Jump to content

broken cam chain guide


ranpan

Recommended Posts

Just signed onto this forum,thanks for having me. I encountered this problem last night when changing the RH cylinder head gasket. On the top chain guide, I found the outer 1 1/8" broke off sometime during the head removal. I'm thinking this happened when the cam bolt broke loose causing the chain to jump.

I know this is a critical part of the valve train, but is it that critical that it requires a teardown for this outer 1 inch or so??? I'm hoping that I can put it together with a "no problem" attitude.

This is on a 97 r1100rt with 60,000 miles.

Link to comment

If enough of the plastic chain guide is still there to prevent chain slap, I'd say leave it as is.

Link to comment

Exactly what I was thinking..the entire guide length looks to be about 10-12 inches long with the outermost 1 inch broke off. That broken 1 inch shows slight wear marks less than 1/2 inch long.

I'm thinking of beveling the broken end, and button it back together, since this is NOT on the tensioner guide.

Perhaps my thinking is flawed, I'm not sure...

Link to comment

I haven't seen it but from your description I would also think you could leave it as is, especially considering how much work a proactive replacement would be. I believe that the 1100 motor has a non-interference design (not sure about that though) so the worst effect of a cam chain guide failure might be an inconvenient breakdown on the road, but the risk is probably low and a gamble worth taking.

Link to comment
DavidEBSmith

considering how much work a proactive replacement would be

 

Requires splitting the motor, no? If just buttoning it back up doesn't work and it breaks, does it really matter if you take out the valves and pistons too? It's just another thousand bucks for some parts on top of a multi-thousand bucks in labor rebuild. crazy.gif

 

There is one of those rails that somebody somewhere was able to get to and replace without splitting the engine by grinding out something on the block, but I don't remember which one or how. If you search here and at AdvRider, maybe you can find it. But if that's not an option, I suspect you're just about as f***ed right now as you will be if you put it back together and start it up to see what happens, so why not go for it?

Link to comment
  • 2 weeks later...

Put the RT together finally. Rode it to work and back the other day (198 mile commute). Everything works fine, no noise, nothing out of the ordinary, until 4500 RPM, then it sounds like the cam chain is rattling.

Have pulled the motor apart again to epoxy the broken piece back together, using a small steel rod for additional support. Hope it works. Tried looking at the ADV Rider site, but didnt find anything useful about this subject. If anyone has more ideas????? I will report back on the results. thanks

Link to comment

Have pulled the motor apart again to epoxy the broken piece back together, using a small steel rod for additional support
If it holds. But what if it doesn't and a "small steel rod" is suddenly loose in the motor? eek.gif

 

I'm surprised that a bit of missing guide would cause cam chain noise under load. It's main purpose is mostly a chain guide at idle. But I suppose anything is possible.

 

At this stage, if I was convinced, I'd probably bite the bullet and spit the case and replace the guide.

Link to comment
Have pulled the motor apart again to epoxy the broken piece back together, using a small steel rod for additional support. Hope it works.
If you prepped the parts well and used something like JB Weld then I think you have a good chance of the repair holding up. Or in any event my fingers are crossed for you as I would not be looking forward to the alternative...
Link to comment
Put the RT together finally. Rode it to work and back the other day (198 mile commute). Everything works fine, no noise, nothing out of the ordinary, until 4500 RPM, then it sounds like the cam chain is rattling.

Have pulled the motor apart again to epoxy the broken piece back together, using a small steel rod for additional support. Hope it works. Tried looking at the ADV Rider site, but didnt find anything useful about this subject. If anyone has more ideas????? I will report back on the results. thanks

 

Randy, pretty well nothing (glue or epoxy wise anyway) will hold that nylon chain guide together.. Especially under the beating loads of a whipping timing chain.. If that piece comes loose (& I’m betting it will) with that pin in it you chance major engine damage..

 

I’m having a hard time believing that broken guide would allow chain noise at high RPM’s but not at lower RPM’s also..

 

I would run the engine with the valve cover removed & see if that chain is actually whipping or even coming near that broken area (in the previous picture it looked way out at the end & away from chain contact area.. It might help to use a timing light to view the chain while running at high RPM’s as that will freeze the chain in motion..

 

Most chains follow the sprocket on the slack side so there is usually a hump away from the guide as the chain leaves the sprocket.. The chain center on the slack side will want to balloon out from centrifugal force but in your picture the chain looked like it was still well supported by the guide in the middle of the chain..

 

If it were mine I would probably just run it for a while & inspect the broken end of the chain guide every few thousand miles to see if any unnatural wear is occurring in that area..

 

Twisty

Link to comment
...Have pulled the motor apart again to epoxy the broken piece back together, using a small steel rod for additional support.../quote]

 

This scares me. I've been looking for a suitable adhesive for repairing a plastic bumper cover on my car, and it's a short list of glue that sorta works. In the heat, vibration, and chemical environment inside an engine, you will be hard pressed to find anything with any hope of durably gluing that rail back together. A loose steel rod rattling around just exactly where you don't want is is another nightmare waiting to happen, probably sooner rather than later.

 

FWIW, my '90 BMW 535i sedan ran fine with a broken nylon chain guide (probably a larger version of the one in your bike), for ~100K+ miles. On that basis, I'd consider leaving well enough alone, if I had your bike.

Link to comment

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...