Cylinder head

[CRS 0]

Hi!

Manage to get the head out in my e36 325i, suspected head gasket which was a broken torn bolt at the bottom of the head in the end. Came out easily so it's all good.

I'm tempted not to check the head, as clearly the broken bolt was the problem, but I'll probably do it to be on the safe side anyway

My question is, who in Chch or Nelson knows BMWs so they know how to take the camshafts out properly? I'm trying to avoid dealing with that myself.

Cheers!

Carlos

[Ahmedsinc 414]

Just out of curiosity, where exactly on the head was the bolt was it that failed?

[yng_750 247]

you dont need to remove the camshaft etc to check the head.

just take it off give it a really good clean up and look for any cracking,pitting or discolouration.

[*Glenn* 854]

you dont need to remove the camshaft etc to check the head.

Yes you do, if it's going to be checked properly , you need the valves out

[yng_750 247]

i will rephrase that.

if you want to quick check by eye you dont need the cams out,

if you want a machine shop to check properly strip it.

though a broken bolt wouldnt normally also cause a cracked head etc.

i would be looking into why the bolt snapped.

if there is oil staining over much of the sheared area i would say it has fatigued, if its clean the whole way it has broken from one big force which could be something much worse.

this is what a fatigued rod bolt looked like after it snapped, you will notice the 1mmx2mm silver area that had been taking all the load until it gave way.

Edited February 3, 2013 by jason H

[CRS 0]

That's how my bolt looks like, the head looks fine but I reckoned better be on the safe side and check it anyway, don't want to have to take it apart again in 6 months. Now, the bolt is the 7th on the exhaust side, meaning closer to the firewall. The head gasket itself looks fine, which of course I'll change anyway.

Any clue on who can do the head, take the camshafts and all?

[yng_750 247]

definantly a fatigue issue.

is it the head bolt?

also did you get the rest of the bolt out.

its so much work to do a gasket your best to get the head inspected and machined.

that being said i personally would clean it up and look for damage before you send it out to a machine shop.

better you find a crack than pay someone $100 to find it for you

[CRS 0]

definantly a fatigue issue.

is it the head bolt?

also did you get the rest of the bolt out.

its so much work to do a gasket your best to get the head inspected and machined.

that being said i personally would clean it up and look for damage before you send it out to a machine shop.

better you find a crack than pay someone $100 to find it for you

For some reason a bit scared of taking the cams out, read somewhere they are quite easy to break or bend...is that true?

[yng_750 247]

i have heard you need to go the opposite way from factory torque guide.

i.e. start at either end and move towards the center, start by cracking them loose one after another then move to actually winding them out.

better to turn the cam to the point where its putting pressure on as many valves as possible, i.e. when one cylinder is just switching between exhaust and intake valves.

i have done it the proper way and the stupid way of starting from one end and moving down , i never had any issue either way, but you can imagine having half the valve springs pushing against the cam when its only held by two bolts at one end.

p.s. most of that only applies to cams that push directly onto the valves hence having pressure on all the time. if you have rockers that can be removed hence releasing the pressure there should be no risk.