Loud metal clash while driving, no longer starts

[Chilezen]

The wonder continues...

[///M42 sport]

how did you manage that?

[Chilezen]

You know, I'm wondering that myself.

TB looks fine, basically no nicks. ICV still buzzed when I tried starting it, so that must be okay too.

I have just taken off the headers, felt inside for a valve, but nope: exhaust valve is gone. It's a bit sharp in there as well. Just a couple more steps before I take off the head.

[redlightpete]

Sorry, dude. You might as well pull the head and see what you've got. It's not going to get any better with the head on.

[TobyB]

The exhaust valve is still pressing against the rocker, even though the cam lobe is on the other side.

its head popped off... that's never good...

I have the same problem with my mechanic. I'd thump him
good, but it hurts too much... I'd fire him, but then where would I work?
Arguments in the pits just make my fellow competitors think I have multiple personalities.
Especially when the team manager and owner chime in...

t

[Chilezen]

And the epic conclusion:



Start naming your theories, gentlemen. What do you think happened?

I think (do correct me if I'm wrong) the valve is 325k miles old, and finally had enough. Maybe.

[15Michaeljoseph]

aliens. knomes. witches.

any of those three. well, at least it didn't happen while you were driving. that would have been a nasty chain reaction :)


--Mike

[Wanganstyle]

And the epic conclusion:



Start naming your theories, gentlemen. What do you think happened?

I think (do correct me if I'm wrong) the valve is 325k miles old, and finally had enough. Maybe.

Well there is no "think" since you pulled the head and the valve is stuck in the piston.

Exhaust valves wear over time; usually the heads drop off but yours broke in the middle of the shaft - Did you grind this valve?

IF the valve is an original 300k+ miles run time part that was ground before install then the failure could be either the grinding work or runtime or both.

Time to start looking for a younger complete running engine :)

[Chilezen]

Exhaust valves wear over time; usually the heads drop off but yours broke in the middle of the shaft - Did you grind this valve?

IF the valve is an original 300k+ miles run time part that was ground before install then the failure could be either the grinding work or runtime or both.

Time to start looking for a younger complete running engine :)

I did grind this valve. Of the 12 valves, I replaced 6 that showed wear. I guess after 300k, all valves are worn. I do appear to be at fault, that sucks :(

Thank you for your input, it's a hard truth to face. A friend has an engine sitting around, I'll take a look this week.

[Wanganstyle]

I did grind this valve. Of the 12 valves, I replaced 6 that showed wear. I guess after 300k, all valves are worn. I do appear to be at fault, that sucks :(

Thank you for your input, it's a hard truth to face. A friend has an engine sitting around, I'll take a look this week.

I had a similar issue in 2006, found a chunk of a titanium valve stuck in my turbocharger.........This was absolutely no fun!

[Chilezen]

I had a similar issue in 2006, found a chunk of a titanium valve stuck in my turbocharger.........This was absolutely no fun!

Really? A titanium valve broke? Because it wasn't ground perfectly?

[Wanganstyle]

Really? A titanium valve broke? Because it wasn't ground perfectly?

Everything breaks.

The Sti-RA version 4 type RA 2000cc Longmotor was original with 24k miles; valves original and untouched. This motor has a full titanium valvetrain from the factory; ball bearing turbocharger fitted

It was ran with 1.1bar boost to over 8500rpm Rev Limit

My particular failure was due to the sodium filled titanium valve head head dropping off; The specific engine was very fragile and really not designed for street use with pump fuel.




The BMW S50b30 US engine has this same problem; Sodium filled head iron alloy valves that are friction welded construction from the factory; The valve heads will sometimes drop during severe duty stress (track use or racing).

The only real good solution for serious duty cycles is to monitor the run time hours and replace it before its at risk - or go to a 1 piece construction valve (aftermarket) - and monitor it's hours.

[Chilezen]

The only real good solution for serious duty cycles is to monitor the run time hours and replace it before its at risk - or go to a 1 piece construction valve (aftermarket) - and monitor it's hours.

Of what material would the preferred valve be?

--

General question: My buddy has an engine from a '91. I have an early model '87.

Do I need to swap over the later model ECU/wiring harness to run that engine?

[Wanganstyle]

Of what material would the preferred valve be?

--

General question: My buddy has an engine from a '91. I have an early model '87.

Do I need to swap over the later model ECU/wiring harness to run that engine?

no idea what preferred valve material would be; consulting a materials engineer might be the best answer to this question

Steel alloy 1 piece construction seems to have the least potential for failure

Best most reliable valves possible? Mazda rotary engine. It has its own failure points though



***

early gen E30 M20b25 is only different from late model in its water pipe routing. If you buy a motor from a early motor just strip it to longblock and transfer all your parts over; easiest

[tig welder]

That's sad to see but as you mentioned ... 300K+ on the miles and some parts replaced was possibly the answer you are looking for.

If there is a silver lining ... I haven't seen one grenade like that in a long time ...