Dreaded Upper Cam Chain Guide Failure

[Great White]

Last time I did my yearly oil change (a couple months after the pandemic hit,) I discovered steel glitter in the oil. I parked the car, set it up for hibernation, and haven't driven it since (except two short drives to renew the registration )


Fast forward to now, I'm finally in a position to repair it. Without further ado, let's get into it.


The pictures below are of the passenger side upper chain guide backing plate, cam cover, and chain. I haven't removed the driver's side cam cover as of yet. My questions thus far are as follows:


Does anybody sell replacement backing plates?


If no, is the driver's side backing plate identical?


If no, does somebody have a print of one so I can get a head start on making one from scratch?


If no to all of the above, I can reverse engineer it from a new plastic guide myself, I was just looking for a faster, simpler solution.


Next question...


Does the chain look okay to you guys?


Last question:


What on earth do I do to gain access to all 4 of the nuts holding the brake booster to the firewall? I haven't found a combination of socket extensions that will allow me to get a grip on all 4 of them. Two of them are easy, but the other two are obscured by the steering column. I managed to remove the throttle pedal assembly to gain a little more room, but now I feel like that was an exercise in futility. I'm not as flexible as I used to be I guess.


Any help is appreciated. Can't wait to hang with you guys in May.

[WARP TEN]

Talk with Jerry at Jerry's Gaskets and Marc Haibeck at Haibeck Automotive. I am sure they can offer some good advice. --Bob.

[AndrewL]

Jerry sells the facings. https://www.jerrysgaskets.com/search...h_query=facing

I can't help with your other questions as I haven't done that job yet.

[A26B]

Originally Posted by Great White

............................ My questions thus far are as follows:
Does anybody sell replacement backing plates?................................

I am making a run of the Cam Cover Secondary Chain Guides now. So they will be available shortly.

I have lots of inventory of all of the chain guide facings, having made those several years ago.

[A26B]

Originally Posted by Great White

..............................
The pictures below are of the passenger side upper chain guide backing plate, cam cover, and chain. I haven't removed the driver's side cam cover as of yet.

My questions thus far are as follows:........................

Next question. Does the chain look okay to you guys?....................................

I think your first question should be what caused this?
The Secondary Cam Chains had to be running very loose and making some sort of racket. I think you are pretty fortunate that you didn't explode the engine. Had the cams jumped timing or broke, valves would have collided with pistons.

Describe how you discovered this in the first place.

[Great White]

There have been no unusual noises. I simply discovered the steel in the oil during a routine oil change. I know it sounds crazy, but there were zero "symptoms" leading up to this discovery.

[Great White]

I finally managed to get the driver's side cam cover off after removing the brake booster.

If anybody is curious, the solution to the brake booster removal was ultimately removing some of the insulation around it and using a 1/4" drive deep-well socket with a swivel and long extension. It took forever and I needed a chiropractor adjustment afterwards.

For posterity I will post pictures of the driver's side upper cam chain guide backing plate, but I can already say it definitely doesn't look any better than the passenger side one pictured above.

[Z51JEFF]

How many miles does the car have?

[Great White]

Originally Posted by Z51JEFF

How many miles does the car have?

I've got the battery disconnected at the moment, but if memory serves correctly the odometer reads around 162,000 mi. A prior owner had the engine gone though by Marc at around 124,000 mi some time around 2008. The engine has his 500hp treatment. I don't know what the actual reason for the work initially was. I will see if I can dig up info on what was replaced in the documentation I have. If I recall correctly, Marc did a pretty extensive rebuild on it.


Since I bought it, I haven't put very many miles on it. I have replaced a lot of parts (injectors, coils, plug wires, starter, vacuum lines, water pump, radiator etc.) but this is my first time having any internal engine issues with it. I run Amsoil and a wix filter for every oil change and I'm easy on it until the oil is up to temp.

[A26B]

You can tell from the lack of response to the missing facings and extensive wear on the guides themselves, that this is an unusual failure, because no one has ventured to answer.

The fact that BOTH L&R guides are affected, is something more than a Secondary Chain Tensioner failure, which is not common, certainly not both of them.

Getting a look-see at the whole chain system would be nice, but requires engine removal. Dropping the pan may not tell you much that is not already known. I don't think an intact facing could make it into the pan unless chewed up in bits. For $25 or so, you could get a flexible endoscope for an Iphone, that might show you bits laying around behind the timing cover.

Here's a picture of the chain system for reference.


Something is not right with the chain tensioning system, which really needs to be resolved. Even if the facings broke or fell off, the chain just does not normally ride that high above the sprockets when properly tensioned. The cam-cover chain guide facings usually don't incur much wear.

Just carefully work your way through it until you find the answer.