help with compression issue

[mikeb200651]

Finally got the $ 250 boat to start for few mins. Did compression test few weeks ago, got ignition switch and wiring harness also. Test was 120 all four cylinders before but after I got it started wouldn't idle so played around revving it to maybe flush out any trash inside. I didn't notice that my flusher had broke and was just watering my yard. Now it sounds like battery issue when try to start but all tested good. Did comp check today and top 2 very low. Under 90. Bottom two were 115. Did I ruin my motor or is this something that can be easily repaired?

 

[pnwboat]

Re: help with compression issue

Obviously the overheat buzzer is either not working or not present. That should be repaired. If the motor overheats due to lack of cooling water, it'll run great until it suddenly seizes up.

If you remove the spark plugs and turn the motor over by hand (clockwise looking down at the flywheel) by grabbing the flywheel, it should be fairly easy to turn. If not, you may have some mechanical damage.

Do you know how long it ran without water? Hopefully, if there was some damage, it's just a bad head gasket. Replacing the head gasket is pretty simple.

Squirt some 10W40 weight oil into the low reading cylinders. If compression increases significantly, then it's usually the rings. Either they're bad or seized up in the ring grooves in the piston or the cylinder wall has been damaged. If no change, could be the head gasket.

Also, you should check/replace the water pump impeller. Only takes a minute or two running without water to possibly trash the water pump impeller.

 

[mikeb200651]

Re: help with compression issue

Pulled the plugs, looked at pistons and the to one is trashed. Second one lil pitted and other two are like New. Just talked to boat shop here and looks like won't be worth trying to fix cause of age and parts availability. Don't know about impeller; no clue where it is, what looks like or what supposed to look like. Guess I'm dead in the water (no pun intended). Hoping can find good motor fairly cheap. Kinda depressed now. My project didn't work out

 

[pnwboat]

Re: help with compression issue

Sorry to hear. This is a good candidate for a parts motor.

 

[Frank Acampora]

Re: help with compression issue

All is not lost! The parts (pistons and rings are still very available at a cost of anywhere from 80 to 125 bucks. Boring would cost somewhere between 40 to 60 dollars per cylinder. Only the bad pistons need to be replaced and only the scored cylinders need to be rebored oversized.

A mechanic or marina will not want to work on the engine and anyway, they would be too expensive. If you want to do the work yourself, we here on the forum can give you all the guidance you need AND no special tools are needed--these engines are easy to work on.

The four cylinder 90 was actually a de-rated 105 and is a nice engine I recommend that you think about rebuilding and also post a couple of photos of the cylinders with the head off so we can evaluate the damage.

It would be good if you give your location: there might be a forum member close enough to help or offer parts.

 

[mikeb200651]

Re: help with compression issue

Thanks frank, I actually started trying to work on it myself. Tour down to pistons and looked at sleeves. Pretty tore up on one and two. Gonna try to patch the sleeves with jb weld and see if can save pistons. May not work bit at least will keep me busy till payday. And If works for summer will be worth it. I'm sure I'm fighting a losing battle but keeps me busy and away from wife so it's worth it. Besides, it's already broke. Can't hurt much more. Lol

 

[mikeb200651]

Re: help with compression issue

Also it's a120. Guy at dealership said would be more expensive to try to fix than finding another motor. I'm not a quitter and if can get running I'm gonna try. Still no manual tho. None in san angelo, tx

 

[Jiggz]

Re: help with compression issue

Pics of the inside, cylinders especially will be very helpful in deciding to rebuild or not.