View Full Version : Rebuild on 1993 PS 190 with 750 hours

08-03-2004, 08:35 AM
I have posted some earlier threads on holly carb problems, etc. However, after having my boat looked at by a professional, I was told that I have low compression and no compression in one cylinder. They are tearing down the engine this week to discuss rebuild options. Just a few questions if anyone has had to do this:

1) How many hours can you typically get out of a rebuild?
2) What can I do to prevent this from happening again - I changed my oil every 50 hours -- I am now told that 40W is the oil you want to use in Florida -- I was using 20W 50 for the hot weather.
3)Is there any preventative maintenance to undertake?

Jimn advised that I do a compression test to see if that was the problem with my idle -- exactamundo -- except it turned out to be a big problem --

Any thoughts would be appreciated.

08-03-2004, 08:58 AM
Is the compression low across the board or just a few cylinders? You may get lucky and only ned the top end worked on, but have them give you an estimate and some options. If they have a flow bench, they can determine quickly if the heads and head gaskets are the problem and if it needs more extensive work or not.

How long will it last? Hard to say, but frequent oil changes, no excessive heat(meaning overheat) ,keeping a fresh impeller in it and the oil cooler clean will will help a lot. Thinner oil gives up heat faster than thick oil, so that's the reason for the 40 W instead of 50W.

east tx skier
08-03-2004, 10:40 AM
I'm no mechanic, but sta-bil in the gas (assuming you're not running a tank through every two weeks) isn't a bad bit of preventative maintenance.

08-04-2004, 11:47 AM
Mechanic called back and dropped the bomb on me. He explained that one of my valve seats was stuck half way and that my piston was only moving half way -- left a pretty bad gouge in my piston and explains the valve tapping.

He is concerned about trying to fix the one head as both sides of the engine have low compression. b/t 100 - 120. Trying to weigh options between dropping a new block in or rebuild.

One last question -- it appeared that some work was done on this cylinder before -- the valve seat was pressed in and not machined in and this is why he thinks it moved -- he had not seen this before

any thoughts to pass along --

08-04-2004, 02:19 PM
Ball's in your court, but freshening up both heads and replacing 1 piston head shouldn't be too terrible. Since it will be apart, the bearings and rings on the piston being replaced can be checked and/or replaced, but if the cylinder walls look good there's no real reason to do anything to them. have him give you some options and see what makes the most sense to you. Valve seats are replaced all the time. Sounds like it may not have been as good of a fit as someone thought.

You can have him do as much or as little to the motor as you want, but if you have wanted any performance upgrades, now is definitely the time to do those since the disassembly will need to be done either way.

08-04-2004, 08:55 PM
Murfsu - I don't have any advice, but I can say it really su(ks.... I was in similiar shoes last year about this time. Hang in there - before you know it you'll be back out there!


08-05-2004, 07:55 AM
Thanks for the encouragement -- I just have to keep my head up -- this was the first Mastercraft I owned -- something I wanted my entire life. I use my boat alot -- but did not pay enough attention to my engine. I guess it takes more than just changing the oil and tranny fluid timely. Hopefully these guys will have some good recommendations -- I will keep you posted

08-05-2004, 10:07 AM
Which leads me to ask, how many hours does the average 350 block usually run before it needs an overhaul? Assuming oil changes every 50 and proper impeller maintenance? I have 910 on mine without many problems, but I always wonder when I should exit from this boat into another.

08-05-2004, 10:37 AM
There are people out there with over 2000 hours on their motor. How long it will last depends on, among other things, keeping clean oil in it, no excessive temperature(especially with old oil in it), warming it up completely before running at high RPM, keeping it tuned properly and not running it too lean or rich.

08-06-2004, 12:27 PM
2200 hrs and still strong on an '87 Indmar. PM is the key.