Replacing motor heads

[JasonS]

Hi everyone, brought my 240 Sundeck to the dealer for a exhaust manifold and riser replacement on my Mercruiser 350 mpi. During the work, the dealer called and said it would be a good idea to replace the motor heads because of some rust. Anyone run in to this problem? Anyone who replaced them have a roundabout cost? Thanks.

 

[scoflaw]

He's probably talkin about the sealing area between the manifolds and heads ? How does it run? If it runs fine I would postpone it. Post up a pic or few.

 

[JasonS]

Here are some pics sent to me. There is a ticking from that side when the motor is on.

 

[scoflaw]

I would put on a good set of gaskets and finish the season.. Small exhaust leak is no big deal, having this guy tear into your motor probably would be. my 2 cents

 

[Golfman25]

I had a cracked head replaced once. As I recall, cost wasn't too bad. Maybe $1500 and my marina isn't afraid to charge. Have him quote you.

 

[Espos4]

At the point you’re at, have them do a compression test as a baseline. Probably an hours worth of labor with the exhaust out of the way.

 

[El Capitan]

Depends on turnaround time. If they can do it ASAP then I’d have it done now v

 

[capecodcruiser]

Something fishy here. Either you aren't able to explain explicitly what the mechanic is saying or they are trying to rip you off. You don't replace a head because of rust. Where is the rust? Why does he think it needs to be replaced? You need to get way more information before making a decision.

 

[BillK2632]

Do a compression test before you do anything else. Without evidence there is a problem - ie low compression in a cylinder, verified water in a cylinder etc -- the only person this is a good idea for is your mechanic. You might very well have a problem, but find out for sure before you throw your checkbook into it. I am amazed at how quick some mechanics are to just start replacing parts. I have had half a dozen boats over a lot of years of boating - 1000's of hours on inboards, outboards, I/Os - I have only had one set of heads replaced and in that case it was clear a cracked manifold was leaking water into a cylinder - that engine had 1300hrs on it at the time - re-worked the heads replaces the manifolds and ran it another 1000hrs.

 

[scoflaw]

I had that issue on my current motor, water gets trapped on top of the exhaust manifolds and corrodes the exhaust surface on the heads. Had to mill about .025 off it with a Bridgeport when the heads were redone with the rebuild. Ticking is an exhaust leak, if the engine runs fine, no biggy.

 

[JasonS]

I did not have the motor compression tested. I did new manifolds, risers,and spacers. They upgraded the gaskets that came with the manifolds. They said the rust on the cyclinder heads not sealing well is causing a ticking noise. If not addressed it could lead to valve damage. I asked if they could do the work and they passed and said they could not do it. After all the work was done they tested and ran the motor and it still has the tick. So the right way to go is a compression test to see if everything thing is alright?