Proper Way to Test Compression on Non-Running Motor

[PCantin]

Hi, all.

I am new to this forum, and I can already see it is a wealth of information! I have a 1955 Evinrude Fleetwin 7.5 hp motor that has not run for many years (but did run when it was put away). I see the compression test instructions in the sticky, but I won't be able to start up the engine to warm it up first.

Is there a different method to use when testing compression on a motor that is cold?

Thanks for any help you can give me.

Peter

P.S. Any leads on good places to buy parts here in Canada? There are lots of great online sites in the U.S.A, but the shipping and duty charges can be a real pain!

 

[Joe Reeves]

I have never bothered to warm up a engine to do a compression test... a matter of opinion.

Remove all spark plugs.
Spray a little pre-mix in the cylinders for lubrication purposes fi they're dry.
Crank the engine over a half dozen revolutions to spread that spray mix around.
Take the compression readings with the gauge.

Always a good idea to mark down the readings... psi and # of cylinder... (No, you won't remember them!).

Top cylinder is always #1

 

[PCantin]

That was quick! Thank you for your help.

Once I get the readings, I will indeed write them down and post them.

I just tried to drain the lower unit, and there was nothing in in (crap). It may be that it was drained before storage (my Grandpa was going senile at the end :grumpy, but it still means it has been sitting dry for years.

Thanks again.

 

[PCantin]

Not the best compression readings...

Cylinder # 1: 80 psi
Cylinder # 2: 78 psi

These values are certainly not optimal, but I am assuming they are good enough to continue. The piston and cylinder walls look OK with a quick visual inspection, and there were no issues with turning it over. I will next check the condition of the coils and points, with the assumption they will need to be replaced.

Thanks again.

Peter

 

[F_R]

Hi, all.

I am new to this forum, and I can already see it is a wealth of information! I have a 1955 Evinrude Fleetwin 7.5 hp motor that has not run for many years (but did run when it was put away). I see the compression test instructions in the sticky, but I won't be able to start up the engine to warm it up first.

Is there a different method to use when testing compression on a motor that is cold?

Thanks for any help you can give me.

Peter

P.S. Any leads on good places to buy parts here in Canada? There are lots of great online sites in the U.S.A, but the shipping and duty charges can be a real pain!

Certainly you have Evinrude dealers in Canada? Do yourself a favor and get a parts book for your motor. Any Evinrude dealer can order the parts if you go in armed with the part numbers. Without the numbers, he might not give you the time of day.

 

[RCO]

Those are actually great compression numbers for that engine. I think that motor has an inspection plate for the magneto, if you see pinkish colored coils with cracks, they are original and junk. If they have been replaced, chances are they are good, and you can clean or replace the points and condensers.

 

[flyingscott]

That compression is fine those motors are not high compression. That motor will run fine a bigger worry for you is the lower unit with no lube in it.

 

[PCantin]

Certainly you have Evinrude dealers in Canada? Do yourself a favor and get a parts book for your motor. Any Evinrude dealer can order the parts if you go in armed with the part numbers. Without the numbers, he might not give you the time of day.

I thought that the parts would be too old to source from a dealer, and that I would have to go an alternate route. We certainly do have dealers in the area, so I will check them out. I will also source out a parts book.

Thanks for the suggestions.

 

[PCantin]

Good to hear that those compression values are good. I will check the coils as mentioned above. Yes, that lower unit is a bit of a worry, so I will have to look into that a bit deeper as well.

 

[racerone]

Some parts for that motor may well be easier to get than parts for much newer motors.---Your location ?

 

[PCantin]

Some parts for that motor may well be easier to get than parts for much newer motors.---Your location ?

I am in Lindsay, Ontario. Being in the Kawartha lakes area should mean there are lots of dealers around!

 

[PCantin]

I am assuming this is what you meant by "pink and cracked"!

Looks like some parts are in order.

 

[racerone]

That is classic damage to the original coils.----All the motors with those coils from the 1950's / 60's / 70's will have that happen. ----Used on the 3 / 5.5 / 6 / 7.5 / 10 / 15 / 18 / 20 / 25 / 28 / 33 / 40 HP motors.----Every boat shop that works on older motors will have them on hand !!-----There is no need to warm up a motor for a compression test.----No need to open the throttle for a compression test on a 2 stroke.