i recently purchased a 1990 740 gle with less than 80 k miles that has been in a front end crunch, above the bumper, air bags did not deploy. It has the DOHC four cylinder. Fan shroud did penetrate the top cam belt cover and knocked a 1x3 inch piece out of the cover. I feared it might have left plastic pieces inside the timing belt area. I removed the timing belt covers and found some small pieces of plastic at the bottom. I turned the engine with a wrench on the crank pulley bolt and the cams are out of time but the engine does not bind up. i turned it three or four revolutions and could not detect any valve to piston contact. When the drivers side cam is aligned with its timing mark the passenger side cam is about 5 degrees before its mark and the crank pulley is about 30 degrees before TDC. I know it was cranked with the starter at the auction house before I got it and it tried to start but would only run rough for a few seconds no knocking or other odd noises. The timing belt appears to be in good condition but it must have jumped time. Can the cams be off by 30 to 40 degrees and not have valves contacting the pistons? I guess the cheapest way to find out what issues I have is to get a new timing belt, line everything up and see how it runs before i spend more money on body parts. Paid $300 for the car with a perfect interior and new tires. Trying to keep busy in my retirement but do not need too deep a money pit.

 

The timing "check" would be where I'd start since in those motors if there is a problem valves crash into pistons! Retime the thing, then go onto other possibilities.
How bad is the body damage? Pictures?
Keep in mind that the 1990 is "one off" year: some of the front end parts are unique and only fit 1990 models.

 

I set the cams in time. It started and ran perfectly, no odd sounds, smooth idle, raised to 3k rpm sounded good . I shut it off quickly as the water pump pulley was off. Must be that the cams can be off quite a bit before damage occurs. Pieces of plastic must have fallen between the belt and the crank sprocket causing the belt to slip a few notches. I have the grille, the hood, and the headlights from the local sell serve wrecking yard. They have only one 1990 740. To be safe I am going to get a new timing belt and balance shaft belt. I found loosening the tensioner was easy with large channel lock pliers. I had to hold the passenger side cam sprocket in place as it wanted to move off of its mark.

 

anyone know where i can buy a new timing belt cover, upper, Mine has pieces missing

 

Should be about $50 at dealer. Or call fcp Groton.

 

Do a compression test before you put another dollar into it to confirm no bent valves.

 

Never trust crank pulley marks! It slips.

Go by crank SPROCKET!

 

It runs smoothly, no miss, knocks or strange sounds so I assume the cams are now in time and the valves are not bent, local self serve wrecking yard just listed another 1990 740 gle so i am off to salvage the fenders and the timing belt cover

 

16 valves on the freeway is a lot of fun! Enjoy.