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Chevy Tahoe - General coolant questiont


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Join Date: Apr 2009
Posts: 1

April 25th, 2009, 9:37 PM   #1  
Junior Member
Chevy Tahoe - General coolant questiont

Hello,

My friends Tahoe seized up this morning when she was going to work. I'm not a experienced auto technician, but I know the basic and I am an experienced aircraft mechanic, so I took a look.

I found, what I believe, to be the engine coolant intake fitting is completely corroded. There is no coolant left in the over flow tank, but I can see some inside of the radiator. I am not sure how to measure the proper amount of coolant from the radiator it self, given no marks on it. If anyone could shed light on that, that would be great (do I need to be at the proper mark in the overflow tank, to have proper coolant levels?)

I did a little research and found that it is a common problem to have the coolant intake manifold fail on V8 GM vehicles that use DEX-COOL. So I am pretty sure this is my problem... as long as that is the intake for the coolant. It is the largest rubber hose going into the block via a metal fitting screwed into the block. The metal fitting is completely corroded through. Seal in the fitting must have gone a long time ago, fitting has actual holes going through it.

MY MAIN QUESTION is can I just replace this fitting, refill the coolant, and be good to go? Or does the system need a complete flush? I read that it is bad for DEX-COOL to get into the engine for it can corrode the head gasket seals... That doesn't make sense to me personally, I thought the coolants point was to get into the engine to cool it. Any light on that would be appreciated to.

Also, if anyone has any good part websites (preferably with online diagrams) that would be awesome.


Thank you for taking the time to read my post and share your knowledge!

Vehicle is, I believe, a mid 90's tahoe.

 
Join Date: Apr 2009
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Orange County, CA

April 25th, 2009, 11:29 PM   #2  
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I would flush it all out and add new Dex cool. As far as the engine seizing, anything could have happened, hows the oil? Did it lock up or it just quit running? Might want to have it checked by the dealer to diagnose the entire engine,compression etc... check for warranty & recall info too. Worse case just get the list of probs from the dealer and repair anything you can yourself.

Thats just my opinion though, good luck!

O yea, welcome to the forum!


Last edited by Mike Sigmond; April 25th, 2009 at 11:35 PM.
 
Join Date: Apr 2006
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KC, MO area

April 26th, 2009, 12:57 PM   #3  
Administrator
Welcome to the Tahoe forum. What year is the Tahoe?

 
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Bowie, MD

April 26th, 2009, 4:41 PM   #4  
Super Moderator
Professional Mechanic
If the engine "seized" fixing the coolant leak will not mak it run again. I would assume it began to over heat and she kept driving untill it quit?

 
Join Date: Apr 2006
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KC, MO area

April 26th, 2009, 9:42 PM   #5  
Administrator
BTW I forgot to mention that the radiator should be full and the HOT/COLD level marks are on the overflow reservoir.

 
Join Date: Apr 2009
Posts: 62
Raleigh, NC|Charlotte, NC

April 26th, 2009, 10:03 PM   #6  
Professional Mechanic
It's true...if the engine did actually seize, you'll have to focus on fixing the engine first. However, if you were just using that as a simple expression to state that it cut off on her but is fine now, then were good!

To answer your questions:
Your radiator should be full...fill it up as much as it can go, and you should have the reservoir up to the full level. Just keep in mind that the radiator may look full but after taking the cap off you'll see a little slit in a piece of plastic that dips down into the coolant...fill up until the level is up to the slit. And NEVER take the cap off when the engine is hot, you can check when it's safe by squeezing the hose that goes to your thermostat...if you can barley squeeze it, give it some time to cool off and if the hose is hot, you should wait some to take it off.

And the hose that you explained that attaches to something that appears corroded sounds like the hose that goes to the thermostat, this should be the one on the top of the engine, you can change out the metal housing you're talking about and while you're at it, should change the thermostat. After changing this out you'll need to change the thermostat gasket and apply a glue/seal solution. Let this dry for 20-30 minutes...I always wait an hour though. It's hard to say its truly the thermostat housing without a better explanation, you should post some pics of what is wrong. But the seal can go bad after a while...but the thermostat usually goes bad before the seal.

There is a chance that the coolant is spewing out through the thermostat housing. Take a good look and try to determine if its leaking through there. If so, just change that out, fill up and you should be good to go. If the car is overheating after replacing this, check levels...if levels are okay your head gasket can be blown. Because there's no telling how long the car was driven hot.

On my 1997 Tahoe I had to change my lower intake manifold gasket. I had so much coolant leaking out one day. If your lower intake manifold gasket is bad it would usually leak out through the bottom of the engine and you'll see coolant coming out from the rear of the engine bay by the passenger side. Your starter, sway bar and engine oil pan could be wet with coolant as well. Fixing this will run you around $600 in labor and parts.

An easy way to determine if you have coolant in your oil is to take the oil cap off and if it has beads of water/coolant on the underside , there may be a leak somewhere and should take it to a shop. Also, the exhaust smoke would be colored.

If you need more info, just let us know!

 
Join Date: Jan 2013
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January 8th, 2013, 5:02 PM   #7  
CF Beginner
coolant light on

Every two weeks my lights come on low coolant when i put coolant in the over flow bottle lights goes out there is never any leaks on the ground had it in a dry garage there were no leaks on the floor the heat in my truck still works good what i need too know where is the coolant going that every two weeks the light come on and the bottle over flow is empty please help thank you.

 
Join Date: Apr 2009
Posts: 62
Raleigh, NC|Charlotte, NC

January 9th, 2013, 8:27 AM   #8  
Professional Mechanic
What year is the Tahoe and how many miles does it have? You need to go to a shop and have the system pressure checked. You may have a bad head gasket. The coolant can slowly be leaking into the cylinders and expelled through the exhaust.

Quick and easy (but not very scientific) test...put your hand up to your tail pipe for a moment and smell and taste the condensation left on your hand. If it tastes sweet...then you have an issue. Double check the gaskets around the engine and make sure there isn't a very slowly leaking gasket.

Update us with more information.

 
Join Date: Apr 2006
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KC, MO area

January 9th, 2013, 11:53 PM   #9  
Administrator
Welcome to the forum.

Other possibility is, depending on what year it is, the coolant is finding its way into the oil.

 
Join Date: Aug 2008
Posts: 40
Archdale NC

January 10th, 2013, 5:23 PM   #10  
CF Junior Member
I'm not sure what years are included,but there was a recall due to bad casting of heads.our 04 had a bad head that was replaced under warranty..


Last edited by schlepprock379; January 10th, 2013 at 5:28 PM.
 
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