Mercruiser 350 intake manifold

[slochner]

Have oil leak in rear end of intake manifold on Mercruiser 350 after having done extensive work. Questions:
1. If I pull the intake manifold without draining coolant, might not coolant run out into the valley? If so, any suggestions on draining coolant other than draining into bilge? What is the size of the coolant drain plug in the side of the Lower block? Perhaps I can pre-rig a hose/hose bib and catch most of the coolant, if required?
2. In prior assembly, my advisor at NAPA said do not use the short gaskets which came with the Fel-Pro head gasket set for the front/back ends of the intake manifold, but clearly it is leaking at the rear end. Perhaps I did not use enough sealant - or should I use the previously discarded end gasket strips?
3. Could a quart too much lubricating oil cause the leak?
4. If intake manifold gaskets remain undamaged in removal process, can I safely re-use them? Engine has run less than an hour since they were installed.

Thanks, Steve Lochner

[Navatech]

Have oil leak in rear end of intake manifold on Mercruiser 350 after having done extensive work. Questions:
1. If I pull the intake manifold without draining coolant, might not coolant run out into the valley? If so, any suggestions on draining coolant other than draining into bilge? What is the size of the coolant drain plug in the side of the Lower block? Perhaps I can pre-rig a hose/hose bib and catch most of the coolant, if required?
2. In prior assembly, my advisor at NAPA said do not use the short gaskets which came with the Fel-Pro head gasket set for the front/back ends of the intake manifold, but clearly it is leaking at the rear end. Perhaps I did not use enough sealant - or should I use the previously discarded end gasket strips?
3. Could a quart too much lubricating oil cause the leak?
4. If intake manifold gaskets remain undamaged in removal process, can I safely re-use them? Engine has run less than an hour since they were installed.

I'm not much of a gas engine mechanic so I'm going to pass on questions 1-2... As for your question # 3 (which is really a general question and not gas or diesel specific), I highly doubt it... As for your question # 4 (which is really a general question and not gas or diesel specific), absolutely not!... I know some people have done it... Successfully even... However, the gasket gets squished between the two metal faces... That's what it is designed to do... Once squished it's not going to get squished again to the required extend... IMHO it's false economy to skimp on what's an essential but consumable part... And they're not that expensive!... And it doesn't matter if the gasket is metallic or some non metallic material...

[Kevin]

Don't reuse the gaskets. I have done intake manifold with and without gaskets on the front and back. I believe the trick no matter which method used is clean surfaces very well. Get all oil residue and ensure mating surfaces are sqeaky clean. Apply rtv and let is set up for ten minutes or so until it is tacky. Don't put the parts together until they tack up.
Between head and manifold must use the gaskets. I only use rtv around the coolant passages, not even sure if it is the right way but have not had any issues.

[Kevin]

I forgot to mention be sure you use a torque wrench. Use the book spec and pattern. Results usually last longer if you do it right the first time. Ask me how I know!

[1962 31]

I never use the strips make sure you use a good sealant I use ultra black napa has it
if you open the sealant and it smells like vinegar don't use it , like the tube they supply in the fel pro gaskets sets

[slochner]

Thank you all for the responses. Have ordered new gaskets and will attack tomorrow. Have picked up a 1/4" inch NPT with hose barb, so I should be able to collect coolant. Steve.

[Mitch]

The ultra black is the only one that will stand up to oil set a large bead of it front and rear the diameter of the width of the block surface more is better let it set up pretty good so when u touch it it doesn't stick to your finger. Set the manifold down perfectly straight
Tighten bolts in at least a two step process like u would head bolts middle out then torque to spec don't start until silicone completely cures