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Compression question. 97 Johnson 200 sleeved last year

J

jshane37

Regular Contributor
Had a 97 Johnson 200 sleeved last year as the result of a who knows what problem. Would this cause a lower compression reading than the other cylinders? I am getting about 90psi in each of the 6 except the #2 which is showing 45psi.
 
Re: Compression question.

Did you check the compression after the repair to get a baseline? Resleaving a cylinder should bring it back to factory specs, unless it was done wrong. Did it run properly after it was rebuilt, did this problem just show up?
 
Re: Compression question.

45 is awful. Any schrapnel on the plug when you removed it? Sounds like major damage to piston. Sorry to hear it. Next stop if it were mine would be to pull that cylinder head and see what you find.
 
Re: Compression question.

Ran great after the work, but has slowly gone down hill with some idle and performance issues which prompted me to check fuel and compression. Talked to the mechanic that did the work last year to the # 6 cylinder (the one that was honed and ultimately sleeved). I told him that the #2 was showing low psi and he suggested running a sea foam type of cleaner through the engine. I am less than impressed with this suggestion as I fear it is more than just a carbon build up. Did not notice any metal shavings on the plug(s) when I pulled them. Sound like damage to another piston to anyone else? If so, what could cause this for a second time in less than a year? Lean condition? VRO failure?
 
Re: Compression question.

I don't think sea foam is going to do you any good. I agree with martino1, pull the head and check it out.
 
Re: Compression question.

An easier solution if you can get your hand on one is one of the new fangled flexible inspection cameras. They sell color ones now for as little as $100. If you have any mechanic friends you may want to see if any of them have one. Some of them should be small enough to fit in the plug hole.
 
Re: Compression question.

jshane37 said:
Sound like damage to another piston to anyone else? If so, what could cause this for a second time in less than a year? Lean condition? VRO failure?
Click to expand...
When you resleeved the motor did you also go through the carbs at the same time? Motors blow for a reason. If you don't fix that reason you're doomed to blow again. I do a lot of work with 2-stroke jet skis and it's extremely common to see one cylinder fry and people just assume the 'oiler' went bad and toss it in favor of pre-mix. 99 times out of 100 if you dig deep you'll find a carb that was plugged or a gasket problem that led to the lean condition on that cylinder alone.

I would check the carb for that cylinder and look for a plugged orifice or fuel circuit in the carb body.

I doubt a VRO failure would cause one piston to roast and the other 6 to be just fine. If the VRO fails you'll have all 6 cylinders simultaneously suffering from a lack of lubrication.

KJ
 
Re: Compression question.

Going to pull it out of the water and have the mechanic tear it down again. He said that he checked the carbs when he sleeved it last year and they looked great. This is the second time in a year that a cylinder has been damaged. I will post something when the mechanic tells me what he finds in hopes of saving someone else the $$ that I have had to spend.
 
Re: Compression question.

Ok so the engine made it up to the mechanic and low and behold once again I have lost a cylinder. He says that the ring came apart and left a nice gouge in the #2 cylinder. Going to have to sleeve this one too. Beautiful..
This is the second cylinder to have been damaged with less than 20 hours on the engine. He tells me the carbs look fine. He does not seemed at all alarmed that this has happened, meanwhile I am in for another $$ bill to get the work done. What in the world is causing this!!
 
Re: Compression question.

The mechanic says, "the carbs look fine." What does that mean? I'd rebuild the carbs as part of the repair you're going to have to do now that you've lost another cylinder. Might even look for another mechanic!
 
Re: Compression question.

I would assume (using the word loosely) that he means they look fine. Will suggest a carb rebuild while he has the power head torn down.
 
Re: Compression question.

Your post stating that "a ring came apart and left a nice gouge in the #2 cylinder" is possibly true, but look at this:

http://www.mar-fab.com/MarFab_Tech_Bulletins_D9579.pdf

I suggest you print that page, go inspect the damage yourself, and see if this is what you experienced on #2.
If so, it is not the carb's fault. The piston design is poor, and allows those ring locating pins to come out.
Note that the bulletin says that the groove will be located in one of the finger ports.
If it lines up there....looks like another loc pin failure.

I have 6 loopers laying around, blown, and two of them have this failure.
 
Re: Compression question.

Great article Doug thanks. Totally makes sense to me. I will swing by the shop and see if the damage is consistent with what is described in the article. Thanks again.
 
Re: Compression question.

Piston dowel pin problems..... moving inwards so as to allow the piston ring to rotate out of place was a common problem back in the 1980's. I wasn't aware that it had raised its ugly head once again as per Daselbee's informative insert. Yes, if that scenario exists with your engine, that would really be a heartbreaker involving replacement of all pistons etc.

However, if that scenario does not exist, think about this. Your mechanic states that he checked the carburetors and found them to be fine...... rather says that they look fine. What does that mean? What did he say was the cause of the original # 6 cylinder failure?

The normal procedure when rebuilding an engine is to completely dismantle the carburetors (all), clean them thoroughly, and rebuild them using complete carburetor kits. A slightly fouled carburetor causes a cylinder to run lean, resulting in piston and cylinder wall damage at a minimum.

When a powerhead is torn down, the carburetors are removed individually. They all look alike.... at least they did in the past and I assume this is still the case in 1997 (otherwise I stand corrected). Should I be correct in my assumtion, I would think that the #6 carburetor was fouled and was the cause of the #6 piston failing. Now, if this # 6 carburetor upon reasembling was installed in the #2 position instead of its original #6 position, it would cause #2 piston to mirror the previous failure of #6 cylinder.

My line of thought for what it's worth.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
Re: Compression question.

Joe he tends to take the "I dont really know what happened approach". Last year he said the wrist pin in the #6 came loose and damaged the cylinder. He had it machined and honed and with just about 5 hours on it the same thing happened to the same cylinder. This time he sleeved it. I know he replaced all the wrings and such on all 6 when he had it broke down the last time. I will strongly suggest a carb rebuild this time in hopes that this is what is causing this rather expensive process. I respect this mechanic and he has been working on engines for many, many years. He actually holds records for hydra plane boats back in the 70's. And of course I value your line of thought Joe. You have never steered me wrong. I will keep everyone posted of my findings. Thanks everyone
 
Re: Compression question.

When OMC added finger ports to the V6 90 degree looper they actually moved the bottom ring locating pin away from the finger port but not the top one. The top pin is still in the finger port. That being said, if everything is as it was designed to be as far as combustion temp goes the pin will be fine. But, if anything happens to add combustion temp (different than water temp) that pin can / does move. Then the ring rotates and the gap end gets sheared off when it gets to the bigger port. We have to figure out what is adding the extra combustion temp. So, that brings us back to what I've been asking - what spark plugs are you using? It could be that simple or it could be a little more complicated.

As a side note, Wiseco did move the top ring so it's not in line with a finger port.
 
Re: Compression question.

Ok here is the explanation of the damage caused to the #2. Apparently (and I am paraphrasing here) a notch on the port side exhaust side sleeve broke off causing a 7/8 inch gouge down, by 1 inch gouge down the cylinder. He believes the notch caught/grabbed a ring on the way through and caused the damage. He says he has seen it on older model engines, when they are broke in and get a little "sloppy". He says he has never seen one do this to a newer engine. I have about 221 hours total on it if I recall correctly. I mentioned a carb rebuild, and he maintains that it was just a freak thing and was not prompted by a fuel issue, oil issue, or temp. So at least at last the mystery is solved......for now. Only 4 more cylinders to go!!
 
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