throttle cables / valve seals

Specific conversations and info for the BMW E28 M5 and M535i.
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SW
Posts: 328
Joined: Feb 12, 2006 12:00 PM
Location: US

throttle cables / valve seals

Post by SW »

So, I am slowly getting the rust bucket M5 back up and running and have 2 questions. Of course the car is mad at me for storing it longer than usual. The plenum bellows cracked--new one on order. But my throttle cables have long been fraying, and I ve been long putting the repair off. I have the cables. Now the old ones are done and sticking. Wide open, thanks. How hard is this this r and r? I can't even see where the cable goes through the firewall...never going to get my hand in there.
The second question is bigger. The engine idles very smoothly, but spits out oil big time. Not smokey, or burned...it spits out tiny globs of oil. If I put a towel behind the exhaust, it will come away with spit of oil. Took the plugs out and 1 - 5 are perfect. 6 not so much. Pretty oil fouled. So, in the absense of a compression test...the car idles smoothly- the oil is not burning (so far as I can tell). Does it make sense these are the valve seals? To me it does, but I could be wishfully thinking. But basically, won't the open valve with bad seals allow oil to be sucked in and exhausted out (especially if the exhaust side seals are bad??)
Philo
Posts: 2197
Joined: Feb 12, 2006 12:00 PM
Location: Long Beach, CA

Post by Philo »

What's up Seth !

I've done the throttle cable several times. For me the hardest part was getting the small square plastic firewall fitting/gromet to seat into the firewall.

To remove the old cable I cut it in half around the brake bomb area and then pull the remains through the firewall from inside the cab. But before I pull it through I tape a piece of thin wire to the end to be used to pull the new cable back through the firewall.

Be careful not to put a sharp bend in the cable as it turns towards the ITBs. just make note how yours is routed and you should be fine. Also, replace the grommet where the cable attaches in the cab. And put a dab of grease on it to make it happy :)
mooseheadm5
Beamter
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Post by mooseheadm5 »

It is possible that it is not your throttle cable that is sticking, but your actual throttles. This happens to S38s when they are stored for a long time. The lube on all the throttle shafts and connectors dries up and they can get a little rusty. To verify this you can open the throttle by hand from under the hood (not running) and see if it snaps closed when you let go. If not, it isn't the cable.

If the oil is getting into the chamber past the valve guide seals it is coming in through the intake seals. It would smoke the most on decel when you let off the throttle.

Make sure the pulleys are not rusty or it'll eat drive belts. AMHIK.
Philo
Posts: 2197
Joined: Feb 12, 2006 12:00 PM
Location: Long Beach, CA

Post by Philo »

Oh.., and I think the "oil" problem is soot and moisture in the cat and exhaust. I have black spots on my driveway from this :) Unless you're absolutely sure it's oil.., and if it is I'm not sure how it is getting into the exhaust system.
SW
Posts: 328
Joined: Feb 12, 2006 12:00 PM
Location: US

Post by SW »

Hello all -- and hi Philo -- I ve been pretty quiet lately on the M5 front. But I may be moving locally, so I have to move the car. I want it to move on its own power.

Re the cables -- thanks for the tips. My throttle bodies were a little sticky, but this is definately a cable hang up issue.

As for the oil -- it could be some soot from the exhaust (no cat on this one). But if it is just soot, then I don't know where my oil is going. I loose, ready...1 quart every 200 miles. Yikes! I can't really see any puffs of smoke on deaccel. The oil is an issue I am willing to sit on a bit because the car runs well. But with the current rust situation and burning oil...it doesn't look good for this one.
SW
Posts: 328
Joined: Feb 12, 2006 12:00 PM
Location: US

Post by SW »

moosehead -- your are in C'ville? I am in DC. We usually run the C'ville 10 miler. Great town. Won't be there this year as my possible move is taking up all my time.
mooseheadm5
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Post by mooseheadm5 »

Yup, in C-ville. If you have too much trouble getting the car back on the road you could send it to my brother's shop in Dulles (RRT.)

If you do get it on the road, bring it on down sometime to hang out with another ratty M5 :)

Quart every 200 miles? You should be crop dusting with that sort of consumption. Either that or the floor under your car should look like the gulf coast.

Definitely get to fixing the cable. My throttles stuck (on both my M5s) due to age/rust. Once it hung pretty far open when I got stuck behind a cop. With my loud ass exhaust. Good thing most cops aren't that observant. You need to lube the throttles, too. Don't use WD40. It evaporates and you are right back in the same spot.
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