Is it just me?
- Thread starter robertjones
- Start date
Now just a cotton picking moment there Musky.No charge for a retest though...
You two will get me a good name.Ha Ha.
Z
zedonist
Guest
Your get a free bumper sticker though.....
Commiserations Robert.
Joe and myself have been working on both our Z3's (M44) as both showed loss of water / blown hoses /blown radiator at various times.
I noticed the same problem as you have, of a mysterious loss of water (never very much) each time I looked in the expansion tank.
Joe and myself contacted a great mechanic who tested the rad pressure by coupling his tester to the filler neck.
As the engine heated up the pressure increased considerably enough for him to switch the engine off quickly.
His diagnosis was warped head.
Both of us have had cylinder heads skimmed as a result.
The annoying thing is both the gasket and head look fine after removal. It is only when the engineering shop check the head with a proper straight edge that any problem can be seen.
The engineering shop we use is based in Ashtead (near Leatherhead) and charge £30 which seems very reasonable.
One problem we found is that after skimming you can't easily re-set the cam timing with the cam clamp and flywheel locking pin which is the accepted way of doing it.
The timing is a gnats whisker out if you do this and both Joe and myself call in the mechanic to finally set the timing (otherwise the engine starts and runs ok at high revs but ticks over very roughly )
I do hope you don't need a head skim but it sounds very likety to me.
Joe and myself have been working on both our Z3's (M44) as both showed loss of water / blown hoses /blown radiator at various times.
I noticed the same problem as you have, of a mysterious loss of water (never very much) each time I looked in the expansion tank.
Joe and myself contacted a great mechanic who tested the rad pressure by coupling his tester to the filler neck.
As the engine heated up the pressure increased considerably enough for him to switch the engine off quickly.
His diagnosis was warped head.
Both of us have had cylinder heads skimmed as a result.
The annoying thing is both the gasket and head look fine after removal. It is only when the engineering shop check the head with a proper straight edge that any problem can be seen.
The engineering shop we use is based in Ashtead (near Leatherhead) and charge £30 which seems very reasonable.
One problem we found is that after skimming you can't easily re-set the cam timing with the cam clamp and flywheel locking pin which is the accepted way of doing it.
The timing is a gnats whisker out if you do this and both Joe and myself call in the mechanic to finally set the timing (otherwise the engine starts and runs ok at high revs but ticks over very roughly )
I do hope you don't need a head skim but it sounds very likety to me.
the only way for te head to warp is if the engine overheats, correct? so if the engine has not overheated then there should be no issue with the head.... I would love to have an alarm fitted to the car that when the temp reached above normal the alarm would go off and you could switch the car off. I find myself driving around and spending as much time checking the temp gage as anything else :-/ I have learnt not to leave the car on idle, certainly when I am out of it, I don't trust her any more, she has done the dirt on me and now I am scared :-/
Z
zedonist
Guest
The other way for a head to warp is if it was not replaced correctly, i.e. Not torqued correct pattern or correct torque, which could suggest the head gasket had been changed previous.
Z
zedonist
Guest
Just checked the TIS and the head bolts are torque to yield, so if not replaced and are reused can stretch after installation causing the head to be loose, hence warping, blowing of head gasket.
Your quote:'the only way for the head to warp is if the engine overheats, correct?"
As zedonist said, the head could be re-installed incorrectly. I once was putting on a head that had a final torque of 62 ft/lbs. After finishing the job, the head leaked. I know that I had the right torque pattern. Upon rechecking the book, I discovered that I had mistakenly looked at the wrong head picture. The one I was supposed to be following had a two stage torque, the first being 21 ft/lbs then 62 ft/lbs. Failing to do this resulted in a bad seal.
I haven't done any head work on BMWs so there are two things I'd have to check. Some cars require head bolts to be measured to see if they have stretched too far and need to be replaced. Some cars require replacement no matter what. I had a VW diesel that required new head bolts, saying that the old ones stretched. I measured them and could find no difference to the new ones. A VW mechanic told me to use them if the measurement was within tolerance. I did so and never had a problem. The other thing I don't know about BMW engines is whether the head and block are made from different materials. Many mechanics feel that when the block and head are different metals, sooner or later the head gasket will fail. Their reasoning is that the heat expansion rates and amounts of different metals that are joined together by a common gasket, cause wear and tear on that gasket that after a long period of time cause it to eventually fail. I don't know this for a fact but I've heard it said by many good mechanics. Frankie
ok guys, yes, obviously if the head was put back on wrong it could do all sorts of things and if you dropped it off a 20ft building it could also warp lol I was of course talking in the case where there has been no issues with the car and everything was as it should be
and if you dropped it off a 20ft building it could also warp lol I was of course talking in the case where there has been no issues with the car and everything was as it should be
Z
zedonist
Guest
You are correct Frankie, the gaskets also corrode over time from the combustion gases. I doubt very much if you could measure the stretch in a bolt with conventional home tools, and it's a mute point, because on stretch bolts (torque to yield) the bolts have been tightened just up to or past there yield point, so that they exhibit permanent set. A bolt is designed to work like an elastic band, I.e when you stretch it and release it it tries to go back to its former length, in doing so it induces a clamping force, the more you tighten it the more clamping load it exhibits, until it goes past its yield point at which point it continues to stretch. On many cylinder heads, bolts are tightened to there specified yield point and then turned x amount of degrees to be sure. as this invariably induces a permanent set condition, and the bolts are said to have stretched, hence the name. If you were to re-apply the torque to these bolts they would stretch further, in doing so the grain boundaries fail, the material becomes weaker, the result is the clamping load falls off, and the head becomes loose. This is why you should fit new bolts.
Jesus Zed man, that's above normal knowledge .... are you a scientist?
No, he learnt it all from bonzo........
Remember Back to the Future,Doc, I reckon that was him.
Z
zedonist
Guest
It must be the cake.......
Z
zedonist
Guest
I was going to go deeper, glad I didn't, I trained as a metallurgist with Merlin, in my youth and as a young man.....
great knowledge to have ;-)
Z
zedonist
Guest
Ahh but I have not told you what I do now, and what skills I have accrued over the years since, which makes me a super Wizard........
Did you know a boy called Potter? Drive a Ford Anglia?
Z
zedonist
Guest
Shush!
Beg to differ but I do think that the spelling went wrong after the W (Where is bonzo when you need him?)
