Oil pressure relief valves don't fit in Auto Linea case.

Suit you, sir…suit you…

 

It's not so bad if you come to a place like this and become aware of a few things... like these naughty "uprated" springs and over sized pumps. Stuff that made it's way from the strip to hot-street because why wouldn't it and eventually Joe muggins sees "uprated" or some such and naturally thinks that must be good. The upshot is that it was a balanced system designed to bypass cool oil and let hot through the cooler. Mess about and you can find oil barely ever does more than trickle through the cooler. Tbh there isn't much else to fall foul of. Oh 4:1 headers - unbeatable on the strip, a high rev performer, not so hot otherwise.

I'll leave you to research now you're aware that it's worth the effort to have the original pump/spring/piston combo.

 

The springs are rated for force at a certain length not just length. This is necessary for the oil pressure to be controlled to something like VW expected values.
After a while the stock springs may have compressed so may need re stretching to meet length and pressure values given.
The figures are given in the VW engine manual..


As you can see the diameter is not stated.

 

Now its time to worry about camshaft thrust bearing clearance, main bearing clearances, piston ring gaps, deck height, head chamber cc etc..

 

These are the only standard size valves I've been able to find. https://www.coolairvw.co.uk/product/111115421kit/
Before I order a set I'll see if I can measure my springs under load. I may only have to get a 16mm piston. https://www.coolairvw.co.uk/product/113115411/

 

I recently had my engine rebuilt in an autolinea case and in the spec I was given by Tudor Morgan, the engine builder, it said “Make special modified oil pressure relief valves for case”. I’m
Not sure that’s much help other than to confirm it’s a thing.


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I would be interested to know what the bore of the galleries that these pistons fit into actually is, whether the problem is created by the cutting of the threads causing the metal to flow into the bore, making it seem narrower.

After all it may turn out that the solution involves a small amount of work with a round file, as there is basically no oil pressure on the big screws at the bottom of the galleries. They dont need all that thread, and they seal on the crush washer at the bottom...

Maybe I will change my oil and inspect one of my Autolinea case relief galleries with a bore gauge when I do it. Or just undo the screw over a tray and work fast. .

 

Pressure control 16mm. Pressure relief 16.5mm. The pistons out of the old engine were .5mm oversized. So I can still use the 16.5mm piston and get a new 16mm for the relief valve. I'm making a rig to check the spring lengths under compression. If they are out of spec I may as well buy a new set of standard springs and pistons.

Max, getting some custom pistons turned was one of my first thoughts. If you've got the equipment and skills to do it, it is probably quicker and cheaper than ordering new ones.

 

Update: There is a step in the bore of the relief valve in my Autolinea case. The upper section of the bore is 16.5mm, and the lower section is 16mm. My springs are still in spec so I'll fit a couple of new 16mm pistons.

 

So I am also finishing off my engine build with an Autolinea case. I had no relief pistons at all so I got the csp set which has the 16mm solid pistons. The flywheel end(short spring) doesn’t screw all the way in. Is there meant to be a shorter piston? All help gratefully received.
Cheers
John


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The springs are meant to be different AFAIR but the pistons should be the same design - if a spring is binding, the piston is not going in far enough.

If there is indeed a step in the side of the bore (see above for a comment about a 16.5 mm becoming 16mm further up .. ) , then it could be you should try to line up the piston with the smaller part of the bore.
If you have pressed it too hard with the piston cocked over slightly (by doing up a screw on a binding spring) , you may have burred the case metal slightly and it may need cleaning up before the piston will go in. Or the piston may need deburring ..

 

Maybe. I’ll check the bore, the piston is straight
J


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I think this problem arose for someone else on here recently but I can’t remember the thread