V8 SHO Catastrophic Shim Failure

[Qshiplvr]

Well, it happened. It started with a soft ticking, which turned into a definite clicking. I knew something was up, so decided to turn into a shopping mall driveway to check it out. By the time I found a parking space, the clicking was now a clacking. I shut it off, opened the hood, and asked my husband to fire up the engine while I listened. The engine now clanking and sounding like it was missing a cylinder, so I said shut it off, and called AAA to tow it home (I was on the way to pick up some meds at pharmacy, so not too far away).

I called my buddy John The SHO guy, and had him talk me through what to do next. It took a few weeks for me to gather up the courage to open up the valve cover, and this is the carnage I saw.

It appears that the shim sitting in the bucket disintegrated. It may have been an occlusion or fracture that eventually led to the shim bifurcating in half and the cam rubbing the pieces against the camshaft tower support that broke one half into shrapnel, and possibly caused shavings to become deposited on the inside of the valve cover.

In a couple of weeks I'll have the SHO towed to John The SHO guy's place and he'll try to assess the damage, replace the shims and hopefully get her back on the road. While we are in there, I think I'll replace the plastic "Y" connector that distributes the coolant between both heads in the valley of the V.

Wish us luck.

 

[bpd1151]

Good luck and much success with all the repairs looming.

Video is must when it's back up and running like the champ that it is!

Sent from my SM-N950U using Tapatalk

 

[luigisho]

If there is considerable damage I saw paul Nimz on the v8sho email list was parting/selling a v8. If you need a replacement head that might be the way to go. His user name on this forum is SHOZ123 if you want to drop him a line or you can join the v8 mailing list
https://groups.google.com/forum/#!topic/v8sho/i3rYypEDCCY

not sure of mileage or condition

 

[shoftw]

Wow this makes me really want to do the 100k inspection on my shims now.

 

[E1]

Wild!

I have seen a couple shims shoot out over the years, but never one break up.

Have you been able to find all of the pieces of it? This would be my biggest worry if this were my engine. That shim is freakin rock hard and even a small bit of it will chew the bajeezus out of anything it gets up against.
You should be able to clean up that head sufficiently to accept a new bucket and shim.

I too have a 'few' parts laying around if you have trouble finding something.

 

[Qshiplvr]

Everyone: Thank you all for the replies. I am REALLY hoping that the head is useable as is, and all I need to do is find another bucket and a shim that fits, plus redo all the rest of the shims, whilst cleaning out the oil and screen for the shrapnel that happened when the shim failed.

Will let you know in a few weeks. John thinks he has all the spare parts we need to get this on the road again. Won't know until we dig deeper into the engine.

 

[luigisho]

No damage to the camshaft lobe on that shim?

 

[99sho-time]

wow ugly and scary I wonder why. Measure the rest of the clearences? My impression based on the observation of other great sho members and my own is that these engines dont wear shims out. which is why this odd to me. that engine doesn't look dirty either.

 

[SHOVNST]

No damage to the camshaft lobe on that shim?

 

[GEN 3 SHO FAN]

Wild!

I have seen a couple shims shoot out over the years, but never one break up.

Have you been able to find all of the pieces of it? This would be my biggest worry if this were my engine. That shim is freakin rock hard and even a small bit of it will chew the bajeezus out of anything it gets up against.
You should be able to clean up that head sufficiently to accept a new bucket and shim.

I too have a 'few' parts laying around if you have trouble finding something.

I never rode a thing like this before too. Can it be caused by the beginning of the desynchronization of the cam ? The piston starts to touch the valve enough to create more friction on the shim... (Just asking.)

We have some cam welding failures reported over time.

 

[luigisho]

Can it be caused by the beginning of the desynchronization of the cam ? The piston starts to touch the valve enough to create more friction on the shim...

We have some cam welding failures reported over time.

I was thinking that to myself as well. More cam weld failures relative to active members last few years.

 

[GEN 3 SHO FAN]

Welding seems good on the photos however.

Can the main sprocket could be desynchronised ? IIRC, the main sprocket is also pressed onto the camshaft and cams/lobes seem also pressed onto the camshaft... If too much resistance was applied on the cam, this one may have possibly moved, no? (Watch if you see small grinding traces under the lobe on the camshaft.)



If it's the case, the best way to secure the motor could be to change this camshaft sadly. According to another picture, isn't the case. Seems in the same possition as his sister.

Good luck,

 

[Stan Phillips]

Well, it happened. It started with a soft ticking, which turned into a definite clicking. I knew something was up, so decided to turn into a shopping mall driveway to check it out. By the time I found a parking space, the clicking was now a clacking. I shut it off, opened the hood, and asked my husband to fire up the engine while I listened. The engine now clanking and sounding like it was missing a cylinder, so I said shut it off, and called AAA to tow it home (I was on the way to pick up some meds at pharmacy, so not too far away).

I called my buddy John The SHO guy, and had him talk me through what to do next. It took a few weeks for me to gather up the courage to open up the valve cover, and this is the carnage I saw.

It appears that the shim sitting in the bucket disintegrated. It may have been an occlusion or fracture that eventually led to the shim bifurcating in half and the cam rubbing the pieces against the camshaft tower support that broke one half into shrapnel, and possibly caused shavings to become deposited on the inside of the valve cover.

In a couple of weeks I'll have the SHO towed to John The SHO guy's place and he'll try to assess the damage, replace the shims and hopefully get her back on the road. While we are in there, I think I'll replace the plastic "Y" connector that distributes the coolant between both heads in the valley of the V.

Wish us luck.

 

[stephen newberg]

Yes, best of luck with it, Stan.

pax, smn

 

[Stan Phillips]

Sorry...could not type a response to the last comment.
I had the shim failure also.
I got the shim out, but it looks like the top edges of the "bucket" took a pounding.
Is it possible to pull the bucket out without pulling the cam off ??
If so, any advise on how to pull the bucket out ?

I have a spare head that I can salvage parts.

 

[gamefanatic]

Not possible to get the bucket. It needs to come up almost 2".

 

[Qshiplvr]

Sorry, this thread is stretching out so long, but Life kind of gets in the way of SHO business, you all know that. JohntheSHOguy was kind enough to dig into my engine, and ALMOST has the head off to check the extent of damage. Took him a couple of trips, one in Jan, one in April to get to the point of pulling off the head, then he took a much deserved vacation, and is back sometime today. I anticipate more news sometime in the next few weeks on how catastrophic the damage is.

 

[gamefanatic]

Hopefully they not damaged too bad. Heads are a dying breed for these vehicles, but still out there!

 

[E1]

I got heads, I got buckets. I got shims. I got cams.
If you can't find what you need, hollar at me.

 

[Stan Phillips]

Trying not to hijack the thread...but going through the same issue. The shim came off the top of the bucket & got lodged in the top of the slide area in the head. Was able to pull out the bucket (project) and put a new\old bucket in it's place. I pulled the cam by sliding the cam gear off the end. I am now to the point where I need to slide it back on...then check cylinder pressure for a bent valve. Of course it does not want to go in place. It is so close to going on, but am afraid to apply too much pressure. I will remove the timing cover if I have to...never done it before. Anyone able to tell me about the "ratcheting" chain tensioner E1 mentioned in an older post ...can I loosen it just a bit to get the gear on the cam ??

Again, any advise welcome.
FYI: I had zip tied the chain the both cams as to not loose the timing.