Alan_525i pls tell us more bout your m20 head problems.
Reply With QuoteIt's scattered across numerous posts as and when things cropped up. I'll tell the whole story here and update it after thanksgiving when I get the car back on friday.
OK, it all starts back in the summer of 2000 when I first got the car. It was a very clean, 54K mile 1990 525i 5speed with cloth interior. I managed to beg the money from my pop and all of a sudden I jumped from a similar vinatge toyota corolla to an E34. I did NOT get a pre-purchase inspection although that wouldnt have held up the purchase. After buying it I had it inspected the Dealer said it needed a head gasket and its windshield wipers could use replacement because they were "noisey". I knew how bad a gasket job could dent my bank account so I got additional opinions. The end result was that its seeping but not leaking and the motor runs fine. I forgot about it.
In summer of 2001 I had the valves adjusted and the tech noted that there was some wear on the camshaft that might need to be addressed in a year or two. Also mentions seeping gasket.
Summer of 2004 I move into Philadelphia from the suburbs and my new apt who promised me indoor parking says i need to wait until a spot opens up. I wait for 3+ months (ridiculous, I know). As payback I notice that I'm loosing coolant. It starts to go at about a pint every 500 or so miles until eventually its consuming coolant at the rate of a whole expansion tank every 250 miles.
I get the car into a new mechanic who I have absolute faith and trust in (and still do despite what happens) because my old one in the suburbs changed ownership. He says he thinks he got it there were a couple leaky hoses back by the firewall. Great. Two weeks later, still loosing.
So I drive around for a while because I'm in no rush to get it fixed and I'm only driving a few hundred miles a month because living in the city means I walk or take the bus. I bring the car back in mid-December before I leave for two weeks vacation overseas. While there I don't hear from him.
When I get back I find out its definitly the headgasket as the oil and water resemble chocolate syrup. Off comes the head. Here is where we make a bad choice.
This shop has a a machine shop on premesis and the head mechanic's father is an old school hotrodder who worked on american muscle until the mid 80s when he got into BMWs. They say, hey, we've got the head off, why don't we make it real nice? I figure that you only live once so lets go ahead and do it. They do most of the work largely for free. But since it is 112K mile head and I plan on never selling it, we do it all. New valves, rocker arms, seals/guides, a good valve job, the whole deal. Its expensive. We also note the wear on the cam and in addition to having the cam re-dressed we have it reground by the same people that do cams for Metric Mechanic and to their specs. This takes them over a month as they are really busy and maybe a bit slow (the cam alone). Taking extra precaution I also do a water pump, timing belt, replace several power steering hoses, a new radiator. I also pick up a clearance Racing Dynamics Exhaust. I finally after dealing with all the stuff getting worked on get my car back the first week in March of 05.
I am very happy, the car runs amazingly well, is very smooth and idles a bit lumpy as you would expect a sport cam to, which delights me to no end. But then a few weeks later the coolant light stares me in the fact. Imagine my dismay.
We hope its the system burping, a bad hose connect etc. But its not. Finally this past August we drain the car and see the oil come out like maple syrup. It's really gross this time. Must be a cracked head. We did pressure test the head the first time around. That was one of the things that took a long time as he didnt have a plate cut to test it properly so they had to make one. It held pressure just fine.
So we take it all apart again beginning the first week of October. Order a new head from Marnal. Its a spanish casting which works fine, but the ports looked like 50 grit sandpaper so all the machine work is redone. We are able to reuse most of the parts from the old rebuild. But the cam is scored. Aparently the cam spray bar got clogged and etched the cam in the couple thousand miles it was in there. So we had to send it back out again. But they can't fix it because it has already been reground once. So we find a stock cam and send it back to them. It will be here monday. They'll put it all back together and things will be good again. I hope.
The only other possibility is that the block is cracked. If so I'm giving up. I'll take the head off the car, sell it to someone and drop way more money than I can afford into a S50 swap which at this point I've almost already spent as much on this.
Now, I want to be clear on this, this is not the shop's fault. They did everything they could to isolate the issue the first time and we knew there was a chance that the head was cracked when we put it back together. We thought it was a small enough chance to take to save the 600 bucks it would cost for a new head. But the shop was good enough to do the work the second time around at no charge. Just the parts that I didn't pay for the first time around. I've known the head mechanic for many years before going to him and I have no doubt that I will continue to go to him.
Well that is my story. Feel free to ask questions, send flowers, or laugh at me.
Al
EDIT: Forgot to mention that they did locate the crack finally. Minute crack under the 2-3 (I think) cam journal that probably only opens enough to leak when the engine is hot, hence the reason it held pressure on the bench. Apparently I've read that minute cracks in this head are not that uncommon (I think usually at the 5-6 journal) because the headers if heated up and cooled quickly over time twist a little bit putting stress on the head. I have a feeling this was in the making as the first drive never got the car real hot (drove less than 2 miles to work every morning for ten years hence the low mileage when I got the car). Will it happen again? Who knows? In a few years I'll do a motor swap anyway.
