M96/23 cam timing slipped

[ninja02]

I have an my2004 2.7l Boxster and the timing of the exhaust cam on cyl's 1-3 has slipped. Not sure why yet until I drop the engine out.

My thoughts at the moment is either IMS bearing failure or chain tensioner

Has anyone else experienced this and what was the cause.

Phill

[harryrcb]

How many miles on your car? and yes it could be either one.

[ninja02]

73 k

The really annoying thing is that I'd only bought the car 4 weeks previous.
Private sale so no comeback

Phill

[harryrcb]

only one thing to do, pull the tranny and engine and go over everything. Wayne had all the articles on this site that you will need plus the really good book 101 projects that covers all that too. Let us know what you find.

[Wayne 962]

Hi there. Can you provide more information? How do you know that the timing has slipped? I think that if this happens, then the engine will stop running and pistons / valves will come in contact with each other. What exactly has happened?

-Wayne

[ninja02]

Hi

Car stalled as I lifted off the gas at the last corner before home. Coasted in and tried numerous times to restart but no luck. I've removed the cam plugs on cyl's 1-3 and the exhaust cam is approx 90 deg out of sync set at TDC



Great book my the way Wayne and shall be using it to guide me.


Phill

[Wayne 962]

I lightened the image for you. Yes, I agree, this looks pretty bad at first glance. Will the engine turn over by hand?

-Wayne

[ninja02]

Turned engine through 360 deg by hand to set TDC. Didn't have plugs removed so usual resistance with compression.

Phill

[harryrcb]

you would think there has to be at least a couple of bent valves. Sorry for you problem. I now that sucks. you need to take the motor apart and check the heads and pistons on that side at least.

[ninja02]

It would be nice if a couple of bent valves are the only damage. Not too sure about the cause until I split it. If the exhaust timing has retarded, would'nt the valves have missed the piston?

Phill

[Wayne 962]

Originally Posted by ninja02

It would be nice if a couple of bent valves are the only damage. Not too sure about the cause until I split it. If the exhaust timing has retarded, would'nt the valves have missed the piston?

Phill

Not sure about that. You know, if this was my engine, I would get the LN Engineering camshaft alignment tools from us (the kit is on the Pelican website), and then I would open up the IMS bearing, replace it, reset the cam timing and then run a compression check. You may have gotten lucky.

-Wayne

[ninja02]

Wayne,

Do you ship to the UK?

Phill

[ninja02]

Engine is now out of the car and the damage report is:

1 Damaged lobe on No 1 cyl inlet cam
2 Expoded follower on No 1 inlet
3 Damaged sprocket on exhaust cam due to debris from follower stuck inbetween the sprockets causing the chain to jump
4 Bent exhaust valves x6, fortunately the guides are not damaged.
5 Numerous pieces of debris throughout the engine
6 Possible damage to timing chain. Def has a sharp edge on the underside of the chain. Not sure if it would of stretched.

Estimated parts bill £1500 GBP

Phill

[mikefocke]

Who knows where the debris ended up or what damage it will do even if you rebuild the complete valve train perfectly. Consider sourcing a used engine from a wreck that has reasonable miles? Or consider a total rebuild including cleaning out all oil passages in the block and both heads and that is gonna be truly expensive.

[ninja02]

Hi Mikefocke.

Going for your second option. Doing the rebuild myself so the only cost is parts. Priced up a replacement M96/23 engine here in the UK and the average price is £4000. It even crossed my mind to scrap the car, but this option would of been a total waste

Phill

[cnavarro]

What kind of oil were you running? (I realize you might not know as you just got the car).

That looks like a classic camshaft and follower failure. I've seen a similar wiped out cam and failed lifter on a similar age 2.7 at the local Porsche dealership a while back. Overall, there is a lot of wear on those parts, even the ones that are not failed.

[ninja02]

Hi Charles

Mobil 1 I was told by the previous owner.

After I removed the cam cover, a friend noticed that the cover had been welded on the inside inline with the broken follower. On closer inspection there was signs of welding on the outside also, but you had to look hard. If you was not looking for these signs, it was so easily missed. I'm wondering if sometime previously, a similar problem has occured but with damage to the cam cover, a new valve and follower were installed but the cam left and the damage seen in the photos could also be partly caused from the previous problem.

Planning to change all the followers as part of the repairs.

Phill

[cnavarro]

Unfortunately, this isn't the first time I have heard of this.

I have had dozens of calls from people who had a failure and said they were going to patch up the engine and sell the car immediately and calls from the people who purchased them. Sad state of affairs.

I had a customer experience this with a low mileage used engine. Here's a write-up about the ordeal:

http://www.flat6innovations.com/used-engine-article

[JFP in PA]

Charles, when I clicked your above link, my firewall went nuts, blocking Jake’s website, saying that the site was loaded with ten malicious web redirect bots. Has Jake’s site got a problem?

[cnavarro]

Loads fine for me in Google Chrome and my security software didn't say anything...

Here is a direct link to the article in PDF format (shouldn't have any malware):

http://www.flat6innovations.com/used-engine-article?format=pdf