Lower Intake Manifold Surface – Chevy Blazer 2001

[fcobob78]

Hello,

I’m in the process of replacing the lower intake Manifold Gaskets on a Chevy Blazer 2001 V6 4.3, with about 130k miles on it.

I discovered after cleaning well the surfaces that the lower intake manifold has a substantial amount of pitting. I’m thinking this warrants a machine work?. I would like to hear people’s experiences with this. I read about smearing RTV silicone in this area, but the gasket instruction does not recommend this. Looking at the surface, it looks pretty beaten down, so I’m guessing a machine work is in order?

The surface of the block has some pitting but is not as bad as the lower intake, so I’m thinking on leaving this alone or using the RTV smearing method.

Another question is regarding the two rear coolant passages. Why does GM seals these passages? It doesn’t seem like the block had any seals, but rather was filled up with gunk when I cleaned. Just curious on why these are sealed. Is there any type of cement paste kind I can put in here to bring the sealed surface back to matting surface level? That surface looks pretty beaten down as well.

Hope the attached pictures help and I would appreciate any advise on machine vs silicone

Thanks,

Francisco

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Topic

[Glenn]

You could take this to a machine shop and let them have a look. Honestly, this is fairly minor cavitation. The way this is usually addressed is by using a very thin skim of black rtv silicone in these areas. Last year, I took the intake off my 3.4L to the machine shop. The cavitation was on par with the pictures you posted here. The owner said it did not warrant addressing and recommended the above to address the issue. I’m sure you’ll get plenty of input from the community here. To me, it looks like minimal cavitation. I’d reinstall it as is. I’m unable to address the sealed coolant passages. I honestly don’t know an have wondered the same thing myself.

[Stephen Bowen]

Did the same procedure with my Bronco II’s intake. Pitting in the same areas.

I just gave it a very light coating of RTV black and made 100% to follow the EXACT method to torque the intake bolts down.

S-

[none]

If your gaskets are any good, they’re going to be metal framed with formed rubber gasket material to seal all the crucial areas. That rubber should be really pliable as is and it’s going to get compressed on assembly. The gaskets should seal just fine. Just do the common sense stuff here. Clean gasket surfaces, which it looks like you’ve already done well. And then follow your torque sequence with the right spec. I think it’s 11 ft lbs IIRC.

[EricTheCarGuy]

I do NOT recommend you use RTV to seal those areas. You may end up creating more issues than you solve. Honestly, that’s normal. If you look closely you can see where the gasket actually makes contact and those areas look OK to me. I say install a good set of gaskets and torque everything to spec and you should be fine. You could also consult a machine shop on this but I’ve personally reused metal like that in the past and didn’t encounter any issues.

Good luck and keep us posted on what you decide to do.

[fcobob78]

Thanks Eric…you are the man and I trust your word :). I will get back on the garage and reinstall and pray that all is good :). It is my first big job like this. Will keep you posted and I hope my follow up would be no more leaks 🙂

[Stephen Bowen]

Re-Install?

You do understand that if you have already installed and torqued down the bolts–you will need to purchase a brand new gasket. Installing any gasket will compress the material. It should not be reused.

Just a heads up. No matter which procedure you choose, we just want to see your success.

S-

[Glenn]

I would only add, as you intend to follow Eric’s advice, don’t cheap out on the gasket(s). Go with OEM equipment or something reputable (like FelPro gaskets. This isn’t a job you want to turn around and do again in a couple months. Best of luck with this…

[fcobob78]

Sorry. When I meant re-install I meant put everything back together with a new gasket on. I think I bought a good quality FELPRO type gasket.
So, I set the lower intake already, now I need to put the rest. However, I bought a cheap torque wrench 1/4″ drive in-pound (Freight Harbor) for the first low torque sequence and this torque wrench was crap. I didn’t get the feel and didn’t realized how low torque this was and the torque wrench never gave me the warning :(. So, for the the first bolt, first sequence I went beyond this and moved to the 2nd bolt and followed the rest trying to get it close to the spec as that torque wrench was not any good. Then I kept following the pattern and sequences for the higher torque specs, but now with my good old 3/8″ drive torque wrench. I just hope going beyond torque on the first bolt didn’t ruin the gasket or warped it uneven. I would really hate to come back and do this job again. Will keep you all posted. Thanks for the help.

[Dorman]

[quote=”fcobob78″ post=111366]I didn’t get the feel and didn’t realized how low torque this was and the torque wrench never gave me the warning :(.[/quote]

I have the 1/4 torque wrench from Harbor Freight as well. It doesn’t have a distinctive click when it reaches the selected torque. That one has more of a give/freeplay feel when you reach the torque. The 3/8 and 1/2 have the click sound.

The 1/4 torque wrench is in inch pounds not foot pounds. Hopefully you translated the torque spec to inch pounds from foot pounds.

+1 on FelPro Gaskets I’ve had good luck with them.

[fcobob78]

Thanks. Yes, I noticed that as well. No click sound. I got that torque wrench just because allows inch-pounds and all the specs are in inch-pounds. I then converted the higher torque to foot-pound in order to be able to use the 3/8″ one.
After further inspection I realized that some of the bolts heads at the outer edges are not flushed with the surface of the manifold. I don’t want to go beyond the torque spec. Is this normal because of the new gasket or maybe excessive RTV on the edges? I did chase the threads to clean the debris and the bolts are brand spanking new. I also applied the medium strength blue gel sealant on the threads of the new bolts.
Should I tighten these bolts until they are flushed?

[fcobob78]

Update: OK- Here is an update. Help! I was not feeling happy with the bolts not going in, so someone told me I did not clean the threads well and decided to do the job again to get it right while everything was disassembled.
I chased the threads and notice some resistance on some. When I got to the last snap! Thread chaser broke in the hole :(. This is turning into a nightmare. Why this happened? The threads were damaged that’s why the bolts were not going in all the way smooth? Like I said most of them show resistance, but this last one was the worst.

Now I’m facing the challenge of getting that broken thread chaser. Tried the easyout thing, but not very successful, to be honest I never got these things to work as supposed. Now I’m thinking on keep drilling carefully until the broken bolt comes out in pieces and then use a tap of the same size to restore the threads? Any ideas how to solve this are much appreciated. Thanks

[Stephen Bowen]

It’s official. That sucks.

Can you take a picture of the affected area so we can get a better idea of what we are up against?

S-

[Its me]

Sorry if this may come too late, but never too late to learn…. Put a rag over the holes and blast the holes with shop air from an air gun before you chase threads….

As said earlier, post pics and we’ll all try to help…

This thread may help as well…

http://www.ericthecarguy.com/forum/18-The-EricTheCarGuy-Video-Forum/49344-removing-broken-fasteners

-Karl

[fcobob78]

YUp. I always seem to learn the hard way :(. BUt that’s how I should take it I guess as a learning experience

[Its me]

Good attitude!!!

You will ALWAYS pay for an education… One way, shape or form… You will never make this mistake again I am sure…

Now, if I can help, I would advise a left hand drill bit to get it out…

A Carbide burring bit can level the drilling surface to get a center hole to get a left hand drill bit on it…

If you have only the prong sticking up above the surface, then try to get some vise grips or a pipe wrench on it… if you can’t get a grip you will need a small carbide bit to get into the hole to make it level… Then you can begin to attack the problem with a left hand drill bit…

Pics of carbide burring bits…

JMHO

-Karl

[Author]

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