Engine just died! Help!

[hnilsen]

I'm new to this site, so I'm not sure if the below thread was recieved by the M42 community yesterday. Here it is again. Any help would be greatly appreciated.
I'm at wit's end with my 1991 BMW 318i M42B18 which probably has about 200,000 miles on it. For about a year there has been a distinct rattling emanating from the upper engine, leading me to guess the problem was maybe valves, hydraulic lifters, maybe a loose timing chain...? The engine, however, seemed to run fine and since the car is so old I didn't do anything about it.

Then 2 weeks ago, I'm driving along at about 40 mph and without any big noise or fanfare, the engine just dies. Upon trying to crank it over, the very first attempt, the engine sputtered just a bit, then every single time thereafter, absolutely nothing. It cranks incessantly but doesnt catch even a little.

Having had a past fuel pump failure give me similar symptoms, I checked this out and the fuel pump is fine. Pulled the plugs and made sure I'm getting good spark...all OK. I site down each of the cylinders and can at least confirm that all pistons are moving up and down.

Thinking maybe I broke the timing chain, I pulled the valve cover. Timing chains look fine. Thinking maybe the timing chain jumped, I checked the timing itself and it looks good too, at least from everything I can tell by studying my Chilton manual. I'm not 100% sure about this, but here's how it looked: I turn over the engine clockwise until the #1 piston is at TDC, at which point the intake and exhaust valves are more or less facing towards each other, and the arrows on the cam shaft sprockets are facing up, and the rear end of the cam shafts where the square end flats are parallel with the valve cover, and the 2 dimples are up. Does this sound right?

So I'm now thinking that I have not slipped the timing, so I do a compression test on the cylinders and find that I've got ZERO compression in all cylinders!!! How can this be? Did I bend all the Valve rods? Is something the matter with the lifters?

Surely I can't have a cylinder or piston ring issue that manifested itself instantly! If that was the case, the engine would have been running like crap, burning oil, etc. for weeks leading up to the failure, and this was not the case. It was running fine right up until it dying.

So that's my dilema. Any ideas about what's wrong and what to do about it? I'd love to hear from anyone with any suggestions>
Hnilsen@canalbarge.com

[DesktopDave]

You're getting spark, so the DME is likely OK.  Are you getting fuel when the motor cranks?  If not, test the crank position sensor first.  IIRC pins 1 & 2 should read about 650  ohms.  It has a tendency to lose signal, then the DME shuts down the  fuel pump as a safety feature.  You can jump the FP relay to test the pump if the crank sensor is bad.  Sounds like you might have done that already?

I'm not sure why you're getting 0psi on readings, the cams sound like they're still timed correctly.  The clattering does worry me...if the tensioner loosened up or the chain is stretched...and the chain even skipped a few teeth you'll likely have a head full of bent valves.  Did you have the throttle plate open when you did the test?  Is the comp tester good?

[B318M42W]

got the right screw-on end on the tester and along with the o-ring?

If you can find a leakdown test down might give more insight.

how did you check your TDC? if you didn't do it using the flywheel locking hole/pin under the starter, i'd redo it that way.
besides that, dave got it pretty much all covered already

[hnilsen]

I figured out my problem. Jumped timing by just one gear tooth, so decided to bite the bullet and pull the head. Found valve indentations on each piston, really heavy on the intake side, less so on the exhaust side. All intake valves are jammed stuck in open position (kind of explains why I was getting zero compression readings from all cylinders).

Now I'm either looking for a good, working replacement head or will have it professionally reconditioned (but I'd rather not part with $1000 bucks).

Also, does anyone think I'm completely insane if I try and avoid replacing the indented pistons and reuse them "as is" (after I grind smooth any high spots that may be present)? The cylinder liners don't have any scoring and look good. I'm thinking about getting a replacement head, bolting it back on, doing a compression check and if all looks OK, going with it like that. I'm only looking to get another 20,000 or 30,000 miles out of it. Am I crazy?
hnilsen@canalbarge.com

[monko141]

Where are you located?

[hnilsen]

monko141,
I'm in New Orleans, Louisiana. Any advice or suggestions?
hnilsen@canalbarge.com