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View Full Version : '89 525i M20 broken timing belt (PICS)


Bruno
03-15-2005, 11:18 PM
Customer with a broken timing belt, see pictures below, the piston #3 hits the exhaust valve pretty bad, bending it (along with two other ones).

With the impact the cylinder head got damaged. What are the chances that the bottom end (connecting rods...) is damaged???
I am putting 2300 Cdn or so of work into the car, and I don't want to have to replace the engine afterwards...

http://www.bmwe34.net/ebay/head1.jpg
http://www.bmwe34.net/ebay/head5.jpg
http://www.bmwe34.net/ebay/head3.jpg
Bruno
03-15-2005, 11:20 PM
http://www.bmwe34.net/ebay/head4.jpg
http://www.bmwe34.net/ebay/head2.jpg

Can you tell the oil change wasn't done frequently, the cam is very worn also.
winfred
03-15-2005, 11:42 PM
it's luck of the draw on if it will pop a rocker tower when the rubber band snaps, i did one last month that bent all 6 exhaust valves and 2 intake and the head was buildable
Bruno
03-16-2005, 09:06 AM
it's luck of the draw on if it will pop a rocker tower when the rubber band snaps, i did one last month that bent all 6 exhaust valves and 2 intake and the head was buildable

Considering that the piston has been hit.... Should I change the engine? Or just the head???

How strong the BMW engine is to withtand a hit like that???

Thanks.
winfred
03-16-2005, 09:10 AM
if it just nicked the tops of the pistons they will be fine, just clean up any burrs with a small file, the only thing that really kills a piston is when a valve breaks off and pulverizes a piston
Bruno
03-16-2005, 09:26 AM
Big thanks, I called my engine builder... and he told me that maybe I should drop the pan and change the main bearings... But cheap customer don't want to spend lot's of money... the usual.
632 Regal
03-16-2005, 10:53 AM
I would offer the customer the option of pulling the pistons that hit bad and having them checked for cracks, thats the only way to make sure. If they opt out of that tell them that you cant guarantee the long term.
Bruno
03-16-2005, 12:40 PM
This seems very low considering that you have a lot of cleanup to do on these old engines.
winfred
03-16-2005, 01:17 PM
5.6 i can whip the hell outta that if everybody leaves me alone and the customer didnt **** it up by trying to work on it
Alan_525i
03-16-2005, 01:51 PM
That sounds like my engine (except for the belt snap). My headgasket went, we ended up replacing all valves, rocker arms, seals, guides, cam reground. I attribute this largely to the prev owner driving the car on short trips (never got to operating temp) and only changing the oil when the service light popped on. The amount of carbon build up was staggering even with only 108K miles on the car.

Parts came to 1800 or so and 23 hours of labor. (Did the waterpump, cap and rotor, radiator, belts and hoses while i was at it.)

5.6 is likely just a straight gasket swap with nothing else.
E34-520iSE
03-16-2005, 07:17 PM
If there's any play in the crank/rod bearings you will hear the clicking noise of the piston tapping the head. It really would be wise to check the bearings at this early repair stage. It cost me £240 (uk) for a complete crank regrind and new bearings (+.25mm) at a local machine shop. My car is an early 1990 (m20), but I was willing to spend the extra money just for my peace of mind. If this engine fails prematurely, your customer will have to spend a lot more money than he saved on this occasion. Just my opinion!

Best of luck,

Shaun