1999 200 Johnson Compression prob

[beng]

I took my boat to the dealer today and they called and told me that my 2 bottom cylinders have low compression all others are 110 and the others are 96 and 93. he also said the piston had some scratches on them. Does anyone have any ideas on what could have caused this??? and what is the fix and about how much does it usually cost to get fix???? I am hoping its nothing major but sure doesn't sound to good though....let me kow something guys i look foward to seeing what you have to say....

justin

 

[lexkyboater]

Re: 1999 200 Johnson Compression prob

My local shop told me $3600 for a rebuild on an 86 GT 150. Scratches/low compression could be caused by foreign particles in engine. Sounds like a rebuild is in order. I guess they took off exhaust cover or carbs to see piston scratches? How much wrenching experience do you have?

 

[Dhadley]

Re: 1999 200 Johnson Compression prob

On a V6 looper you cant see scratches on the piston skirts unless you remove the pistons. Is that what they did? Or are they talking about scratches on the cylinder walls. Is the head(s) off?

 

[lexkyboater]

Re: 1999 200 Johnson Compression prob

Didn't realize that dhadley - thanks for the correction. I wonder if they're talking about tops of pistons, which wouldn't matter much at all?

 

[Dhadley]

Re: 1999 200 Johnson Compression prob

Yeah, on a crossflow like yours you have the option of pulling those covers. On a looper those covers aren't there. Good in some ways, bad in others.

3600.00 seems awful steep to rebuild a V6 crossflow. I have a 1990 150 V6 crossflow I'd sell for that. And it comes on a 20' Dusky. On a tandem trailer.

 

[beng]

Re: 1999 200 Johnson Compression prob

no scratches to come to find out just low compression in the 6 cylinder a bad power pack on 5 cylinder and a coil thats by the fly wheel was bad...

my questions is... If they are going to replace the listed above could that make low compression in the 6th cylinder????

its not much like all others were 110 and it was 96 i talked with the machanic today and this is straight from him...

if that doesn't fix it then what might be the next step to fix it or can i run it like it is with no problem??? Also what might have caused this problem???
i am pretty much stupid on outboards but can work on cars and so forth....

they are running it in the test tank when the above is replace... i sure hope it fixes it ....

thanks for the help

 

[Solittle]

Re: 1999 200 Johnson Compression prob

Unless you know when the engine was decarbed last you might ask the mechanic to do that in the test tank. Could be just a couple of stuck rings.

In any case I recommend that you try to be there when he takes another compression test or better yet take it yourself to verify what you are being told. Remember that many mechanics are honest but there are those who get your money out of your pocket by telling you all the nasty things that are wrong with your engine and he knows just what to do to get it back purring like a kitten.

 

[beng]

Re: 1999 200 Johnson Compression prob

what is decarbing and how is it done? yeah i am going to go in on friday morning and watch and see the test for myself...

 

[DHPMARINE]

Re: 1999 200 Johnson Compression prob

I don't think I've ever seen Compression over 100 PSI on an OMC/BPR V6 .Well not in the past 20 years.90 to 95 is the norm.

So the 110 PSI readings could be carbon.I would decarb a couple times and retest.

DHP