Merc 20 blow up

[arjin]

Hello,

I have a Merc 20HP (1979, Belgian Electric). Yesterday I had to give full power back when all of a sudden a huge white cloud exploded from the exaust and the engine stopped. After the first panic I restarted it and to my surprise it still ran, as long as I kept enough gas on. It didn't happen again (yet).

I'm thinking it may have overheated due to too lean mixture. But that doesn't explain the white cloud which I think was for the most part steam and a bit of oil judging from the smell of it.

Has anybody got any idea what it was and how much damage it may have done to the inside?

Arjin

 

[arjin]

Re: Merc 20 blow up

By the way, the serial of the Merc 20 is: 9231226. It's a Belgian Electric from 1979.

 

[James Tobias]

Re: Merc 20 blow up

sorry i can't help with your problem. but i am searching for pics of 20hp mercs.
can yu send me pic of yours?
jt4345@comcast.net

 

[achris]

Re: Merc 20 blow up

You need to start with a compression test and have a look at the firing end of the spark plugs. After that, I'd pull the powerhead and exhaust covers and have a look at the piston crowns and as much of the skirts as possible. At 1979 it may just be a cheaper exercise to buy a new engine if it's not looking to good. If you'r capable of doing all the labour yourself then it may be economical to do it... As it only has 2 pistons, they're not too expensive, the biggest cost (if it needs it) will be the cylinder machining.

Good luck and let us know the results of the compression test.

Chris................

 

[Harker]

Re: Merc 20 blow up

I wonder if you just flooded the upper exaust ports with water while backing down heavily. Check compression and see if the plugs are steam cleaned.

 

[arjin]

Re: Merc 20 blow up

3 years later, just for the record: Harker was right: I had water entering from the rear and that caused the blow out of steam. Compression is still ok, havent had a problem since.