leaking intake manafold/1979 corvette/advice needed

[mdazzo]

just noticed that i have a weeping intake manafold leak,right behind the engine lift bracket. cylinder # 1. i notice that i was getting a small pool of anti freeze
in one of the cast dimples.anyway i guess this will become a winter project.
i have never completed this type of repair before so i do have a couple of concerns.
-should i try to tighten the two engine bracket bolts to stop or slow down the leak?
- i also noticed for what ever reason some of the bolt heads look stripped and rounded any suggestion on how i would go about removeing these bolts i know there is only 30 lbs of touque but i cant even get a lock plier on them?

-this is a 1979 ...350....
some gasket sets have the front seals for the manafold and some sets dont,it looks like the manafold has a bead of rtv....which application would be the correct ?

and of course how hard is this job?

 

[wishuwerehere82]

#1) Your leak is typical of a manifold that has experienced some corrosion on the coolant passage between the heads and the intake manifold. The fact that the bolt heads are rounded off indicate that someone has tried to torque them down to stop the leak before. Rounded bolts are never fun, especially if they have been overtorqued. You could try filing or grinding new flats on them to fit a 1/2" socket since they are 9/16" now, or sacrificing a metric socket and hammering it onto the bolt head. Ether way, it's a pain in the a$$.

#2) Most new gasket sets come with a tube of silicone adhesive to fill the gap at the front and rear seal areas, but the good way to do it is to get a tube of The Right Stuff http://www.neverseezproducts.com/gasketmake.htm and use that instead of the supplied tube. The separate seals are prone to extruding out from between the manifold an block over time, so that's why most kits don't have them any more.

The job is not too hard to do.
You need to drain the radiator and the block.
Mark the distributor and rotor position and remove the distributor.
Disconnect the fuel lines and radiator hose.
Disconnect the throttle cable.(and transmission cable if automatic)
Remove the manifold bolts.
Pry the manifold off the heads with a screwdriver.
Clean all mating surfaces with a scotchbrite pad and degrease with laquer thinner.Make sure you place a cloth in the valley to keep crumbs from getting into the engine.
Position your new gaskets with a thin coating of Right Stuff on the coolant passages to gasket surfaces, and run a bead of Right Stuff on the front and rear seal areas.
Place the manifold back on.
Torque to spec. and let sit overnight for the gasket seals to cure.
Replace the distributor and align your marks back where they were originally.
Reconnect throttle cable.
Hook up the fuel lines and radiator hose, refill with anti-freeze.
Change the oil and filter in case you got some crumbs and anti-freeze in the engine.
Crank 'er up !!!!
Reset the timing.

 

[mdazzo]

pete thanks for the steps...i am going to follow them...i picked up a used manifold off of a 1979 which is 100% better over all condition i am going to use it.

should i put a thin bead on both sides of the gasket or just the side going on to the heads.i am going to torque all bolts to 30 lbs...ok do i have to chase all of the bolts threads,if i do do you know what size die i have to purchase?

 

[wishuwerehere82]

pete thanks for the steps...i am going to follow them...i picked up a used manifold off of a 1979 which is 100% better over all condition i am going to use it.

should i put a thin bead on both sides of the gasket or just the side going on to the heads.i am going to torque all bolts to 30 lbs...ok do i have to chase all of the bolts threads,if i do do you know what size die i have to purchase?

Yes, do put a thin film on both sides of the coolant ports but not around the intakes. Just smear a thin film around with your finger so it doesn't add much thickness to the gasket but adds to the seal around the coolant ports.
Wire brushing off the bolt threads should clean them up enough for re-use. Of course you are going to replace the rounded ones.

 

[glen242]

pete thanks for the steps...i am going to follow them...i picked up a used manifold off of a 1979 which is 100% better over all condition i am going to use it.

should i put a thin bead on both sides of the gasket or just the side going on to the heads.i am going to torque all bolts to 30 lbs...ok do i have to chase all of the bolts threads,if i do do you know what size die i have to purchase?

Use sealant on the manifold bolts. They are not blind holes, and oil can wick up the threads if not sealed. Permatex #3 (I think) can be used or anything that is oil resistant and non-hardening. I would not use RTV.