Disaster....

[Gerard van Santen]

A few days ago I opened a thread about a broken balancer in my crankshaft pulley that caused a slipping timing belt. Last evening I had fixed everything and was lucky that no valves were broken and that I had no problems with my pistons. So far so good.

I started the engine for a testdrive. Below 1500 rpm the engine wasn't smooth (now I know the reason for the heavy balancer). But it was fast, very fast .... It accelerated as never before.

But than it happened. A lot of rattle, a big bang and the engine stopped. It seemed that the Comptech supercharger failed. No movement was possible.

I loosened the supercharger belt and tried to start the engine.

Disaster happened ....

It was like somebody let a handgranate explode in the engine bay. A lot of white smoke and this was the result.

 

[RP-Motorsports]

WTF! would cause a long chunk of the valve cover to break like that? Timing off caused extreme pressure ?????

 

[Yellow Rose]

Can you spin the supercharger by hand without the belt attached?

On my car two CTSCs let go.....both seized tight.

 

[Gerard van Santen]

Can you spin the supercharger by hand without the belt attached?

No I can't

 

[hlweyl]

JEeez, sorry to hear that Gerard. It probably went way too lean when the supercharger seized and multiple cylinders detonated.

I've never seen a valve cover blow like that though. Ouch

 

[mdb]

If the SC seized, wouldn't that make things very rich since no air could get in? Wow, I've never seen that happen before. Any marks on the cover to inidicate something hit it? I didn't think that was a sealed chamber up there, so any building pressure would have just come out the crank breather... What does the underside of the cover piece look like?

 

[Gerard van Santen]

Tomorrow I will remove the charger and the cylinder head cover.
I'll keep you informed.

What do you think? Will there be more damage? Internals

Another view:

 

[DanO]

WOW! I’m sorry to see this!

I have no idea how the valve cover could blow like that? The only thing I can think of is a sparkplug let go or something similar that pressurized the valve cover?? Or somehow the breather tube got pressurized, but I think that’s impossible b/c the tube is before the t-body. I have no other idea how there could be that much pressure in the valve cover.

Did you do a compression test before/after the t-belt install?

I hope the damage is limited to the valve cover.

DanO

 

[Gerard van Santen]

This morning I removed the supercharger and this is what I found. A broken valve

 

[Gerard van Santen]

And this how the supercharger looks now. I can't spin the pulley. It is all stuck.

 

[Gerard van Santen]

Another picture with the broken valve.

 

[Gerard van Santen]

Here it is

 

[DanO]

OH NO! That is an ugly sight! I’m sorry.

Well, that’s how the cover got pressurized, the compression went up the valve stem hole after the valve broke off (who knows what happened to the stem…probably still in place). The valve head was blown back into the supercharger witch caused it to seize. Hopefully, the damage is only limited to the CTSC and to the intake valves on that one cylinder. Obviously, there was piston interference with the valve but maybe it wasn’t significant enough to cause piston damage. My only question is, where’s the other valve?

Please keep us posted and again I’m awfully sorry that this happened.

DanO

 

[matteni]

Question is - what did that to your valve? T-belt job off significantly (from your previous post)?

A mystery for sure. Also - don't know if it is possible but it seems like it would be cheap insurance to have steel mesh between the supercharger and the engine to keep big stuff from going down (or up).

Very sorry to see this / interested to see what contributed to this.

 

[RP-Motorsports]

How did the head of the valve or even the stem make it up to the charger???? They should have bounced around on top of the piston. Looks like another benefit of a centrifugal system.

 

[j14nsx]

For a valve to go back up to the intake, it must of gone through the valve seat in the head, no? If so it must of been pushed by the piston forced through the head and flew up the intake port.

I guess then area of the head around the valve seat maybe ruined, and therefore the head.

 

[Arata]

How did the head of the valve or even the stem make it up to the charger???? They should have bounced around on top of the piston.

When things are broken at high RPM all sorts of parts get deformed, I would suspect it is a head from an exhaust valve, exhaust valves are smaller than intakes, that you will find both intake and exhaust valves broken off, and the exhaust was simply able to go up the intake tract back to the supercharger.

Well, that’s how the cover got pressurized, the compression went up the valve stem hole after the valve broke off (who knows what happened to the stem…probably still in place).

As soon as a valve is bent or broken, either valve, there is no compression. The only way compression could blow off a cover is if fuel leaks into the crankcase and ignites, as happens with nitro, but even that is not too likely, more likely is that something that broke off in the cam area pushed on the cover and broke it.

I suspect the head, many valves, cam, followers, pistons, and perhaps cylinders will be damaged.

 

[D'Ecosse]

Gerard, what were you thinking? I don't want to sound like a jerk, but surely it wasn't wise to risk just re-setting the timing belt w/o checking for damage first? (someone had to say it - I'm sorry!)
As j14 suggested, now you're probably now surely looking at new head as well as the S/C and possibly (hopefully not, but likely I would expect) piston & maybe cylinder damage. You might have been lucky & just had to replace a valve or two if you'd checked out the head first rather than risking this eventuality.
Again, not trying to rub salt in would - I feel for you, hopefully the internal damage is minimal.

 

[Gerard van Santen]

I suspect the head, many valves, cam, followers, pistons, and perhaps cylinders will be damaged.

Thanks Arata,

The little hope I had, you just stole from me

I really hope you're not right. Luckely I have an engine in parts. I have two heads with valves and camshafts and pistons. I hope the crankshaft isn't damaged.

 

[Gerard van Santen]

Gerard, what were you thinking? I don't want to sound like a jerk, but surely it wasn't wise to risk just re-setting the timing belt w/o checking for damage first? (someone had to say it - I'm sorry!)
As j14 suggested, now you're probably now surely looking at new head as well as the S/C and possibly (hopefully not, but likely I would expect) piston & maybe cylinder damage. You might have been lucky & just had to replace a valve or two if you'd checked out the head first rather than risking this eventuality.
Again, not trying to rub salt in would - I feel for you, hopefully the internal damage is minimal.

I did check the compression but surely that wasn't enough.

No hard feelings for what you said. I know you all feel for me.

 

[len3.8]

Gerard, what were you thinking? I don't want to sound like a jerk, but surely it wasn't wise to risk just re-setting the timing belt w/o checking for damage first? (someone had to say it - I'm sorry!)
As j14 suggested, now you're probably now surely looking at new head as well as the S/C and possibly (hopefully not, but likely I would expect) piston & maybe cylinder damage. You might have been lucky & just had to replace a valve or two if you'd checked out the head first rather than risking this eventuality.
Again, not trying to rub salt in would - I feel for you, hopefully the internal damage is minimal.

Ken, I understand what your saying, but a dealer or experienced master NSX technician could have made the same mistake.
I think it was a matter of missing a step. I know it happened to me with a Master NSX technician at the helm. (TWICE)
Gerard I know how it made me feel. Just recover. No one wants to hear I told ya so at this time.

 

[mdb]

Oh man, I'm really sorry to see that! There's only one way for that valve to get there I can think of, and it isn't good. With a little luck the valve stayed off the cylinder walls, and your just looking at a head and maybe a piston. The SC maybe just stuck on part of the valve, so perhaps it isn't a total loss?

Good luck and keep us up to date!

 

[Arata]

The little hope I had, you just stole from me

Sorry,

Keep in mind, no one got hurt, it is just metal, anything made can be fixed, if someone gets hurt that's a whole new story.

 

[len3.8]

The SC maybe just stuck on part of the valve, so perhaps it isn't a total loss?


You can see all of the gouges in the SC, it is beat up pretty badly.
Don't try to save it. It is toast. There will be even more metal on the pulley end of the SC... Also the SC walls will have been scored as well...

I agree with Arata... Just build it again, and make it even better.

 

[Yellow Rose]

Similar Situation

On my car, seizure #1 was a result (my theory, not Comptech's not Wipple's.....say, I never heard back from either of them as to the cause) of blower bearing failure that allowed the rotating elements to axially float into the housing.

Seizure #2 was a result (not theory, but fact as pointed out by Comptech) of valve guide stem bits being sucked into the blower inlet.

Indeed, how can something under the blower - valve stem guide or valve head - travel upwards to the blower, when gravity is working in the opposite direction?