Chevrolet Suburban Runs hot unless thermostat is upside down

skmay01
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Joined: Wed Jan 16, 2013 9:31 pm

Chevrolet Suburban Runs hot unless thermostat is upside down

Unread post by skmay01 » Wed Jan 16, 2013 9:35 pm

i just did a topend on my stock 350 suburban, now the engine runs hot when the thermostat is positioned properly , now have to run it with the thermostat upside down ... WHY???

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ProTech
Posts: 651
Joined: Wed Oct 17, 2012 10:08 am

Re: upside down thermostat

Unread post by ProTech » Thu Jan 17, 2013 8:54 pm

Well, first of all, putting the thermostat in upside down is basically defeating the purpose of the thermostat itselft. If the truck is running hot with the thermostat in the correct way, are you sure you just don't have a bad thermostat? Otherwise, if it ran at normal temperature before you did the top end work, I'd have to say it's something you did during your repair, or lack of repair so to speak. There is no real reason other than something being messed up. Maybe try a new thermostat, installed correctly, and see what happens. If it still gets too hot, you'll have to recheck your previous repairs.
GM Dealer Technician For 18+ Years
In the automotive industry for 20+

skmay01
Posts: 3
Joined: Wed Jan 16, 2013 9:31 pm

Re: Chevrolet Suburban Runs hot unless thermostat is upside

Unread post by skmay01 » Fri Jan 18, 2013 11:45 pm

I bought the truck with a blown head gasket and full of stop leak. Repairs are by the book. I boiled the new thermostat to see if it was opening correctly, at full boil it opened only about an 1/8 th inch , it is a standard 195 degree t stat , could you tell me if that's typical or faulty?

skmay01
Posts: 3
Joined: Wed Jan 16, 2013 9:31 pm

Re: Chevrolet Suburban Runs hot unless thermostat is upside

Unread post by skmay01 » Fri Jan 18, 2013 11:56 pm

I'm also wondering what can go wrong with my gasket job , I'm not trying to be smart , but its a pretty easy job , definitely not my first repair ( or lack of repair ) I'm asking because it doesn't make since to me thermostats open when the engine gets to temperature , if its not opening enough its a problem, but thanks

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ProTech
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Re: Chevrolet Suburban Runs hot unless thermostat is upside

Unread post by ProTech » Sat Jan 19, 2013 12:50 pm

I'd be weary of anything that previously had stop leak added to the cooling system. That crap will do nothing but clog up cooling ports in the block and heads.

And there's plenty that can go wrong in an 'easy' gasket replacement....wrong gaskets, debris getting in somewhere, not a good enough cleaning of the deck surfaces, wrong torque specs, etc. Everybody makes mistakes, not saying you did that here, but it's always worthwhile to go over your work. Since I don't know your technical ability, I have to mention all the possibilities, even to the schmucks that can't fix a thing. And on that note, I do have to ask...you are installing the thermostat correctly right? Maybe you're putting it in backwards when you think it's the correct way, and vice-versa, which would obviously cause a problem.

All in all, you've probably got a crap motor.
GM Dealer Technician For 18+ Years
In the automotive industry for 20+

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