78 Evinrude 150HP V6 Questions

[motoroilmccall]

Alright, here's the story. I bought this Bass boat a few weeks ago, and have been fishing on it for a few weekends, although the motor has never run real great, I figured it was thanks to the old gas and gummed up carbs. I've been running carb cleaner through it hoping it would clear up, but it seems to be getting worse. Finally, last night I decided to run a compression check. The Seloc manual I have doesn't give any number spec for the engine, it just says they should all be within 5-10psi of the others. Well 80psi seems awful low to me. Although, they were all within 5psi of that.

Now the engine needs to be timed and sync'd, but that has nothing to do with compression. I deal with diesels and chain saws, not outboards. How hard is it to re-ring one of these things, and how expensive is it to have somebody else do it? I could probably tear it down and fix it, as long as there aren't any specialty tools I'd need, but I'd still need somebody to tune it.

I'm guessing the last owner (who told me his kids used it) probably put straight gas in it once or twice.

Advise?

 

[wilde1j]

Re: 78 Evinrude 150HP V6 Questions

Your compression readings are not unusual for that motor.

 

[Daviet]

Re: 78 Evinrude 150HP V6 Questions

Running carb cleaner through the carbs will not clean them, you need to remove the carbs and dismantle them and remove all orifices and clean all passages.
I would do this first and see if it helps.
Compression might be helped with a good decarb job.

 

[motoroilmccall]

Re: 78 Evinrude 150HP V6 Questions

Alright, thanks guys, gotta call the marina on monday to see if they have 3 carb kits in stock for it. I'll pull and clean the carbs next week. Also, a good tech out here said it could be a wiring issue with ignition. Wants me to pull the plugs and check each for spark. Sound like a plan?

 

[emdsapmgr]

Re: 78 Evinrude 150HP V6 Questions

If that engine has the stock 323456/457 heads on it, your compression should be in the 105-110 lbs range. Yours is low. Agree with Daviet, try some decarb on it and see if the compression comes up any. Certainly won't hurt.

 

[mikesea]

Re: 78 Evinrude 150HP V6 Questions

Agree with all the suggestions.there were alot of different set ups regarding the heads.Seems they had hi and lower comp.heads,also there was a thicker head gasket avail to reduce comp.after the lead was removed from the gas.As for the re ring.its a bit different for these high RPM 2 cycles.There are sleeves ,but unlike diesals they need to be machined out .On rebuilds its more common to bore oversize.There are no oversize rings,that can be used with std.pistons..Only oversized piston kits.The cyl.walls tend to become oval shaped ,so putting a new round ring in an oval hole dont work.you need to bore strait and put new oversize pistons in.They are expensive.About $90 a piecefor the piston ,rings and wrist pin X 6.But you will have a nice clean running engine ,if the rest of the eng is nice.Being a 78 ,you need to think if its worth rebuilding what you have.That is a great engine.If yours is like a lake run,seasonally used eng ,then its likely worth it.If its a rust bucket ,with tore up wiring etc.Id suggest you buy newer .I like the mid 90's looper engines.