Assembling exhaust manifolds, risers and elbows - Loctite 510?

[khe]

The Mercruiser service manual #24 (for the 5.0 and 5.7 engines) says to use Loctite 510 around all holes in the riser/elbow gaskets. There was no evidence of any sealer when I took them apart to test them for leaks. I have Loctite 515 which is very similar. Should I use it or assemble them dry?

 

[Bt Doctur]

Permatex Aviation sealant is your best friend

 

[khe]

Permatex Aviation sealant is your best friend

I have a container of that. It is the "perfect seal" equivalent.

I'm assuming on both sides of the gaskets? The gaskets are the compacted graphite type gaskets and usually, those types don't require any sealant.

 

[04fxdwgi25]

The graphite gaskets go on dry..... No sealant on them.

Believe they are talking about the bolt holes (bolt threads), not exhaust / water holes, unless you are using the cheapo paper gaskets. If paper gaskets, then slather away.

 

[khe]

The graphite gaskets go on dry..... No sealant on them.

Believe they are talking about the bolt holes (bolt threads), not exhaust / water holes, unless you are using the cheapo paper gaskets. If paper gaskets, then slather away.

The gaskets I purchased were the compacted graphite type - Quicksilver OEM so they're going on dry. The gasket type must have changed since the service manual was printed.

 

[Bondo]

The Mercruiser service manual #24 (for the 5.0 and 5.7 engines) says to use Loctite 510 around all holes in the riser/elbow gaskets. There was no evidence of any sealer when I took them apart to test them for leaks. I have Loctite 515 which is very similar. Should I use it or assemble them dry?

Ayuh,.... You don't need a loc-tite compound, you need a thread sealant, like BD said,.....
Permatex #3 or perfect seal works great,....

 

[Lou C]

Permatex Aviation or Evinrude gasket sealer. It will stop corrosion by sealing out moisture.

 

[khe]

Those who are saying use Avation gasket sealer/perfect seal, etc. I have compacted graphite gaskets - Do I coat both sides, just around the bolt holes and/or the threads? Below is the screen shot from the service manual which I believe refers to the paper gaskets. The Aviation sealant is much thinner and would coat the entire face.

Do I need to use any sealer on the graphite gaskets?

 

[Bondo]

Ayuh,...... The bolts, 'n holes,...... Not the gaskets,.....

 

[khe]

Ayuh,...... The bolts, 'n holes,...... Not the gaskets,.....

Can you clarify? The illustration I posted from the service manual seems to show a bead of sealant around all the holes whether rectangular or round. The perfect seal is thin - do I just put it around the round holes in the gaskets or coat the entire surfaces of both sides? I have studs that are in the manifold and the risers and elbows slip over the studs and are retained with nuts.

What do I coat on the studs? The outside diameter, threads?

Is this needed with graphite gaskets?

 

[Scott06]

Can you clarify? The illustration I posted from the service manual seems to show a bead of sealant around all the holes whether rectangular or round. The perfect seal is thin - do I just put it around the round holes in the gaskets or coat the entire surfaces of both sides? I have studs that are in the manifold and the risers and elbows slip over the studs and are retained with nuts.

What do I coat on the studs? The outside diameter, threads?

Is this needed with graphite gaskets?

bondo is saying put the gaskets on dry , use the perfect seal on the bolt threads. Perfect seal seems to be a magic potion keeping the threads from corroding so you can get them apart next time ….

 

[04fxdwgi25]

The graphite gaskets are put on with no sealer on them. period.. Sealer is used on the metal and paper gaskets and on bolt threads....

Does you excerpt state it is a graphite, metal or paper gasket? No.
The sealer non-use on graphite gaskets was stated earlier, but you can do as you wish.

 

[Scott Danforth]

What do I coat on the studs? The outside diameter, threads?

yes.

This is so that in 7 years you can remove the bolts again

 

[khe]

Thanks for the clarification Scott06, Scott Danforth and 04fxdwgi25.

 

[Lou C]

Yep I had to take mine off to replace a leaky steering actuator about 4 years after I installed them and they came right off.
My original one piece V6 manifolds on the OMC used zinc plated studs and nuts and guess what even in salt water I never had a problem removing them. Changed the exhaust on this boat 3 times over 20 years of use here in salt water. Last time (2017) was the conversion to the 2 piece later exhaust so I used the bolts in the Barr Marine kit, with Evinrude gasket sealer.