In reply to Kendall_Jones :
Well, I know who I'll be giving a call to tomorrow then.
In reply to Kendall_Jones :
Well, I know who I'll be giving a call to tomorrow then.
The pistons are marked up pretty bad, cylinder walls look ok I think. Looks like the screw came and left each of the back three cylinders before it exited. It wasn't in the intake. Not sure what to do from here.
Yikes.
I'm sorry. I was REALLY hoping to be wrong.
Now that you have it apart, looks like an investment in a few parts (pistons) would be worth saving the rest of your investment in the engine.
I've had similar things happen with similar results and I've repaired about dozen customer's heads because of exactly the same thing and always reused the original bottom end. It doesn't look like anything took a big hit
Lame, this was just supposed to be my hold over engine until I prepped the VVT I have. Well E36 M3.
accordionfolder said:Compression looks even across the board, 130ish. What says the hive?
Run it. If compression is good, I've seen cylinder heads and pistons that looked like a bomb went off inside and we had no idea until pulling the head off for some other reason.
Actually, I agree with Knurled.
If you're gonna switch to VVT anyway, run it.
In reply to Knurled. :
Even under boost? I was concerned about hotspots since it looks fairly awful on the piston top....
In reply to accordionfolder :
If it makes you feel better, sand the sharp edges down.
This is personal opinion: It's aluminum. If it got hot enough to cause preignition from hot edges, the aluminum would be nearly molten, and the sharp edge would melt down.
It's not ideal, no, but good enough oftentimes is good enough, especially if you have another engine in the wings. Call the gasket kit, fluids, and time spent an educational expense. Now you know that you don't have something lodged in the piston getting ready to melt its way through (a thing that I have seen happen).
In reply to Knurled. :
I'm no engine builder (or even a mechanic)! I'm just parroting what I've read could be problems. I mainly want to run laps, I joined a driving club so I have a ton of days this year if I can keep the car together - that's more where the frustration is - I didn't go for crazy power or pushing limits, I just tried to build something reliable. The motor, prior to ingesting a screw, was running like a scalded dog. Very spicy.
Anything I should check for in the head? I'll try to get a picture of it, but there was one fine scratch on the cylinder wall, but didn't seem to have dug in.
Pull the cams so the valves are all closed and check for leakage past the valves if you want but if compression was ok you’re probably fine
Talked to Jesse at Jesse Prather Motorsport, and he's got a fix for the 1.6 throttle body. Slightly pricey, but pretty much no other options for the 1.6 (and cheaper than blowing up another motor).
I don't know a damn thing about this but it seems to me the best thing is clean up the pistons as best as you can, fix the TB issue and send it. Make the second engine a priority. If this one is already kinda written off, it seems like you might as well run it with no cares. At least it's a supercharger and not a turbo so you don't have to worry about any bits coming out the back and taking that out.
edit: you have an Exocet right? Do you have a thread on that? I would enjoy going through that. I have the wants for one badly.
In reply to spandak :
I tried to start a thread, but I'm bad at updating. You can follow along sort of via
https://goo.gl/photos/5Jq66DXYm8ku7VDR6
If you use red loctite the TB screw ain't coming out, even if you want it to
In reply to Peabody here :
To be clear, the throttle screws are staked from the factory - the harmonics at higher rpms cause the throttle shaft and screws to go boom (or that's my understanding). It's a fairly well documented issue. For 1.8 cars there's and a tougher aftermarket throttle body by skunk2, but nothing like that for 1.6 cars. In my case, the back of the staked screw is still in the plate. Before this I had the shaft explode.
In reply to accordionfolder :
So the screw actually broke? That's... scary. No magic goop or Loctite is going to cover for that, the screws must have been made of the infamous Mazda peanut butter spec.
Knurled. said:In reply to accordionfolder :
So the screw actually broke? That's... scary. No magic goop or Loctite is going to cover for that, the screws must have been made of the infamous Mazda peanut butter spec.
Yes, the screws break in the center, the staked-on shaft stays in the throttle plate and the head goes through the motor. BPs vibrate a lot especially at higher revs. Some people coat the heads with epoxy, others claim that just leads to epoxy breaking off and going through the motor.
Supposedly the aftermarket Skunk2 throttle body will solve this problem for a 1.8, but it doesn't fit the 1.6.
Ah damn, this is a roller coaster. What do we think about this? It's not sharp. I can feel it with a finger nail, but it doesn't catch your nail hard.
It might pass a little oil, but I have seen far worse run fine. That might not even be from the screw to be honest.
Enough oil to cause detonation issues? Hard to say. Probably not while under boost.
Just look at the piston close to make sure the debris isn't lodged in the piston top.
This isn't a forever engine, right? Something better waiting in the wings?
In reply to accordionfolder :
That score depends on whether it was caused by a stroke or two with the head of the screw embedded in the piston, or is it from a broken ring caused by a pinched ring land? With that many dimples, I'd sure pull pistons and see whether the rings are still free.
In reply to accordionfolder :
Sorry, I didn't realize that. In that case I would probably drill through the screws lengthwise with a small bit, maybe .045" and wire it.
I would run that
In reply to Knurled. :
It definitely isn't the forever engine, but I'm also not wanting to oil down the track on my warmup lap, ya know?
I think my only goal right now is to not yoink the engine out again mid-season and try to avoid missing too much track time (I joined a driving club, trying to maximize that "investment")
I'm going VVT next year or later (if the 1.6 will hang on) and hopefully LFX in my full bodied miata.
In reply to Streetwiseguy :
I've pulled pistons to make sure the rings were free moving after valve collision events, but have never seen a piston dented hard enough to do it. I HAVE seen a couple bent piston skirts, but those never did anything worse than have a righteous slap especially when cold.
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