K75 timing chain cover (do I have to drain everything?)

[mathias]

Hello everybody,

   I just got my first BMW a few weeks ago, a 1994 K75S, with about 42K miles on it. It didn't come with any service documents, so I'm going through all the fluids, lubes, etc. It had the typical off-idle hesitation, so I'm in the middle of overhauling all the rubber bits around the intake manifold and just got my injectors back from being overhauled by Mr. Injector (they look beautiful). I'm also checking my valve clearances - the exhaust shims needed to be replaced. Still waiting for the parts from BMW.
   Another thing I want to take a look at is my timing chain tensioner. The bike has the "can of nails" rattle when pulling away off idle. Common and harmless, it seems, but irritating.
   So to my question: on the K75, to get to all the bolts to remove the timing chain cover it seems that I also have to remove the water pump cover! The water pump cover has a lip at the top (which doesn't seem to be present in other models) covering a few of the bolts. Am I right about this - to remove that cover, I have to drain all the oil and coolant from the engine???
   I just switched out those fluids, so if that's the case, I might just hold off on doing that.
   Thanks,

Mathias (in Portland)

[TimTyler]

I am not speaking from experience with this, but I would advise you get the bike running with good valve clearances, balanced throttle bodies, lubed splines, fresh fluids and probably check the HES first before messing with the timing chain.

[mjydrafter]

Have you checked your (monkey) nuts?  :dunno2:

They are real easy to check, but I would probably order a set and just replace them as a PM task.

[mathias]

Ah, I forgot to mention, I've already replaced the monkey nuts, that was my first suspicion for the rattle. No improvement - the old ones had some wear, but nothing catastrophic.

I expect to have all the work mentioned by TimTyler done in about a week (if the parts get here), other than checking the Hall Effect Sensor. Is there any reason to check that if I don't suspect that it's failing?
Right now the bike sits without the valve cover (waiting for shims), so I thought that this would be a good time to take a peek at the tensioner. I don't really plan to mess with the chain, other than to see if the tension is suspect, or if I can see any wear on the hydraulic tensioner. If I button everything up now, I'll have to take the valve cover off, apply fresh RTV sealant, etc., all over again, just to take a peek. But if I have to drain everything just to open up the cover, I'll probably just wait.

[mathias]

Setting aside wether I should open up the timing chain cover, isn't there anybody who can confirm that to do it I have to remove the water pump cover (and that I have to drain the coolant and oil first)?

[wmax351]

I believe you can remove it without the water pump cover. You will have to loosen the valve cover and crank cover, and then break the (goop) seal.

[mathias]

That's what I was expecting. But there seems to be two different versions of the water pump cover. There's the easy one:



Which seems to have cutouts to access the timing chain cover bolts. And the annoying one:



Which has an upper lip that covers two or three of the bolts. This is the one I have. Like this one (picture stolen off the web):



Judging from this picture...



...it looks like I won't have to drain the engine oil, just the coolant? It is coolant that is being pushed through that impeller, right?

[JamesInCA]

That is the coolant area, yes. I don't think you'd have to drain the oil to do what you're proposing; it should all be resting in the sump area below the level of the timing cover.

On the other hand, draining it into a pan and pouring it back in afterwards isn't a big deal -- for both coolant and oil. (Separate pans, though.)

If you're in the U.S., WalMart has handy 6-quart "shoe storage" boxes in the plastic storage bin aisle for 99 cents. They make great catch pans for oil and coolant, and at that price are practically disposable.

EDIT: And, that pic you stole has to be the cleanest engine I've seen on one of these. Clearly a repaint, but sure is a nice one. Food for thought....

[mathias]

Thanks!
And you're right, draining the coolant (and reusing it) is not all that much of a hassle. It helps to know what's behind a cover before removing it!
It seems like the parts for my throttle body/intake rebuild might be here tomorrow, so I'll probably be preoccupied working on that (and then riding the bike, the weather will be gorgeous) before dealing with the rattle, if it still is happening.

Both the photos are from an interesting thread with a guy repainting all of his bike, I'm reading it now:
http://www.bmwmoa.org/forum/showthread.php?37363-K75S-DIY-painting-(-amp-polished-tank)-thread
I'm jealous of his shiny exhaust headers, that's by far the rustiest area of my bike.

[Scott_]

I'm jealous of his shiny exhaust headers, that's by far the rustiest area of my bike.

Looking at the picture a little closer the silencer can is colored from heat.
I'm guessing that he had the headers ceramic coated, or re-chromed.

[mathias]

I'm jealous of his shiny exhaust headers, that's by far the rustiest area of my bike.

Looking at the picture a little closer the silencer can is colored from heat.
I'm guessing that he had the headers ceramic coated, or re-chromed.

He says that they were treated with a Chromex ceramic coating. Not sure how long they will stay looking that nice.