labpuppy

Hi. I have an 1988 L98 car with almost 36K miles on it (stock). The intake manifold is nice and dry except for 1 bolt at the base. There is a little bit of oil seapage on the top side of the manifold around the bolt head; looks like the oil is traveling up the bolt). I have tightened it down a little bit more and it has lessened but has not completely gone away. The only way to properly torque it down is to remove the thermostat housing as it is in the way of getting the wrench in there.

Now for my question. I was told by a mechanic that, if simply tightening does not completely solve the problem, to remove the bolt and use a little bit of "silicone sealant" on the bolt and then torque it back on (the sealant is to keep the oil from traveling up the bolt). Not wanting to do this twice, what type of sealant have you used when installing the intake manifold bolts (at the base of the manifold) ? Have you used a sealant or did you simply torque it to specs? Also, exactly how long is this bolt anyway?

Any input will be appreciated. Thanks in advance.

65Z01

I don't use silicone sealant, like RTV, rather I prever Permatex #2 on those bolts.

Pull the bolt, chase the threads and apply a layer of sealant about 1/2 way up the threads.

The torque spec is 35lb-ft, which is a firm tug.

Achilles

I used Permatex #2 on my rebuild with no problems. Some people like RTV and that probably works fine too...I'm just old school.

The intake bolts go through the heads into the lifter area of rhe block, so they need sealant. If you ever pull your intake use "The Right Stuff" for the front & rear seals.

labpuppy

Thanks guys. I will look for the permatex #2. Much appreciated.

Aggravated4life

I bet the intake gasket is very old and getting brittle now..low mileage rules,but wont stop a leak when they age with the years.If what you try doesnt work,youre going to need new gaskets.A little oil leak is usually ok,but if it leaks coolant,thats a fix that needs to be done asap.

RRT vette

with the above statments.

Thrak

I'm getting oil coming up on the passenger side... it actually pools up a little bit in the area's between the injectors...

It appears only 1 bolt is "leaking".. can I just remove that one and seal it, like suggested above? Or would it be different since its on the side of the manifold, instead of the top?

65Z01

Nope, that can be tried on any bolt leaking oil or coolant.

Permatex #2 is available at Auto Zone and AC Delco stores.

SunCr

GM's Service Bulletin issued back in Nov '89 blamed gasket misalignment for the leak which led to galvanic corrosion and subsequent head gasket failure which was showing up under warranty (and still prevalent around here today). Their solution was a redesign of the head counterboring the front and the rear intake bolt holes for gasket retainers. I'd R & R the gaskets and make sure your cooling system is clean.

larryfs

do you have a copy of that service bulliten please??
I'd like to see if it pertains to my 1989 LB9 F -body 305 motor.

BADDUCK

I like High Temp copper RTV. Let it cure 24 hours.

SunCr

Somewhere - should be #892836A. Initially, it included a specific reference to galvanic corrosion, but that language was subsequently removed. Applied to all aluminum head V8's. Redesign head was only installed on the '91's. Use intake gasket 12525814 for the Vette which includes the restrictors in the rear coolant passages. F-Body gaskets and current 113's (used on the ZZ4 motors) don't have the restrictors, but do have the counterbored bolt seats for the gasket retainers. Some of the initial complaints, which led up to the redesign, were summarized at www.nhtsa.gov. I don't know if they're still posted. Problem was common to alot of the early OEM aluminum head motors and from what I read, traced to incompatible head gasket materials. GM blamed misalignment of the intake gasket. Who knows - though the '91's and ZZ4's don't seem to have the head gasket failures which always seem to leak/fail at #7 on those that had the problem.

larryfs

I'm thinking the LB9 305 Fbody motor had iron heads, even though it had the TPI intake. So it may not pertain to F-bodys.

coupeguy2001

2 things here

1. get a product called "the right stuff" at checkers or auto zone, and do each bolt liberally
2. if that doesn't work, get copper washers of the right size, and use "the right stuff" in addition. The copper washers are soft enough to conform to both the bolt head and the manifold surface.
The problem comes from the oil wicking up the threads AND the gasket mismatch AND the bolt not squishing into the aluminum enough to create a seal

coupeguy2001

didja get that