more M5 head questions...

[TheGeak]

okey, long story short here....

car overheated, blew headgasket (last time i let my dad drive the car ANYWHERE!!!!)

From what i've heard odds are that it warped the head. My question is.... is it worth it for me to get a new head or just to remachine the old one? I've talked with two people so far, i said you can remachine it and it'll be fine, the other said remaching will work, but its likely to crack down the road.

Anyone care to chime in on this?

[winfred]

depends how warped it is, i've had several heads cut for customers and had no come backs for that, some shops can straighten a warped head in a special oven with clamps, i've never tried this service

[TheGeak]

interesting...i heard the M5 head was a little different because of the higher temps...any truth?

[Hector]

more than 12 mils of material. At least this is the case for the M30 according to Bently.
hector

[TheGeak]

hrm...anyone have a bentley for an M5 around? mine is at my parents house :-\

[Rainman]

hrm...anyone have a bentley for an M5 around? mine is at my parents house :-\

[TheGeak]

yeah, i figured the manual would say something like that. BMW makes no money if you resurface a head as opposed to buying one from them. I was more curious as to if anyone had done it.

[ryan roopnarine]

may as well take a looksee in the catalogue and see if there's a hidden specification for resurfacing...

[TheGeak]

its a '91 3.6L

[ryan roopnarine]

the catalogue would have part numbers for the m50 extra thick gasket, therefore listing one for the m5 if one existed, but no, the thicker m50 isn't listed, both are set at 1.74 mm, and the TIS says m5 head cannot be resurfaced....maybe if it is cracked you could get someone to weld the crack, or thicken iit if it needs to be milled, as i doubt you're going to come across a m5 head easily.

[Paul in NZ]

why dont you check it out first.It may not be warped......You wont be any worse off than you are at this moment.If your Dad overheated it on one drive it was gonna happen.There must be a reason,ie coolant leak ,blown hose ,failed h2o pump etc

[Dave Menheere]

If your head needs cut, get it cut and make up the difference with a laser cut spacer. They can be cut to almost any thickness needed ... a guy in Australia saved himself a new head with an .080 spacer for $80. Check out e34bmwm5.com for more info .... I think his name was Robinson.

good luck and hope it isn't warped!

Dave, 91 M5

[Bill R.]

cannot resurface the head, bmw has no such qualms about the m30 , m50 etc so I would venture to guess that the m5 head is different, perhaps a precision thinwall casting and there's not enough material to play around with.. I don't know the reason .. The other caveat is that if it is warped and you resurface the sealing face to straighten it out then the rest of the head is still warped and that means that the cam bores are not longer true either, which causes its own problems. I don't know who does align boring or honing on these either.. The alternative that winfred stated seems like the best if you can find a shop locally that does it.. and thats when they straighten a head thats warped by putting it in a furnace bolted to a trueing plate and anneal it back to flat. But if you have any eroded surfaces this won't help and you still have to find a way to repair those






If your head needs cut, get it cut and make up the difference with a laser cut spacer. They can be cut to almost any thickness needed ... a guy in Australia saved himself a new head with an .080 spacer for $80. Check out e34bmwm5.com for more info .... I think his name was Robinson.

good luck and hope it isn't warped!

Dave, 91 M5

[TheGeak]

In response to WHY it overheated....i found out why. water pump craped the bed. so thats obviously going to be repaired. I had heard about the 'furnace' option. I'll have to look into that. Like i said, i'm HOPING this is all unnessessary and my head ISN'T warped. But like i said, i heard that M5 overheating almost always causes head warping...but we'll see. Until then, wish me luck!