To the "brain trust". Two experienced engineer/mechanics have described the following:
When our Type IV engines are at operating temperature and rpm's exceed about 3,000 the pressure relief valve (ball bearing valve seen in the oil filter bracket) opens up and prevents or reduces oil flow through the filter. Thus, this reduces oil flow through external oil coolers attached via a "pancake" to the engine, greatly reducing there cooling effect when needed most, e.g. at the track. They have altered this valve so that it cannot open, and advised to keep rpm's low until the engine is warmed up -- particularly in cold climates. there are various ways to "plug" this valve, easy when removed from the engine, -- drill and thread a bolt with lock nut to hold the ball bearing closed, press in an aluminum plug, etc.
Two questions: 1) are there other (than too high an oil pressure with cold engine with higher rpm's) unintended consequences, and 2) can this valve be "plugged" and how, without removing the engine to get at it?

AFAIK, the only downside to disabling the bypass valve occurs if your oil filter becomes clogged somehow.
At that point you will have no oil pressure and will cook the bearings right away.
Personally, I would prefer to increase the cracking pressure of the bypass valve rather than completely disable it.
But I haven't devised a method yet.

Doesn't that valve open by oil pressure depressing a spring? Would a stronger spring help?

Yes there are heavier springs.

You can go up until you risk popping the oil filter (or cooler).

If you are generating so much heat at high RPM (high oil flow, high airflow) and still have a problem cooling, you either need a bigger cooler, thinner oil, or a dry sump system. (IMHO)

It isn't designed to be a user serviceable item.
Therefore, changing the spring is complicated.

You can totally disable the bypass valve without danger of popping the filter.

Am I miss-remembering, or doesn't the spring and ball on in through a easy to access threaded plug on the bottom of the engine.

And didn't some vendor (in the 80's at least) have upgraded springs?


EDIT:
http://www.ephotomotion.com/914engine/page08.html

It is a piston valve not a ball valve.

Keith called it a relief valve, but he described the bypass valve.
The pressure relief valve is located in the location you described.

Njay they are referring to the filter bypass ball in the oil filter console. The op obviously misstated "relief" valve.

At what pressure does that open?

a couple psi

I am referring to the valve that has a ball bearing looking "thingy" one can see when the filter is removed.

I ran my racecar for a whole season with a sandwich adapter to my oil cooler with the bypass valve in stock form.

I didnt have any trouble keeping the car cool.
(I DID get pissed however when I dumped about $40 worth of brand new Brad Penn on the floor of my garage by getting the o-ring pinched during a routine oil change)
One secret is to make the lines to the OC as large as possible to reduce pressure drop across the OC loop.

I used 12 AN to the front & back.

I have since changed to the OC adapter plate mod instead of the sandwich adapter.
(anyone need a sandwich adapter with 12AN fittings?)

Haven't started my 2056 build yet, so i looked closely at the pressed in ball seat in the oil filter console & noted that it was somewhat cocked and not pressed in fully.
The ball had very little preload from the spring. I pressed the ball seat down flush and it seemed that the spring preload was now greater. Pull your filter console off and inspect that ball seat !

This is the focus of the OP I believe:




I considered drilling & tapping the hole for a plug.
Since I run a K&P oil filter, & clean it frequently I didnt see it ever getting clogged enough to trigger that valve.

But if you have a OC loop in between the bracket and the filter and the oil is really cold and the oil doesnt want to flow towards the oil cooler (yet) I thought leaving the ball valve stock was sort of a thermostat.

This might help:

Thanks for the input and flow diagrams.

It is clear from the flow diagrams that the filter relief valve has the ability to reduce the flow to an outside in series filter and cooler that is connected directly to the stock oil filter console. This confirms the explains the experienced advice.

Unfortunately it is also clear that while there are several ways to eliminate this by pass valve function, they require removing the engine to either; 1) access the upper oil filter console nut to remove the console for modification, or 2) to connect the external filter/cooler system to the galley plugs next to the oil pump.

Question: does the oil filter relief valve in effect reduce the flow or pressure to the cooler ?

ONLY if you are using an oil cooler plumbed via a sandwich adapter from the filter bracket.

Mine will fall into that category; should I plug the filter relief valve ? Bring in So Cal where it doesn't get very cold; good ?

I've taken to pulling them out and TIGing in a plug. I'll let the oil filter do the bypassing if it needs to...

Just picked up on this topic (was away racing last time this came up).

I have a vexing oil temperature problem on my street car. Just basic driving around during the summer and my oil temperatures hit the red zone on the center console gauge, dipstick thermometer reads 260+ and oil pressure goes below 5 psi at idle. Chris installed his oil pressure relief valve and it didn't seem to make a difference. I've checked as best I can (short of pulling the engine covers) that the oil cooler is free of debris. The thermo bellows is working fine and I can hear the doors moving and whacking their stops when I actuate it manually.

In reading through this and looking at that diagram above...I'm now wondering if that filter bypass valve is either soft or mis-located? If I read that correctly, if that ball is not properly seated then it would allow oil to not only bypass the filter, but the cooler as well.

Chris mentions above that oil flow would stop if if that bypass were disable and the filter becomes plugged. However, don't all modern oil filters come with an internal bypass valve? If the filter spec'd for the T4/914 does not have an internal valve, I have to imagine you could find one with the same physical specs but with an internal bypass?

Why would we not want to take this legacy bypass valve completely out of the system and go with a modern bypass oil filter? Is this something that can be disabled while the engine is still in the car?

Greg

Edit: Just looked at Post #15 diagram again...what caught my eye was the EXTERNAL oil cooler, not the stock cooler. So then this valve doesn't appear to have an effect on stock oil cooling flow.

However, same query applies: why not replace with a filter with a bypass and disable that internal valve?

Does all the oil pass through the filter and then through the remote cooler ?