Mercruiser 165 manifold water leak

[marvinjansen]

I have water running down the left side of the block from the area above the first freeze plug. It seems to be coming from between the manifold and head. I think I need to pull the manifold and head and replace some gaskets. It seems there is some water leaking (small amount) from between the head and block on the spark plug side.

 

[Don S]

Re: Mercruiser 165 manifold water leak

It seems to be coming from between the manifold and head. I think I need to pull the manifold and head and replace some gaskets

Sounds like freeze damage, pull the manifold and look for a crack in the block, about 3/4 to 1" below the head gasket.

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

your probable right about a crack in the block. I did drain after each use but it makes most sense. Will pull manifold in a few weeks and see. Next week I go sailing, no motor or drives.

 

[Bondo]

Re: Mercruiser 165 manifold water leak

your probable right about a crack in the block. I did drain after each use but it makes most sense. Will pull manifold in a few weeks and see. Next week I go sailing, no motor or drives.

Ayuh,... There really ain't no gaskets holdin' back water there,...
My guess is the block, or maybe the manifold cracked...

 

[Don S]

Re: Mercruiser 165 manifold water leak

I did drain after each use

What did you drain, the block or the manifold? You MUST do both.

 

[ziggy]

Re: Mercruiser 165 manifold water leak

assuming ya drained both. manifold and block. could be just a rusty, worn out manifold from '73. specially if it ain't been replaced. within 2 weeks of getting Lime Time the manifold went south. maybe ya aint as bad off as ya think... i hope..

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

i drained both manifold and block and large hose. But wife reminded me I may have left water in it one nite it wasn't supposed to freeze but did get to 32. I will pull the manifold and look for a crack or rusted out manifold. Hope it is the manifold. Any luck welding or brazing or JB weld?

 

[achris]

Re: Mercruiser 165 manifold water leak

Pretty 'standard' on those blocks to develope a small crck above the centre core plug under the manifold. Pull the manifold and take the boat to an engine specialist Call ahead and find out if they do a 'sticking' service. What they do is drill a series of small holes along the length of the crack and then insert rivets and peen them over. It's usually successful in sealing the crack. The other place those blocks like to crack is from the head surface down to the port side top screw hole where the engine circulatin pump sits.

Cheers,

Chris........

 

[ziggy]

Re: Mercruiser 165 manifold water leak

great to see ya around achris.

The other place those blocks like to crack is from the head surface down to the port side top screw hole where the engine circulatin pump sits.

interesting. my '72 L6 did that. i've never heard an explanation for it. my crack was from the very ft. port head bolt hole. the crack ran from the hole fwd to the end of the block, down to the circulation pump hole. on the port side, the crack ran from the ft head bolt hole to the port side. the crack never exposed itself on the outside of the block.
do you know why they do this achris?

 

[achris]

Re: Mercruiser 165 manifold water leak

Only explanation I came up with was a long past overheat. The block is quite thin in that area and an overheat stresses it. The next time you replace the circ pump and disturb the mounting block or the head bolt, 'ping'....

The 4 pot blocks like to do the same thing... (2.5l and 3.0l, were called the MCM120 and MCM140)

HTH,

Chris....

 

[ziggy]

Re: Mercruiser 165 manifold water leak

Only explanation I came up with was a long past overheat.

cool, no pun intended..... i'll add another to your list of possible confirmations then. that '72 L6 i know had multiple overheats in it's lifetime. at least one, pretty severe.

The next time you replace the circ pump and disturb the mounting block or the head bolt, 'ping'....

i believe that. i never have tried to rebuild that block or even bolt the head or circ. pump on. it just looked like a 'ping' waiting to happen....

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

Upon further check without pulling manifold, I can feel an old patch above the freeze plug. Will need to pull manifold and look at it and try to seal the leak.

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

Update, Good news! Pulled the manifold and found a small 7/8" freeze plug rusted out in the head. Removed the back one too as it was almost rusted thru. No cracked block or me being stupid enough to leave water in to freeze. Off the get plugs and a new manifold gasket.

 

[Fishermark]

Re: Mercruiser 165 manifold water leak

That is good news. Be sure to put brass plugs in.

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

Good advice and what I will do since there are no brass or steel available in Tuscaloosa today. I will order Dorman 565-016 brass 15/16" plugs. I hope to use some in Mobile Bay and will need all the salt protection I can get.

 

[achris]

Re: Mercruiser 165 manifold water leak

I usually put Stainless steel plugs in. Even in normal car engines....

Chris....

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

Where can I get Stainless steel plugs?

 

[Bondo]

Re: Mercruiser 165 manifold water leak

Where can I get Stainless steel plugs?

Ayuh,... Use Brass...

 

[marvinjansen]

Re: Mercruiser 165 manifold water leak

I can get brass and have the Dorman 565-016 part number. Still happy it wasn't a cracked block!

 

[ziggy]

Re: Mercruiser 165 manifold water leak

Still happy it wasn't a cracked block!

yeah, glad it wasn't. + plugs are way cheaper than manifolds and risers too. ya got away sinful. way to go. love it when things go the right way, which usually isn't often enough.

man, yer gonna have an almost new boat with all the work ya been doing to yer nineteen man. bet she'll run like a top this summer...