60 Hp compression readings

sweaver · Oct 24, 2005

I'm rebuilding a '92 60 Hp evinrude for a friend. He burn a piston out so I had that cylinder bored .020 over. All of the rings and bearings were replaced . The compression checks as follows #1(new piston)120, #2 110, and #3 110. Is this acceptable? The other two cylinders were honed and as I said new rings were installed. Also, can someone tell me how a leak test is actually done? I've heard this is a better way to judge the condition of the cylinders and seals. I was just wondering if there is a way to make one of these setups. Thanks

rodbolt · Oct 24, 2005

Re: 60 Hp compression readings

not an economical way, for one test just take it to any shop that can do it. most autoshops can as well as most marine shops. test takes about 15 min or so on that motor.takes about as long to set up the equipment than running the test. and yes its a much better method of testing cyl sealing than a compression test. it inserts air at a known pressure and measures the amount of leakage to maintain that pressure.

koolerb · Oct 24, 2005

Re: 60 Hp compression readings

Just out of curiosity was it the number one cylinder that had the burnt piston?

sweaver · Oct 25, 2005

Re: 60 Hp compression readings

Thanks Rodbolt. I was just curious wht the test setup looks like. I do a lot of service on different brands of motors and thought this might be something to look into. You are right Koolerb! It was the top cylinder. Anything I should know about?

Dhadley · Oct 25, 2005

Re: 60 Hp compression readings

What caused the problem with the original piston?

sweaver · Oct 25, 2005

Re: 60 Hp compression readings

Dhadley I'm not too sure. Motor had been setting up for a while and there was definitely some starting fluid involved.

Dhadley · Oct 25, 2005

Re: 60 Hp compression readings

If the cause of the problem isnt found and corrected it may well happen again. How were the carbs? Which impeller was in the water pump? What spark plugs was he using?

sweaver · Oct 25, 2005

Re: 60 Hp compression readings

Dhadley: I had been through the carbs several weeks before. I don't understand what you mean when you ask which impeller was in the H2o pump. Water flow was good when I rebuilt carbs. Spark plugs appeared to be OK.

Dhadley · Oct 25, 2005

Re: 60 Hp compression readings

Look real close at the carbs, especially the top one. The actual damage is to the piston may give us a clue as to what caused it. Naturally rebuilding the carbs now is a standard part of the rebuilding of the powerhead so look close at that carb. Some early water pumps had 3 bblade impellers. They need to be changed to the new style impeller. What brand and type spark plugs is he using? Have all the upgrades been done including the temp sender?

sweaver · Oct 25, 2005

Re: 60 Hp compression readings

Dhadley: I replaced the Champion plugs with NGK. Neither of which was a perma gap style. I have no way of knowing if there has been an upgrade on any of the components. Do you have any info on this? When the motor was brought to me originally it was because it wouldn't run. I pulled the carbs. and found them very gummed up. I put kits in each one and took it to the river to set it up. That is when I found the cylinder problem. the compression in #1 was around 85 compared to 110 on #2&#3. When I pulled the head cover you could see the wear on the cylinder wall. Sounds like you have been around these things for awhile. Now I'm really scratching my head. I have already mounted the powerhead and was just fixing to start setting up the timing. Maybe I need to backup and regroup.

MCM · Oct 25, 2005

Re: 60 Hp compression readings

Just a note: find another aplication for the NGK'S and put Champ's back in, L77JC4 gapped at .030 for sustained high speed or .040 for sustained trolling (low) speed. NGK plugs run to hot for OMC motors

Dhadley · Oct 25, 2005

Re: 60 Hp compression readings

Ditto. Especially in that motor.

koolerb · Oct 25, 2005

Re: 60 Hp compression readings

I just rebuilt one this summer. I had the head re-sleeved, installed new piston and three sets of rings. I've got about two hours on it, nice smooth engine. But I'm concerned about what may have caused the damage in the first place.

rodbolt · Oct 25, 2005

Re: 60 Hp compression readings

use QL series plugs in that motor, the plain L series can interfere sometimes. you can do a leakdown test with the powerhead on the bench. just need a way to turn and hold the crank.

Per · Oct 26, 2005

Re: 60 Hp compression readings

Also do a search for service bulletins for the 3-cyl OMC around 89 to 93, there have been a lot of them. I know for example that the tell tale hose elbow on the engine should be moved and that the maximum spark advance was altered. You should be able to find all this info right here in this forum. If you don't find them I might be able to help you with the service bulletins # //Per, proud owner of a molten johnson 70hp -91

sweaver · Oct 26, 2005

Re: 60 Hp compression readings

Thanks everyone for the input. I gather no one else here has had problems with Champion plugs? Well, from past experience with this site, you can bet I will be changing the plugs. Koolerb, sounds like you've been to the same dance I'm at. After posting on here now I'm really concerned about what could have caused my problem. rodbolt: Can you give me a little more info on the leak down setup? Per: I could really use the help with the Service Bulletins. Where on this site could I possibly find them? Thanks for the help guys.

Dhadley · Oct 26, 2005

Re: 60 Hp compression readings

Theres a very good, detailed article about what's needed and proceedures in this months Bass & Walleye Magazine.

Per · Oct 26, 2005

Re: 60 Hp compression readings

I don't think you could find the actual service bulletins here just the info in them, sorry for the confusion.. Just use the search function and search for; 2221 2225, 2271 2276R1 These are service bulletin numbers, I'm sure you will come up with plenty of posts. I have found them earlier when I was looking for info on my johnson 70hp -91 so you need to check that they really apply to the 60hp Also do a search for 432955, this is a part # for a revised water pump kit. Hope this helps...

koolerb · Oct 26, 2005

Re: 60 Hp compression readings

432955, yep, that's the water pump kit I installed. With two hours on the engine, and no carb work done post repair, all three plugs look good. The previous owner was using WalMart 2-stroke oil in the thing, I don't know if that had anything to do with the failure.

koolerb · Oct 26, 2005

Re: 60 Hp compression readings

Just read the info on all the SB's. Look like I have some more work to do.

60 Hp compression readings

Seaman Apprentice

Supreme Mariner

Petty Officer 1st Class

Seaman Apprentice

Supreme Mariner

Seaman Apprentice

Supreme Mariner

Seaman Apprentice

Supreme Mariner

Seaman Apprentice

Lieutenant Junior Grade

Supreme Mariner

Petty Officer 1st Class

Supreme Mariner

Cadet

Seaman Apprentice

Supreme Mariner

Cadet

Petty Officer 1st Class

Petty Officer 1st Class