1989 V4 110 Multiple Ring Failures

[sludgeguy68]

Hello, wondering if I could get some opinions here. Model BJ110TLCEM had this motor since 2016, ran very well until last fall. My compression test showed 80 psi on both starboard holes, ring failure seen in the intake ports. I tore it down and both pistons appear to have failed in the same manner on the exhaust side. Seems like the outer ring got caught on the port for some reason?

I have receipts from PO showing replacement of 2 pistons in 2011. All 4 pistons got new rings, all 4 cylinders were deglazed. VRO was deleted and was presumably the issue. Three months later, the other 2 pistons were replaced along with the trigger. I do not see any honing performed on the second job.

1. Can the damage on the exhaust ports in the cylinders be repaired with a re-boring? Don't want to waste my $ if the block is fubar.

2. I'd like to know why the rings failed. I had an overheat on muffs due to swollen diverters in the head and crusty old thermostats; I shut it off pretty fast but I heard it's often too late when you hear that temp alarm go off. Does this damage seem to correlate? Or maybe starboard holes weren't honed/cleaned up when those rings first failed?

Thanks in advance.

 

[racerone]

Every one of these V-4 motors will suffer this fate.-----Not a good idea to put new rings in worn bores and worn PISTON GROOVES !! .-----Boring and using 4 of a different brand of piston will help.-----With a case of beer as a reward I could show you many blocks in this state of failure and explain why they fail.

 

[flyingscott]

VRO had nothing to do with the rings failing. The holes would have needed re-boring after the rings broke. The crossflow Vblocks are known for that happening. The top ring is a wedge and carbon build up gets behind it and pushes it out, until it catches and breaks. Sounds like the motor was never properly rebuilt. A properly rebuilt crossflow should last a lifetime. Use good quality oil and make sure the thermostats are working to help prevent carbon build up.

 

[sludgeguy68]

Cool thank you, I'll take it to a good machinist. Will most likely have all 4 bored oversize, may as well do it right.

Yes it seems like the shop just started throwing parts at it - the old t-stats and swollen diverters hinted at a sloppy rebuild job to me. What a waste of time and money.

 

[flyingscott]

If.you want to avoid the ring issue.completely use Wiseco pistons. They use a flat top ring and not.a wedge.

 

[Faztbullet]

From the carbon build up on pistons several items need checked...... the cooling system as temp could been low, the fuel ratio as could be over oiled, or cheap 2 stroke oil from the look of ash deposits baked onto crown. If using Wiseco make sure cooling is 100% and you break it in with several heat cycles

 

[sludgeguy68]

Hm, yeah I was using an off-brand "master pro" oil as my local store stopped selling Penzoil. I was under the impression any TC-W3 rated oil was OK, but apparently not... I'll switch back to the Penzoil.

I mix 50:1 in 5 gal containers with the big gallon jugs of oil with the reading on the side - and always err on the heavy side - so yeah the mix isn't super accurate and might've been over-oiled. I'll figure out something more accurate.

T-stats are brand new and temp seemed fine, but will definitely double check it with the gun when I get it started again.

Thanks for the Wiseco tips. I put them in my Merc inline and haven't had any issues.

One more question - the two top bearings look pretty solid on this motor, I'm considering leaving them in the housing and just changing the seal, would that be acceptable on a rebuild? The bottom bearing was a real bear to get off the crank.

 

[flyingscott]

Go on Ebay/Amazon and find a WSM kit for.your motor, will have everything you need to PROPERLY rebuild your motor.

 

[Faztbullet]

Touch up the ports with a Dremel tool before boring...look like it will need to go at least 030

 

[sludgeguy68]

Got the block back, machinist had to go .044 oversized. From what I understand, the crappy hone job didn’t reach the bottom of the bores and they were all out of round, making vase-shaped holes.

I paid him to dress the crank and assemble since he had the proper tools, including a press for those bearings. Really wanted to watch him do it, but covid and all... anyway, Wisecos are in, no binding, powerhead assembled.

Do I need to change my stock jets with these OS pistons? I run 89 octane gas with ethanol. Thanks in advance!

 

[Faztbullet]

go up .002

 

[sludgeguy68]

Ordered .069 high speed jets to replace the stock .067, thanks!