The Dang Truck Engine Again

drbarbara · #1 08-20-2008, 05:39 PM

After I changed the truck carburator on my boat which has a Ford 302 off a truck for a Marine Holley, I got the carburator from a not very reputable carburetor place. The boat was not running well so I ended up taking the boat to a mechanic, had to have the carb rebuilt again and now the mechanic is telling me that the boat is running reasonably well considering the #7 cylinder has a significant (very significant) exhaust leak. He recommended to run the boat the way it is until the engine croaks and then either repower the boat or take it out to the back and put it out of it's misery. My question is how hard is it for a newbie to try to install new exhaust valve on the head.

Thanks again for helping the newbie.

THEFERMANATOR · #2 08-20-2008, 05:46 PM

I would reccomend getting a leakdown test so you know for certain where it is leaking. If it is in fact just a valve, then a top end rebuild would be in order. One word of caution though, I have seen many a set of rings go right after a top end overhaul when the bottom end is older. Have you tryed running it yet to see how it runs?

spareparts · #3 08-21-2008, 03:47 PM

is that an exhaust leak, or a valve leaking. If it is an exhaust leak, it could be just the exhaust gasket or manifold, if it is an exhaust valve that is bad, then it mean more involved issues. I previously mentioned checking compresion, a leak down test would futher investigate the condition of the engine. Teh next thing I would do if everthing checkd out, would be to remove a freeze plug and check to see how rusted it is. true marine engines have brass freeze plugs so they won't rust. Automotive engines generally have steel ones that don't last too long as a boat engine. If it doesn't look too bad, remove the circulation pump and timing cover. Inspect them both for corrosion in the water jackets. What you are looking for is any signs that the engine is a rust bucket internally. If it all checks out, go ahead and pull the engine, carry it to a reputable maching shop, have them tear it alll down and give you an estimate to put it back right, or dispose of it as needed. Make your decison at that point. I used to do head cylinder head jobs on boat motors, but I had too many come back with other issues, the owners didn't understand that I wasn't a fortune teller, the head job held up fine, the rest of the motor didn't. If you motor is junk, check with PCM engines, and ebasicpower.com for a warantable replacement long block. FIguire replacing the manifolds and elbows as well. SOmewhere along in this discusion, some one is going to sugest replacing the I/O with an outboard and a bracket. Its worth discusiing if you are prepared to invest soem money into the boat

drbarbara · #4 08-21-2008, 05:57 PM

what the guy told me was that the #7 cylinder was only compressing 25 lbs.

spareparts · #5 08-21-2008, 07:27 PM

need to do what is called a wet/dry compresion test. You check compreion on the cylinder as is. Then squirt some oil down the spark plug hole and recheck. If the compresion comes up big time, you've got ring problems, if it comes up just a little, or none at all, you have valve or head gasket problems. A leak down test would give you more clues.