Oil pressure relief valve??

[kpghia]

So I'm finally rebuilding my stock Ghia motor. Building a 1915 daily driver. As I'm putting the case back together I notice both oil pressure relief valve and the oil control valves are identical.
Neither has a slot. The Wilson book says the oil pressure valve "with the long spring, nearest the crankshaft pulley." should be slotted.
So as both had been installed previously, will it be a problem to put the valve back in or should I order a new slotted valve?
Will the oil pressure suffer with the larger motor?
How does the slot in the valve make a difference in the oil pressure?

Thanks in advance,
Kevin

[neil68]

Stock Type 1 engines had plain valves in both locations, so that is what I always use. The consensus seems to be that the Type 3 engines came with a slotted valve, and that's where they belong.

Some of the aftermarket kits come with one of each, so that's probably why we see more of them now.

I run plain valves in my 2332 cc street-strip Beetle and it runs almost as cool as a stocker

[kpghia]

Neil68,
Thanks for the reply. Just didn't make a whole lotta sense reading the Wilson book. I'll reinstall both.
On a related note, I've modified the case for full flow, tapped and plugged the case at the oil pump output galley, do I need to tap and plug the oil pump as well? Seems like overkill.
This is my first complete tear down and rebuild. This is a great forum all around.

[Marc]

The slotted plunger was first adopted in the dual-carb 1500cc Type III engine, and is therefore commonly referred to as the "1500S" plunger. It was only used in single-relief cases, and not all of them.

In the "Blue" Bentley manual (`66-`69 Beetle/`Ghia) it is stated "In the 1500 engine, from chassis 117 054 916 and engine H0 225 117, piston (plunger) of oil pressure relief valve is modified. This version of piston has annular groove, which allows oil to pass directly to the sump, relieving pressure and lowering engine oil temperature."

The photo on the same page (copyright date 1972) showing the assembly order features the earlier, non-slotted plunger; a few pages prior there's a picture showing a 1500 engine case which does feature the slotted plunger.

In the Orange manual (`70-`79 Beetle/'Ghia) which should only be covering dual-relief engine cases, Bentley used a similar picture to show the assembly order, but this one (with a later 1974 copyright date) features the slotted plunger - it would've been appropriate in the Blue manual, but has no business being in the Orange one. The picture does not show the flywheel end of the case so you can't easily tell that it's a single-relief, but if you'll look closely you'll see the small-diameter oil pickup tube characteristic of pre`70 engines. On the same page there's another picture which clearly shows a dual-relief case, with non-slotted plungers in both positions. The inclusion of the inappropriate assembly-order picture has unfortunately left many folks with the impression that a slotted plunger is a valid configuration for a dual-relief case...IT IS NOT!...

The Bentley publications are officially endorsed by VWoA, so it would seem safe to accept them as gospel - but unfortunately nobody's perfect. Evidently the Wilson writers used Bentley as their source and were also confused by that "stale" stock photo used in the Orange book.

...I've modified the case for full flow, tapped and plugged the case at the oil pump output galley, do I need to tap and plug the oil pump as well? Seems like overkill...

The intent of plugging both is to prevent pressure loss from oil seeping out between the pump body and the case - if the pump's a snug fit as it should be I agree that it shouldn't be necessary.
Ordinarily I plug only the pump, rather than the case, but that's really just a distinction without a difference. If you must use a sloppy-fitting pump it'd be a good idea to plug both (although that still doesn't address the issue of aeration caused by suction-side leakage, better to just not use such a pump).
In practice the only time I've ever found it necessary was with a Melling cast-iron pump - one more reason that I've never been fond of them.

To tap the pump deeply enough for an NPT plug to fit below flush you may need a "bottoming" tap. Common "plug" taps can be too long for the job. Personally I just use my best plug tap to do as much as it can, and grind a bit off of the end of another to cut the last couple of turns.

[kpghia]

Very nice...thanks for the reply and explanation Marc. As they say, a picture is worth a thousand words, it can also confuse a newbie when you look at the book as "gospel". I ordered a 26mm Schadek pump that is pre-tapped. I have some good pics I will try to post.

[Leatherneck]

Just don't overtighten, though JB Weld is holding strong with no leaks. lol I shouldn't laugh.