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Oil leak through head gasket - tightening head bolts...



 
 
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  #1  
Old June 8th 06, 07:46 PM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...

I am going to tighten my head bolts as a possible easy fix for an oil leak
on a very high mileage 1990 325is.

It seems to be leaking between cyclinder 4 and 5. The leak is on the
exhaust side.

One tech recommended tightening the 4 head bolts just in the area of the
leak.

Another tech recommeded tightening all of the head bolts, in the proper
sequence, uniformly.

Which is the better way to do it?????

I do not have the money to get my top end redone, so that is out of the
picture for now.

Thanks in advance.

- Ben


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  #2  
Old June 8th 06, 08:43 PM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...

"Ben Martin" > wrote in message ...

>I am going to tighten my head bolts as a possible easy fix for an oil leak
> on a very high mileage 1990 325is.
>
> It seems to be leaking between cyclinder 4 and 5. The leak is on the
> exhaust side.
>
> One tech recommended tightening the 4 head bolts just in the area of the
> leak.
>
> Another tech recommeded tightening all of the head bolts, in the proper
> sequence, uniformly.
>
> Which is the better way to do it?????


If this is what you will try, it is probably nest to torgue them all in
the proper sequence. That way they will not be applying an
unbalanced force which could warp the head in a different plane.
Good luck deciding on a torque value since these are "stretch
bolts" which are torqued to a value, then a number of degrees.

Bob


  #3  
Old June 8th 06, 10:35 PM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...

Bob Smitter wrote:
> "Ben Martin" > wrote in message ...
>
>> I am going to tighten my head bolts as a possible easy fix for an oil leak
>> on a very high mileage 1990 325is.
>>
>> It seems to be leaking between cyclinder 4 and 5. The leak is on the
>> exhaust side.
>>
>> One tech recommended tightening the 4 head bolts just in the area of the
>> leak.
>>
>> Another tech recommeded tightening all of the head bolts, in the proper
>> sequence, uniformly.
>>
>> Which is the better way to do it?????

>
> If this is what you will try, it is probably nest to torgue them all in
> the proper sequence. That way they will not be applying an
> unbalanced force which could warp the head in a different plane.
> Good luck deciding on a torque value since these are "stretch
> bolts" which are torqued to a value, then a number of degrees.
>
> Bob
>
>

I have owned 4 six cylinder E30 BMWs and they all leak oil from the
front of the engine ( cylinders 1 and 2 ). It has never been excessive
nor has it been a problem in terms of oil consumption. It is a little
unsightly and makes a mess of the front of your engine but I have never
bothered about it. I suspect you may have something similar. As one
reply said "be CAREFUL" that head is thin alloy should be treated
catrefully. Personally I would ignore it unless it becomes a problem.
  #4  
Old June 8th 06, 10:45 PM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...


Bob Smitter wrote:
> "Ben Martin" > wrote in message ...
>
>> I am going to tighten my head bolts as a possible easy fix for an oil leak
>> on a very high mileage 1990 325is.
>>
>> It seems to be leaking between cyclinder 4 and 5. The leak is on the
>> exhaust side.
>>
>> One tech recommended tightening the 4 head bolts just in the area of the
>> leak.
>>
>> Another tech recommeded tightening all of the head bolts, in the proper
>> sequence, uniformly.
>>
>> Which is the better way to do it?????

>
> If this is what you will try, it is probably nest to torgue them all in
> the proper sequence. That way they will not be applying an
> unbalanced force which could warp the head in a different plane.
> Good luck deciding on a torque value since these are "stretch
> bolts" which are torqued to a value, then a number of degrees.


I agree, torque them in sequence. Without a torque spec, I'd see what
torque (defecting beam wrench works best for this) it takes to move the
first one 10-15 degrees, then set my click wrench to that value. Then
put it back together and see if it helped. If not, you might go back
next week and try another 10 lbs in the area of the leak.
  #5  
Old June 9th 06, 12:29 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...


"Bob Smitter" > wrote in message
news:V5%hg.211430$5Z.140298@dukeread02...
> "Ben Martin" > wrote in message ...
>
>>I am going to tighten my head bolts as a possible easy fix for an oil leak
>> on a very high mileage 1990 325is.
>>
>> It seems to be leaking between cyclinder 4 and 5. The leak is on the
>> exhaust side.
>>
>> One tech recommended tightening the 4 head bolts just in the area of the
>> leak.
>>
>> Another tech recommeded tightening all of the head bolts, in the proper
>> sequence, uniformly.
>>
>> Which is the better way to do it?????

>
> If this is what you will try, it is probably nest to torgue them all in
> the proper sequence. That way they will not be applying an
> unbalanced force which could warp the head in a different plane.


I agree.

> Good luck deciding on a torque value since these are "stretch
> bolts" which are torqued to a value, then a number of degrees.


Less sure about this. The bolts must surely still be in the area of Hooke's
law, otherwise mere thermal expansion and contraction of the [aluminium -
high cte] block would damage the [steel - low cte] bolts.

Maybe you slacken them off slightly (and evenly) and then retighten to the
specification plus a few degrees. It is also possible that one or more of
them has become slightly loose.

>
> Bob
>
>


PS Bob, what about replacing them - feasible or a waste of money on a car of
this age & mileage?


  #6  
Old June 9th 06, 03:02 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...

R. Mark Clayton" > wrote:

> PS Bob, what about replacing them - feasible or a waste of money on a car
> of this age & mileage?

You know, that might not be such a bad idea! Complete sets of
bolts can be had for less than $20. Then you just torque them
as specified.

Bob


  #7  
Old June 9th 06, 07:27 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...


"Bob Smitter" > wrote in message
newsF4ig.211482$5Z.136789@dukeread02...
> R. Mark Clayton" > wrote:
>
>> PS Bob, what about replacing them - feasible or a waste of money on a car
>> of this age & mileage?

> You know, that might not be such a bad idea! Complete sets of
> bolts can be had for less than $20. Then you just torque them
> as specified.
>
> Bob
>

IMO leave well alone unless your going to do the job properly. once you
remove head bolts you will run the risk of oil escaping into further area's
of the leaking head gasket (which might have previously been sealed) and
causing a bigger leak than you had in the first instance.
if its not a major leak just carry spare oil in your car and top up as
necessary until you are ready to do the job properly.
if your going to do anything, then just tighten them, dont slacken them off
until the head is ready to be removed.
Steve.


  #8  
Old June 9th 06, 10:59 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...

> Less sure about this. The bolts must surely still be in the area of Hooke's
> law, otherwise mere thermal expansion and contraction of the [aluminium -
> high cte] block would damage the [steel - low cte] bolts.


I was under the impression that they were torqued past the bolt's
elastic limit. Isn't that why they're single use?


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  #9  
Old June 9th 06, 11:29 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...


"John Burns" > wrote in message
...
>> Less sure about this. The bolts must surely still be in the area of
>> Hooke's
>> law, otherwise mere thermal expansion and contraction of the [aluminium -
>> high cte] block would damage the [steel - low cte] bolts.

>
> I was under the impression that they were torqued past the bolt's
> elastic limit. Isn't that why they're single use?
>


Your're right, but they only go just into the plastic deformation area -
this is to allow for less accurate [factory] assembly and for relaxation of
the gasket after running.

It might be worth investigating whether the bolts in the failed area can be
replaced with non stretched ones.

OTOH I definitely follow the advice that if the oil leak is small and you
are not losing compression or water, then just top up.


  #10  
Old June 9th 06, 11:34 AM posted to alt.autos.bmw
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Default Oil leak through head gasket - tightening head bolts...


"R. Mark Clayton" > wrote in message
...
>
> "John Burns" > wrote in message
> ...
>>> Less sure about this. The bolts must surely still be in the area of
>>> Hooke's
>>> law, otherwise mere thermal expansion and contraction of the
>>> [aluminium -
>>> high cte] block would damage the [steel - low cte] bolts.

>>
>> I was under the impression that they were torqued past the bolt's
>> elastic limit. Isn't that why they're single use?
>>

>
> Your're right, but they only go just into the plastic deformation area -
> this is to allow for less accurate [factory] assembly and for relaxation
> of the gasket after running.
>
> It might be worth investigating whether the bolts in the failed area can
> be replaced with non stretched ones.


Ooops - but you may have to retighten them after running in.

>
> OTOH I definitely follow the advice that if the oil leak is small and you
> are not losing compression or water, then just top up.
>



 




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