Low compression on Evinrude 6hp

[Adalimbi]

Evening FRs

Both of my Evinrude 6hp have low compression, one is 50/60 psi and the other is 70/70 psi from memory.

What I would like to know is how exactly do I check if it is the ring or not?

I know you're supposed to put oil in the ignition chamber and do the compression check again but what sort of oil? How many pulls? all that sort of stuff.

Thanks for any help.

Cheers.

Bill.

[Geoff]

Remove the spark plugs , using an oil can which has a pump device , give it 2 or 3 squirts into to the plug holes , connect the compression gauge & pull the starter cord several times untill the reading on the gauge no longer increases.

Geoff

[Adalimbi]

Thanks Geoff...too easy!!!

Does it matter what type of oil I use? (I don't own an oil can and I'm sure that they will be empty when I go to buy one)

Edited April 12, 2013 by Adalimbi

[a boat]

Hi, all compression gauges read differently and depending on year model small engines do not have a lot. The most important thing is they are even which you say they are from memory. If you suspect damaged bores then using 2-stroke oil is what you want but if there were big difference between each cylinders on little engine like this it is so easy to remove the cylinder head, good preventative maitenance anyway every 15 years or so, and check what the bores look like. Do they run OK?

Cheers,

Huey.

[Adalimbi]

The one that is 50/60 psi has a few parts missing, spark plugs, fuel pump and fuel lines.

and the other one that is 70/70 psi runs ok.

what should the compression be on 1976 / 1978 6hp Evinrudes?

[a boat]

Hi, as I said there is no specs for any outboard made on compression. Every single compression gauge will read different and there are right ways to do compression checks. The best form is a leak down test but not a big thing on such a small outboard and the fact that the two cylinders are even is the main thing and if runs fine then compression is good. As I said, considering these are almost 40 years old and I bet the head gasket probably has never been replaced, it is a very simple and easy job to remove the head, clean the water passages and re-fit with new gasket. Doing this allows you to see the bores and chances are you will be still able to see the hone marks on these bores. These engine are built proof and go forever if looked after.

Cheers,

Huey.