97 Jimmy - Broken Thermostat Housing Bolt

crford · #1 04-22-2006, 04:07 PM

So, I was planning on doing a quick thermostat replacement on my 97 Jimmy, and seem to have screwed myself pretty good. The nut looks to be almost welded to the bolt, so I shot it with everything that I have to try to loosen it up. I was only using an open end wrench, and I'm not a great big body builder, but the bolt seems to have broken off in the housing somewhere. I haven't pulled it all the way out, as it seems to be threaded into the housing apparently. I haven't tried the other bolt, because I don't want to totally ruin my day.

What are my options for that bolt? I can't, by some strange twist of fate, get the other half out of the bottom of the housing can I? Am I going to have to drill and tap it and try to get another bolt in there? I don't really want to spend $500 to replace a $9 thermostat....

blazee · #2 04-22-2006, 04:17 PM

You haven't messed anything up. There's not a bolt, it's just a stud with a nut attached to it, which functions like a bolt. It goes through the housing and threads into the intake. The stud can be removed and reinserted with no problems.

Markgc · #3 04-22-2006, 04:22 PM

I don't know your engine in detail but I am assuming the you have a stud screwed into the inlet manifold and a nut screwed onto the stud. You may have a long bolt screwed into the manifold instead

You really need a good socket. An open ended wrench isn't a great idea. You need to get the other nut/bolt off. I would soak it with WD40 and then use a socket and t bar on it. A jarring or rocking force will often work where a sustained force will just shear off a bolt. That is why air tools are effective. Failing that you can try hitting the t bar with a lump hammer to try and jar the other nut off. No guarantees that that one won't sheer off too. Once you have the second nut of then you can set about getting the thermostat housing off. Tapping on it with a hammer and using a piece of wood to avoid direct hammer to metal contact may help. You don't want to put anything between the gasket surfaces if you can help it. Once you get the thermostat housing off then you may be lucky and find that the stud has broken off leaving some exposed stud sitting proud of the manifold threaded hole.

Let us know what you find. Go slowly and avoid damaging the more expensive and difficult to replace parts. Damage the thermostat housing but treat the manifold very careful. It will be an expensive part.

Mark

crford · #4 04-22-2006, 04:46 PM

Some days it's good to feel like a moron, and today is one of those days. Right after I posted this I went back out to survery the damage and look for options. I went ahead and took the bolt the rest of the way out and realized that it isn't a bolt at all. It's a nut/bolt stud thing like blazee said. I feel much better. My only real loss was one good pair of underwear.

Thanks for the help guys. This forum rocks.

crford · #5 04-22-2006, 04:49 PM

Oh, and sorry about multi-posting the question.

Totally uinrelated, but do you happen to know what the round thing with the wires coming out of it that is directly to the right of the thermostat housing is, and is it supposed to be full of soot when you remove it to get to the thermostat housing bolt?

Did I mention that I don't know anything about cars? I'm a computer engineer and I have the "i'll figure it out mentality."

Markgc · #6 04-22-2006, 04:59 PM

Excellent - sounds like the stud came out with the nut attached to it. I would unscrew the nut from the stud and clean and lubricate up the top threads. You can grip the stud on the unthreaded part - never grip on a thread as you will damage it. Once you have done that then you can lock 2 nuts together in the middle part odf the threaded section using two wrenches and scew the stud back into the manifold using one wrench on the top nut. You can then unlock the 2 nuts using 2 wrenches and easily unscrew the 2 nuts off the studs which is now tight in the manifold.

If you are going to do more work on your vehicle then it would be a good idea to get a decent shop manual for it. At the price of mechanical labor, the manual will soon pay for itself. It beats reading pc manuals anyway LOL

Mark

blazee · #7 04-22-2006, 05:00 PM

Quote:

Originally Posted by crford

Oh, and sorry about multi-posting the question.

Totally uinrelated, but do you happen to know what the round thing with the wires coming out of it that is directly to the right of the thermostat housing is, and is it supposed to be full of soot when you remove it to get to the thermostat housing bolt?

Did I mention that I don't know anything about cars? I'm a computer engineer and I have the "i'll figure it out mentality."

Do you mean the EGR valve?:

It should be dirty inside. If it gets too much or chunks of carbon in there, it could cause improper operation. It's a good idea to clean it out with some carb or brake cleaner ocassionally and install a new gasket. The gaskets cost less than $2.

Markgc · #8 04-22-2006, 05:02 PM

Is it soot or just dust and engine grime?

blazee · #9 04-22-2006, 05:49 PM

Quote:

Originally Posted by Markgc

Is it soot or just dust and engine grime?

The EGR valve sends exhaust gas back into the intake. The build-up is a combination of the combustion byproducts that were once suspended in the exhaust gas:

crford · #10 04-22-2006, 09:15 PM

Dang blazee, you're the man. That's exactly what I'm talking about. I took it off to get the thermostat out, and dusty, carbony soot came out of it. Which, according to your chart, looks OK. But I bet it's never been cleaned. I know I haven't cleaned it, and I've had it since 2000. But it didn't have a gasket on it, unless it's really stuck and doesn't look like a gasket... I'll get some carb cleaner and clean it up. Is it OK to just squirt it up in there? Is there anything I need to be careful of?

And Markgc, it wasn't really a stud with a nut on it, it's a stud and nut combo. All one piece. Just enough to fool you. And I have a Hayne's manual that says that it's two nuts and bolts, which is why I thought I had broken it. Is there a better manual that I can get, because I think I'm going to be doing quite a bit of work on the Jimmy in the near future. It's starting to run pretty bad.

Thanks again for all of the help guys.

Markgc · #11 04-22-2006, 09:55 PM

If you don't mind spending the extra the factory manual is always worth having since it will cover your model in great detail. I have the factory manuals for all my vehicles. The first hour of a mechanics labour that you save will pay for it.

Mark

blazee · #12 04-23-2006, 08:29 AM

Quote:

Originally Posted by crford

Dang blazee, you're the man. That's exactly what I'm talking about. I took it off to get the thermostat out, and dusty, carbony soot came out of it. Which, according to your chart, looks OK. But I bet it's never been cleaned. I know I haven't cleaned it, and I've had it since 2000. But it didn't have a gasket on it, unless it's really stuck and doesn't look like a gasket... I'll get some carb cleaner and clean it up. Is it OK to just squirt it up in there? Is there anything I need to be careful of?

And Markgc, it wasn't really a stud with a nut on it, it's a stud and nut combo. All one piece. Just enough to fool you. And I have a Hayne's manual that says that it's two nuts and bolts, which is why I thought I had broken it. Is there a better manual that I can get, because I think I'm going to be doing quite a bit of work on the Jimmy in the near future. It's starting to run pretty bad.

Thanks again for all of the help guys.

Yeah, it's okay to squirt it in there, just don't go crazy and spray it all over the electrical componets.

As for the manual, check out http://alldatadiy.com For $25, you get everything the factory manuals have and more.

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