Got the head off. Need some help

[civilnerd]

Hello everyone, its me again. I've got a 91 325i sedan, auto. Last summer, timing belt sheared off a few teeth. I didnt know what i was doing and tried to start the car several times that day.

Fast forward to me doing enough work to try to start the car again and see if i was lucky enough to have not done damage. No such luck. Car wouldnt start.

I decided to pull the head myself, take it to a local shop that will do a full valve job for me and then put it all back together. So, this weekend, i pulled the head off. Everything is very dirty. Tops of the cylinders are nasty black and dirty. Here's number 1:






you can sort of see the little dent in the piston from hitting the valve on the intake side. QUESTION: do i need to replace pistons that have been dented?

Also, is there an easy way to clean things up before i start putting it all back together? Are there things I should replace or address now while everything is torn down so much?

Any advice is appreciated. Thanks a lot!

[Jeron]

To clean the piston tops, tape off the area around and use something like this

http://solutions.3m.com/wps/portal/3M/en_US/3MAutomotive/Aftermarket/Products/Product-Catalog/?PC_7_RJH9U5230GE3E02LECFTDQCEK3_nid=GSGP7GF1W9gsG S1QC8SSZVglGS2D5P6JQRbl

I bought some thing like that at Pepboys and it came with 3-4 abrasive pads. I tried other this but that worked great.

As far as the dented pistons I dont know but I would be worried about a bent rod or broken pin.


Use engine degreaser. Spray the engine degreaser on the piston and lay a paper towel on top so it stays wet and let it soak a couple of minutes. Then use the abrasive disk on your drill.

[1stbim]

Using abrasives on the piston!? No way I would ever do that. There's no way to know that some of the abrasive came off and got down in the rings only to come out later and screw up the cylinder bore, and the oil pump, before it hopefully geys stuck in the filter.

Rent a power washer from any warehouse store - doesn't need to be the baddest, highest pressure one. It will take the crud right off. No abrasives. Then, when you have it all back together, put new oil and filter in and run the engine for about 30 seconds or so the emulsifiers in the oil can suck up any stray water. Change the oil and filter again, and you're good to go. Recycle the oil.

That's my put.

[Jeron]

The abrasive disk I used was not sand based it was Scotch Brite type material. I assume it was some form of plastic.