Worth buying a 1994 Johnson 90hp with low compression?

[BonairII]

Got a call from a guy selling a 1994 Johnson 90hp (I had a "90hp wanted ad on CL a coulole weeks ago). Says the motor has low compression on 2 cyls(around 85psi)...and 120 psi on the other 2 cyls. I'm hoping maybe a bad head gasket.

Motor has power trim and LU was completely rebuilt last year. He's asking $350.

Are these motors known for problems? Are they crossflow motors(gas hogs)?

 

[Bosunsmate]

Re: Worth buying a 1994 Johnson 90hp with low compression?

I suppose the LU could be sold for most of that money.
If it was just the headgasket the risk would be why have they not done that, but ive bought things for less than half price that have needed just a bit of copper wire to be worth their full price again

 

[kjdunne]

Re: Worth buying a 1994 Johnson 90hp with low compression?

If the low compression cyls. are on the same side, may very well be just a head gasket. If it's clean and looks otherwise well maintained, I'd offer him 250 and bargain from there. If it's a corroded salty, don't even bother. Does he have proof of lower unit rebuild, receipts? Worst case is you can part it out for a profit, lower unit, tilt/trim unit, starter, etc. all sell quickly if you're not too greedy. These crossflows are good motors, real workhorses and there is a ton of them out there. A bit thirsty compared to today's new motors but not really bad if they are running well and propped right for your boat. Simple, reliable, and affordable in my opinion.

 

[emdsapmgr]

Re: Worth buying a 1994 Johnson 90hp with low compression?

When you get out to look at the engine, take a pencil flashlight and a spark plug wrench. Pull out a spark plug or two and shine the pencil light into the spark plug hole. You should be able to see the condition of the piston crown and the cyl walls. That should tell you something about the low compression problem.

 

[ezmobee]

Re: Worth buying a 1994 Johnson 90hp with low compression?

Motor has power trim and LU was completely rebuilt last year. He's asking $350.

As mentioned, that's $350 worth of stuff right there. And it COULD be a bad head gasket. However, ya gotta wonder why he wouldn't have at least pulled the head on that side and checked it out.

 

[papachaz]

Re: Worth buying a 1994 Johnson 90hp with low compression?

As mentioned, that's $350 worth of stuff right there. And it COULD be a bad head gasket. However, ya gotta wonder why he wouldn't have at least pulled the head on that side and checked it out.

maybe he's one of those 'not in any way mechanical' type guys. My FIL can't change a blown fuse, and I have a nephew the same way. Some people just don't know how to, or don't want to try to do anything themselves, and assume it will be too expensive to have someone else do it for him. Kind of curious how he knows the compression is low though, so that may shoot my theory right out of the water, HA

 

[Crosbyman]

Re: Worth buying a 1994 Johnson 90hp with low compression?

sounds like a good project motor.... Anybody ever looked into cylinders with those snake TV probes (to look into wall cavities.) ?

they are dirt cheap ($50) and some models simply hook up on a USB prot of a laptop to save on the small video screens and give a real big view of things.

 

[wayneo99]

Re: Worth buying a 1994 Johnson 90hp with low compression?

low compression could be several things as indicated above including a very worn cylinder, broken piston rings. I will prob run good at mid range or top end but it may not idle well at all.
my 79 85 v4 wouldn't idle well and always required choke and high idle to start even when warm. that became old real fast. had low compression and broken rings once we tore it down. It would still be running today if I had the patients for the starting issue

my advice would be to look for a better motor. unless you like major projects and cans of worms and have good mechanical skills.
but maybe you will get lucky and it is a simple head gasket.

 

[gm280]

Re: Worth buying a 1994 Johnson 90hp with low compression?

The price of anything is dependent on finding that someone willing to pay it. However, you could find it is a simple head gasket and have a nice OB for a good price. But like previously stated, low ball the price first and go from there. And if he takes your low ball price, then you may have a problemed engine too...