1979 528i power loss!

[oceancab]

This site's been a great resource to me as a lurker since I bought my e12 back in June. But now I've got a problem with my car.

About a week ago, I adjusted all my valves using cam/rocker measurements. I didn't want to take off my fan clutch to get to the crankshaft, and my street is on a hill, so I merely pushed my car backwards to move the cams. Me in my excitement of doing my first valve adjustment, put the engine back together and forget to reconnect the AFM connector, and the wire that goes to the distributor from the coil causing the engine to not start, but I reconnect those and it starts fine. The first thing I notice after taking it for a drive is that there's a big loss in horsepower. I have to pretty much floor the gas pedal to get anywhere and staying at 60 on the freeway in 5th gear is a herculean task for the car now.

I'm wondering if rolling my car backwards would have caused the timing chain to skip a tooth? or if one of the things I did would have caused something. The engine runs and idles smooth, I don't smell gas. The car pulled prodigiously before the adjustment.

Thanks in advance!

[D.]

Well, what'd you set the valves at? They were cold, right? I had this problem with a 533. Previous owner had set two valves at .007. Car had zip power when warm. Put 'em at .009 intake, .010 exhaust, wonderful stump pulling torque.
Also, if the car has to roll backward, just put it in reverse. Hookum-skookum.

[Dimitrov]

D. is right. If the car had been in reverse gear, there would be no trouble rolling it backwards. But if the car had been in any other gear there is a pretty good chance the chain to had slipped off 2-3 teeth. That would explain your power loss. I think now there is no other way, but to remove that fan clutch Remove the front chain/cam cover along with the distributor and check if the crankshaft and camshaft are in correct position (search in the forum for description of their marks). If the marks are not like they should be, then you must release the chain tensioner and adjust the shafts. Be careful when the chain is released, rotate the shafts slowly, so you can feel if the valves touch the pistons' foreheads.
After that measure the compresion of the cylinders, because you might have some defects on the valves due to that chain problem.

I hope that the problem will be somewhere else. Good luck!

[Mike W.]

M30 timing chains don't jump when turned backwards, they just don't. Especially given your technique you most likely misadjusted some valves. You need to make sure both cam lobes are pointed down, not just not appearing to be not opening the valves. The cam affects things sooner than it appears. The cam position needs to be just so, not close enough.

[oceancab]

Hmm, I did roll it backwards in 4th...I set all the valves to .009 on the cam side.

I guess it has to be the cam timing then. Is it possible to just loosen the tensioner and just turn the cam sprocket under the chain enough to set it right? My haynes book doesn't cover this subject very well.

Sorry if I sound kinda dumb, this is my first car and don't have a ton of experience in anything inside the engine

[D.]

If you're absolutely sure of the valve gap (you rotated the engine completely four times checking each one twice). Take the fan off. Clean the rim of the harmonic balancer, see the marks. Line up all the marks with the cam gear. Ahh, heaven. I always change out the chain ($50 at the dealer with your CCA membership-NO master link bullcrap) and the cam gear ($45 at autohausAZ). Maybe it's just an aspirational purchase, but, the car always runs better, quicker accel to my mind, easier revving.
I've had stuff move on me while it was all apart. 533. I didn't notice, dunno when it happened, etc. Missed it by one tooth. When started, engine sounded like a diesel. Really loud. Reluctant to start. Valves were brushing piston tops. Now, I don't mount the fan and shroud until the fat lady sings and I CAN STILL LINE UP THE TIMING MARKS ON THE HARMONIC BALANCER.

[oceancab]

The cam timing's still spot on...

I'll check the valves again tomorrow, I'll bet I slightly pushed down some of the valves into the combustion chamber as I lifted the rockers up to do the clearances. would a .10 clearance on the cam side be a safe number?

And...one of my valve cover bolts snapped while I was tightening it, is there an easy way to get it out?

[BimBim2oo2]

easy out or drill it out, re tap it. At least that is what I would do. But I do believe the are aluminum, maybe? If they are you might be in a bigger problem then expected. how on earth did it snap off? Do you have a TRQ wrench?

[oceancab]

It is aluminum

I do have a torque wrench, but i was tightening it with a crescent wrench to just a whole turn past hand tight.

[T.Hanson]

Original BMW 528i Owners manual, page 116 : inlet and exhaust valves, set cold, .012 in. - .014 in. Assuming the engineers, who designed and built the engine, told the type setter what to write.

In lieu of having to type an extended reply, perhaps a link to a site explaining, " stump pulling torque, " variations (including half the factory recommended clearances) perfected by individual garage tuners.

No offense intended, my goal has been doing AND learning. Adjusting for worn cam lobes sounds plausible, oil viscosity for old rings, updating to newer, better technology.

Thank you, I'm off to search valves, cams, rocker arm settings.

[T.Hanson]

http://www.malloc.nl/BMW/635CSi/pages/en/index.html
https://www.bmwtechinfo.com/repair/main/057en/index.htm

The top one is for much better photos, and pay attention to pre-1981 instructions. DO buy a torque wrench, preferably a click type, with Nm settings besides foot pounds. That will make using the listed specifications, torque settings, a lot easier.

Only from your using a crescent wrench, tight plus a turn, I strongly suggest a trip to tool store if you intend further do it yourself adventures. When you get your torque wrench you'll see a full turn," tightens the krikeys," out of most fasteners.

Or, they bust off, to find out the door knob who coined the term EZ out should be shot.

[BimBim2oo2]

It is aluminum

I do have a torque wrench, but i was tightening it with a crescent wrench to just a whole turn past hand tight.

Try a easy out. If it doesnt work then drill it out, re tap it and go from there.

Most autoparts stores with ahave a tap and die set you can borrow for free just have to ask. Make sure you get a metric kit. If you have to go standard than so be it you will have to make sure you get the right bolt. My suggestion would be try and be as spot on with bolt size as possible. Last thing you want is a odd man out with your valve cover bolts.

If none of this will work replace your head

Invest in a trq wrench as well. This is hypocritcal of me as I do not have one but I have a pretty good feeling for these things, Knoch on wood

[D.]

Ahh, tools. Steel tools. Old steel tools. Keep the crescent wrench in the rollaway for when the lawn mower breaks down way far away from the shop. Fixing German machines is akin to acquiring more and more tools. You're saving $ big time doing it yourself. You don't have to trust a stranger with your rig. A guy I worked for once, wanted a stereo put in his new to him Porsche. "We gotta drive the car when we're done." He told Nordber. "Why?" "You know....... to see if anything is rattling or anything." He reluctantly agrees. They finish. Car comes back, Nordber drives the car. First gear has a brand new whine in it. They munched it on a downshift, racing the car during the "test."
My cousin is driving my aunt around Seattle 45 years ago, they're T-boned in an intersection by a red Ferrari. It goes to court, witnesses at the bottom of the hill where the Ferrari started its daytime speed run said the car was accelerating so fast it's front wheels were off the ground. At the top of the hill before it tried to stop at the light, they said it was going 90 mph. Guess who's driving? The mechanic. The "test".
Valve cover studs and bolts are steel. Often there's a nub left to grab with vise grips. If you do have to drill, file it flat, prick punch what's left of it dead center (absolutely dead center), start drilling with small brand spanking new bits. A right angle drill works well if you're next to the firewall.

[JodyStevens]

What I would do is try to get a set if vice grips locked on it, if that doesn't work if see if I could cut a slot in it to turn it with a screw driver, and if that fails id use an easy out or drill it out.