my 92 318i M42 motor will not start. my camshaft broke and i replaced the head and now the car will not start. it gets gas, it gets spark and it is timed. i took the top portion of the intake manifold off and i am getting fire out of it everytime i try to start the car like a backfire im assuming, all the electrical connections are in the right spot my sensors are reading what they should. it just does not want to start. any ideas? ive been talking to one of the guys on here and he has been very helpful and patient but he is on vacation. if anyone has any suggestions please let me know. thank you
Are you absolutely certain the cams are timed properly and not 180 deg off? Are you absolutely certain that the balancer is lined up properly (though this is diffcult to mess up)? Does the engine have good compression (please post numbers.) I'll do what I can to help.
i did not know that the cams could be 180 degrees off. i used the locking tools for the fly wheel and the cams, and the lobs face one another above cyl #1 and the arrows on the cam gears face up, i did not do a compression check though.
That sounds right. One more thing I just thought of: do you have the plug wires on the coil pack in the spots? It will backfire if you have a pair switched. I am trying to remember if there is a way to get the sensor ring on the cam, but I don't think so. Did you buy the head used and assembled or did you have to put it together? Can you think of anything you might have had to mess with to get the job done? I don't think you can plug the cam and crank position sensors into the wrong sockets, but that may be a good thing to check (you can on the earlier Motronic cars.)
well i tried to do a compression test but i did not get a reading, so i put the compression tester in one cyl and had another open w/out a plug in it and the one w/out the plug had a shot of air come out, so i switched the 2 and the same thing happened. but it only happens once and but not all the time. after that i took all the plugs out and turned the car over to see what would happen and there was no shots of air coming out it was just turning the motor. i tried switching those sensors your talking about and still nothing. i got the head out of this car because i pulled the motor out last year and just replaced it w/ another one, thats a long story and one of the biggest wastes of money ha. thanks for helping
To do a proper compression test, you must pull all the plugs and disable the ignition by unplugging the coil or ECU or just crank it with the key off (use the diagnostic connector pin 11- if you put power to it, the engine will crank, but do this at your own risk!) Anyhow, The compression test should be done with the throttle wide open. It sounds like the pistons are moving air, but there may be several different possible issues. It could be that the valves are not opening or are not opening all the way. This car has hydraulic lifters and if they drain down and you don't get enough oil pressure to them, they may not be able to open the valves very much, so the car might not fire correctly. Perhaps you just need to crank the car for a while to get the lifters pumped up. If you want to try this, you should do it with the ECU unplugged so you don't fire the injectors. It could be that you have bent valves on one or more cylinders. This may not be super likely, but you might be able to tell this way: put #1 at BDC with all valves closed on that hole. If you blow air in through the plug hole, and can hear air coming out through the intake or exhaust, then you have bent valves. Check all 4 cylinders. If no bent valves, and the cams are timed properly, the plug wires are plugged into the right holes, then I would think about the lifters. Make sure you have a good battery and try the compression test again. I would. But remember to crank for maybe 30 seconds at a time then let it cool off. Otherwise it is too much strain on the starter and battery.
still nothing, im beginning to think its my head though. ive never heard this head run. i sent you an email. Thanks
