How do I interpret head bolt torque specs???????

I obtained the "Cylinder Head Assembly Specifications" for a BMW 325 that is
leaking oil through the head gasket.

They a

Step#1 - 22 ft-lb
Step #2 - Torque angle 90 degrees
Step #3 - Torque angle 90 degrees

The proper tightening sequence is also provided.

I have 3 questions:

Q.1. - Since these specs are for assembly, it would mean (I guess) that a
new gasket is being used. And this might mean that the specs are not really
applicable to my situation since the gasket I have has been in service for a
long time. Or it might be that these specs only apply to a situation where
the head is completely dissassembled. Does anyone know?????????

Q.2. - I would guess that what the specs say is that every head bolt is
tightend in the proper sequence to 22 ft-lb, then 2 more sequences are
performed where a quarter turn is applied to each bolt. Is that what the
specs are saying????????

Q.3. Heck- what if I just tighten the bolts uniformly in the proper
sequence in an effort to stop the leak???????? Would there be any great
harm in that?????

Thanks in advacne.

All responses are appreciated.

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Ben Martin > wrote:
> I obtained the "Cylinder Head Assembly Specifications" for a BMW 325 that is
> leaking oil through the head gasket.
>
> They a
>
> Step#1 - 22 ft-lb
> Step #2 - Torque angle 90 degrees
> Step #3 - Torque angle 90 degrees
>
> The proper tightening sequence is also provided.
>
> I have 3 questions:
>
> Q.1. - Since these specs are for assembly, it would mean (I guess) that a
> new gasket is being used. And this might mean that the specs are not really
> applicable to my situation since the gasket I have has been in service for a
> long time. Or it might be that these specs only apply to a situation where
> the head is completely dissassembled. Does anyone know?????????

head gasket replaced. you don't reuse head gaskets.

> Q.2. - I would guess that what the specs say is that every head bolt is
> tightend in the proper sequence to 22 ft-lb, then 2 more sequences are
> performed where a quarter turn is applied to each bolt. Is that what the
> specs are saying????????

yes, but they're stretch bolts and have to be replaced. don't reuse
them.

> Q.3. Heck- what if I just tighten the bolts uniformly in the proper
> sequence in an effort to stop the leak???????? Would there be any great
> harm in that?????

yes, the bolts could break or threads could strip.

replace the gasket and use new bolts...

"Ben Martin" > wrote in message
...
> I obtained the "Cylinder Head Assembly Specifications" for a BMW 325 that
is
> leaking oil through the head gasket.

I would just nip them up a bit. Tighten each bolt slightly, in turn, and
see if it makes any difference. If it still leaks you could tighten them a
bit more. Use your judgement but I wouldn't tighten them more than about 10
degrees. Do this at your own risk and don't blame me if you break
something. If it doesn't work you need to change the gasket or just live
with it.

You could do a compression and leak down test to actually see if the head
gasket is leaking. If it is leaking, putting more clamping force on it will
not fix it. Once a head gasket starts to leak, it needs to be replaced.


"Ben Martin" > wrote in message
...
>I obtained the "Cylinder Head Assembly Specifications" for a BMW 325 that
>is
> leaking oil through the head gasket.
>
> They a
>
> Step#1 - 22 ft-lb
> Step #2 - Torque angle 90 degrees
> Step #3 - Torque angle 90 degrees
>
> The proper tightening sequence is also provided.
>
> I have 3 questions:
>
> Q.1. - Since these specs are for assembly, it would mean (I guess) that a
> new gasket is being used. And this might mean that the specs are not
> really
> applicable to my situation since the gasket I have has been in service for
> a
> long time. Or it might be that these specs only apply to a situation
> where
> the head is completely dissassembled. Does anyone know?????????
>
> Q.2. - I would guess that what the specs say is that every head bolt is
> tightend in the proper sequence to 22 ft-lb, then 2 more sequences are
> performed where a quarter turn is applied to each bolt. Is that what the
> specs are saying????????
>
> Q.3. Heck- what if I just tighten the bolts uniformly in the proper
> sequence in an effort to stop the leak???????? Would there be any great
> harm in that?????
>
> Thanks in advacne.
>
> All responses are appreciated.
>
>

Richard Sperry wrote:
> You could do a compression and leak down test to actually see if the head
> gasket is leaking. If it is leaking, putting more clamping force on it will
> not fix it. Once a head gasket starts to leak, it needs to be replaced.
>

A head gasket seals 4 different environments from each other.
Combustion Chamber, Oil galleys (crankcase), Water galleys (cooling
system), Outside world.

A compression or leak down test will only check the integrity of the
head gasket seal between the combustion chamber and the others. It will
not, for example determine of there is a breach between the oil passage
and the outside world, as is suspected in this circumstance.

--
-Fred W