no compression on inline 1992 merc 3.0L

[Bayliner1992]

What's up lady's and Gent's, I seem to have lost power, yesterday i went out fishing and on the way back i lost power! today i was checking and removed all my plugs, cap, rotor and wires and exchange with new set, i also put in a new merc carb today which i had put away for a rainy day, aftwer testing again i still had the same problem no RPM while in motion, well i checked for compression and two out of four have real low compression! the two center plugs have low compression the two outer plugs want to blow off your fingers. nopw what is the problem? did i loose my valves?

 

[Haut Medoc]

Re: no compression on inline 1992 merc 3.0L

Low or none?.....
Adjacent cylinders?.....
What are the readings on the compression gauge?......​

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

really really low!!

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

Sorry did not use a gauge that's how big the diffrence is.
yes they are the two center plugs.

 

[macr6]

Re: no compression on inline 1992 merc 3.0L

blown head gasket? Had the same problem. When I took the engine cover off I could hear the compression being lost out the head. a loud pfft pfft pfft

 

[Bondo]

Re: no compression on inline 1992 merc 3.0L

Ayuh,....... I agree with Marc,.....

My Guess is the Headgasket is Blown between #2,+ #3.........

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

Thank god its the end of the season for north folk lol, i guess i'll have to change it ! every thing else is fine, i do not over heat but man i go 10 miles per hour WOT..and thanks i will see what else is going on.

 

[Don S]

Re: no compression on inline 1992 merc 3.0L

Do a leakdown test if you REALLY want to know what is wrong BEFORE you take it apart.

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

what's a leak test captain?

 

[Bondo]

Re: no compression on inline 1992 merc 3.0L

what's a leak test captain?

You blow Air into 1 of the cylinders,+ Listen for Where it's escaping......

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

blow in to a hole jejeje okay. now what should i be hearing for? if i have a bad head gasket would i be looking for water in the oil or any other signs.

 

[Don S]

Re: no compression on inline 1992 merc 3.0L

Click Here and start reading. I think you will understand it in very short order.

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

Thanks Don, I will do the reading and figure this out thanks again for your kind help in this matter. I want to add another question ! if it's not the head gasket causing the two cylinders side by side with low compression what else can it be?

 

[Haut Medoc]

Re: no compression on inline 1992 merc 3.0L

Bad rings, valves or holed piston......
It's prolly the head gasket.......
That's why I asked if it was low or no.......​

 

[thrasher]

Re: no compression on inline 1992 merc 3.0L

If you are going to remove the head, I would also re-seat the valves whilst the head is off. It doesn't take long and can only help improve engine performance (assuming the work is done correctly! ).

Gary

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

Thanks again, the boat comes out saturday and i have all winter to tinker so again i give thanks.

 

[Bayliner1992]

Re: no compression on inline 1992 merc 3.0L

Hello, this post is from last year but i had to bring it back, thanks again it was a busted head gasket right in the center, i replaced it after several other atempts at other angles, what i got out of it was a new prop , if you read back i thought it was the prop first, new fuel tank, new carb and all it took was a head gasket and some elbow grease, thank god i got speed back planes like a baby, just feels good to be back out there. boat sat all season in the slip could'nt take it no more lol.....Thanks again