Pass the Cam, Please

[mdrose]

Bikes in the shop this week for spring renewal, Brake Juice change, Coolant Flush, New Tires, and Valve Adjustments.

Odometer, 60k Miles

Today's Monday first day under the wrench and I get a call from the service manager with a question, now I'm nervous. Have you or did you remove the cam shaft in this bike? No Sir, why do you ask ?
It appears the intake cam shaft sprocket guide is worn down (I would have called this a cotter pin but this appears to be machined into the cam shaft). Its normally about an 1/8 of an inch pin type protrusion, and half of it is worn down, and theres play between the cam and sprocket.

Herman the German (my nick name for the service guy), says I'm going to need a new one. :eek: I sit down, take a breath and ask, and the costs are? Hermie say: the cam is $333.00 and sprocket is $57.00 which will also have to be replaced, and we'll have to order it.
He goes on to say: we'll need your approval, do you wish to proceed.

I pause, I think, I have no choice here, so go ahead an doit. :(

I asked how is this possible, "Herman" said, it appears the cam was not installed correctly.
Interesting, because the original dealer (in another state), where I purchased the bike used, 3 years ago did the last valve adjustments on it.

So, to quench my thirst for knowledge, I'm checking in with the guys who know everything there is to know about BMW LT's.

My search in the great Halls of Wisdom for cam shaft references, yielded nothing. I searched the LT group threads and found nothing.

Now Folks, I understand the function of all the internal engine components, but I've never heard this one before, can anyone explain this worn cam shaft guide pin to me?

I'm I being hosed?


What a way to start the riding season.

[Morley]

If he is talking about the cam dowel pin that goes into an aligning hole in the cam sprocket...There shouldn't be any way for it to "wear down". It is merely a pin that keeps the cam sprocket from spinning on the cam shaft. Also, I don't know about the bike's cams, but on auto engines the dowel pins can be replaced, easily.
In the picture in an automotive camshaft and you can clearly see the dowel pin. They are pressed into the cam and there is a corresponding hole in the cam gear that it goes into.

[mtrevelino]

I had my cam replaced during either my 24k or 36k service. The dealer said that one of the lobes had some marks on it. This was covered under the BMW warranty.

[dshealey]

It did not "wear", as that is practically impossible. I have seen one that was installed imroperly though, and that is almost guaranteed to be the problem. If the mechanic did not get it properly aligned before tightening the bolt that holds the sprocket on, either the hole in the sprocket or the pin in the cam, likely both, will be "sheared" when the sprocket is forced onto the cam.

I always be sure the sprocket can be pushed back solidly against the face of the cam by hand before tightening the bolt.

[mdrose]

Dave, that makes perfect sense. I knew you would nail this question.

I guess that dealer in North Chicago, will not longer be receiving the benefits of my praises.

Just my luck, I get the mechanic, who's having a bad day. I'm wondering if he would like to pick up the cost of the parts ?

To all whom responded,,,,, Thanks for the insight.

[mjordans2000]

As the 'proud' owner of the cam and gear David referred to I agree 100%. After allowing the dealer in question to adjust my valves do to a busy schedule I observed what you are describing. The pin wasn't worn, it was partially sheared do to misalignment. I was lucky enough that the damage to the cam wasn't enough to force replacement of the cam. The gear had to be replaced (no charge for the parts) and all was well. 24K later it's still running good (that's not to say I'm happy it happened in the first place)