Intake Manifold Gaskets

[bbeck]

I just tore the girlfriend's 3.4 apart and found that the LIM gasket was definitely leaking. I had her buy the gasket kit from autozone. Now, I'm wondering if there's anything else I should do while I have the intake off? How often do these LIM gaskets go bad?

[SappySE107]

Do it properly and it will last a long long time. http://wot-tech.com/shop/articles/la...cs/cat_66.html Do a search for lower intake manifold bolt to get the specs. Be sure to clean the bolt threads and apply a thread locker to keep them from backing out.

This is all assuming the 3.4 is a 3400.

[bbeck]

it's the DOHC. I've done the single cam 3400s many times

[SappySE107]

Ah yeah, DOHC section. I clicked off the main page and didn't even look. The DOHC lower gaskets go bad after 100k miles usually so nothing too special there.

[bbeck]

I'm not sure of where my manual is at the moment. Does someone have the torque specs on the 3.4 dohc intake manifold gaskets?

[bszopi]

http://60degreev6.com/content.php/129-3.4L-%28DOHC%29-Specifications

[pocket-rocket]

Now, I'm wondering if there's anything else I should do while I have the intake off?

Replace the short 2-2 1/2" section of heater hose that hooks to the bottom of the TB and replace those stupid squeeze clamps with regular worm gear clamps. This is if it's a 91-95 engine. I forgot how the TB coolant line goes on the 96-97 cars atm. Also inspect your distributor plug for oil leaking since all 60v6's are prone to it leaking. If it's leaking I've used a Chevy 350 distributor gasket and some black silicone to seal it up, SofaKing did his a different way and I forgot what he used, but last I heard it held. These are just patch jobs though (but do usually hold for quite some time). The real way to fix it requires removing the rear head to do correctly...

[Schurkey]

Check the brake booster vacuum hose; sometimes they deteriorate at the engine end.

[bbeck]

Well, I ended up replacing the vaccuum hose in the valley under the LIM- that thing was so old and deteriorated that it fell apart when I grabbed it to twist it off. Other than that, I fixed a couple of small vaccuum leaks that couldn't be seen at the firewall before under the UIM. Also replaced the thermostat while I was in there. The car fired right up and runs better than I've ever seen. Next, will be the timing belt. Wanted to do them both at the same time, but she couldn't afford it and it desperately needed these gaskets. The poor DOHC liked to bounce off the rev limiter when started once in a while. It was definitely leaking at the lower gaskets- you could see it after it was apart.

[bbeck]

She's now been driving it for a couple days, and it runs great- I'm sure the mileage will increase as well. The only issue is that the motor will die once in a while if you apply the brakes farely hard and sudden.

[RollinonZ34]

Vacuume Hose

She's now been driving it for a couple days, and it runs great- I'm sure the mileage will increase as well. The only issue is that the motor will die once in a while if you apply the brakes farely hard and sudden.

If you did not get to it, another common thing is you need to replace the Vacuum Hose coming off break booster. Those things get soft and suck in when breaked not letting it do it's job. Might be the problem, but they are cheap and easy to replace. did mine and a world of differance.

P.S. I sure hope you took the time and did what pocket-rocket sugessted with the distributor plug O-ring or gasket replacement after you had it apart that far...Perfect time to do it cause it's not if, but when that damm thing starts to leak.

[bbeck]

I already had the intake on by the time that I saw his post about the o-ring. So, hopefully she holds for now.. I'll check into that brake booster line- and get it done this week if I can get one. Thanks

[BERTZ34]

my manual says i.m. to cylinder head 1995 22 ft lbs, 1996-97 116 INCH lbs, plenum to intake. 1995 22 ft lbs, 96-97 19 ft lbs. i just lost my intake manifold gaskets. i heard a poof with some steam and i had coolant draining into the valley so yea thers ya torq specs.

[RedZMonte]

thoes specs sound about correct BUT i thought they where inch/lbs not ft/lbs.. I have always just snugged them up so they felt good without crankin on them and have always held. thoes O rings are a whore.... And thats all i got to say about that... but you should see if they are puking oil out it will leak all over the block and trans, just clean it really well and keep an eye on it.

S

[BERTZ34]

the book specifies inch lbs or ft pounds its all good! i just snug them up too make sure the threads are clean! had to helicoil a plenum bolt stripped out cuz some sh*^ got in it.