Plaineman

I have a 2000 7.4 MPI with roughly 950 hours on it... always run and kept in salt... corrosion is heavy in entire bildge area.

Anyway... I had to pull the exhuast manifolds due to a small leak in the manifold itself. I had a hell of a time getting them out and thanks to some OSO members got the help I needed to deal with the frozen bolts. (for anyone who was watching that... a good bolt extracter kit from sears did the trick... along with some blood and a few broken tools but it worked)

My question now is if my heads are also toast... there was a lot of corrosion and even some pitting around the edges of the ports. I also have two bolts stuck in the head as they broke when I got tourque on the bolt head. I am sure I can drill those out but should I be replacing the heads as well?
I really dont feel like doing this work only to have to pull it all out again in another month or so.

Whats the usual rule about choosing to change up the heads? It looks like this will be another messed up wrestling match with rusted bolts... but not as bad.


ALSO... I was looking to purchase a set of Eddie Marine high performance manifolds but now I wonder if I should just go stock.

Any insite on this will be a great help....

Thanks in advance.

B

Chris Sunkin

With 950 hours, my guess is you're going to end up with a complete rebuild before you're done. There are lots of little bits that have been wearing and deteriorating right along side of those heads and exhaust. I wouldn't be surprised to see cam chain wear, lobe wear, cylinder bore wear, etc.

MOBILEMERCMAN

Looks like exhaust has been leaking for a while. I think Chris is right rebuild or repower is in order. Shame is the leaking exhaust ruined it , anyone else reading this change your riser gaskets inspect internally your manifolds. This motor would have probably run longer if it didn't get water in it.

It will likely run a while if your just put it together. It just will be down on power. Do a compression or leak test and than make your decision.

Plaineman

So I have been told... I am really trying to avoid that this year and was only wondering if I could just install a new manifold and run with it... seems the worst that could happen at this point would be a leak at the connection between head and manifold. I guess at this point it's not going to hurt to try.

Thanks for taking time to answer Chris....

Brian

Plaineman

Thanks Mobil....

I have to say though... I have really been on top of risers and gaskets...and also changed the manifolds at about 400 hours... I take care of this engine really well and she runs strong. I have always had a really bad corrosion issue with this boat. Any new parts that go on are completely corroded in about one season. It sits on the water all year and gets used pretty heavy in the summer. I did have a bad case of water intrusion the winter before last due to bilge pump failure... bilge filled up with rain water and got into the cylinders. I cought it quickly and was able to get it all out... change oil a few times and had a good season last year.

The reason I am having to change manifolds was due to an actual small hole in the manifold itself. Initially sounded like a blown gasket but upon further inspection I was able to feel the exhaust air popping out of the side of the manifold.

I think I may just slap a new set of manifolds on and see what happens. I was going to upgrade but probably just gonna stay stock for now.

Thanks also for your reply.

B

Strip Poker 388

http://www.offshoreonly.com/forums/s...ted+head+bolts

MOBILEMERCMAN

Strip, You had stainless risers in the picture. I don't know why or who the genius was that put stainless on cast iron. It is old news it doesn't work. If anyone has stainless risers on there big block stock manifolds you better throw them away. They will inevitably leak and ruin your motor. In my opinion.

Chris Sunkin

I can appreciate your sentiments. Nobody likes spending $$ to just stay where they are at- rebuilds suck. But looking at those head bolts leads me to think you may be popping the motor out just to work on it. You may be able to get away with just rebuilding or replacing the heads. That motor has a common and inexpensively available head on it. If it were me, I would look at replacing them- if your exhaust rotted, the heads may not be far behind. Why put guides, valves and machine work into shells? You'll probably spend more having those exhaust bolts machined out than a nice set of used heads anyway. Those head bolts look like they're going to bneed an abrasive disc to remove them.

You should also consider using salt neutralizer. It will greatly reduce the effects of salt water. You can use it when you flush the motors and if you keep some in a garden sprayer, you can hose your bilge out with it. Everything will last much longer.

Plaineman

Thanks for all guys.... Strip, that motor was really bad man... I thought I had it bad but I realize a lot of people have a similar problem. I am probably in for a similar problem with these head bolts.... YIKES!!!

Hey Mobil, I did not see any pics of stainless steal risers but gotta ask... Eddie Marine is trying to sell me a performance upgrade with a set of cast aluminum manifolds with stainless risers... supposedly adds like 30 horse or something. They say it is safe and should last longer than stock... is this not true?

Chris, I have been looking and I am finding some cheap heads for this engine and may just try that... and the salt nuetralizer??? Will I find this at the local marine supply? I will give it a shot... thanks.

Looks like I will be keeping dry for a while... sux but gotta do what we gotta do.

Thanks....

B

Strip Poker 388

Im missing something? the engine in the thread was a 415mpi 1996 stock exhaust.