325i HEAD

Wed Mar 09, 2011 9:41 pm

Does anyone know where i can source a good s/hand head for a 1990 325i. Or a good quality new head casting?
mine has been pressure tested and skimmed, but has picked up slightly on the cam bearings. would use the head if i wasn't fitting a new cam.

Wed Mar 09, 2011 9:46 pm

Or a good quality new head casting?

BMW.....at a price.

Thu Mar 10, 2011 11:06 am

Could you not get the cam bearings metal sprayed and and then re-bored ? presuming the cam runs in the head.

Dave

Thu Mar 10, 2011 11:35 am

I know that opinion is divided on this matter, but I was talking to a mechanic at a classic car show the other day who bought a reproduction head, cast by AMC.

Before fitting he measured all the ports, valve seats journals etc and compared them with his original head to make sure it would be OK. He said he was impressed by the close tolerances and happily fitted it to his car, this was two years ago and it's his daily driver, still going strong.

Thu Mar 10, 2011 12:16 pm

Interesting, I would say buy an old one and get the engineering work done, but it looks like you've tried that route and been caught out.

Isn't there some way to repair the cam bearings? That does surprise me.

Thu Mar 10, 2011 7:38 pm

I was told it would cost about as much to line bore the head and fit shell bearings, as it would for a new casting. Think i've found a new casting for £320 from America still a lot of cash though.

Thu Mar 10, 2011 10:53 pm

Its a pain in the ass, things like this are getting harder to find in good condition and we are working with a finite resource.

The heads made by AMC aren't bad but there are a few points to note, dispite what the fella said at the car show they are not finished in the ports quite as well as a BMW head, but this can be sorted. I also have a theory that the material they are made from is a little softer, which means you have to be careful with the threads when doing up or undoing the studs, but I have never seen one crack in the usual place, under the cam, which I believe is because of the less brittle alloy.

PM sent

Fri Mar 11, 2011 1:34 am

SAMB0 wrote:I was told it would cost about as much to line bore the head and fit shell bearings, as it would for a new casting. Think i've found a new casting for £320 from America still a lot of cash though.

A tested s/h head is worth about £250....at least with a new casting you should get some sort of warranty.

Fri Mar 11, 2011 2:27 am

Welded heads...what's the verdict?

This is wiki or FAQ material this...

Fri Mar 11, 2011 7:48 am

skipunda wrote:Welded heads...what's the verdict?

This is wiki or FAQ material this...

I think it depends how badly cracked it was in the first place, but I would say that a cracked head is not mean that it is scrap head. The problem is the casting is so thin in that area and i believe the head expands and contracts at different rates, plus the cam spinning and vibrating an inch away, causes it to crack. Good servicing will help, coolant should be at the correct ratio to stop corosion.

I have even seen heads welded before they crack, which I think there is some merit in

Fri Mar 11, 2011 11:39 am

Has anyone successfully welded a crack under the cam?

I expect that as good heads get scarce we will have to find a way to fix them.
As I understand it,the cam runs direct in the head casting with only an oil film between it and the casting,when the things crack here they crack across the cam bearing journal,so any attempt at welding means that the thing will need line boring to re-shape the cam mounts.This will be costly....

Welding around the exhaust port,the other common fail point,will be almost easy by comparision!

When I was playing with elderly Daimler V8's(the 'proper' 50's one designed by Edward Turner!)it was usual to have to have the sides of the cooling passages close to the chamber re-built by welding.Indeed,a pair of heads re-built by Russ Carpenter in this way gained even more value!

Fri Mar 11, 2011 6:56 pm

A lot of these heads would not be f*cked now if people were not so tight and changed the coolant regularly and to the correct ratio. NOT a 25/75 mix of coolant/water!

Fri Mar 11, 2011 7:51 pm

Check the weld. Lets lay it to rest, i was of the opinion that welded heads were sh!t and to be avoided. Add to the mix a trick worked Alpina head and you consider the options more wisely. As they were £3000 odd new. Of all the people with C2 2.7s i met ALL have cracked the head at some point usually 100,000 to 130,000 miles.

Any how this Alpina head from the touring wagon was over hauled by FAB back in 2000 after over heating problems. Boxer motorworks performed the rebuild to a very good standard i'd say. Head has been welded 10 years now and covered 50,000 miles since and 30 laps of the ring for good measure. The engine is a peach and theres no fear of beasting it and it sh!tting itself! Of all the M20's i've had this one is my favourite by some way.

nowt wrong with a welded head in the right way.

Fri Mar 11, 2011 8:05 pm

Heres a shot of my old head that was welded. It had no issues and as far as I know is still running. Some say they are stronger once welded (if done properly).

Sat Mar 12, 2011 1:39 am

I can see Simon's POV regarding repairing an Alpina worked head that costs £3k to replace new,against the quote above for a pattern head at £320!

Anyone paid to have a head welded and line bored?
How much?

BTW,Barryboy,I use a 33% antifreeze/water mix,as recommended in my handbook....(that's a litre of blue stuff,two litres of tap water,repeated until the thing is full and purged of air)

Sat Mar 12, 2011 6:54 am

Here we go again

Sat Mar 12, 2011 7:59 am

daimlerman wrote:I can see Simon's POV regarding repairing an Alpina worked head that costs £3k to replace new,against the quote above for a pattern head at £320!

Anyone paid to have a head welded and line bored?
How much?

BTW,Barryboy,I use a 33% antifreeze/water mix,as recommended in my handbook....(that's a litre of blue stuff,two litres of tap water,repeated until the thing is full and purged of air)

Malco it cost £734 to get the head sorted from FAB. this was in 2000 so will cost more now. There was more work done like reprofile on the cam, valve guides exhaust side lapping valves etc

Sat Mar 12, 2011 1:00 pm

Thanks,Simon!

So it seems that at the moment,whilst the pattern head is available along with a supply of good,used heads,the repair option is only viable for the specialist,re-worked stuff.

Good to know that there are places out there that can cary out this kind of work.

Sat Mar 12, 2011 3:39 pm

B7 wrote: (if done properly)

This is the key and a big if imo as the ally used is shite and a right pain in the arse to weld.

Sun Mar 13, 2011 12:13 am

daimlerman wrote:BTW,Barryboy,I use a 33% antifreeze/water mix,as recommended in my handbook....(that's a litre of blue stuff,two litres of tap water,repeated until the thing is full and purged of air)

Keep that up Malcomoldman and you to will soon have a f*cked head.

50/50 mix end of.

Sun Mar 13, 2011 12:18 am

bss325i wrote:
daimlerman wrote:BTW,Barryboy,I use a 33% antifreeze/water mix,as recommended in my handbook....(that's a litre of blue stuff,two litres of tap water,repeated until the thing is full and purged of air)
Keep that up Malcomoldman and you to will soon have a f*cked head.

50/50 mix end of.

For what its worth I use deminerilsed water and not tap water.

Sun Mar 13, 2011 12:24 am

E30 owner's handbook states a concentration for the coolant of 40%.

Sun Mar 13, 2011 12:35 am

town325i wrote:
B7 wrote: (if done properly)
This is the key and a big if imo as the ally used is shite and a right pain in the arse to weld.

Very true, they are hard to weld. Its because the aluminium absorbs the oil and coolant so even grinding it back to what looks like clean metal, may not be as clean as it seems.