1989 Johnson150 Comp Test Results

[winfieldh]

Hi,

This motor is new to me and not been run in 3 years. Was kept up prior to that.

I'm a little nervous to post these results, but here goes....
top left 80 top right 75
mid left 82 mid right 90
low left 80 low right 93

The right cylinder head looks newer than left (left looks original). I have not run the motor, only comp test. I am going to curb my amateur thought process on what is going on, and what to do next, and see what you might suggest. As always, any input greatly appreciated.

Thanks,
Winfield

 

[bignefan]

Re: 1989 Johnson150 Comp Test Results

there only supposed to be a 10% difference between the highest and lowest reading,but your doing the test on a cold motor.did you turn the enine over at least 5 or 6 times each, make sure you battery is fully charged so your starter turn over at the proper rpms. put a little oil into the cylinders see if it bring them up.

 

[JB]

Re: 1989 Johnson150 Comp Test Results

You need to run the engine up to running temp and repeat the test. Do not put oil in the cylinders as that can mask problems.

The numbers are out of spec, but only slightly. Testing conditions and/or technique could account for that.

If the span still exceeds 15% (factory spec) do a decarbon treatment and try again.

 

[bignefan]

Re: 1989 Johnson150 Comp Test Results

Does the motor run?

 

[winfieldh]

Re: 1989 Johnson150 Comp Test Results

Hi,
Thanks for the replies. I have only recently acquired this boat and was informed by previous owner that it did run. He and I are in USCG Auxiliary together and I do trust his care/maintenance. The engine hasn't run in 3 years and he needed to move it along due to medical issues. Because of engine age and sitting for so long, I'm trying to go about this as carefully as possible so as not to cause more issues by simply firing it up and taking off. This comp test is more for a base line, but I wanted to get feedback as I progress.

The battery is brand new, deep cycle. I did spray some light gun oil in the cylinders and hand crank prior to comp test. This was such a small amount I doubt it had an effect (only on my psyche). During comp tests I had wife turn engine over until comp gauge stopped increasing, 5/6 revs/cylinder.

Seems like next step is to run it. Would you suggest replacing water pump impeller first, or get it running and plan to replace once other factors are all taken care of? The current plan is to replace water pump imp, change gear lube, change thermos, change plugs (not necessarily in that order)

Another issue I noticed was the starter seemed to stay 'extended' after a couple of the comp tests. I could not push/tap down, but when key switch turned back on it would drop down, then pop up/engage flywheel and crank engine. Should a starter rebuild/inspection be put on the list or is that normal operation procedure?

Thanks again,

Winfield

just in case, pictures here, engine at bottom:
http://picasaweb.google.com/winfieldh/SeaOx1?authkey=Gv1sRgCJmxhcLupcPrQQ&feat=directlink

 

[Daviet]

Re: 1989 Johnson150 Comp Test Results

If it were mine, I would get it running on muffs, will cover a defective water pump, and do a good decarb on the engine. Then recheck the compression numbers. You might not want to invest a lot of money in it if it has to be rebuilt. Just a thought.

 

[14ftgrumman]

Re: 1989 Johnson150 Comp Test Results

What Daviet says.

Doesn't pay to stick money where it won't do much good.

 

[Dhadley]

Re: 1989 Johnson150 Comp Test Results

First, look at the heads and make sure you have a matching set. What are the casting numbers on each one?

 

[emdsapmgr]

Re: 1989 Johnson150 Comp Test Results

You might want to pull the top starboard plug and shine a light inside the cylinder. Give it a good visual check. Look for cylinder wall scuffing or any dents/pits in the top of the piston. Agree on the decarb procedure and checking the head part numbers with the original factory parts list.

 

[bignefan]

Re: 1989 Johnson150 Comp Test Results

If you Know who you got it from and trust what he has told you just go to Top secret file and follow the link on "it's been sitting 2 year,what to do"
Heres the link

http://forums.iboats.com/showthread.php?t=158086

 

[keefallan]

Re: 1989 Johnson150 Comp Test Results

Don't jump to any conclusions yet. There is nothing more that I can add because evryone else previously has stated everything what you need to do to check your engine. Seriously. Don't worry about the difference in the compression #'s between opposing banks of cylinders. Just keep an eye on that #1 cylinder. See what you can do about that. That's the one to look out for.

 

[coolguy147]

Re: 1989 Johnson150 Comp Test Results

what's wrong with oil being put into the cylinders?

 

[JB]

Re: 1989 Johnson150 Comp Test Results

The idea of a compression test is to see what happens under normal running conditions, Cool one.

Putting more oil in there than is in there under normal conditions is a bogus condition and can give you bogus results.

 

[winfieldh]

Re: 1989 Johnson150 Comp Test Results

No worries folks. The input is all very much appreciated.

Conclusion is that I am going to drain carbs (if there is anything to drain), fix up separate 5 gallons tank of gas/oil, hook to hose and see if we can accomplish ignition. If we pass that test, then I will proceed with decarbing. If no ignition, then a different thread. Assuming ignition is successful and decarbing accomplished, then I will re comp test for an additional base line reference, see how it runs. If runs good then will probably float test, if not then pull/clean carbs and further diagnose. Water pump/thermos on the list too.

Thank you again for input and look forward to telling the rest of the story.....

 

[Daviet]

Re: 1989 Johnson150 Comp Test Results

Sounds like a good plan, let us know what happens.

 

[winfieldh]

Re: 1989 Johnson150 Comp Test Results

Hello Again,
Thought I would pass along results of afternoon activity.....

pulled, cleaned, gapped old plugs and reinstalled.
Drained carbs of goo and sprayed with carb cleaner.
Mixed new 5gal with oil and hooked to engine, leaving the oil line from vro in place.
Put a livestock waterer under lower unit to immerse hub (backpressure, I think?)
Took 5 tries and then off she went!!! I have let it run for about 30 minutes (2-2.5 gallons or so)
The water coming out the lower unit is warm to touch, water coming out 'pee' hole is cold. Heads are warm to touch, but not 'hot' (?).
I'm going to let it run out some more of the premix before calling it a day.

Now that it is "alive", any other items to check??

I'm still working on draining old fuel (that's the biggest pain).

Thanks.
Winfield

 

[Dhadley]

Re: 1989 Johnson150 Comp Test Results

Did you ever look to see if you have a matching set of heads?

 

[winfieldh]

Re: 1989 Johnson150 Comp Test Results

Hi DHadley,
No I didn't, but I will later today or tomorrow.

I did notice 2 items:
One is that I don't think the oil level in the vro tank budged. The oil alarm was sounding when I first cranked it and it did it's little chirp at each subsequent start and then silenced. Any good ways of checking if the vro pump is actually pumping?

The other is when I put a voltmeter across the battery terminals while motor running and (it is a cheapo voltmeter) I think it read no more than 12.5v so I've got to investigate the charging system to see if it is working where I need to tweak it to get charging going.

Thanks for the response.

 

[Dhadley]

Re: 1989 Johnson150 Comp Test Results

If the battery tested at 12 or (probably) slightly less before running the motor and it measures 12.5 with the motor idleing then it's charging. If the tach works it's most likely charging.

 

[emdsapmgr]

Re: 1989 Johnson150 Comp Test Results

One way to check the fuel/oil pump functioning is to add 50:1 premixed fuel to the main fuel tank when it is almost empty and run the engine with the oil tank still connected. Mark the oil level on the side of the oil tank with a magic marker. After you run most of that fuel through the engine, check the oil tank and see if the oil level has gone down any from the previous mark. This process will double oil to the engine during this test period and it may smoke a lot-but you are assured that you won't burn up the powerhead if the fuel/oil pump is defective.