Compression drop 1982 Evinrude 175

[pastorbud]

So I bought an Evinrude E175TRXCNB 175 hp last year and ran a quick compression test. All six cylinders showed 100-110 psi. I fired it up briefly on a stand.

it sat in the garage close to a year, then I moved it to the backyard to start getting it ready to mount on my project boat. It ran pretty lousy, then wouldn’t start at all.

I checked for spark. All six good.

I pulled the plugs and they had quite a bit of fuel on them and what looked like loose carbon particulate on them. It wasn’t attached to the plugs: you could blow the little pieces right off.

i cleaned up the plugs... still no start.

i checked compression again and they were all around 75 psi.

Two things: second test was done in much colder weather and with a different compression tester.

Could either of those things explain the drop in compression readings?

(PS... no, I didn’t go through the carbs before I fired it up! Always in a hurry...)

 

[racerone]

Remove bypass covers to inspect pistons / rings.----Easy to do.-----It may also have thicker head gaskets installed.-----I can not see them in post #1 so all bets are off.

 

[pastorbud]

Hadn’t thought of that. Thanks! I’ll take pictures.

 

[oldboat1]

FYI -- just worked on a friend's late '80s 175 today (cold starting issues). My oem manual notes that a compression difference of 15psi between cylinders is excessive -- not the 10% I was used to. Try adding some fogging oil, and tilting the motor up overnight, then test again.

On spark, I was getting no spark on two of six, so checked the secondary coil circuits (all good), then replaced plug wires (no continuity on two of them). Additionally, I took the dirty starter apart and cleaned it with electrical cleaner.

Spark in retesting was just under 1/2" using an open air adjustable tester. When you say "good" spark, that is what you should be seeing. For testing both spark and compression, remove all plugs to insure it's spinning fast enough -- need around 300 rpm for spark. Keep the boots away from open cylinders.

 

[pastorbud]

Thanks. I just put an inline tester on each plug, one by one. Got spark on all six. I have a voltage averaging adapter for my multimeter. I guess I could check the voltage out of this CDI box if I looked up the specs. Mostly I’m concerned about the low compression right now.

 

[pastorbud]

Okay here is a Video from the inspection of the pistons and rings Behind the bypass covers. I opened the top two on the port side, and the top one onthe starboard side. They all look the same, so I quit opening them up for now.

 

[flyingscott]

Inline tester is not a good test.

 

[pastorbud]

Remove bypass covers to inspect pistons / rings.----Easy to do.-----It may also have thicker head gaskets installed.-----I can not see them in post #1 so all bets are off.

What are thicker headgaskets and what are they for? Can I take a picture to in some way identify them?

 

[racerone]

They offered a ---" low compression kit " ----for the 82 model 149 cubic inch motors.

 

[pastorbud]

They offered a ---" low compression kit " ----for the 82 model 149 cubic inch motors.

Wow! Glad to learn that. Is there a way to identify?

 

[pastorbud]

Can NOT get that video to load. Trying here.

 

[pastorbud]

Here’s a video of it running. Someone else who saw the video noticed my exhaust ports weren’t clear. Also the previous owner ran the tell-tale tube around to the front.

 

[pastorbud]

Here’s a video of it running. Someone else who saw the video noticed my exhaust ports weren’t clear. Also the previous owner ran the tell-tale tube around to the front.

Never mind on second video! I give up. Hopefully That first video will tell everybody what they need to know.

 

[pastorbud]

Inline tester is not a good test.

I have seen those adjustable testers in the parts store. I never knew what the advantages were.

 

[hardwater fisherman]

The inline tester indicates spark.. The open air gap tester indicates the strength of the spark by making it jump the gap.

 

[pastorbud]

Got it

 

[pastorbud]

Remove bypass covers to inspect pistons / rings.----Easy to do.-----It may also have thicker head gaskets installed.-----I can not see them in post #1 so all bets are off.

The video is in a post above showing what I found after the bypass covers were off. Do you see anything out of the ordinary?

And does anyone know what those marks are?

 

[Faztbullet]

Well that motors NOT a virgin as it been into. The piston in question has very little wear and someone even used gelseal on transfer gaskets. Next step is to pull heads and inspect cylinders as it might have been a hone and go repair.

 

[flyingscott]

Pull the heads at this point like fazt said

 

[pastorbud]

Heh. I bought this motor for my project boat, and turns out it’s a project motor.

I have a 150 horse force outboard in the garage that is in much better shape. I went with this Evinrude because the boat was already set up with Evinrude/Johnson controls, and the old motor on it was a Johnson 150.

I am kind of wondering If I should just re-fit it for the Force outboard.

A lot of guys don’t like Force outboards, but I’ve kind of gotten used to them.