New Timing Belt is in but it WONT START...HELP

[carolina525]

Well i finally got the new timing belt and tensioner yesterday. I installed them last night and now the car wont start. the engine seems to have virtually no compression due to the ease the starter spins it. I lined up the crank and cam pulleys as per the haynes manual so I think the timing is correct. Anyone have any ideas? Its a 1990 525i with the M20 engine

[Jeff N.]

Double check the timing. If the timing is retarded by a tooth or two, the engine will make very little compression and behave as you've described. Should start with one tooth retarded; maybe not two.

Make sure you have the plugs installed, torqued and leads correctly restored. (sorry to suggest this but I've forgotten to put in simple stuff before).

Did you take the distributor apart? Check the rotor and cap for correct installation.

Make sure that all electrical sensors and harness plugs have been reconnected - Crank position sensor, spark leads, fuel injectors, etc.

Sorry I'm not an M20 expert and can offer more suggestions. Just going from M30 experience.

Jeff

[carolina525]

Thanks I will check the teeth of the belt and my connections again. Thanks for the input.

[carolina525]

to retard the timing should I turn the cam sprocket a couple teeth clockwise or counter clockwise?

[Bill R.]

after spinning it over you now have a bent valve or two... But first doublecheck your cam timing again and if its off , after you correct it and put it back together you'll have to do a compression test to find out if you bent any valves... Or a valve adjust will show you right away because some valves will be much looser than they were before if they are bent.






Double check the timing. If the timing is retarded by a tooth or two, the engine will make very little compression and behave as you've described. Should start with one tooth retarded; maybe not two.

Make sure you have the plugs installed, torqued and leads correctly restored. (sorry to suggest this but I've forgotten to put in simple stuff before).

Did you take the distributor apart? Check the rotor and cap for correct installation.

Make sure that all electrical sensors and harness plugs have been reconnected - Crank position sensor, spark leads, fuel injectors, etc.

Sorry I'm not an M20 expert and can offer more suggestions. Just going from M30 experience.

Jeff

[Jeff N.]

Can you hear the valves crash when you do the initial spin? Suppose you've never heard or done this either soooo maybe you don't know either! :D


after spinning it over you now have a bent valve or two... But first doublecheck your cam timing again and if its off , after you correct it and put it back together you'll have to do a compression test to find out if you bent any valves... Or a valve adjust will show you right away because some valves will be much looser than they were before if they are bent.

[Jeff N.]

Set the bottom of the motor to the TDC mark and then inspect the cam shaft location per Bentley's for correct position.

TYPICALLY - but I can't say for sure on the M20 - at TCD, the number 1 piston is UP and both of the #1 lobes are pointed DOWN. If the motors at TDC and the lobes are UP, you could be 180 out. CHECK THE MANUAL FOR SURE!!!!

Jeff


to retard the timing should I turn the cam sprocket a couple teeth clockwise or counter clockwise?

[Bill R.]

Can you hear the valves crash when you do the initial spin? Suppose you've never heard or done this either soooo maybe you don't know either! :D