Dead Cylinder...Now What?

[randyhall]

Well, crap! After cleaning up my carbs on my 1988 XP 200 (on a newly acquired 1988 Champion Bass Boat), I went to drop in new plugs and decided to do a compression check. Here's what I found: 59, 99, 99, 99, 99, 96.

So...now what? Do you do like car motors and tear it down, replace the other 5 rings, bore out the dead cylinder and get a bigger piston? (assuming it only needs to go up 10 or 20) Or do you bore them all out? Do you just get a whole new top end? What?

I'm on a tight budget. So disappointed right now...

Any suggestions? Help!

 

[Monte1961]

Re: Dead Cylinder...Now What?

Pull the plug on cylinder that has lowest compression. Bring that piston to or near the top and look with a flashlight to see if it has pit marks on it or not. Post back results. Monte

 

[randyhall]

Re: Dead Cylinder...Now What?

Thanks for the quick reply, Monte. It's raining pretty good outside and it's dark, but I took a quick look. I will be able to see better tomorrow but to me it didn't look very pitted. I compared it to the one below it and it looked pretty similar.

Here is a quick picture from my phone. Not sure if you can even see, but there is a little light pitting, but nothing too bad (I hope). I can take a better pic in the morning.

 

[randyhall]

Re: Dead Cylinder...Now What?

Since I'm seeing some carbon build up, should I try something like a seafoam decarb before I get too carried away with thinking I have to tear it down and rebuild? If a decarb is worth a shot, what's the process for doing it on a motor like this?

 

[jbjennings]

Re: Dead Cylinder...Now What?

Just my opinion,
BUt I don't think a decarb will do anything to bring up compression on that low cylinder in your situation.
To answer a few of your questions above:
No, you don't have to bore the other 5 cylinders and replace the pistons. You can just replace the one piston with an oversize piston and it will still be balanced. (The piston manufacturer somehow checks the weight on the oversize so that it is the same as standard ones, I believe) Hone the other 5 and put new rings on the other 5 pistons. Since it sounds like you can tear down the block yourself, I think you could fix it for a reasonable price. Keep in mind, I rarely work on these big motors, so.........
Bad head gasket hopefully.....
Good luck,
JBJ

 

[BonairII]

Re: Dead Cylinder...Now What?

You can just replace the one piston with an oversize piston
JBJ

Is it possible for him to just replace the piston ring with an oversize ring to get compression up? Or do oversize rings not exist?

 

[jbjennings]

Re: Dead Cylinder...Now What?

Is it possible for him to just replace the piston ring with an oversize ring to get compression up? Or do oversize rings not exist?

No, if cylinder boring is needed, he will be required to buy an oversize piston. There's a good chance that the old piston will be scored anyway.....

 

[archcycle]

Re: Dead Cylinder...Now What?

Bad head gasket hopefully.....

+1

Try the $30 route first!

 

[randyhall]

Re: Dead Cylinder...Now What?

Good point. I'll start cheap. I'll do the head gasket and maybe the seafoam decarb (to satisfy my curiosity) an report back what compression numbers I find.

Side note: I need to somehow dispose of the 52 gallons of 2-year old gas so I can get some fresh 87 in there too. Apparently the only local waste disposal facility wants to charge me $150 to take my old gas. Is it safe to run in anything? Neighbor's 4-wheelers? Have a big 4th of July bonfire? Any ideas?

 

[randyhall]

Re: Dead Cylinder...Now What?

So, tonight I did a decarb with the Evinrude Tune Up stuff. The odd thing is that it only bogged down the motor when spraying into the port side carbs, but it didn't bog down the motor at all when doing the starboard side. I think I read on here that when your VRO goes out it shuts down one bank of cylinders. Is it the starboard side? And does this mean my VRO is bad? And does that mean it may have been running lean even on the 3 cylinders, which killed the top port side cylinder giving me the low compression? Should I disable/bypass the VRO and just go pre-mixed now?