Machine shop News

[JeLani]

Dropped the 885 off the other day at a local machine shop for a pressure test and Valve job/check. They called me today and my head passed the pressure test , however they told me that my Cylinder 3 valve was not making a good seal. What can I do about this? And how does this affect driveability? And i dont want it back in unless thats taken care of.. But now they just have to resurface it and I'll have it back.


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[DesertBMW]

That is an easy fix. There is a valve seat cleaning paste, you put it on the valve seat and just spin the valve around to clean the seat and then it will seal perfect.

[JeLani]

Do they just need to be re-adjusted to make sure?


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[digger]

if the valve itself is ok, you get the seat recut/reground depending on what equipment the shop has. to do this the guides need to be within spec otherwise you cant cut them properly. you dont use the lapping paste to fix leaky seats...that paste/compound is a final process to check/smooth the contact face. many people advocate not using the paste at all as you can cut a seat or grind it to seal straight off the bat and a tiny bit of the fine grit from the paste can get trapped in the seat leading to lower seat life as its hard to remove 100%

[JeLani]

to me it looks like they need to be re-adjusted. Cylinder 5 ( i think ) is the one that is stuck open, i'll give a picture of it later but they told me on the invoice that 3 of my exhaust and 3 of my intake valves failed.

[JeLani]

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[digger]

what does that show exactly? hopefully you know if the cam and rocker are installed some of the valves will always be open at any point

[jeffnhiscars]

What exactly does "valve failure" mean ?

[JeLani]

What exactly does "valve failure" mean ?

i assume a valve leak test

[JeLani]

what does that show exactly? hopefully you know if the cam and rocker are installed some of the valves will always be open at any point

Did not know:(

[digger]

why not get the shop to do a refresh?

[JeLani]

why not get the shop to do a refresh?

If by that you mean a resurface? I did get that done as well as a pressure test that checked out well

[TobyB]

No, he means a 'valve job' where they grind the seats and valves to make a nice, spanky seal.

Often, on a SOHC bmw, that means guides, too.

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