M30 Head overhaul

bizz · Post by **bizz** » Fri Jun 14, 2013 10:06 pm

Hi guys,

My '76 528 has leaky valve seals which need replacing fairly soon.

Fortunately I have a spare later model head from a 528i that I will overhaul.

Just wondering if a 'head gasket set' from bavauto or similar will cover all the gaskets/seals I need, or should I consider doing anything else at the same time? (eg. valve guides?)
Can anyone advise of the best quality option?

Also, the spare head I have has a broken rocker arm - I will purchase a replacement but is there any value in replacing them all, or is this overkill?

Thanks

Mike W. · Post by **Mike W.** » Sat Jun 15, 2013 12:15 am

IMO valve guides are overrated. Not a bad thing, but seals are the critical part. You won't know if you need new rockers or not until you disassemble the head, they can have a ton of miles and be fine or have not that many and be scalloped, in which case you will want to replace them. It all depends on the care of it previously. Rocker shafts can be worn or good, again, unless you want to throw money at it you won't know until you take it apart. Same with the cam and even valves themselves.

bizz · Post by **bizz** » Sat Jun 15, 2013 1:40 am

Good advice, i'll start pulling the head down and go from there

Before I do this I will get the head tested for cracks

T.Hanson · Post by **T.Hanson** » Sun Jun 16, 2013 8:52 am

Just out of curiosity, how massive an undertaking to disassemble a head ?

As in to save money before bringing to the machine shop.

My experience thinks there are special tools needed to do it right, and buying the tools makes the probable one time use not worth the fooling around. Just bring the head, heads, parts to the shop and write the check.

Mike W. · Post by **Mike W.** » Sun Jun 16, 2013 10:36 am

T.Hanson wrote:Just out of curiosity, how massive an undertaking to disassemble a head ?

As in to save money before bringing to the machine shop.

My experience thinks there are special tools needed to do it right, and buying the tools makes the probable one time use not worth the fooling around. Just bring the head, heads, parts to the shop and write the check.

It's work, but I wouldn't call it a massive undertaking. Not much in the way of special tools, a valve spring compressor and a long rod to drive the rocker shafts out is about as special as it gets. You've got to be careful not to split or mushroom the rocker shafts, but that's mostly just being careful and not getting in a rush.

GripGreg · Post by **GripGreg** » Sun Jun 16, 2013 11:14 am

Tom
Investigate renting tools from Autozone or maybe Napa or wherever else or O'Reiley's maybe.
Good luck,,,,Greg
Ps,,,Pep Boys?

bizz · Post by **bizz** » Sun Jun 16, 2013 10:14 pm

Just to further this resource:

http://www.firstfives.org/faq/cylinder_ ... ad_faq.htm
http://www.armchair.mb.ca/~dave/525i/26Jun05/

Falkenberg · Post by **Falkenberg** » Mon Jun 17, 2013 3:57 am

My 2002 had very bad seals, it would leave a cloud of burned behind oil whenever I used engine brake at a higher RPM (like 120km/h in 4th gear). I found the guides to be quite bad as well, but do to budget reasons I thought I would give it a try only with new seals. It worked, no more smoke, no more 1 liter per 500km oil consumption.

I only wonder how it keeps up in time - will the seals wear quicker if the guides are bad? Blow by, lateral movement. Possibly. I never got the chance to find out.

Mike W. · Post by **Mike W.** » Mon Jun 17, 2013 1:21 pm

Falkenberg wrote:My 2002 had very bad seals, it would leave a cloud of burned behind oil whenever I used engine brake at a higher RPM (like 120km/h in 4th gear). I found the guides to be quite bad as well, but do to budget reasons I thought I would give it a try only with new seals. It worked, no more smoke, no more 1 liter per 500km oil consumption.

I only wonder how it keeps up in time - will the seals wear quicker if the guides are bad? Blow by, lateral movement. Possibly. I never got the chance to find out.

It doesn't seem to be a problem. Seals go bad due to time and heat, not wear. The old ones were neoprene which just isn't up to the job. Starting in 85 or so they went to viton seals and it holds up to much more heat.

bizz · Post by **bizz** » Mon Jun 17, 2013 6:11 pm

In that case, what's the best replacement option? Am I better off ordering something like:
http://www.iemotorsport.com/bmw/E12-val ... seals.html

Or will I be safe using the ones that come in the head gasket 'kit'?

bizz · Post by **bizz** » Mon Jun 17, 2013 6:35 pm

Me again, sorry. Can the cylinder head bolts be safely re-used?

GripGreg · Post by **GripGreg** » Mon Jun 17, 2013 6:54 pm

Bizz
In response to the choice between Viton or urethane seals:
For one dollar, why not go Viton???

If the big dawgs say Viton is better, why even ask the question!
ONE DOLLAR , MAN!!!! 1$!!

Mike W. · Post by **Mike W.** » Mon Jun 17, 2013 9:54 pm

I forgot to add something, if you have the old style valve guides, 14MM I believe, the seals are pretty much non available. I think all the new ones that fit the smaller 11MM guides are now viton, although they weren't always. Even the originals went 100K miles or so, or almost 200Km so they weren't all that short lived.

And yes, head bolts on M30s/M10s are reusable.

bizz · Post by **bizz** » Mon Jun 17, 2013 10:38 pm

GripGreg wrote:ONE DOLLAR , MAN!!!! 1$!!

haha, your point it is valid!

I guess i'm wondering what type of seal comes in those kits you buy that include the head gasket, manifold gaskets etc.. If they are viton then we are golden! (i wouldn't use the urethane ones given the choice)

But yes, I could always buy them separate

D. · Post by D. » Tue Jun 18, 2013 1:45 am

Heat the head if you're driving the long rods out. I bought two identical hot plates at Sears. Heats it in minutes, the rods practically float out.

Firstfives.org

M30 Head overhaul

M30 Head overhaul

head rebuild