Is this a chain tensioner failure?

[markm]

Holy shite, that looks like a real mess, sincerely hope the case is okay

[911hillclimber]

When my 3.2 let go at 7000rpm there was a light rattle and the damage was awesome.
The one cylinder had failed, the piston skirt had disappeared and the crown was wedged in the cylinder which had split from top to bottom.
The impact of this lot bent all the valves, and did local damage to the mighty 3.2 aluminium block, one head and nearly everything else.

Took 3 hours to split the case as the rod was twisted round part of the internal case webs.

The skirt was mulched by the engine chains and anything else moving at 7K.
Stripped the lot down and the swarf was just everywhere, in the oil pump, the galleries and the oil cooler.

Local damage was machined by Redtec and parts found by Bob Watson to get the engine back ready to rebuild which I did and it is fine today, 4 years on.
The cost was startling for all the parts.

Good luck with what you find, after a good clean it will look better!
I had to throw my cooler away, it was so full of swarf and I could not wash it all out.

[johnM]

That looks a terrible mess.

For info the case has defiantly been split previously as the case bolts have been fitted the wrong way. (Not that it makes a difference)

What year is the car / engine?

[tim69s]

What year is the car / engine?

Car is a 69 shell, but the engine is(was) a 74 2.7 CIS


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[johnM]

Car is a 69 shell, but the engine is(was) a 74 2.7 CIS


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Makes sense.

[tim69s]

Well that, as they say, is that.
Guess I am in the market for an engine








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[Bootsy]

Oh dear, that's some failure

[Gary71]

Shame to see that big gouge in the case.
Gutted for you.

[911hillclimber]

Yes, done-for.
The shells don't look too good imho, but the case is scrap.
Never seen an early crank failure in a 911 engine, and can only recall Jonney Tippler's 964 crank snapping some years ago.

As I said above, ensure the cooler is not full of swarf and also the oil pump, possibly the only parts salvage able in the bottom?

[hot66]

Go big or go home as they say

[Gary71]

Sadly I don’t see anything from the oil system going back into a new engine.

Maybe heads, cams, cam housings, timing cases etc are salvageable but not much else.

I’d imagine a full engine is the solution, but obviously many £££.

[fetuhoe]

Sadly the 6-Bolt 70.4mm crank does tend to suffer from torsional vibrations and this can cause fatigue crack initiation at the fillets.

I think that there is a high order 4th/5th) gas torque that will cause fatigue damage to accumulate at high revs and will ultimately cause crack initiation.

If the crank has been re-ground and the corner radius has sharpened it can also help it to crack more easily.

When these cranks are re-ground it is worth specifying a minimum radius of 2mm just to be sure that there is no increase in the stress raiser in this area. it is also worth shot peening this part of the crank to give it the best chance.

I would also be inclined to 'shot peen' the fillets even if I weren't grinding the crank as this would help to remove any accumulated damage to the crank's microstructure and improve its fatigue life.

[Simon Rudge]

Ouch, sorry to see this!

Sadly I think the whole lot is done for. It would be easy to try to clean the oil cooler for example, I know they are a wad to buy, but a real false economy. In my view, it is not possible to be certain that a cooler is clean and therefore just a failure waiting in the wings. One is enough!

Good luck with a new build!

[gridgway]

I thought it was a cardinal rule of rebuilds after swarf, throw the cooler away!

ETA: commiserations on the failure OP, that's not a nice sight, nor nice for the wallet.

Graham

[tim69s]

My car has a front wheel arch oil cooler as well. Anyone know if the swarf could have got round there?
I'm thinking not, as the engine stopped as soon as the failure happened, so there was not time for it to get pumped around the system.

Will look to remove and flush it anyway.


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