3.2 liter M30 engine

Hi.
I have a 732i 1986 that has some motor problems.
Diagnosis so far:
Engine runs very rough

Changed all spark plugs, no change.

Checked compression on cold engine
Cylinder, Comp
1, 11.5 kg (approx. 165 psi)
2, 0 kg
3, 0 kg
4, 8.5 kg (approx. 125 psi)
5, 8 kg (approx. 120 psi)
6, 10,75(approx. 155 psi)

I'm thinking the head gasket is blown as there is no compression on 2
cylinders next to each other. When I look at specifications for BMW engines
it seems compression should be about 149 psi, so 2 of the cylinders are a
bit hi and the working two others are a bit low, could this be due to broken
piston rings? Allso I have no spec as to how much to tighten this spesific
engine, the book I have lists all other engine types, but I'm hoping I can
use the spec for 733i. Any thoughts on this, anyone?

Best regards

Lars

"Lars Høiby" > wrote in message
...
> Hi.
> I have a 732i 1986 that has some motor problems.
> Diagnosis so far:
> Engine runs very rough
>
> Changed all spark plugs, no change.
>
> Checked compression on cold engine
> Cylinder, Comp
> 1, 11.5 kg (approx. 165 psi)
> 2, 0 kg
> 3, 0 kg
> 4, 8.5 kg (approx. 125 psi)
> 5, 8 kg (approx. 120 psi)
> 6, 10,75(approx. 155 psi)
>
> I'm thinking the head gasket is blown as there is no compression on 2
> cylinders next to each other. When I look at specifications for BMW
> engines it seems compression should be about 149 psi, so 2 of the
> cylinders are a bit hi and the working two others are a bit low, could
> this be due to broken piston rings? Allso I have no spec as to how much to
> tighten this spesific engine, the book I have lists all other engine
> types, but I'm hoping I can use the spec for 733i. Any thoughts on this,
> anyone?
>
> Best regards
>
> Lars
>
If the compression on the low cylinders increases when you pour some oil
into the head, then the rings are the likely reason. Otherwise, the head
gasket is suspect.

It is no wonder that the engine runs rough. After all two cylinders are not
working at all.
Jim

In article >,
Jim > wrote:
> It is no wonder that the engine runs rough. After all two cylinders are
> not working at all.

Depends. Cranking compression testing doesn't tell the full story,
depending on what the problem is. Hence the big variation allowed
while still within spec. At higher revs those cylinders may well do some
work.


--
*OK, who stopped payment on my reality check?

Dave Plowman London SW
To e-mail, change noise into sound.

"Lars Høiby" > wrote in message
...
> Hi.
......
Allso I have no spec as to how much to tighten this spesific
> engine, the book I have lists all other engine types, but I'm hoping I can
> use the spec for 733i. Any thoughts on this, anyone?
>
> Best regards
>
> Lars
>
Thank you both for input. Time has not yet allowed me to continue, I'll be
trying again this weekend, I'll keep you updated on the progress

Regards

Lars