^^^ what he said, but I'd start with perhaps a little heat to see if yoy can get it to pop out without resorting to a hammer.

Give the spring a good inspection, as well as the valve - and use a mirror and light to verify there isn't any swarf or crud in the base of the hole holding the valve open...

If all looks good, I'd consider shimming the spring slightly (don't try stretching it, that is called yeilding and is bogus). Something so simple as a washer will do it. Start with something around 80-thou thick and see how that works out.

 

Its been a couple weeks since I last worked on my rover. Tore it down again today simply because I could not get that blasted relief valve out. Took it out, no scoring from what I can tell. Pulled Front and rod bearings. From the looks of it they dont look all that bad. It has 105K miles on it.

From looking at the pictures does anyone know if this is enough wear to cause virtually zero oil pressure when hot? Tried to wiggle the crank, didn't budge so I'm assuming the main bearings are about the same wear as these. Pretty tight from my perspective.

If the bearings arn't the issue and the valve isnt' the issue...what is left???

Any help would be great. Thanks

 

Pressure relief valve......anyone see any issues I'm not?

 

I am having the same issue as you. I replaced rod bearing, crank bearings, oil sending unit, checked the pressure relief valve...Can not think of where to go next. let me know what you try next. I will update you if I have any luck on this end.

 

Have you actually removed the valve in these pictures or just the snap ring, cap and spring?

 

I think I removed everything.....is this little gem the valve? Also there is another tube on the timing cover with a snap right and cap..any idea what that is?

 

What is the purpose of the relief valve?
Guessing - that if oil pressure is too high the valve triggers and bypasses the filter??

 

The purpose of the relief valve is exactly that - to dump off excessive flow. The pump is sized based on the oil viscosity, idle speed, and known flow at various parameters, and then given a safety margin of approx 50% at the "worse case" (almost always hot idle). Hence a pump turning at 800 rpm has potential to pump (say) 1 litre/min (but the engine probably only needs 0.5 litre/min however)....

Increasing engine speed to 2000 rpm, it is probably able to deliver something in the region of 2 litre/min; 4000 rpm would deliver approx 4litre/min, and so on...

The engine however, doesn't typically demand a lot more oil as rpm increases - it does increase, but nothing like a 1:1 ratio, more like 10 or 20%.
So, you have a relief valve to modulate the pressure, so that at the higher flow potential of the pump it dumps off the extra flow.
The valve is positioned immediately after the pump - and is basically a plunger acting against a spring. As the pump pumps, so it delivers more volume than can be squeezed out of the various "leak points" such as main bearings, cam journals, lifter galleries, rockers, etc. When the pump delivers greater flow than the "leak" so a pressure is created. When the pressure in the line increases to a set point, the plunger will be forced back against the spring. Adjacent to the plunger is a hole that dumps the excess oil back into the sump pan.
In reality however, especially with a multi-tooth gerotor there is an equilibrium that the plunger basicallyt ends up staying open at a set point. As RPM increases, hence flow increases, and hence therefore pressure goes up, becuase the "leak" has not sinificantly increased wrt rpm - so the plunger will likely be open a little more (and dump off more fluid) as the revs climb.



While you have the pump off, you need to take a look at the axial clearances. Spray the cover and gerotor down with brake cleaner, and set the gerotor into the front cover. Now put a straight edge over the cover (on the surface that the pump cover mates with). Then put a feeler gauge between the straight edge and the gerotor assy and measure the gap. The optimal gap would be between 2 or 4 thou. An acceptable gap is probably 6, maybe 7 thou absolute max. EDIT - SPEC FROM MANUAL STATES 4 THOU MAXIMUM AXIAL CLEARANCE!
Anything more than this is not acceptable. Move the straight edge around a few different locations and see how it looks.
If you do have an excessive gap, there are a few reasons: 1) Your replacement gerotor is too thin, 2) The pocket in the front cover is too deep, either because it's worn or Rover never made it propely in the first place!
Either one, is actually pretty easy for someone with a milling machine (like a machine shop) to fix - they just have to set it up in the mill, level the front cover using an indicator and shimming it, and then machine enough from the backplate mounting face until you have just a few thou of clearance between the mounting face and gerotor.

Here is an image I just found for checking axial clearance in a Powerstroke oil pump:
http://www.thedieselstop.com/faq/949...j/stj31d61.htm

Here is another link that I just found googling for images of oil pump clearance:
http://www.autozone.com/autozone/rep...96b43f8037c630




If your cover is fine however, then I think the goal here is obviously to raise oil pressure as it is currently too low. Sure, there might well be a problem elsewhere, but you don't know if your relief valve spring is a little weak, and hence opening too early and dumping off excess oil. I haven't seen a spring length in the manuals, so you might want to just assume yours is weak and work in this area for now. EDIT - SPRING FREE LENGTH SHOULD BE 60MM (2.362")

First, measure the free-length of the spring and post this up as a reference for others.

Easiest way to shim the spring (add pre-load to the relief valve), is to find some washers the same OD as the spring, and then re-assemble the relief valve assy with the new "shims". Start with packing out to 0.08" and see how that works out. Basically, you are compressing the spring more, hence the valve will not crack open until a higher pressure is reached.

DON'T be tempted to "stretch" your current spring. If you can succesfully stretch a spring, you have yeilded it, pure and simple - in other words, it is now f*&%ed.

What this exercise might end up doing however, is raising your baseline pressure at higher rpm, maybe to something like 40, maybe 45psi.
The only downside to this higher pressure, is that you are wasting energy by making the pump work harder - but you won't exactly notice losing 1% in fuel economy now will you?
Beware though,go too high (like 55+ psi) and strange things will start happening with the lifters - so you need to pick a happy medium that works all around.


EDIT - just found that the 4.0 / 4.6 manual does have figures for axial wear and spring length. These are shown in red above!

 

BTW - it doesn't look like the srping is available seperately. If yours is a lot lower than the 2.362", it might be worth finding a spare cover and stealing the spring from that.

 

Did you change out your timing cover and oil pump as well?