, any time you need to replace, or refill your coolant.
 

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Discussion Starter · #19 ·
This might be goodbye

Driving home from work today, I saw the oil pressure drop to zero. Shortly after I hear a metallic "POP" and then claterring frieght train noises coming from the engine. Check Engine Light On. Clattering and zero oil pressure all the way home.

I think that's it for me...there is a warranty on the engine...hopefully it will be honored and then after the repair I'm putting it up for sale. This thing has brought me nothing but trouble, heartache, and money down the drain.

Anyway, thanks so much for making me feel welcome and for all your support. I guess it's just not the time for me to have a Suburban right now :(
 

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RE: This might be goodbye

Wow, I'm sorry to hear that you'd have one more stroke of bad luck with your 'burban.

If I may, don't let this suburban put you off of them for good. This one was obviously abused past it's years before you ever got it. Most 'burbans are beasts that live for normal wear and tear.

Maybe you were meant to have this one, so that you could find a better one.

Not doing so good on the pep-talk huh...

Well, good luck with it, and don't be a stranger on the board.
 
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