Mercruiser 8.1Aluminum Manifold Failures
07-06-2009, 10:25 AM
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Mercruiser 8.1Aluminum Manifold Failures
I had to replace the risers, elbows, and aluminum exhaust manifolds on two 8.1S Mercruiser engines due to leakage in the manifolds. The total cost was over $5000.
Just this week I came across this thread which is worth reading if you have stock aluminum manifolds: http://www.clubsearay.com/forum/showthread.php?p=65805 Looks like Mercruiser is well aware of the problem
The work was done by a Mercury authorized mechanic and based on the thread above I'm going to see if Mercruiser will make good on the expense. It's apparently a silent recall with no service bulletins.
Has anyone else had this problem, and did you receive any reimbursment from Mercruiser?
Just this week I came across this thread which is worth reading if you have stock aluminum manifolds: http://www.clubsearay.com/forum/showthread.php?p=65805 Looks like Mercruiser is well aware of the problem
The work was done by a Mercury authorized mechanic and based on the thread above I'm going to see if Mercruiser will make good on the expense. It's apparently a silent recall with no service bulletins.
Has anyone else had this problem, and did you receive any reimbursment from Mercruiser?
Last edited by Richard Seccombe; 07-06-2009 at 10:31 AM.
07-06-2009, 11:13 AM
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Didn't have the problem, but I retrofitted full fresh water cooling to include my aluminum manifolds.....
Even if you use the iron manifolds, the replacement time frame for salt water usage is not that long. The elbows are SS and you should not need to replace them, risers and elbows are a single unit (I think?). Ask for the old ones, and if they are in good shape, refuse to pay for the new ones.
Even if you use the iron manifolds, the replacement time frame for salt water usage is not that long. The elbows are SS and you should not need to replace them, risers and elbows are a single unit (I think?). Ask for the old ones, and if they are in good shape, refuse to pay for the new ones.
07-09-2009, 12:36 PM
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Just a thought here, yes Mercruiser did have a problem with the aluminum exhaust manifolds leaking water through rot out in engines being used in salt water that were not flushed after use with fresh water. Since there are a lot of 496 owners changing out their exhaust for headers, there are a lot of low use fresh water 496 manifolds sitting at shops, in garages and some being advertised on Ebay etc.
I would shop around for a good pair of the late model 2005 and up iron manifolds and save a lot of money if you are near replacement time.
Remember that for years even iron manifolds have been rotting thru for 3 or 4 decades now, nothing new there. Just set up a fresh water engine flush on your engines and run fresh water thru them when you return to the dock and wash down the good ol boat! If your a trailer boater do the same after getting back on the trailer, don't leave salt water laying in your raw cooling system!
Best Regards,
Ray @ Raylar
I would shop around for a good pair of the late model 2005 and up iron manifolds and save a lot of money if you are near replacement time.
Remember that for years even iron manifolds have been rotting thru for 3 or 4 decades now, nothing new there. Just set up a fresh water engine flush on your engines and run fresh water thru them when you return to the dock and wash down the good ol boat! If your a trailer boater do the same after getting back on the trailer, don't leave salt water laying in your raw cooling system!
Best Regards,
Ray @ Raylar
07-09-2009, 06:31 PM
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Thanks for the input
Thanks very much for the input.
Everything has already been replaced and paid for. One of the problems prior to the manifolds rotting was that the setup used a combination riser/elbow. There was a 6" riser that was sandwiched in between the top of the manifold and the actual elbow to raise the water output of the elbow to the muffler to achieve enough drop to keep seawater from coming back up into the manifold. The whole mess was bolted from the top of the elbow, through the riser, and then into the aluminum block. The studs used to sandwich all of this together were quite small in diameter and i was constantly stripping the studs out of the soft aluminum. Unbelievable that this was a stock Mercruiser setup direct from the factory.
When I replaced the manifolds with cast iron, we found extra tall Mercruiser elbows that eleviated the need for the Mickey Mouse risers, and now the elbows are cap screwed right into the top of the cast iron manifolds.
All of this work was done over a year ago, and if I hadn't seen the thread on the Searay site I never would have known that Mercruiser (on occasion) would admit to the bad engineering and pay off on the parts and labor to make things right. All the work was done by a Mercruiser factory authorized mechanic which I believe was one of the stipulations for any kind of cooperation.
One year ago or not, I'm going to go to the mat with Mercruiser over this. My main reason in posting this thread was to see if anyone else other than the guys on the Searay forum had been through this wonderful experience.
Thanks again for your input,
Richard
Everything has already been replaced and paid for. One of the problems prior to the manifolds rotting was that the setup used a combination riser/elbow. There was a 6" riser that was sandwiched in between the top of the manifold and the actual elbow to raise the water output of the elbow to the muffler to achieve enough drop to keep seawater from coming back up into the manifold. The whole mess was bolted from the top of the elbow, through the riser, and then into the aluminum block. The studs used to sandwich all of this together were quite small in diameter and i was constantly stripping the studs out of the soft aluminum. Unbelievable that this was a stock Mercruiser setup direct from the factory.
When I replaced the manifolds with cast iron, we found extra tall Mercruiser elbows that eleviated the need for the Mickey Mouse risers, and now the elbows are cap screwed right into the top of the cast iron manifolds.
All of this work was done over a year ago, and if I hadn't seen the thread on the Searay site I never would have known that Mercruiser (on occasion) would admit to the bad engineering and pay off on the parts and labor to make things right. All the work was done by a Mercruiser factory authorized mechanic which I believe was one of the stipulations for any kind of cooperation.
One year ago or not, I'm going to go to the mat with Mercruiser over this. My main reason in posting this thread was to see if anyone else other than the guys on the Searay forum had been through this wonderful experience.
Thanks again for your input,
Richard
