Brand New Sierra Exhaust manifolds failure

[kf6cmp]

My mechanic built me a new motor for my skipjack. I bought two Sierra brand new 18-1931-1 manifolds. At sea trial I had water intrusion into the Pistons on the port side of the engine. With inspection it turns out the Sierra exhaust manifold had a crack on the inner jacket. I replace this manifold with a new one and started the engine at home and the starboard side did the same thing. We pulled the manifold and exactly like the port one had a crack on the same spot allowing water intrusion into the engine. Mind you the engine has less than 2 hours on it. The manifolds have the exact same casting numbers. 180912. Also one of the freeze plugs on each of the manifolds was leaking. My mechanic said he has never seen such failures. He said it must be a batch of bad castings. Has anyone had the same issue from this particular Sierra manifold? If you have purchased these manifolds be aware of this issue. If anyone has had the same issue please write in this thread.

 

[racerone]

Locally we have a " state of the art " casting plant that is sitting idle.----Produced quality automotive castings for a number of years.-----But buyers for the car companies found castings that are " just as good " somewhere offshore.----Does the packaging for these cracked manifolds say where the things came from ?

 

[Bondo]

Also one of the freeze plugs on each of the manifolds was leaking. My mechanic said he has never seen such failures. He said it must be a batch of bad castings. Has anyone had the same issue from this particular Sierra manifold?

Ayuh,...... Welcome Aboard,...... I ain't had that problem, with those manifolds, But,......

I did buy a set of GLM manifolds, 'n had a water in the cylinders problem,.......
On those, when ya put a straight edge across the top of the manifold, the inner exhaust sealing surfaces, were 'bout .010" to .015" Below the outer water jacket sealin' surfaces,.....
I brought 'em over to my friendly local Machine Shop, 'n explained the problem to the guy,.....
'bout a minute or two on his big ole tabletop belt-sander, 'n they were Good to go, 'n are still goin',.....

Anyways,.... All of those manifolds are chinese knock-offs, 'n bad castin's are sorta expected,......
Bad castin's can also happen at our domestic foundries too,.........
Look at the Bat-wing 4.3l manifolds,.....
State of the art castin's, that suffered massive failures, because of core-shiftin' problem,......
Some folks run 'em for years, without issues, But, I've been intimately involved with 3 motors, that were Killed, Dead, by the known issue,.....

Has yer motor survived the ordeal,..??..??

 

[Lou C]

I also replied to your question on the hull truth forum....and as far as aftermarket manifolds, the only ones I've used were Barr marine cast in USA and the sealing surfaces were excellent, lay a straight edge across and even a .001" feeler gauge would not fit in. Installed em with the steel/composite gaskets provided by Barr and no leaks.

 

[Scott Danforth]

Sierra is a "will fit" aftermarket supplier. Their sources are the lowest cost that will fit. Many castings are chinesium sourced

Barr is the OEM casting house for many boat motor companies and Edelbrock.

 

[Lou C]

I think if you check prices Barr is not much more money than Sierra. I was able to get them from a local shop that gets them from a distributor out in Riverhead Long Island NY (Lighthouse Matine).

 

[Lou C]

In this case while I advise checking flatness it would not have prevented the failure since it was not because of that.
If all I could get was made in china manifolds, what I'd do to protect myself would be to add an additional step:

assemble the manifold and elbow off the engine, torque the 4 elbow bolts to spec. Then rig up a way, to put warm water through them while they are propped up level and watch the exhaust ports. See if you see any leakage, if so return them till you get a set that does not leak. Much better than, hydrolocking or otherwise damaging a new engine!
I have a slop sink down on my basement where I could do this without making a mess....just have to rig up a hose to make it work...

Otherwise though, I try to buy the best of the aftermarket and its not easy due to outsourcing. I HOPE that Barr stays in business and keeps their manufacturing stateside since they seem to make a good product at a decent price.