No detonation events that I can think of and I've been running 18 psi forever with a not overly aggressive tune.

Anyway, took off the oil pan tonight as part of my journey towards the failed oil pump, found a piece of thin shiny metal here and there, and some small fragments trapped in the mesh oil intake. Ruh roh.

Peek up the cylinder bores and sure enough, one of the pistons is missing a big chunk of piston off the bottom. Any ideas how this could have happened?

Also, is replacing a single piston a thing or do people just replace all four typically?

My jimmies are so unbelievably rustled I'm not even mad.




fuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuck

 

Huh, it looks like the piston collided with the oil squirter. The oil squirter is not in its hole and when I found it it looked very beat up. Also, the piston has damage exactly under where the squirter is.

I don't really understand how this happened. Maybe it came loose over the years and bounced off the connecting rod or something? It doesn't make any sense.

 

it means Your A Bitch and it need your genetic material for donation

now what do

run it *****

make balance like natural fact

it is like animal

it has matessex with cylinder wal

it makes
trues


the natural fact of the universe is
exemplified

in your sweet
smooht
bore

 

Do you know your oil pump failed? Knocking off an oil squirter would drop your oil pressure big time.

 

Yeah, it seems quite likely the pump is fine. I'm still going to replace it with a forged unit, but the oil squirter hitting the piston explains everything I observed. I just don't get how it happened in the first place.

edit- I've found a whole bunch of threads discussing problems with wiseco/squirter clearance, but this car was running fine for years with these pistons and all the other pistons are ok with non destroyed squirters.

 

Is the bolt for the squirter still in the hole?

--Ian

 

No, the bolt is out completely. The hole where it screws in is just empty.

 

The bolt might have just vibrated out or come loose. The thread isn't damaged and the bolt head hasn't snapped off so it must have unwound. Maybe the squirter/ bolt bounced off the crank into the piston?

I run Wiseco pistons and don't run the squirters. I'm not F/I though. I loctite those bolts in and use a crush washer to seal the hole.

 

Maybe I'll just get coated pistons and seal off the squirters. Does anyone offer that as an option or is that the sort of thing I have to send them off somewhere special for?

Then again, sealing off the squirters won't really help anything if the bolts I use to seal the holes come loose. Maybe it's just a freak occurrence and I shouldn't stress too much over it. Just loctite and hope it doesn't happen again, I guess.

 

I'm in process of assembling a motor. I feel the torque spec on the oil squirter is very light. What did you torque this to?

 

I use high grade button head bolts with a copper washer to cap the hole (no squirter). I tighten them until I think I might snap the allen key, usually with an extension bar on it. Getting them undone is usually the issue especially with the use of Loctite.

 

I was told by FM that their old version of Weisco was compatible with oil squirters, but the off the shelf weisco's are not. Their new version is also not compatible.

My guess is yours don't have the clearance and it hit. Or the bolt that secures the squirter to the block vibrated loose. One of those two things happened.

 

FM's version of the weisco is tripple coated and does not use oil squirters by design. Off the shelf solution.

My new block I had those holes tapped to small NPT threads and sealed shut. You could do that, or use bolts with washers and permenant assembly lock tite. Make sure and have the parts oil free before applying lock tite of course.

 

This engine was driven hard for nearly a decade with no problems. Judging from the gouges all over the bottom of the piston, it seems like it just came loose and bounced around between the piston and the crack.

 

Well this would have been nice to know 6 months ago... I run a set of the the non FM Wisecos with oil squirters installed. Is this something I should be concerned about? I've never heard of a motor being run without oil squirters.

I don't believe over had any problems with that so far.

EDIT: After reading a 5 page thread on the matter, it doesn't sound like the end of the world. I might take them out next time I'm in there.

 

could you explain please? it's about 1.6 or all engines?

 

https://www.miataturbo.net/engine-performance-56/oil-squirters-piston-oilers-discussion-82895/

This is the thread I read through. I imagine this is relevant for 1.6 motors as well as 1.8

 

My humble opinion is that this engine is toast and you should start with a fresh one.

 

When you say fresh one, what do you mean? From what I can tell (so far), there is nothing wrong with this block besides the oil squirter and piston issue. The head needs a valve job and new valve springs but that's just semi-routine maintenance. My autopsy isn't over yet, but obviously I'm not going to throw it all back together if the bearing surfaces are ruined.

Every symptom I observed is explained by an oil sprayer bolt working its way loose and then bouncing against a piston and shattering the skirt up to the oil ring. That would explain the sudden drop in oil pressure and it explains the chunks of shiny piston metal in the oil pan. It's not like I went and ran an enduro with metal shavings in the pan. The car was running normally minus the low oil pressure and I just pulled over and got the car towed home. Maybe it's fucked, maybe it's fine. I'll know soon enough.

 

Fresh like one that doesn't have shavings in it from losing a pump and various parts inside the engine

But I know most of the crowd here thinks that if it's not blown to smithereens, it is PERFECTLY GOOD, which is why I stated it's just my humble opinion.