E30 Zone

Ok so 2 month ago i changed the head on my M20 325i and did a thorough job on it, all has been fine until today when i noticed oil in my expansion tank for the radiator.

Any ideas? Im so worried now as i spent loads of money sorting the original problem.

did you re-tighten the head bolts ? never done a bmw head before, but some manufactures you have to re-tighten the bolts, if this is not the cause did you flush the old oil ? before initial start up i e could be contaminated oil !

Ill try and check the torques but im not sure if i did or didn't now. Haines manual jobbie! Thought i did flush it but it was a bit half hearted! ill do these things tomorrow.

I hope she aint fooked as i might give up e30's. What with the hassle and fuel costs! (Smack that boy!!!)

With luck this is a bit of oil that was left from last time,perhaps it was stuck in the radiator or an odd corner of the block.I flushed and flushed mine out,but I still get a bit of oil even now,some 12 months after my rebuild.Keep a close eye on it,any other signs?

Thought that but to be honest the oil looks too new, not mayo! No other signs at all, nothing on the cap or dipstick.

If i wasn't so damn macho id feel like crying!

do i recall the heads being alloy ? if so did you check if the head was not warped ?

got it from a place called bridge cylinder heads, years warrenty so if worst comes to worst i should have some comeback, depends if they are cowboys i suppose. should be ok.

It definitely has not overheated since i changed it, i might just re-do the gasket, oh the joys of old car ownership!

Think i should start looking for a new engine maybe? swap over, might be cheaper in the longrun. did u re-build the whole lump or just the head?

as mentioned above mate, could be condensation and old gunk just saying hello... give the cooling system a flush and see how you get on

Assuming the original problem was oil in the water, it can take months for every trace of mayonnaise to come out of the cooling system, and it all migrates to the header tank.
You can't check the torque of the head bolts - they are single use, angle torqued, stretch bolts.

Brian, do you think a new set would be necessary then? Im not even sure if i torqued em right in the first place. If i just replaced the bolts would that be ok without removing the head again?

There was a problem with one particular make of hex headed E30 head bolts, and the recommended way of replacing them was one bolt at a time, so it is possible to replace bolts without disturbing the head gasket.
I wouldn't consider doing anything to your car, until you've established that you do have a problem. As I said above, it's more than likely just residual gunge from the original problem.

You did fit a set of new head bolts?

are they not stretch bolts ? if they are stretch bolts, that would be the problem i would think

They are the stretch ones but as it was my first head i think i tightened them too much. I remember i loosened them a bit as i was worried they would snap. Would this have stretched them too far?

I wont do anything yet as it seems fine as far as temp and running goes thenm if it continues i will replace the bolts.

Cheers for all the advice, appreciated!

wrobstar21 wrote:They are the stretch ones but as it was my first head i think i tightened them too much. I remember i loosened them a bit as i was worried they would snap. Would this have stretched them too far?

I wont do anything yet as it seems fine as far as temp and running goes thenm if it continues i will replace the bolts.

Cheers for all the advice, appreciated!

i would say yes as stretch bolts can only be used once, and as you said you loosened them that would make them inafective !

also my opinion would to be.......start again strip it all down and check if its all okay and put back together with new stretch bolts

Yeah, id been kinda tryin to avoid thinking about that but if its gotta be done, you know!!!

Its just having the space to work on it. I got a bloody 45° drive with a small garage at the end which my 325i barely fits in. Weathers crap!

I need a lockup or big shed on a farm! that would be wicked!!

wrobstar21 wrote: as it was my first head i think i tightened them too much.

How, exactly, did you decide on how much to tighten them, and what method did you use to do so??

i looked in the haines manual but in my haste didn't realise that there are two different torque settings, always read everything through first!!

I tightened to the tighter setting first then a few hours later realised my error and loosened them a fraction then tightened to the correct setting. Im guessing now that this is a no no but its a learning curve, so they say.

Does this sound like it could be the culprit?

Does the phrase 'angle torquing' mean anything to you?

absolutely nothing im afraid. Im guessing it should though!! care to enlighten me?? I love to learn!

Head bolts haven't been simply torqued up for years! What Haynes manual have you been using?
325 head bolts are first torqued up to 30Nm in the correct sequence with a normal torque wrench, then they are each angle torqued by turning each, in sequence again, through 90 degrees, using an angle gauge. Then they are finally torqued another 90 degrees.
A good tip is, after the initial torquing, mark a line on each bolt head with a felt pen, so that you can see at a glance if all the bolts have been turned the required 180 degrees.

It is an old haines manual i must say, car boot jobbie!

From what you say i dont even think i have tightened them correctly at all. Sorry to keep asking but do you think if i change them over one at a time and tighten them all as you describe it might do the job?

Do i have to run the engine at all between tightening stages or just leave it for a while between them?

Thanks for the comments Brian, i appreciate it!

wrobstar21 wrote:Do i have to run the engine at all between tightening stages or just leave it for a while between them?

Varies with the engine type and type of bolt, but, for the M20B25 with torx head bolts, it's all done cold and with no waiting necessary.
I do normally consider it tea break time between the angle torques, though.

bit of an expensive lesson all this but hope its helped you out and hopefully saved your engine

your not wrong but i thought i did ok as a complete novice. I didn't even fook the timing up etc....

cheers lads

wrobstar21 wrote:your not wrong but i thought i did ok as a complete novice. I didn't even fook the timing up etc....

cheers lads

Your biggest mistake was not getting the correct information in the first place. A simple post on here, and you'd have got all the info you need!

Also rather than resorting to the Haynes Manual why not use BMWs very own manual:
http://ee1394.com/bmw/docs/factory/repair/en/index1.htm

It gives all the procedures for every job and torque setting/tightening sequence.

abelai wrote:It gives all the procedures for every job .

Problem with this is that it constantly refers to various special tools, 99% of which are unnecessary.

I know what you mean but there aren't that many used on the M20 lump and when they are it's normally just to make the job faster. It does have some good pictures to help and the procedure for the job will normally be the same. Point well taken, but if you have a look through for the m20 I don't think it really uses any, m42 likes its special tools though

Now i know to come here 4 advice... Hence the nonstop posts just lately, Its good though! wont make the same mistake twice!!