car wont start after doing a cylinder head

Post Wed Mar 15, 2006 10:14 pm

Well it looks like i'm doing a cyclinder head gasket this weekend? What do I need to know?

Are Cynlerder head bolts torx screws? does anyone know the size for m40's?

I'm getting new exhuast manifold studs... Ive taken one of those off before!

Do you recon I actuall need to seperate the inlet manifold form the head? would this be a short cut?

I know this is a risk but i'm not going to get the head tested.., but i will look for bubbles with the cam cover off. And pressure test the cylinders.

I'm going to try and keep tension in the cambelt, has anyone got any good suggestions on how to do this? I need to do it in the shortest time, so that can wait for another day.

Thanks!

Post Thu Mar 16, 2006 7:39 am

I think the bolts maybe torx E14, I just bought a cheap set for about Ãƒ”šÃ‚£5. You will need a torque wrench and the head gasket should come with instructions on what torque to tighten each bolt to and in what order. I don't think that you'll be able to keep tension on the belt, cause the belt will have to come off the top pulley anyway so you may aswell change the belt whilst your there so don't be lazy!

I normally leave the inlet manifold on and just take off the exhaust manifold unless the bolts start to snap, then I would take the exhaust manifold out with the head also.

If you really want to keep the belt on there whislt doing this (I don't recommend it), you can set the camshaft/crank in position then undo the camshaft pulley and use a big screwdriver to push the pulley off, then make sure that the pulley stays in the same place in the belt, it would be a good idea to mark it. Refitting is the reverse of removal.

Post Tue Mar 28, 2006 8:55 pm

M40 are E12

Post Tue Mar 28, 2006 10:18 pm

Oh well Thanks for info! missed all the reply's... done now!

Took inlet manifold off.. and yes I was lazy and didn't change cam belt, kept tension with a piece of string... I will change it when i get it back from manchester...

Got stuck on 1 head bolt kinda managed to strip it a bit, so ended grinding it down, which added about 5 hours to the job....ooops!

Then it wouldn't start but i'm pretty sure it was the cam sensor as all the HT leads etc were a bit fcuk'd... with the zone being down could get in contact with BM bob who was sending me another set!

So the zone being down is oing to cost me another trip to manchester... oh well its a bit of fun!

Post Tue Apr 18, 2006 3:54 pm

This ruddy m40 is still not startinf, changed all the leads, rotor, cap, and cam sensor but still it just turns.

Its soaking the plugs, so there is fuel
The plugs are also sparking when I ground them.

What else can it be?
Maybe I have the wrong timing... might have set the bottom end to the wrong TDC (as their are two per cycle right?)... could it be this?

Or maybe AFM, ECU or possibly coil...

What do you all think?

Post Tue Apr 18, 2006 8:19 pm

the first thing i'd do is check the timing. but if its not the timing then i guarantee you're losing compression somewhere...

you said you stripped the thread on one of the cylinder head bolts. this can cause loss of compression, as the gases can escape, and will eventually rupture the gasket.

also, you havn't mentioned if you used new head bolts for the rebuild or if you put the old ones back in??? when removing the head you MUST use brand new bolts when putting it back on. the bolts are designed and built to stretch slightly under compression, and putting them in and removing them stresses the bolts, making them lose their stretching characteristics

you also mentioned that you were not getting the head 'warp and crack tested', which is just a ridiculous thing to do, IMO. if you have the oppurtunity to get it done, you cant be lazy about it. its definately worth doing. it maybe the cause the engine went wrong in the first place

anyway, let us know how you got on

Post Tue Apr 18, 2006 8:31 pm

yea I used new bolts.

Probably right about the cyclinder head but the car to me is not worth spending Ã‚£50 on that I though I would give a go with out doing that.

Surely the car would still start though even if the compression isn't perfect? When I turn the engine by hand with the plugs in it "feels" like it building up compression.

Its not firing up at all.

Post Tue Apr 18, 2006 8:46 pm

Pull the plugs out.

then remove the fuel pump fuse

crnak the engine @ full throttle.

refit plugs and fuse, try again for startup.

all the above is assuming you've checked the timing is spot on.

Post Tue Apr 18, 2006 10:07 pm

thanks ant tried that as I thought I had probably flooded the engine.

Looks like I have been a plum with the timing.

Car is in Manchester still at my sisters, so I kind of need to know if it could possilby be anything else so I can take parts up to it. Could it be the AFM ECU or Coil? or anything else?

Post Wed Apr 19, 2006 7:17 am

I had an M40 a month or so ago which was producing good spark & soaking it's plugs, but wouldn't start.

Turned out to the the AFM, so might be worth a try.

I'd still check the timing first though!

Post Thu Apr 20, 2006 3:30 pm

Also could it be thte DME relay? Do m40s have these? What do they actually do again....

Post Thu Apr 20, 2006 3:56 pm

Every BMW has these!!! (well, nearly!)

the DME relay sends a signal to the DME to activate it, once the ignition is turned on...

theres a black cover on the bulk head, just above the rocker, about 18" long and curved...

remove this, and there should be two relays, one white, and one orange. white for the fuel pump, and orange for the DME...

when the ignition is turned to terminal 15, both the relays should 'click'. you will hear the fuel pump prime (1 second buzz), and things under the bonnet start clicking!!!

if you aint got this, your car aint starting...

HTH

Post Thu Apr 20, 2006 4:11 pm

stuartgallafant wrote:Every BMW has these!!! (well, nearly!)

the DME relay sends a signal to the DME to activate it, once the ignition is turned on...

theres a black cover on the bulk head, just above the rocker, about 18" long and curved...

remove this, and there should be two relays, one white, and one orange. white for the fuel pump, and orange for the DME...

when the ignition is turned to terminal 15, both the relays should 'click'. you will hear the fuel pump prime (1 second buzz), and things under the bonnet start clicking!!!

if you aint got this, your car aint starting...

HTH

Cool I know what they are, with have IS there next time i go up so will be able to swap.

Post Thu Apr 20, 2006 4:20 pm

ok mate, good luck...