checking a non running engine for purchase

[dsujen]

I am going to look at a 1983 evinrude E90ltct today. The guy says he is selling for his dead uncle and knows nothing, as usual. Has no controls. The motor is mounted on a half *** stand. How can I check compression? What should compression be? I have the gauge.Cordless drill on flywheel nut? Any tips appreciated. How to check lower unit for problems? He's selling for $400 so I am very interested.

 

[Scott Danforth]

Re: checking a non running engine for purchase

I would bring a starter pack and a jumper wire for the starter myself. there is no way in hell a cordless drill will turn the motor over. you would be looking at a chorded 3/4" drill or maybe larger

 

[HighTrim]

Re: checking a non running engine for purchase

Yeah just jump the starter off a battery with cables.

Roughly 100psi, and should be even between cylinders.

Crack the lower drain screw in the gearcase and see if water or metal shavings come out.

For 400, if all checks out sounds like a good deal.

 

[gm280]

Re: checking a non running engine for purchase

If this engine is on a suspect stand, make sure it can hold up while doing the compression testing...

 

[Bob_VT]

Re: checking a non running engine for purchase

Pull all the plugs to do the compression test. The cordless may not spin fast enough and a 12 volt set of jumper cables and a car nearby would help. The key is over 100 lbs per cylinder and all 4 with 10% of each other. Jumper's will allow you to see if the $100 + starter works too

To check the lower unit....... check for play in the prop shaft and look for signs of leakage. You could drain the entire lower unit and just re-install the right oil or as mentioned above just look for shavings which I doubt you will see w/o draining it.

The V-4's are fairly bullet proof and are great motors.

 

[dsujen]

Re: checking a non running engine for purchase

Looked at the motor today. Cordless drill worked but didn't spin fast enough. Got 60 psi on 3 of 4 cylinders assuming okay cause of slow speed drill. One cylinder got a 0 psi reading and the drill spun effortlessly. Told the guy no deal cause of one bad ring or piston or something. Good thing I checked it before buying it.

 

[emdsapmgr]

Re: checking a non running engine for purchase

Good call on your part.

 

[wayneo99]

Re: checking a non running engine for purchase

if the tilt/trim works and the lower unit has no water,oil is not milky it could be good for parts.

 

[tpenfield]

Re: checking a non running engine for purchase

I guess you now know why the engine was "non running" :thumb:

 

[bob johnson]

Re: checking a non running engine for purchase

I am wondering how the flywheel spun so differently from testing one cylinder over the others????????????????????????????????????????


cant get my head around that!!

motors are usually on a stand for a reason,.....unless they are small motors like 15 hp and less which many people take off theri boats to keep from getting stolen

bob

 

[orbanp]

Re: checking a non running engine for purchase

Ho Bob,

When you are checking the compression, the cylinder you are measuring, you are working against the compression in that cylinder. Remember, all the other plugs are out. When there is no compression, there is no resistance except for the friction, which is the same.

Peter

 

[HighTrim]

Re: checking a non running engine for purchase

I am wondering how the flywheel spun so differently from testing one cylinder over the others????????????????????????????????????????


cant get my head around that!!

motors are usually on a stand for a reason,.....unless they are small motors like 15 hp and less which many people take off theri boats to keep from getting stolen

bob

As stated, with all plugs out, the gauge in that cylinder is the only resistance. You are sort of isolating that cylinder. With enough practise, you can hold your finger over the plug hole, and spin the flywheel, and determine the condition of the rings in that cylinder.

 

[bob johnson]

Re: checking a non running engine for purchase

it spins that much different???60 lbs vs no pressure??

seems the force needed to rotate the flywheel and turn the crank and drag all the pistons along is enough to even out a low psi vs a poor psi cylinder!

i guess I have always used the starter motor and a battery... and it cranks and sounds the same no matter what.. I picked up a V6 intruder last year with 10 lbs in one cylinder...and i never noticed the stsrter sounding any different....

but maybe with a cordless drill its a different story

the codger I get work down with sometimes , told me if you hold your thumb tight against the spark plug hole and cranking physically forces your thumb off, then the compression is ok...

bob

 

[HighTrim]

Re: checking a non running engine for purchase

Yeah you sort of aquire a feel for each size motor and how much push it should have against your finger. I still use a gauge though.

Even if you use your starter, notice the difference in RPMS when you have your plugs out compared to plugs in? Cranks the stuffing out of it with no plugs in, and no resistance.