Mercruiser 260 rebuilt - Water in cylinders and oil?

[RogersJetboat454]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

The valves and seats were in rougher shape than anticipated. It took me almost 4 days to get the valve seats cleaned up and lapped. I spent most of today putting everything back together. I plan on adding that last few things in the morning and then doing the test run. Stay tuned...

It concerns me a bit with all the work you say you had to do. Gunky valves make me wonder how good your valve guides are. A valve stem in a loose guide is a catastrophe waiting to happen. As far as the lapping is concerned, if it took that long to make it look good, chances are you needed a valve job instead. Lapping is really just a clean-up and surface matching of the valve faces and seats. Not really meant to replace a valve job. During a valve job, the machinist would be checking the seat and face angles, valve margin, and if there is any excessive depression into the head (critical especially if these heads don't have hardened exhaust seats). With out a go-through by a machine shop, this pair you have sounds like a roll-of the dice to me.

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Yeah, roll of the dice sounds about right... I am sort of experimenting/learning as I go. On the good side, I dont have much invested (but time) in these heads and I do plan on replacing them in the near-ish future. The valves and seats had some pitting, but they seemed to clean up decent. I didnt get overly aggressive with the lapping, the time consumption was from the tar cleanup on everything. The lapping just seemed worse to me this time because I took it slow and double/triple checked everything as I went along. The other set of heads were much cleaner to begin with, which is why I used them first (not knowing they were 305 heads). The 882's I have on now looked like they were run on an old truck without a thermostat in it. The valve guides did have a little more play than the other heads but I felt comfortable using them (they weren't sloppy, just not as tight as the others). I put my best set of valve guide seals in and am hoping for the best... The next set will be new, or close to it, and they will be done right from the get-go since I plan on making them long-term. The current set I expect 1 maybe 2 seasons out of. I have another block in the garage that I want to prep for a future heavy mod rebuild after I finish rebuilding my truck engine.

I'm off to retorque the head bolts and check everything over before running the next 5 gal can through her... Stay tuned...

 

[girl]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Hi, Took the boat out (260 Mercruiser) yesterday; started fine, ran fine at first, then water spraying out both water manifolds. Both had cracks, I suspect from freezing - did have it winterized. Dried out the boat (about 150 lbs water). Can anyone tell me about how much it will be to have fixed? The boat is a Glastron, I think 1985 so dont want to put too much into the boat but it worked great the last couple years. Is there anyway to seal the cracks such as J B Weld? Thanks, first year I had this boat alone. Would it be better to just sell? How much is the motor worth? Help, girl

 

[Bondo]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Hi, Took the boat out (260 Mercruiser) yesterday; started fine, ran fine at first, then water spraying out both water manifolds. Both had cracks, I suspect from freezing - did have it winterized. Dried out the boat (about 150 lbs water). Can anyone tell me about how much it will be to have fixed? The boat is a Glastron, I think 1985 so dont want to put too much into the boat but it worked great the last couple years. Is there anyway to seal the cracks such as J B Weld? Thanks, first year I had this boat alone. Would it be better to just sell? How much is the motor worth? Help, girl

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