Sear Ray 410 compression ring??

**Richey rich** · 09-28-2012, 08:22 AM

I just bought a 2000 410. I spoke to the mechanic who did the tune up this spring and he told me that they diagnosed a problem with the port engine as well but did not fix it. he says compression is down 30% in one cylider. could be a stuck or cracked compression ring. he tells me that on the 7.4 horizon when you take it apart you need to ring the entire engine and this would cost $4000. does that seem reasonable and does anyone have any advice for me.

**fwebster** · 09-28-2012, 09:45 AM

Hire a current mechanical survey by a competent Mercruiser mechanic that you hire. Do both a compression and a leak down test and pull off the exhaust elbows to examine the internal passages. If you have low compression on one engine, my guess is that you will find more issues and more $ than ringing one engine in your future.

**Air O'Nautical** · 09-28-2012, 04:44 PM

Ring the entire engine??

Maybe, slang for rebuild the engine with all new rings, ect, ect..
You can't really replace just one ring, nor would you want to since the engines being removed.
Get another opinion.

Good luck.

**Richey rich** · 09-28-2012, 09:29 PM

Yes, basically this mechanic wants to rebuild entire engine. Pull motor,new gaskets,new rings,new pistons, and bore cylinders. Whole job is $4000. Basically a total rebuild. I have never done any engine work so I just don't know if this is a decent price.

**rondds** · 09-29-2012, 12:12 AM

Were you burning oil? Do you know what cylinder it is? I'll bet it's 5 or 6. I could be that you have a bad valve seat, in which case you may only need to have the heads redone. Still not a cheap job but not $4000 and not as catastrophic either.

Also, take a look at the plug in the "bad" cylinder - see if it has any oxidation or rust on it. Typically, the crappy block-out gasket btwn the top of the manifold and the riser fails, coolant leaks in slowly and over time it can corrode first the valve seats (#5 or 6, since these are just below the exhaust riser/elbow).

Get the elbows and risers off first and check for evidence of liquid in the exhaust passages of the manifolds.

OK, just re-read the original post. New boat to you so you can't tell if the motor burns oil. Any blue smoke when moving under load?

Good luck!

**Richey rich** · 10-04-2012, 02:10 PM

no blue smoke while under load, and as far as the old owner could tell me it does not burn a drip of oil. The mechanic that diagnosed this says he did a drip down test and it is getting past the ring...Boat seems to run fine and perform well but at idle will make a slight noise, not sure how to describe but it goes away as soon as your past idle.