1992 Mercruiser 4.3LX Exhaust Manifolds

[nismo.hanson]

Hi Everyone,

My name is Rob, long time lurker just joined the forum officially today.

I have a 1992 Rinker 186 Captiva with the 4.3LX motor. When I bought it I noticed a crack in the exhaust manifold that had be JB welded years before. Previous owner said he just reapplied the JB every few years or something like that.

Boat passed the sea trials I put it through so I bought it. Boated all last year with a small drip from the manifold. I'd like to replace the manifold this spring before I start using the boat again.

Does it make sense to only replace the cracked one?
Any recommendations on brand or material? likely have to use cast iron due to cost.
Read several stories on here about GLM and Sierra being China castings and spotty quality.


Looking for some guidance on what direction to go. Planning on handling the labor myself.

 

[alldodge]

Hi Everyone,

My name is Rob, long time lurker just joined the forum officially today.

I have a 1992 Rinker 186 Captiva with the 4.3LX motor. When I bought it I noticed a crack in the manifold that had be JB welded years before. Previous owner said he just reapplied the JB every few years or something like that.

Boat passed the sea trials I put it through so I bought it. Boated all last year with a small drip from the manifold. I'd like to replace the manifold this spring before I start using the boat again.

Does it make sense to only replace the cracked one?
Any recommendations on brand or material? likely have to use cast iron due to cost.
Read several stories on here about GLM and Sierra being China castings and spotty quality.


Looking for some guidance on what direction to go. Planning on handling the labor myself.

:welcome: to iboats Rob

My guess is your taking about the exhaust manifold but as with most things, and especially here where we cannot see what your seeing

 

[nismo.hanson]

1992 Mercruiser 4.3LX Manifolds

Hi Everyone,

My name is Rob, long time lurker just joined the forum officially today.

I have a 1992 Rinker 186 Captiva with the 4.3LX motor. When I bought it I noticed a crack in the manifold that had be JB welded years before. Previous owner said he just reapplied the JB every few years or something like that.

Boat passed the sea trials I put it through so I bought it. Boated all last year with a small drip from the manifold. I'd like to replace the manifold this spring before I start using the boat again.

Does it make sense to only replace the cracked one?
Any recommendations on brand or material? likely have to use cast iron due to cost.
Read several stories on here about GLM and Sierra being China castings and spotty quality.


Looking for some guidance on what direction to go. Planning on handling the labor myself.

 

[nismo.hanson]

Alldodge, you are correct. exhaust manifolds. I cant believe i missed that.

Boat is in storage right now, pics unavailable until spring. damn you MN winter!

crack is below the riser on the starboard side, maybe an inch long

 

[tpenfield]

Mercruiser, Osco, Barr would be the brands to consider. I would do both of them, as it seems that they both may be older and just to be sure the water flow would be the same.

 

[alldodge]

Alldodge, you are correct. exhaust manifolds. I cant believe i missed that.

Boat is in storage right now, pics unavailable until spring. damn you MN winter!

crack is below the riser on the starboard side, maybe an inch long

In that case you could get by with just the manifold, it was probably not winterized properly. Barr makes so decent ones and many have had good luck with Sierra. Just look real close at the riser for anything

 

[Bondo]

Alldodge, you are correct. exhaust manifolds. I cant believe i missed that.

Boat is in storage right now, pics unavailable until spring. damn you MN winter!

crack is below the riser on the starboard side, maybe an inch long

Ayuh,.... I merged yer 2 threads, so it reads abit funny now, but anyways,....

Do ya have Manifolds, And Risers,..??
Not the 1 piece, pieces of poo, correct,..??

If so, pull the risers off the manifolds, so you can get a Good look at the failure point, the gasket surfaces of the castin's,....
Clean 'em up, 'n finish 'em off with a Flat File, bein' careful to flatten 'em, flat, 'n true,...
Yer wantin' to know the width of the webs, at the gasket surfaces,..
I believe, 1/4" wide is Good,... 1/8" is scrap iron,...

If the hull has never seen saltwater, it's probably a moot point, but ya gotta start somewhere,...

At that point, you can decide on whether to replace just the one, with a freshwater used one maybe,...
Or, replace the whole set, both sides,.....

Whatever ya do, I've found the metallic graphite gaskets from Merc, on dry surfaces, at the manifold/ riser joint, works Best,....

 

[nismo.hanson]

Ayuh,.... I merged yer 2 threads, so it reads abit funny now, but anyways,....

Yea I wondered what happened. I hit the post button and it said "working" Let it sit for 10 min or so and it was still "working" Thanks for the assist.

The crack is below the riser connection by an inch or so. You make a good point about the surfaces under though. Don't think the hull has been in salt water, kind of a hike from MN but you never know. I think the best bet would be to get the boat home and inspect everything before ordering parts. Then i'll be able to provide pictures too!

 

[Bondo]

Yea I wondered what happened. I hit the post button and it said "working" Let it sit for 10 min or so and it was still "working" Thanks for the assist.

The crack is below the riser connection by an inch or so. You make a good point about the surfaces under though. Don't think the hull has been in salt water, kind of a hike from MN but you never know. I think the best bet would be to get the boat home and inspect everything before ordering parts. Then i'll be able to provide pictures too!

Ayuh,... When in doubt, hit yer Refresh Button,....

Odds are, everything posts,....

The Refresh button, 'n key F5 are my most common used functions, since last years software regrade,...