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998 Oil Pressure Valve Seat Removal


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#1 AndyR

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Posted 08 November 2019 - 04:54 PM

Hi all

 

I have a 998 a series block and head that im preparing for a winter rebuild.  Before sending it off to the machine shop i am attempting to remove the oil pressure valve seat from the block. 

 

I have tapped it to 3/8 UNF and inserted a long head stud, along with a slide hammer to remove it - like i have done on all the other engines ive rebuilt. But.......this one will not budge!

 

Ive tried heating down the oil passages and the outside of the block at the level of the seat, as well as dousing it in WD40 special penetrant, but still nothing.

 

Any ideas?

 

Andy



#2 Moke Spider

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Posted 08 November 2019 - 05:23 PM

It may have been run at some point with a Ball instead of the original Shuttle for the Valve and flared.

 

Keep at it with the Penetrate, though I prefer to wind them out with a Nut rather than a Slide Hammer.

 

If it's still no go, then I've Machined them out. I basically put a Drill Bit through them, I use one that is a little smaller that the OD of it, then collapse what's left in on itself. I prefer to do that rather than risk going on size and then having a 'moment' with it.

 

Even if you do this successfully, there's a risk the bore may already be damaged so it may need sleeving.



#3 AndyR

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Posted 08 November 2019 - 06:11 PM

Thanks Moke Spider.  Glad to hear im on the right track. I did try with a nut, but it locked up really tight, and i chickened out!

 

I fear i may have to drill it out, but i dont fancy trying to find a new one or having to make one.

 

Andy



#4 Dusky

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Posted 08 November 2019 - 06:23 PM

Put pressure on it with the nut, then use the slide hammer. If it doesnt come out then, change religion 😅

#5 AndyR

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Posted 09 November 2019 - 06:22 PM

Bit of an update.....

 

Left it overnight drenched in penetrant, and under load with a nut and large washer.  Usually works on a stubborn flywheel.  Tried it under load and with the slide hammer, heard a crack and got all excited.  Pulled the threads out the seat :xxx:

 

So, looks like im drilling it out.  Just need to build some tie downs for the drill press so it goes out straight.

 

Andy






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