Crank won’t turn over

[Zach3vans]

I just bought a 1988 325i convertible (m20b25) with 260k miles and drove it home 300 miles no issues, no overheating, engine sounded and felt healthy took it to red line twice and it felt great. Right when I got it home I go to do timing belt, water pump, etc... and my crank will turn about a quarter and then get stuck. I removed my spark plugs and it still won’t budge. To my understanding a possible problem is the piston hitting the valve and caused it to bend, but I’m just confused why it would run and feel fine and then when I go to do timing belt it won’t move. Does anyone have any insight on this?

[bmwdirtracer]

Welcome to the forum.

What have you removed so far? Valve cover off? Timing cover? Did anything fall into the timing belt area or the cam area?

Is the car in gear perhaps?

[Zach3vans]

Thank you,
I have valve cover off, I took off top timing cover, then tried to turn crank with harmonic balancer and lower timing cover on and it wouldn’t go so I took those off inspected the are and didn’t see anything in its way then reinstalled both to try and get to tdc but no luck. The car was in gear I took it out of gear and tried but it still wouldn’t go anywhere. I’m getting a borescope to inspect it from the firing chamber to see if I can see anything in its way or a bent Valve. I’m going to drain oil and see if there’s any shaving in it as well.

[Zach3vans]

I decided to leave my timing belt on and it wasn’t turning because I hadnt put my harmonic balancer but I put all new belts on, water pump, distributor, temperature gauge, and intake gaskets. But now it will run for 15-30 seconds but will die if I don’t give it gas. I took my fuel injectors out for the intake gaskets and they were really dirty but it was running fine prior to Me taking them out so I’m not sure if that would be the issue. It seems like it’s a fuel/air related problem so I’m going to do a smoke test, clean my fuel injectors, and clean icv. but does anyone know what else it could be or what else to look for?

[MarcoZandrini]

Send the injectors to RC Injection. https://www.rcfuelinjection.com/
It’s considered the best company fir cleaning fuel injectors.