Author Topic: fricken blown head gasket (Read 4046 times)

Geoff · « **on:** November 11, 2011, 06:57:45 AM »

Well, I am not a happy camper. My 91 is, which I've only had 2 months, blew the headgasket, and with very little warning too. I hadnt overheated it, and it was running fine. Then, Tuesday morning on startup, it had a slight miss. Sounded like a fouled plug, went away in like 10 seconds, then ran fine. Later that day, it stumbled on startup again, but cleared out quickly, and ran good all the way home (35 miles) The next day, try to start, starter goes 1/2 turn then stops..hmm..try again, its the same..check battery, its good...something about the way the starter sounded reminded me of a starter I heard once before..trying to start a car with a hydrostatic lock...I pulled the spark plugs, then tried to crank engine. It did, and coolant shot out of #2 cylinder, about 40 feet. Took my other ride to work (64 sprite:rolleyes:) and during the course of the day totally jacked my back up, which is bad due to years of racing, riding motorcycles and lifting stuff at work..since I can hardly walk, doing the headgasket myself would probably kill me..so I have to pay a shop to do it, which I hate. Well, thanks for letting me vent, and remember-dont ignore the little things-they could be trying to tell you something.
Geoff

DesktopDave · « **Reply #1 on:** November 11, 2011, 07:56:37 AM »

Sorry to hear about your troubles. BMW made a great car but I'm coming to the conclusion that the head was definitely under-engineered. The earlier M10, M20 and M30 last a long time. The later M50, M60 and M70 just don't.

bflan2001 · « **Reply #2 on:** November 11, 2011, 10:32:37 AM »

this is true dave..i've overheated my m10 many times (pegged in the red) for various reasons and it has never blown..i wonder if it's worth it to spend the extra money on a multi-layer steel gasket, even on a stock motor.

Geoff · « **Reply #3 on:** November 11, 2011, 12:36:55 PM »

yeah, when I drove my e-21 I had the hose for coolant to the manifold deteriorate, the car lost coolant and overheated good..was fine afterwards, headgasketwise, tho I still dont recommend overheating them, haha. If there is a bright side, the place where I got the car is willing to stand behind the car, even tho my 30 days are up. I do not expect them to eat this entirely, but they were very nice. I'm paying for the parts, and 1/2 of the cost of labor, which includes the head going in for a mill and crack test. So it could have been worse-tho it aint over till its over, as they say.
Geoff
ps-also freaked out to find 2 of my plugs completely immersed in oil..I guess that valve cover gasket needs replaced every couple years or so

DesktopDave · « **Reply #4 on:** November 11, 2011, 12:48:12 PM »

I haven't seen any info on MLHGs, but I wouldn't think it's a bad idea if it was matched up with studs. IMHO it won't solve the problem, but it might postpone it.

I think it's the head design personally. BMW engineered it to be as light as possible, I'm guessing. Oddly, they optimized the head for airflow and ignored the usual friction reduction techniques. The M44 refresh turned the four-cylinder DOHC into BMW's "economy" car.

The result for all the M4x motors is a durable bottom end with a head that can't tolerate overheating.

They're still doing that with their newer motors. Less metal, more composites, higher casting accuracy, higher performance. From what I've seen every generation pushes the envelope even more. The N52's composite block is a great example. Nice and light, great power and economy, really nice to drive. But overheat it once and it's done, block and all. A BMW tech I know nicknamed the newer motors "time bombs." BMW replaces them with crate motors. They' won't rebuild them.

IIRC he's rebuilt a few with time-serts on the sly...since when the head warped it ripped the head bolts out of the block, threads and all.

Geoff · « **Reply #5 on:** November 11, 2011, 03:44:44 PM »

actually, I cant see myself going any newer than the e-30. newer ones are too expensive and complicated, and some of the uberengineering is too over the top for me
Geoff

DesktopDave · « **Reply #6 on:** November 11, 2011, 04:37:03 PM »

Me too! e30 FTW!!

Though I must admit I do get tempted by the occasional e36 M3.

Geoff · « **Reply #7 on:** November 18, 2011, 03:26:27 PM »

Well the blown gasket was bad enough, but it turns out the head has a crack in it. No luck atall, it would seem..

Geoff

victor.askew · « **Reply #8 on:** November 18, 2011, 06:04:08 PM »

I feel your pain as I just went through this last month. Double 02 BMW, Hayward Calif, has at least 1 more of these in stock. give them a call. I picked up a complete head minus the cams for $480. You will need to send it to a machine shop to be rechecked and surfaced/machined. good luck

Geoff · « **Reply #9 on:** November 19, 2011, 07:56:02 AM »

the guys who are working on the car were able to locate a head. however, now I have this weird pain, in my wallet:rolleyes:
however, if I had done this job myself, and not noticed the crack, it could have been even worse
Geoff

Isamemon · « **Reply #10 on:** November 20, 2011, 01:46:48 PM »

not to make your wallet feel lighter
I do hope that the head you bought is warranty
it should have been , or needs to be flow tested/pressure tested to check for cracks

I had a head, looked excellent. ended up the machine shop found a little bitty crack way up high in an exsaust port, between the water channel and the port. It never would have shown wihtout the test, or pulling the valves first

best of luck. been there done that

victor.askew · « **Reply #11 on:** November 21, 2011, 08:05:00 PM »

If the machine shop you are using is a good shop then the head will be fine. Any defects in the replacment head should be caught by them before they begin to rebuild it with parts by testing it first and giving you a follow up report on its pre build up condition.

Geoff · « **Reply #12 on:** November 22, 2011, 06:23:55 AM »

yeah, they found the first crack. if there's one in this head I guess they'll find it also
Geoff