Ok quick history,took the E30 to its 1st autox and it overheated in the staging lane on my wife.She flagged me over and I told her to get out of line and hit the street to cool it down as I figured the clutch fan was at least partly to blame.She doesn't make it across the paddock and the upper outlet snaps off the plastic rad.Tow dolly home.
So I replace the water pump,tensioners,thermostat(oem 92 degree),rad with an aluminum ebay unit and add an electric fan and delete the oem clutch fan as the clearance with the 24v swap is very tight.Had a bugger of a time bleeding the coolant and went thru a few cycles of run until the 3/4 mark on the temp and let it cool and repeat.(front of the car in the air,adding coolant as needed).The electric fan didn't seem to do the job as the temp would continue to climb just running in the garage.
Decided to take it for a spin to confirm/eliminate the fan as the problem,car went straight to the 3/4 mark and stayed there while moving at 40+ mph in 4th gear,slowing for a turn etc and the temp continued to rise.After it cooled I ran it again in the shop and paid attention to temps and when the t-stat opened,didn't open until the 3/4 mark.Swapped in the cooler t-stat that was in it and redid the bleeding process and now its fine with the stat opening just before halfway and when I hooked up the fan(not wired to the temp switch yet)it cooled down easily to a little over the 1/4 mark.
Phew,long story to get to the real question-now if I blip the throttle hard it oil smokes on the overrun and never did before.I have no signs of oil/coolant cross contamination,pulled all the plugs and no signs of coolant in any cylinder and no white smoke/smell of coolant out the tail pipe.Do I have a cracked head??.
I would start with the basics:
- Pressurize the cooling system.
- do a leak-down/ compression test.
What color is the smoke?
Oil smoke is blue
I don't have the ability to pressure test or leak down but I have it booked in a local euro shop on thursday and wanr to be well informed when I get there.
You have an M52 swap and were running the stock clutch fan?
and from the sounds of it.. the stock radiator
Ya ya,bought it that way-failed before I got to it.In a perfect world money would grow on trees and we'd all have the best equipment possible.
Head gasket/cyl head got a clean bill of health today so that's good,probably valve seals regarding the oil burn on decal.I'll moniter it and see what happens.I'm probably picking up a supercharger this weekend for it so the head will be coming off over the winter for an upgrade.Will do seals then.
If you overheat an M/S series BMW motor you are looking at a HG job now or not too far off. It will pop right between the #4 & #5 and pressurize the cooling system. It might crack between the valve seats if you get it really hot.
Since the head is coming off over the winter, no biggie - beat it mercilessly and get every pennies' worth of what it has left. ARP head studs when it goes back on... pricey but they keep them from pulling away from the gasket easily when you get them hot enough to want to.
Cheers ;)
Drove it for nearly 2 hours last night with no problems,forgot how much I like this little car.
Thanks for the advice Mr snorklewacker,I'm sure I need more again as I am picking that charger up tomorrow.Cars fun but it can always be made funner
Also check and verify spark timing, late spark will heat treat exhaust and boil the best coolant.
GPSnorklewacker speaks the truth; no M50/M52 head gasket is long for this world after a rad failure or other big heat event.
I concur it sounds like the valve seals are shot if you are only getting smoke when you lift off a high revving throttle and the head vac goes way up temporarily.
When these suckers burn coolant, there's no doubt about the tail smoke; it's white like snow.
Where I differ with the GPS is on his advice to keep beating it. I wouldn't, because with my luck somebody in the family would pop the HG and fry the top end so much, my machine shop bill would climb.
Speaking of machine shops, GPS are you DistMarVa, and if so who do you trust? Tyson's Machine? I've got two heads in need of a refresh, one M50 and one M20.
