Yet another Noob B28 question- sanity check on motors

[Wingnut]

All,

Thanks again for the input over in the ethanol section! Next boat and another set of questions:

This one is a '87 B28 with typical Mercruiser 350 / 260's that are original. Hours around 900. Boat is immaculate with all records down to oil change hours , raw water pumps, etc.

I had $$ down on this boat contingent on a sea trial. It didn't go so well!

Boat has tank replaced with anodized aluminum-beautiful but... Boat was on the hard for the last two years. Starboard motor started right up, belched out the fogging oil and pumped out pink anti freeze. Ran good.

Port motor ... Clunk on the starter Uh oh... After much clunking and me putting a wrench on the motor it won't turn.. Yikes.

Mechanic is called and goes through all the connections and the starter. I told him it wouldn't turn but he is methodical in his approach- good!

Eventually pulls the plugs and port side has two center cylinders with fluid in them. He says it could be from bad risers OR too much fogging oil drained into cylinders. I saw the stuff come out and it was ugly but hard to tell what it was.

At any rate, a week later I get a call that the boat is running well and the oil diagnosis was the correct one. Mechanic says all cylinders are between 145 and 150 PSI on compression.

I really want to get at least a season out of the motors and I know there are no guarantees on something this old. 50 hours would be plenty.

I'm concerned that the fluid in the cylinders was antifreeze from the risers and there is still a leak there. I may take a gamble on this boat knowing that re-power is near anyway.

Am I nuts? What are your thoughts? What would risers installed run me? Boat is freshwater cooled otherwise if that makes a difference.

Thanks again ,

JD

[In Memory Walter K]

First thing I would do would be find another Mercruiser mechanic to look at that engine and have HIM do another compression test. If his numbers match what you were told, I'd feel a little better (and surprised). Have the headgasket checked. Those being OK, find out the price of a set of risers and deduct them from his asking price. You state that the owner kept good records. When were the risers changed last? If they're original, they have 900 hrs on them (both engines) and certainly have served their lifetime. Freshwater cooled is a big difference. Wouldn't touch a saltwater cooled again. Been there, done that. My thoughts. Walter

[Tony Meola]

If two cylanders had that much oil it probably hydrolocked. Problem with that is that in spinning it over, they could have bent a push rod or worse a valve. Might not have bent it enough to make it run rough but still bent. Trust me, saw that on our old 454's. Enough of a bend so that if you rolled it on a flat surface you could easily tell it was bent. Engine stll ran fairly well with the bent rod.

If the risers are leaking you will know. Should be hard to start and you should see steam coming out the exhaust.

For a final safe secure feeling, I would send an oil sample out for an anaylisis. That will tell you if there ae any problems they are not telling you about.

Also to back up Walter's comments, risers, even fresh water cooled only have a 5 to 8 year life span, depending on where you are.

[Wingnut]

Walter,

Thanks and yes, they are original.

Mechanic seems like a straight shooter but I know you are right.

I could do the compression check myself.....

Thanks,
JD

[JK]

Are you set on a 28? There was a 31 with diesels in Bear DE listed for 41K. I have address somewhere if you are interested.

--JK

[John F.]

Fogging oil doesn't look like anti-freeze. The mechanic should be able to tell you what it was. Compression can be fine even though the risers are shot. Last I checked, risers and gaskets were around $150 each (x4), and are relatively easy to put on. If the boat is old an has been sitting, I'd do both sides anyway. Better yet, get the seller to do both sides, and if the manifolds are original, get it all done. 350 Chevys are the best gassers made.

I bought my B31 w/454s (second best gassers made) and she had been sitting for awhile. She could only idle. I was hoping to get a season out of the motors. Starboard motor broke a rocker which took out 2 (bent) pushrods in the first 10 hours. After lots of doom and gloom, I replaced the rocker and pushrods for a cost of about $25, and 6 years later they're still running. I also did carbs, risers, ignitions. Starting to get tired though, but the compression numbers were a little lower to start.

Good luck.

[captbone]

I would have a leakdown test done. Much better indicator on total engine health (i.e. valves) vs compression. With compression and leakdown done, you will have your answer. If those are good, everything else can be fixed.

If those come back good, I would do cap, rotor, manifolds, risers and elbows just for good measure along with waterpumps and plug wires. After doing those, I would have no problem trusting those engines offshore.

Good Luck.

Just my 2 cents.