Ferret
10-26-2006, 10:18 AM
First post!
Firstly I'll explain what 'the experiment' is...
In january I was given a rather beautiful looking '91 525i (non-vanos) in alpine green or whatever it's called. Given... lol... more like had the keys thrown at me in disgust because the owner was fed up with it. Local dimwits at the garage had diagnosed it with a blown head gasket and replaced it at a cost of around £800... only to have it suddenly start blue smoking and ejecting water out of the bores when the spark plugs were removed...
Over the next few months I stripped it down leisurely and took the head off, to find the head came away from the crank case nearly in three pieces the cracks were that big.
I spent the next two months being frustrated trying to find a replacement head that I'd not have to chop my arm off to pay for it... all to no avail. I was trying to do this on a shoe string and replacement heads in scrapyards were always there because they'd failed...
Eventually I discovered that the heads from the 2.0 are an exact plumbing match for oil and water etc, though have a smaller combustion area. Practically handed a 2.0 head I decided to experiment, after all I had a dead 525 on the drive and it wasnt going anywhere. Result is that it ran quite happily, noticably more thrashy and powerful in the low revs... but lots of black smoke/unburned fuel in the high revs.
However, almost immediately it developed an idle misfire that vanishes the instant you open up the throttle. I dont think it's a piston ring/valve issue because occasionally it runs almost spot on with only a smooth, but slightly wobbly idle expected from a high compression engine, not a misfire.
Cylender 3 repeatedly carbon fouls up sparkplugs, that when you take apart are covered in fuel, not oil. However, as there's a nut missing off the manifold behind cyl 6 I have a suspicion air is leaking into that cylender. They're a strange 9mm thread that you just cant really get with encapsulated washer, so havent had chance to replace it yet.
Hrm... does anyone think a leak into 6 could cause a problem with 3?
One of the problems I'm having is because of the compression and misfire it's really piddling oil up the breathers - when you top out the rpm, the car occasionally blue/white smokes. Again I know it's the breathers because I've pulled one off when revving the car up, that and the manifold is full of oil. I've got this in hand though because I'm making up a t-junctioned breather that's going to drain back into the sump.
Does anyone know if the brake light circuits are housed inside the LKU? Just I dont want to go pulling it apart to find there's no brake circuit in it, looking for the cause of the irritating gong 'BRAKE LAMP'
One last technical issue I'm having, and someone might be able to help here - after retro fitting the OBC, both buttons on the dash have packed in... (and stay packed in when you remove the OBC) I've got the stalk, but not fitted it yet. Has anyone else come across a similar problem? Should the OBC display on the dash under its own control without the stalk?
Any thoughts ladies and gentlemen, would be greatly appreciated.
Firstly I'll explain what 'the experiment' is...
In january I was given a rather beautiful looking '91 525i (non-vanos) in alpine green or whatever it's called. Given... lol... more like had the keys thrown at me in disgust because the owner was fed up with it. Local dimwits at the garage had diagnosed it with a blown head gasket and replaced it at a cost of around £800... only to have it suddenly start blue smoking and ejecting water out of the bores when the spark plugs were removed...
Over the next few months I stripped it down leisurely and took the head off, to find the head came away from the crank case nearly in three pieces the cracks were that big.
I spent the next two months being frustrated trying to find a replacement head that I'd not have to chop my arm off to pay for it... all to no avail. I was trying to do this on a shoe string and replacement heads in scrapyards were always there because they'd failed...
Eventually I discovered that the heads from the 2.0 are an exact plumbing match for oil and water etc, though have a smaller combustion area. Practically handed a 2.0 head I decided to experiment, after all I had a dead 525 on the drive and it wasnt going anywhere. Result is that it ran quite happily, noticably more thrashy and powerful in the low revs... but lots of black smoke/unburned fuel in the high revs.
However, almost immediately it developed an idle misfire that vanishes the instant you open up the throttle. I dont think it's a piston ring/valve issue because occasionally it runs almost spot on with only a smooth, but slightly wobbly idle expected from a high compression engine, not a misfire.
Cylender 3 repeatedly carbon fouls up sparkplugs, that when you take apart are covered in fuel, not oil. However, as there's a nut missing off the manifold behind cyl 6 I have a suspicion air is leaking into that cylender. They're a strange 9mm thread that you just cant really get with encapsulated washer, so havent had chance to replace it yet.
Hrm... does anyone think a leak into 6 could cause a problem with 3?
One of the problems I'm having is because of the compression and misfire it's really piddling oil up the breathers - when you top out the rpm, the car occasionally blue/white smokes. Again I know it's the breathers because I've pulled one off when revving the car up, that and the manifold is full of oil. I've got this in hand though because I'm making up a t-junctioned breather that's going to drain back into the sump.
Does anyone know if the brake light circuits are housed inside the LKU? Just I dont want to go pulling it apart to find there's no brake circuit in it, looking for the cause of the irritating gong 'BRAKE LAMP'
One last technical issue I'm having, and someone might be able to help here - after retro fitting the OBC, both buttons on the dash have packed in... (and stay packed in when you remove the OBC) I've got the stalk, but not fitted it yet. Has anyone else come across a similar problem? Should the OBC display on the dash under its own control without the stalk?
Any thoughts ladies and gentlemen, would be greatly appreciated.