1996 88 SPL Piston Ring Problems...

[Darrell W.]

I had a local dealer rebuild the engine 4 years ago because of a broken piston ring on starboard side. Last week I lost power and did compression check to find that 3 cylinders were okay but lower cylinder on starboard side was kaput! I pulled the starboard head and found damage to both the upper and lower pistons. I disassembled engine and found missing ring parts on both starboard pistons. The port pistons looked great (original from 1996)!

Here's the question - why did the rebuilt side experience all the damage that it did? Did the dealer do something wrong? I found no apparent malfunctions with engine as I disassembled it (no carb probs, no reed probs, all gaskets in place, etc.) I would really like to find out what caused the problems so I can correct the issue when I rebuild.

One issue mentioned in service manual is "chamfering the ports". I noticed that there is not much, if any chamfering, on both the starboard and port cylinders. So, if the ports are pretty much the same, why did the starboard side create so much damage?

Any help is sincerely appreciated!

 

[jonesg]

Re: 1996 88 SPL Piston Ring Problems...

damn, looks bad.
Did you decarb regularly?
a ring can get stuck with carbon and snag a port, the rest is ugly.
I use startron in my fuel to keep carbon down.

 

[emdsapmgr]

Re: 1996 88 SPL Piston Ring Problems...

When the engine was overhauled did the mechanic determine what the reason was for the original failure? If the pistons on the other side look OK, it's not the fuel/oil pump. Neither piston has a lot of carbon accumlation. One piston is starting to scuff-transfer aluminum to the cylinder wall. Possible that the one side of the block was running hot. Normally, both stats should be replaced at overhaul- were they? Does the overheat sender on that head work correctly? Were the powerhead rubber water diverters correctly in place on the bad side of the block? Were both carbs overhauled? How do the the mid and high speed jets look in the barrels that feed both failed cylinders? Any debris in them that would restrict fuel flow?

 

[Darrell W.]

Re: 1996 88 SPL Piston Ring Problems...

The mechanic did not give me a reason for the original ring breakage - I thought it was "just normal". Now I know better! Thermostats looked okay! Water diverters in place! Carbs overhauled and looked great when I re-overhauled them! All jets in both carbs looked good and were of the same size! I used "Carbon Guard" at times in gas - ran de-carb through carburetors about 2 years ago! I didn't see any carbon build-up in cyclinder when I took her apart! The only thing I can think of after research on internet is "too much heat" on starboard side - but don't have a clue why?

I really hate putting her back together with out knowing why the damage occurred...

Thanks for the help...

 

[emdsapmgr]

Re: 1996 88 SPL Piston Ring Problems...

Did anyone remove the cyl head covers during overhaul? You could have debris in the head, blocking water flow through that bank. When you get it back together and get ready to start it, borrow a laser temp gun. Check the head temps for the first half hour of running. It will take 10-15 minutes to fully heat up on the hose. Esp check the head cover temps. You should see 140-150 temps at idle. Also, make sure the pressure relief valve is functional on the starboard side of the thermostat housing. Did you check the bridges between the intake and exhaust ports for cracks before the last assembly? Serious overheats can sometimes crack the cylinder liner in that port area and any crack can catch rings when running.

 

[modsrx]

Re: 1996 88 SPL Piston Ring Problems...

is it on intake or ehaust side the ring broke ???