11 replies to this topic

[Lima31]

Pulling apart an engine off gumtree, with what looked like a spun No.3 main bearing. 

 

Found a welsh plug blocking off the relief valve in the oil pump, I'm thinking this needs to go ...

 

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[CI 0308]

This is one of the best info sources I have read on Holden oil pumps, Have a read. The original photos are reposted on page 7.

 

https://www.aussiev8...rmance-use.html

Edited by CI 0308, 02 October 2018 - 05:05 PM.

[grumpy xu1]

This is one of the best info sources I have read on Holden oil pumps, Have a read. The original photos are reposted on page 7.
 
https://www.aussiev8...rmance-use.html

Tony is a very knowledgeable guy, good information in there !

[ozyozyozy]

Blocking the bypass valve is common on the performance engines it forces ALL the oil to go through the filter, which is a good thing.
The bypass is not just for when filters are plugged, also for when people give the engine a rev on cold starts, the thick oil cant pass through the oil filter fast enough.
Downside to blocking bypass, big rev on cold start, blows the seal on the oil filter or splits a cheap filter.

[Lima31]

I understand about blocking the bypass, but I've shown someone blocking the relief valve, it still had the bypass valve.  That thread by TK383 is brilliant but it didn't discuss blocking off the relief valve.

[ozyozyozy]

Its been a while and i dont have one to look at(using a different setup), its def a plug for the relief? Not a plug for casting
If that is for the relief then its a stupid thing to do, must have been having pressure issues, hence spun a bearing.

Edited by ozyozyozy, 05 October 2018 - 10:50 PM.

[Lima31]

No probs, I had to double check myself.

[Lima31]

As a follow up the other thread doesn't cover in a lot of detail rerouting the relief valve.

 

The relief valve regulates pressure, so that during operation it will likely be partially open.  That's a problem because it allows unfiltered oil to bypass the filter.  The welsh plug that was originally put in mine sent all the unfiltered oil directly past the filter, this mod forces it all through the filter.

 

I through tapped that hole and put a grub screw at the bottom as recommended, others use M12 x 1.0 or 1/2 UNC.  I used 1/4 NPT which is tapered such that the grub screw can't work out of the bottom and block the outlet.  Used locktite anyway.

 

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I figure that the grub screw semi-blocks the relief valve piston on the pressure side which should increase oil pressure, so I didn't bother shimming the spring like others.

 

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Also the thread suggests a 21 mm welsh plug, mine was off a late 1990s cast steel oil pump housing, that needs a 20 mm plug.  Used a small amount of sealant around the lip to be sure.

 

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[kavesh]

Sorry to bring up an old thread, just to be clear after the hole was tapped through, a grub screw was put in and screwed all the way to the bottom? I assume the spring would push up against therefore no need to shim the spring?

[Lima31]

Yes to the bottom of the hole, but not so far as to block the passage from the centre of the oil filter if you know what I mean.

 

The spring is in the section to the side, and shimmed to increase preload and pressure to open / reduce pump pressure.  You probably could shim it, or use a tapped thread and bolt behind it as suggested by TK383 to change preload.  I didn't shim it because I've partially blocked the passage that pushes the spring back, which might have the same effect.

[kavesh]

Yes to the bottom of the hole, but not so far as to block the passage from the centre of the oil filter if you know what I mean.

 

The spring is in the section to the side, and shimmed to increase preload and pressure to open / reduce pump pressure.  You probably could shim it, or use a tapped thread and bolt behind it as suggested by TK383 to change preload.  I didn't shim it because I've partially blocked the passage that pushes the spring back, which might have the same effect.

So as long as i shim the spring I dont need to worry about tapping and inserting a grub screw?

[Lima31]

So as long as i shim the spring I dont need to worry about tapping and inserting a grub screw?

 

Well I didn't shim the spring because the grub screw I used partially blocks that passage. But technically they do different things.  

 

Shimming the spring increases its preload and makes it harder to open that relief passage so increases the pump oil pressure level. 

 

Tapping and inserting a grub screw as shown above is more about ensuring oil can't return to the engine without going through the filter first.