Johnson outboard ran with straight gas

[doug9238]

Hello,
My friends boat was ran last weekend on a 5 gal tank of straight gas that was not mixed with oil. The guy running the boat said that the engine started running rough and he took it back to the dock. That is when he fessed up that he did not mix the gas with oil.

I did a compression test and 3 of the 4 cylinders have about 110-115 of compression, and one of them has no compression.

The engine is a 1978 Johnson 85HP V4 magna sea-horse (model # 85ML78C)

Can this be fixed? And if so, what are the next steps?

 

[F_R]

Re: Johnson outboard ran with straight gas

The first step is to pull the cylinder head and exhaust covers for an inspection. The first thing to go when running without oil is the pistons. Sounds like one of them is toast. I'm really surprised that all four aren't.

 

[wilde1j]

Re: Johnson outboard ran with straight gas

Big trouble time. A rebuilt powerhead is ~ $2000. Probably not economic to repair or fix.

 

[GMWIGGS]

Re: Johnson outboard ran with straight gas

Thats bad. Its maybe fixable, but hes looking at a serious overhaul. Depending on the condition of the smoked cylinder, and actual damage done to the other 3, it should be fixable. Will it be worth it? Not knowing other conditions of the engine, how it was maintained and ect., its hard to say if its finacially worth overhauling.

 

[doug9238]

Re: Johnson outboard ran with straight gas

We found a used powerhead for sale locally from a 115HP Johnson/evinrude motor that is an early-mid seventis one according to the seller. He only wants $100 for it. The lower unit from that engine does not mate up to ours, becuase the splines are different and so is the diameter. I checked the welch plug on that powerhead, and it reads J3043646

Can this be used to make one good motor out of two?

 

[BigB9000]

Re: Johnson outboard ran with straight gas

different midsection, different lower, different drive shaft.

Depending on how complete your new powerhead is would be the kicker on this project.

If you got the flywheel, starter, carbs, coils, electrical, basically unbolting the powerhead and handing it to you if might be worth it.

There isn't much of a market for an early 70's mid sections. Someday ebay will come up with one on the cheap.

Some of your old parts will work on the new engine you might be making, but not much.

Really, you would be better off going on a roadtrip:
Ebay 85hp

 

[doug9238]

Re: Johnson outboard ran with straight gas

Wish the ebay one was closer, becuase we could certainly change out the power packs on this one and have one working motor...

I also found a 1977 85HP motor for sale locally that is missing the lower unit. Do you know if the Johnson 1977 & 1978 uppers, mids & lowers are identical?

 

[BigB9000]

Re: Johnson outboard ran with straight gas

Do you know if the Johnson 1977 & 1978 uppers, mids & lowers are identical?

They are not identical.
They use different part number.

However, this doesn't mean It will not fit. They could have came up with a better design or a new screw hole, thus having a different number.

But, the good thing here is both the 77 and 78 use the same Driveshaft
0387934 DRIVESHAFT ASSY. 20 INCH TRANSOM MODELS

I would take your lower off, and take it with you over to the 77 and see if it'll align up / fit