E30 Zone

right guys this one is a little odd
took the car the other week to get it remapped and had a little bit of smoke out of the exhaust which got worse on the way home and its blue so its burning oil which we believed to be the valve stem oil seals as it seemed to drop idle every now and then
so i ordered a new set i got the car home still drove home fine,
that weekend i took the head off replaced all the stem seals new head gasket from euro car parts it was a victor rainz one
got it all bk together got it running and noticed in the filler cap it was like milk shake
thinking there might have been water get in there while the head was off i dumped the oil changed it new filter got it running again and water in the oil again now there wernt non in there when i drove it home and only started doing it since i put the new head gasket on could it be just a case of dodgy head gasket ?
obviously water in oil normally points to head gasket or a cracked head or block maybe but was fine all the way home that night
and i know that the engine has never got hot or boiled over

any thoughts or suggestions guys ??

You may have cracked the head doing it back up again. Also did you mop the oil out of the bottom of the stud holes in the engine before bolting the head back down? I have done this on a race bike engine and on the odd occasion the hydraulic pressure of the oil in the holes can crack the block.
Either way its gotta be a head back off and have a peek job IMO

Hi, looks like something went wrong with the gasket swap, you might need to skim the head and order a new gasket and another set of head bolts.

there was definatly no crap in the threads
ive got the head back of again and i really cant see nothing visable

SGP wrote:Hi, looks like something went wrong with the gasket swap, you might need to skim the head and order a new gasket and another set of head bolts.

head bolts are arps wont be swapping them for new ones lol
i means thats the only thing ive done and changed since its started doing it is the head gasket

Ok next thing I would do is put the head down on a flat surface. I use a surface plate but you can do it on a work top with some success. Get out some feeler gauges and test if the head is still flat.

yeah i suppose i have put a straight edge over it to some degree cant see its out that much
but even if it is out would that really leak that much ?

Oh definitely the pressures under there are absolutely mental. If the thing is not very flat it will definitely leak. Obviously the amount depends on the warp. I skim them if they are over 0.007 (seven fag papers) but i'm a perfectionist. The motorbike engines i use have to be within 0.003 otherwise they burn when the gasses escape.

thats pressures on a normal engine mines turboed aswell lol

ross2009 wrote:thats pressures on a normal engine mines turboed aswell lol

Precisely. I would imagine you would be looking at similar pressures to those I see inside the bikes. That head needs to be really nice and flat. A straight edge won't give you the answers. I would put it on the kitchen top and get someone to hold it down. Then try and slide some paper under the end and the middle. If you can get it under fold it in half and try again. this will give you an idea of how its bent and by how much.

I've got feeler gauges so I'll try it and have a look so you reckon 7 thou?

I recon if you can get 0.007 under there it will need a skim mate.

Mind you maybe a bit less with the turbo. I skim at 0.007 with a normally aspirated car.

ok I'll have a look

right well ive just had a quick go but i really dont think my surface was flat enough i had it on a glass table the only thing thats close to flat and could get .006 under it easily but i turned the head around and tried it the same place and was still .006 on the other end of the head so i dont think thats quite acurate

No No a glass table is perfect. Right just so i can get my head around it, If you put the head flat on the table you can get 0.006 under one end?

well around no 5 and 6 but other end is fine
but when i turn the head around 5 and 6 is fine but 1 and 2 arnt so i dont think its that flat

Got ya. Right that head is warped IMO. I would say it definitely needs skimming. The heads original thickness is 4.921" to 4.929" If the head has been skimmed before the re conditioner needs to be careful when they are grinding it to no take off more than 0.012". Otherwise you can get valve head strike.

So in summary you need to measure the overall height of the head and it must not end up less than 4.909"

right just checked each corner first corner is 4.930 2nd is 4.929 3rd is 4.925 and 4th is 4.927
which I find strange as that's the upper limit yet it's been skimmed before

Yeah that is a bit odd but its not inconceivable with machining tolerances. Did you measure that with a mike or a vernier? I'm only going by previous experience and what it says on BMW's microfiche.

My suggestion would be to have the bare minimum surface ground off until it cleans up. Some conditioners mill them and its crap IMO. It also is a bit too brutal and they can take off too much by mistake. That way you should still be within tolerance. Obviously you still want a working head after you spend money on it.

Make sure you wind it over by hand though once its seated to ensure it doesn't clobber the piston heads.

im an engineer by trade mate i know about tolerences and machining
you cant grind ali it just clogs the wheels up they get fly cut one single tipped cutter that does the whole lot
yeah measured it with a vernier
my pistons and forged low comp there plenty of clearance there lol

And me mate. I grind ali every day with a 90 grit white wheel and plenty of Soluble and it cuts fine. I grind the heads on the bikes and I did my 320 head.

I recon with a mike it will probably be a bit smaller in reality and with your pistons it will be fine I should think.

really ? that works i would have thought it buggers the wheels up
yeah a mic will be more acurate but ive only got a 0-25 mm one not big enough to do a head
i think ill take it down and get it skimmed might be best

I think that's for the best mate.

That really works, I grind solid ali and magnesium alloys without any issues at all. They need dressing more than steel but they cut absolutely fine.

head skim it is then new gasket is on its way if that dont cure it i dont know what to do pressure test maybe

Personally I would never skim a cylinder head until it has been hot pressure tested first.

just incase it is cracked ?
but like i said it wasnt like it before i took the head off so thinking about it, it must have distored when i took it off

maggspower wrote:Personally I would never skim a cylinder head until it has been hot pressure tested first.

True but the head is off already. Plus the cost will be negligible as ross is an engineer

ross2009 wrote:just incase it is cracked ?
but like i said it wasnt like it before i took the head off so thinking about it, it must have distored when i took it off

In all honesty it is probably warped, aluninium is a very strange metal, it constantly changes throughout its life as a solid object.

I have never experienced replacing a head after a rebuild, to find out its cracked, but I would imagine it is quite exasperating but I have always tested them.

Its just a peace of mind thing, that and the fact that you could be throwing money away skimming it.

yeah i know they move all over the place
and mine being turboed aswell it will get hotter than most normal m20s

i suppose i really should get it pressure tested its about 40 quid i know a guy that can do it
at least it will stop me worrying that the head is cracked

Yes you can get it tested off the car, £40 is about right.

yeah the head already off i just need to strip the valves and the cam out of it the rockers are already all off
could even get it skimmed with him too just to save time

All a pressure test on a head does is tell you is whether the valve seats are sealing properly or not.
Correct me if I'm wrong

SGP wrote:All a pressure test on a head does is tell you is whether the valve seats are sealing properly or not.
Correct me if I'm wrong

Pressure test checks for cracks from the coolant jacket. Nothing to do with valves.

yeah what Brian say
they get a tank of water heat it up they clamp plates over the water jacket holes
dunk the head in the hot water so if there is any cracks it opens them then they add air pressure to the head if bubbles come up its cracked if they don't it's all good