Rb26 Engine Failure - Who's Fault?

[webber]

Hey guys,

we had an RB26 head rebuit, basically (it already had cams) to standard spec with new valve guides etc.

What would cause this:

As can be seen in the pic, there is a fragment gone from this cracked piece.

Something went through our rear turbo, which sent fragments back into cylinder 5 and scored the bore on our rebuilt forged N1 bottom end. The pic is of the front exhaust valve guide on cylinder 6. Our engine builder who will remain unnamed at this point claims to have never seen anything like it. What would be the opinion of people on here, is this crack from valve guide instalation of has the guide grabbed and travelled.

Also a valve seat on cylinder 5 has dislodged and is sticking below the chamber enough to catch my finger nail.

Is this just shoddy workmanship or something else?

we havent taken the engine back to them yet, and are considering taking it to another rebuilder to get their unbiased opinion. Can anyone recomend someone?

Any comments would be appreciated.

Thanks

[zebra]

Standard turbos?

If so then a turbine wheel has let go and sent bits of shit back through the ports (this happens a fair bit to RB26s)

Of steel wheeled turbos then no idea.

[webber]

engine ran for about 30 minutes, (mostly idling) I am well aware of what happens to ceramic turbo's. Yes these were ceramic. They are what done the damage to the engine for sure. but would this cracked/chipped piece around the valve guide be enough to take out the turbo, and is it the builders fault that it chipped off. since they rebuilt the head and replaced the valve guides? This engine basically got up to temperature idle, colled down, back up to temp & failure.

Even with 30 minutes use, this head should be brand new...

[webber]

Also if the ceramic wheel "just let go" why is the head cracked around the valve guide at all?

[zebra]

Not sure, maybe the valve jammed in the guide and got whacked by the piston?

[Mark-32]

Same thing hapend to my rb26 engine. Fresh rebuild, had it going 3 days then broke a valve guide in No5 cylinder..

Massive job pulled the engine back out lifted the head.

The only damage It did was the bent inlet valve and broke the valve guide in no5.

In my case I just sent the cylinder head back to my engine builder who fixed it and returned it.

How bad is the bore and damage to top of piston? Pics?

I feel for you buddy hope you get it sorted under warranty

[The Dan]

The turbine can't get back up into the cylinder unless it's peaking off it's ringer.

Is it possible you bounced off the limiter as it happened?

Also, the piece looks to be cracked but has not dislodged. If a piece came away and went through the turbo, then you could blame that piece, but that piece is still attached inside.

The valve seat could just be in the post casting. I have seen this many times before on standard ports. You won't know until you get the head off and inspect it properly.

[OMGGTR]

You cant run in an engine on idle.... any fresh engine must not idle!!!! i think the builder is at fault...

[Sinista32]

Been there done that (twice).

1. Give your engine builder the "right of repair". If that fails (almost always)

2. Call Fair trading, lodge a form. Fair Trading will organise a mediation hook-up.

and then if that fails

3. PaY $600 FOR AN INDEPENDANT ENGINEERS REPORT. I Recommend Geoff Senz & Associates.

4. Once you have the report (and it identifies the cause and who is at fault) fill in this form http://www.cttt.nsw....hicles_Division

5. attend court and receive judgement.

PS. Claim all your costs plus the cost of Repair/Replace.

But give your engine builder first right of repair. You might have a decent guy.

Dont be intimidated or hoodwinked. Just follow these steps.

Edited May 4, 2011 by Sinista32

[MrStabby]

Been there done that (twice).

1. Give your engine builder the "right of repair". If that fails (almost always)

2. Call Fair trading, lodge a form. Fair Trading will organise a mediation hook-up.

and then if that fails

3. PaY $600 FOR AN INDEPENDANT ENGINEERS REPORT. I Recommend Geoff Senz & Associates.

4. Once you have the report (and it identifies the cause and who is at fault) fill in this form http://www.cttt.nsw....hicles_Division

5. attend court and receive judgement.

PS. Claim all your costs plus the cost of Repair/Replace.

But give your engine builder first right of repair. You might have a decent guy.

Dont be intimidated or hoodwinked. Just follow these steps.

Excellent advice. Also, make a handwritten log of everything you do and say including with times and dates. Include notes of what the builder says.

[beemae30]

A= Do everything sinista said.

B= Never idle a brand new engine. As soon as it has started rotate the engine speed till it is warm and then work its ring out. I know many people don't beleive this method but i have used it on 5000hp plus diesel engines worth millions and works perfectly. Ive also used it on every small engine i have built same result. As elite said the turbo would not return back into the ports unless the engine was working which you said it was not. You wont know till you pull the head or do a boroscope to the engine.

There is a high possibility of a faulty assembly. I.e. Not enough lube on the valve stems, Incorrect valve guide install, contaiminets left in the manifold, head, cylinder, I have seen small filings go through an engine then take out the turbo before on very rare occasions.

[webber]

Thanks Guys, Bottom end had been built early last year, was already ran in but car had not been driven much. on the day it failed the car got a few revs - 4-5000 after it went to the exhaust shop and had the exhaust modified, but definatly not rev limiter and only 3-4 sharp bursts to mentioned revs to hear it (and that was 4 hours before it occured)... then it drove next door to have a wheel alignment, then back on trailer, when it was taken off the trailer it idled away, turned it off. was started 10 mins later, and when selected reverse to move it a metallic noise was heard, engine dropped to 5 cyl and was shut down immediatly. was at not much above idle when that occurred.

Elite, the piece cracked has a small chip missing behind it. There are marks on other valve stems on other cylinders that look tight, and have scrape marks on them.

It is going back to the builder tomorrow, if he admits fault it will be left with him, if not i will have an independant inspection

Thanks for the help

Cheers

[The Dan]

Thanks Guys, Bottom end had been built early last year, was already ran in but car had not been driven much. on the day it failed the car got a few revs - 4-5000 after it went to the exhaust shop and had the exhaust modified, but definatly not rev limiter and only 3-4 sharp bursts to mentioned revs to hear it (and that was 4 hours before it occured)... then it drove next door to have a wheel alignment, then back on trailer, when it was taken off the trailer it idled away, turned it off. was started 10 mins later, and when selected reverse to move it a metallic noise was heard, engine dropped to 5 cyl and was shut down immediatly. was at not much above idle when that occurred.

Elite, the piece cracked has a small chip missing behind it. There are marks on other valve stems on other cylinders that look tight, and have scrape marks on them.

It is going back to the builder tomorrow, if he admits fault it will be left with him, if not i will have an independant inspection

Thanks for the help

Cheers

Goodluck

[Room42]

There shouldn't be scrape marks on the valve stems. Sounds like someone owes you a rebuild (give or take). But if a simple thing like fitting valves was messed up then can you trust that your engine will be properly sorted? Good luck mate.

[beemae30]

If there is scraping on the valve stems. There is a mechanical fault. Either not enogh lube on the valve stems for start up, Valve guides not lined up/ pressed incorrectly. Or possibly incorrect valve adjustment.

[sinistaGTR]

what was the outcome of your meeting

[GTRNUR]

What exactly is that piece of debris in front of the valve stem. It looks like a piece of the port, as in aluminium that has been cracked away from the head casting when the stem was pressed in.

If it is aluminium, it is likely that this port isnt where your trouble started. I'd wager that some or most of the other ports would have similar damage, and possibly a few bits missing from around the ends of the valve stems. Im thinking the machinist used the wrong interference fit for the valve stems or incorrect assembly method to press the guides back into the head.

Elite, the piece cracked has a small chip missing behind it. There are marks on other valve stems on other cylinders that look tight, and have scrape marks on them.

A tight cylinder? Unless the machinist forgot to check the piston/bore clearances I doubt its the cylinders that were at fault. Im guessing colateral damage as a result of debris from the ports ended up causing the damage. I'd be pulling the valves from the head that marry up to the damaged cylinders and inspecting the ports and combustion chambers. Debris from the ports have probably hammered into the head and piston crowns in the quench pad area too.

Pictures of the combustion chambers for the damaged cylinders with the valves removed, and the damaged cylinders and pistons in the block will reveal more.