Logo
FULL SITE MENU

Damaged Cylinder Head, Repairable or Replace?

WaitUpGuys

WaitUpGuys

Contributing Member
Howdy folks! So long story short, I bought my first outboard boat and found out that I have 0 compression in one my the cylinder. I took the head off and found that maybe the ring broke and it caused some gnarly stuff. I've never worked on something like this and thought I would ask the masses. I'm planning on replacing the piston and ring. Question is, can i sand/buff/polish/or whatever i need to to repair the damaged cylinder head or do i need to replace it? Thanks for your time.
cylinder head.jpg
 
That will buff out.-------------There are lots of motors running with that kind of damage.---------No need to worry about this till you are ready to assemble this motor.
 
racerone said:
That will buff out.-------------There are lots of motors running with that kind of damage.---------No need to worry about this till you are ready to assemble this motor.
Click to expand...

Best news I've heard today. :) Thanks!

What can I use to buff this out? Sorry to be such a newbie.
 
Take a magnet and make sure there are no metal ring pieces embedded in damage as they can cause preignition..then just buff up with dremel sanding disk as the aluminum burrs wont glow but may break/melt off...
 
Thanks for all the suggestions. I'm gonna try and tackle this project this week. I'll update you all on how things go.
 
Your gonna want to take it apart first before buying anything and determine if it is serviceable. It may be cost effective to just buy a good used powerhead and go.
 
Alright alright alright...so it ended up being the rings. Guess it lacked lubrication or something, but it got broken off. I thought it was just 1 piston, ended up being two! #1 and 3.


Looks like i need to bore the cylinders too. I ran my finger through it and there were some small grooves. So...speaking of boring the cylinder, can you bore 2 and leave 2? What are the best option? Bore the 2 cylinder and re-sleeve them to keep the piston the same size? Or bore all 4 and replace all 4 (larger) pistons? Or bore all 4 and resleeve to keep the piston the original size? Or the last is bore the two, get two new pistons (larger) and keep the other two the same. Would that eff up things since two pistons are 1 size and the other two slightly larger?


The goods (bad actually):



 
You need to bore them all the same with oversize piston kits. How does everything else look? Bearings, connecting rods and crank? As long as the grooves are not too deep and depending on the model. You need to try and determine the cause the most common being a faulty VRO pump or not premixing the fuel. There may be crank and bearing damage. A good used powerhead is a nice option as long as it has good compression numbers? Whats the model number?
 
Last edited:
kimcrwbr1 said:
You need to bore them all the same with oversize piston kits. How does everything else look? Bearings, connecting rods and crank? As long as the grooves are not too deep and depending on the model. You need to try and determine the cause the most common being a faulty VRO pump or not premixing the fuel. There may be crank and bearing damage. A good used powerhead is a nice option as long as it has good compression numbers? Whats the model number?
Click to expand...


I haven't done a thorough inspection yet but from what i've seen so far, nothing look out of the ordinary. Just the 2 pistons and the cylinders and obviously the head. I suspect the oil pump failed. The grooves aren't terrible. You can feel a slightly when you run your fingers through it.

the model for this outboard is: VE90tlets It's off of a 1993 Sunbird.
 
Last edited:
You can go .020 and .030 over and I think the wiseco pistons are higher quality myself. You do want to have the pistons on hand for the machinist to get the proper ring gap. Do you have a book? Those are the proper pistons for your motor hopefully the grooves in the cylinder walls are not too deep?
 
kimcrwbr1 said:
You can go .020 and .030 over and I think the wiseco pistons are higher quality myself. You do want to have the pistons on hand for the machinist to get the proper ring gap. Do you have a book? Those are the proper pistons for your motor hopefully the grooves in the cylinder walls are not too deep?
Click to expand...


Thanks for the info. Good point about having the pistons on hand. I would have just had the machinist hone it and then buy the pistons. Newbie, i know. :) There's a guy that bore for 30/cylinder locally, so i am going to have to give him a ring.
 
If the other 2 cylinders are in good shape and MEASURE ok then you can bore just the 2 cylinders.------------Most new O / S pistons are precision made and match the weight of original pistons.---------No need to have the pistons on hand before the boring.----That is somering that was common 40 years ago !
 
I agree, you can bore one, two, or whatever is required. No sense in wasting precious metal or machining charges by boring good cylinders. We used to have a boring bar machine at our shop and bored cylinders for ourselves and every other outboard shop in town. That amounted to lots of cylinders.
 
You do not mix piston brands or mix cast and forged. "Mike" the cylinders and your likely going to find them past the wear spec looking at skirt of piston you posted. As posted earlier you do not need pistons on hand to bore, let the shop bore and tell you what size you need to order.This is not a oil failure as if it was ALL pistons would show scuff damages. What your seeing is common problem with V-4 pressure backed ring, carbon builds up in ring,ring groove wears and ring flutters,carbon continues to build and pushing ring outwards and it catches in exhaust port and breaks. The carbon build up is from low quality oil, cooling system problem(overcooling)as cylinder doesn't get hot enough,improper propping/RPM(dogging). The best thing about WSM as they come in .010 sizes( .010/.020/.030.040) and you want to refrain from .044 and .064 as cylinder sleeves get too thin and cooling system need too be top notch. The draw back to wiseco is they need a tad bit more cylinder clearance, need to go thru several heat cycles to "temper" the pistons as they are soft new, and you will have to let engine warm up before WOT operation or sking.
http://www.maxrules.com/fixphead_omc.html
 
Last edited:
If it was me I would change all the pistons in your motor. If you leave any of the old pistons they will still have the ring design that caused the problem in the first place. Wiseco I know for sure does not have that ring design they improved the design to make it more dureable and not have that problem. You also can get away with not boring with a wiseco as they use a little larger bore anyways. I don't know if WSM pistons do or not. JMO
 
Thanks for all the advice. You all made some pretty good points. I think at this juncture, since I have everything totally disassembled, I will will go ahead and get the cylinders bored and honed (due 2 of them have small gouged from the damaged pistons/rings), new pistons and rings. I hate to go through the trouble and only do 2 now and then later down the road the other 2 craps out and I have to get it all apart again. This is also assuming I can put this back together in working order. This is my first engine rebuild ever so I'm hoping if I follow the manual step for step, I will be solid in the end.

This is random, but is red on the piston rod from just being exposed to heat. Just some discolorations right?
 
WaitUpGuys said:
Thanks for all the advice. You all made some pretty good points. I think at this juncture, since I have everything totally disassembled, I will will go ahead and get the cylinders bored and honed (due 2 of them have small gouged from the damaged pistons/rings), new pistons and rings. I hate to go through the trouble and only do 2 now and then later down the road the other 2 craps out and I have to get it all apart again. This is also assuming I can put this back together in working order. This is my first engine rebuild ever so I'm hoping if I follow the manual step for step, I will be solid in the end.

This is random, but is red on the piston rod from just being exposed to heat. Just some discolorations right?
Click to expand...
Yea I`m from the old school I guess it makes no sense to me just boring 2 of 4 cylinders. Just take your time and confirm end play on connecting rods and crank are to spec. Definately make sure the block is serviceable before buying parts. I checked and they stopped making pistons .020 over so this would the last time that engine could be bored over they cannot be sleeved.
 
I checked and they stopped making pistons .020 over so this would the last time that engine could be bored over they cannot be sleeved.
Click to expand...
You can get aftermarket cast pistons up to .040 and forged at .044 and .064 and OEM up to .030(396588). You can sleeve that block, not economically feasible but can be done.
 
kimcrwbr1 said:
Yea I`m from the old school I guess it makes no sense to me just boring 2 of 4 cylinders. Just take your time and confirm end play on connecting rods and crank are to spec. Definately make sure the block is serviceable before buying parts. I checked and they stopped making pistons .020 over so this would the last time that engine could be bored over they cannot be sleeved.
Click to expand...

Just shot an email to the seller to see about specs. Hoping it's the same as oem pistons so I can use the connecting rods. Here's a few look at the cylinder. There are some small grooves. Gonna take it to the shop to see if it's worth boring or just hone. I think it's need boring, but i don't know what I am talking about.







 
Hoping it's the same as oem pistons so I can use the connecting rods.
Click to expand...
The connecting rods will work on any oversize piston. Just bore it .020, throw some new wrist pin and rod bearings in it ,new upper/lower seals, surface the heads and get it together and get wet!!!!
 
Called some local machine shops and was quoted upward of $450 for 4 cylinders and a 2 month turn around time. NOPE! Looked on CL and found big John. Charged $36/cylinder. Was planning on dropping it off and picking it up later, he ended up knocking it out while I was there. An hour later, and these cylinders look brand new. .020 over pistons have been ordered. Now I wait...
 
Now go stick in in a plastic tote filled with hot water and Dawn, take a commode brush as clean,clean rinse,clean and rinse. Take a white paper towel and wipe cylinders and ports, if ANY grey transfer repeat the above till clean. Then wipe cylinders down with 2 stoke oil... a slight rust haze may occur but it will be fine.
 
faztbullet said:
Now go stick in in a plastic tote filled with hot water and Dawn, take a commode brush as clean,clean rinse,clean and rinse. Take a white paper towel and wipe cylinders and ports, if ANY grey transfer repeat the above till clean. Then wipe cylinders down with 2 stoke oil... a slight rust haze may occur but it will be fine.
Click to expand...

Aye Aye captain. :) My elbow is already aching just thinking about how much scrubbing is ahead of me. I'm planning on cleaning pretty much everything so it can be ready for paint once i put everything back together. It's gonna look like a brand new 1993 motor again. haha.
 
Back
Top