3 replies to this topic

[foreverfixin]

I’m about to begin my 998 pre A+ standard engine rebuild. The precision engineering has been done by a local expert who has also assembled the crank, rods and pistons for me. I have noticed that the oil pressure relief valve bullet seating in the block could do with a good clean (which, in retrospect, perhaps ought to have been done whilst the block was bare) before fitting a new spring and bullet. I’m sure that I’ve read somewhere that a new bullet should be lapped into the seating so the question is how to avoid any debris getting into the oil ways? Minispares lists a new seating (2A797) which is said to be internally threaded to aid removal but I don’t know if the existing is also. The next question is therefore how to remove it if renewal is considered necessary? Any advice on this topic would be greatly appreciated. Thank you in advance.

[Spider]

The standard seats aren't threaded to aid removal (The automatic ones are, but they are also a different seat).

I run a 3/8" UNC Tap in to them, then I have used a short Head Stud here, screwed the course end in to the seat, then using the fine end, a flanged head nut and some spacers, use the nut to pull the seat. They are tight and need a bit of force to remove them.

The seat is in fairly deep and the tap I have is only just long enough to reach and get about 4 or 5 threads in it. I don't have a length measurement to hand, but if you need to buy a tap, I would suggest measuring how deep it is first and being sure you end up with a tap that's long enough.

 

I actually pull the seat at the block stripping stage so that when chemically cleaned and then cleaned in the workshop just prior to assembly, the Main Oil Gallery can be cleaned, as the seat crosses it, this is why on the OD, the middle part of it is wasted.

 

As for lapping them in, it would be good workshop practice to do so, but I have to say, I've never done it. I just make sure the seat and bullet are in good order.

[KTS]

I recently pulled mine out following Spider's method (cheers!) without any drama

 

a couple of photos in the post below

 

https://www.theminif...14#entry3693367

[foreverfixin]

Thank you Spider for your reply and KTS for the link to your previous post with the photos. I’m familiar with the method described and shown as I’ve previously used similar to pull in front suspension top arm needle roller bearings and front hub bearing races. I’ve managed to find some cross section drawings of the release valve area so now understand the whole thing much better. I called in Minispares at the weekend as I was passing by Potters Bar on the M25 and at thought it best to get a new bullet seating. I’m going to have a go at cleaning up the existing seating in situ first and see how it goes. If I’m in any doubt I will be ready prepared to install the new seating. Thanks once again for your time, it’s much appreciated. Foreverfixin.