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What can cause high compression on one cylinder

It's called an exhaust relief port. A hole drilled into the side of the cylinder about 1/8" in diameter, maybe bigger..... Maybe not clogged, but certainly could be purposely filled, without doing the three others. Or maybe someone drilled exhaust relief holes in three but missed one....something like that.
 
Thanks for that!! Okay so before I left I had them do compression test again so I could see myself cause it just didn't add up to me,, sounded kinda shady to me, And they were not what they had told me before. The only truth I read from them is there is more then a 20 psi jump across banks.. these are the numers we saw.. cylinder 1: 135, cylinder 2:112, cylinder 3: 125, cylinder 4: 110.
 
Bay marine lost some points from me, one mechanicntells me one thing, and I had a different one show me the same test with different numbers from what the first mechanic told me. And I did not see the first test occur, just the one from today. And those numbers are what I personally watched myself from the compression test.
 
One and three are raised, two and four are lower.
Examine the casting numbers on both heads....see if they are the same. Maybe you have mismatched heads from this rebuild.

Hmmmm....EDIT.....maybe the casting numbers will not be the same due to right and left heads. I am going to look it up.

OK same part number for both heads. Double check the casting numbers, and there is a possibility that one head has been milled and the other has not.
 
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Iwill look into this more likely Thursday. My head has had enough for one day.. im worried about this along with my lower unit repair.. I thought I was gonna buy an sei foot but I'm second guessing it... just gotta put some power Z's to it
 
It's a remanufactured powerhead so if the numbers are not the same then OBR (where the block came from) messed it up. Do I have to pull off the heads to see casting numbers or do I just pull the engine cover off and look? Cause I know casting numbers are usually where the spark plug holes are.
 
I did just notice the part number on the thermostat cover for both don't match what is made for my specific model number.. so they must not have replaced the exact powerhead match for my model number..
 
johnnygjr said:
Ahh the plot thickens, so heads are different casting #s, which tells us what?
Click to expand...

No one ever said they had different casting numbers.....just to check. Maybe the combustion chamber is a different volume. Who knows.

More likely one is milled and the other is not.
 
Georgiaboy67 said:
I did just notice the part number on the thermostat cover for both don't match what is made for my specific model number.. so they must not have replaced the exact powerhead match for my model number..
Click to expand...

It is tricky. Most numbers stamped on parts are the casting number. Not the part number. A good way to tell is to take that number and go to a parts search page. Search for that number which you know is correct, because you are looking right at it. If it comes back part not found, then it is a casting number.
If it finds the part, then obviously it is a valid part number.
 
Ithink with 2 and 4 close to 110 I think is fine, it's 1 and 3. And the fact that two banks are different. I agree with dave, definitely have a big mess to tackle on my hands
 
The number said 338632. If I remember that correctly, I went to the search bar for my model and that number matched the part number for the C suffix models. Mines an A suffix model which is different part number and different price
 
Oh boy, sounds like you may have the wrong parts? I love a challenge, but my boat has put that to the test this year. I've taken that damn engine a part from the carbs, all the way down to the powerhead & back again. I was starting to think we had a relationship going (LOL, maybe I do). Every weekend I was out there working on it. I replaced the carpet last spring. I thought that was a pain in the ass, nope I was wrong. This engine issue is driving me crazy. Finally fall came & I just quit working on it. got sick of replacing part after part, hoping something would give. Well it did, one thing went away, another popped up. Unless its a brand new boat, they're gonna have issues, heck even brand new ones do, but at least they're covered under warranty.
 
It could point to a potential problem... I could be wrong, but you never know with boats... not til I can dig into it. Could be a powerhead that's not meant for my model number. Never know, could be similar but not exact. Just gonna have to pull the heads and see what i can find.. do I need to re-seal anything when I pull the heads? I've pulled them before but that was on the block that had the detonation. I didn't care what happened to that one.. lol I wanna make sure I meet all steps possible to make this baby pur again
 
Never mind I just got that question answered lol. Keep forgetting I have this oem manual I bought from here for a reason.. clearly says install head screws dry, do not use sealant on threads lol
 
Remember on these v-4s starboard bank is usually 5 psi higher than port side as far as compression goes,so that puts 1and 3 on starboard and 2and4 on port correct? I thought you said engine had no running issues,why bother pulling heads ?
 
You are correct. And my concern is that 1 and 3 is 20-25 psi higher then 2 and 4. Obviously something isn't right if the jump is that much.. it might run fine now, the warranty expires on the block February 25 next month.. and I don't want anything to make this thing go to the crap house and I'm out all the money I sunk into it within a year..
 
My last suggestion on this..........CALL OBR and quit messing with it, if they read all that's been posted about this engine and the shoddy redressing/reassembly and set-up they could deny warranty.If the piston came installed wrong as was originally posted and service center did not get a OK to repair it warranty is void now.
 
Probably the best advice to take faztbullet... I haven't torn into it, and I've never seen someone use a bore scope before so idk how they work... and unless you have to pull the heads off for the scope, then none of us have torn apart the powerhead, I have the warranty til February 25th and then it's gone. Bay marine, if no one read the diagnosis they gave said that they wouldn't know what to do except get another powerhead
 
Just sent an email to the Gwinnett marine service manager. Told him my issues, awaiting a response tomorrow since they are closed. I had gotten 2 carbs adjusted with them around September or early October, and I remember him saying my compression was good.. so if I sense any type of bull**** response from him it's gonna be a fun ball game from now til feb 25th
 
A boroscope is a modern tool / tiny eye that you insert trough a sparkplug hole.--------Lets you inspect cylinder walls/ markings on pistons without taking anything apart.---------------I doubt that pistons were in backwards.
 
Today he also said that he's "pretty sure I don't have an issue, And that if it's warrantable work there will be no charge, but if they find no issue I will be charged." When I did this through them it's warrantied for a year, through February 25th 2017. I got the new powerhead, carbs rebuilt, head gaskets, fuel pump, water pump, new plugs etc. and his exact words were any work they did will be warrantied for a year. With the block and such. So is he able to charge me if nothing is wrong with the compression from the powerhead they installed? I'm not trying to argue with them for any nonsense but if he has that right to charge me then so be it.
 
1997 115hp Evinrude/Johnson cylinder head numbers:

I retired in 1991 and the design may have changed, so it's possible that what I have to say here is moot.

However............... The part numbers were always a six digit number ie 123456 and were always raised numbers on the side of the cylinder head, near the gasket area, between the cylinders. The exception was that a small circle appeared on the top face area of the head with the raised numbers circling inside of that circle.

One head would have the numbers listed as (sample) 123456 with the opposing head reading 123457.... one digit higher.

What numbers do you find on your cylinder heads?

Having retired in 1991, I don't have the proper books but that head number information would be of help to fellow members.
 
Joe...these loopers have a casting number on the heads, not the part number. The heads are interchangeable, i.e. they only have one part number, and the parts list (cylinder and crankcase section) calls for 2 pieces per assy. Part number 0335810 for the 115hp engine.

I am still waiting for the number that is stamped on the heads.

It is also noted that the cyl head for the 90hp engine is DIFFERENT, in that it's PN is 0340950. Now THAT is significant because that head would still fit on the block just fine.
But there is a difference in the heads. Suppose a tech at the engine rebuild company just grabbed two heads, and got one 115 head and one 90 head.....
 
Daselbee...... Okay, I appreciate that info. As mentioned, I wouldn't be aware of the design change due to my retirement date... however I was aware that the looper models were marked as you state... BUT... wasn't aware that the later model 115 was a looper.
 
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