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Oil pressure relief valve problem?
https://ausmini.com/forums/viewtopic.php?f=2&t=96777		 Page 1 of 1
Author:  deluxe67 [ Fri Feb 09, 2018 1:37 pm ]
Post subject:  Oil pressure relief valve problem?
Hi all, need some help...

Lately upon start up it's been taking longer and longer for the oil pressure light to go out and the oil pressure guage to swing up to 75 psi. It's now taking maybe 20 seconds, which I feel is just not right. (no fresh lube to the bearings for that long cannot be a good thing?).
I figured it was probably a problem with the relief valve so I removed the hex nut with spring to find a ball bearing inside rather than the proper relief valve. I don't recall doing that but I've had the engine for 30 odd years so it must have been me. Why would I have done that?
Here's the thing, when I cranked the engine over I was expecting the ball to fly out but it doesn't. It just sits there.
When the engine is cold and running the oil pump delivers 75 psi so the pump itself must be good but why the delay in delivering pressure? It's like the oil has drained away somewhere, but how and why? I'm a bit stumped. I'm not using an oil cooler, just the standard setup to a spin on oil filter.
Any ideas would be much appreciated.
I won't be using the car until I've sorted it. I have no idea if 0 pressure for 20 seconds or so is/ will cause damage..?

Edit: After an hours driving when everything is hot I get about 60 psi at 100 km/h and 25-30 at idle. If the bearings were worn would I get 75 psi on start up but those pressures when hot? The engine has probably done 20,000 km max since a full rebuild.

Thanks

Michael
Author:  timmy201 [ Fri Feb 09, 2018 1:42 pm ]
Post subject:  Re: Oil pressure relief valve problem?
The ball bearing type:
http://www.minispares.com/product/Class ... 36KIT.aspx
Regular type
http://www.minispares.com/product/Class ... 53KIT.aspx
Author:  deluxe67 [ Fri Feb 09, 2018 2:06 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Thanks for the links timmy but they don't really give me any answers to what is going on..
Minispares say the ball type is to "boost oil pressure". I've never had an oil pressure problem with any of my cars so no idea why I have the bearing type. I just got it out, kept cranking the engine. Of course oil went everywhere despite stuffing heaps of rags in there. It would seem the pump is ok...
Author:  winabbey [ Fri Feb 09, 2018 3:27 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Sorry, can't help with the problem diagnosis, but replacing the plunger with a steel ball is seen as a way to avoid the plunger getting stuck in the bore due to a bit of swarf.

For what it's worth, here's the method DocMini described in another post.

1. Make sure the spring is straight, or get a new Cooper S one.

2. Pinch a CV ball (9/16") or go buy a new one from a bearing shop.

3. Grind a chamfer inside the best end of the spring so it sits on the ball better. I use a pointed stone in the die grinder. It's not essential if you can't do it.

4. Cut a piece of smooth 5/16" or 8.0m steel rod 40mm long, deburr the ends and put it inside the spring. This stops the spring bending and pushing the ball sideways off the seat (with instant oil pressure drop).

5. Remove the old relief valve plunger. I use a 10mm dynabolt, put it inside the plunger and then do the nut up a bit. Then you have a handle to pull the sucker out with. But sometimes they come out easy with your finger (if the right size).

6. Assemble it all into the valve, refit the cap, start engine and check pressure. If it's too high, trim 2mm or more off the outer end of the spring.
I run mine @ 70-75psi hot from 2500rpm up. Cold, it's ~90psi... :D
Author:  drmini in aust [ Fri Feb 09, 2018 3:42 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Or just fit a new plunger instead. The ball can be more trouble than its worth. Its only benefit is it seats better at idle.
Author:  1071 S [ Fri Feb 09, 2018 3:44 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Or maybe easier to just get (borrow) a proper spring/plunger, install and see what happens. I don't think it matters what kind of OEM unit you use. If the S one provides extra pressure (not as far as I know but....) then it won't matter as any pressure will show if this is your problem.

Pressure is easily reduced by fitting a spare sump plug washer (or 2 or 3 to taste) under the relief valve cap.

Increased pressure requires a few washers installed inside the relief valve cap (between the cap and the spring). Unfortunately I can't advise on the internal washer size as I've not had to do this.

Even with a replacement plunger I would be making sure the seat (and plunger bore) is clean before installing the plunger...

Cheers, Ian
Author:  phillb [ Fri Feb 09, 2018 4:09 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Going back to the original posters question. I also find if I have not run my car for a while (eg 2-3 weeks) there is a delay in the pressure coming up. Never as long as 20 seconds but definitely a delay. I’m also interested as to why this would occur and is there a risk of damage. If I change the oil I tend to spin the motor with no plugs till I see pressure because I know the filter will be empty.

My pressures are always pretty good. 75 cold 70-75 at speed hot and 20-25 hot idle.



Sent from my iPhone using Tapatalk
Author:  deluxe67 [ Fri Feb 09, 2018 4:37 pm ]
Post subject:  Re: Oil pressure relief valve problem?
Thanks for your tips Doug.

But it already has the ball bearing instead of the standard relief valve. The spring looks good and straight.

I don't have the equipment to do the other things you suggested.

When I removed the spring, the ball was snug down the end of the bore so I still don't understand how/ where the oil is draining to when the engine is off.. Something weird is going on...

Do you think I'm risking/ doing damage if the engine runs for 20 s without pressure?

Thanks

Michael
Author:  simon k [ Fri Feb 09, 2018 5:32 pm ]
Post subject:  Re: Oil pressure relief valve problem?
deluxe67 wrote:
I still don't understand how/ where the oil is draining to when the engine is off.. Something weird is going on...


the oil will drain back into the sump while the engine is off, maybe not all of it, but I'd expect the galleries that feed the crank to drain at least a bit

when cranking using the starter motor, the oil pressure will come up eventually, but never straight away, it takes time to bring it up through everything and pressurise the system

I think if I was you take the oil pressure light/gauge fitting out, then I'd take the plugs out and crank it over with the starter until oil comes out of the oil pressure light/fitting hole. I'd put my thumb over it and feel how much pressure was there. Then I'd probably put it back together and run the engine till it was warm, then turn it off, and repeat the test - just to see if I could tell any difference - then maybe I'd leave it an hour or two and do it again

it could just be that there's some crap in the oil pressure light/gauge fitting and it's getting in the way...
Author:  miniron [ Sat Feb 10, 2018 5:41 pm ]
Post subject:  Re: Oil pressure relief valve problem?
If you fit a new relief valve it's a good idea to lap the valve onto the seat as well as clean up any marks on the seat.
A piece of dowel that is a tight fit inside the valve and some fine valve grinding paste do the trick.
Use bearing blue to check the final result. A nice clean line around the tapered face of the valve and seat is what you need to aim for.
Don't forget to clean off the residual grinding paste.
The valve and seat can wear and bits of your gearbox can damage or scratch the valve and seat as well.
They don't do your oil pump much good either.
I always check the valve and seat at each rebuild and find there is some wear so it gets lapped onto the seat.
I've never seen this but apparently the actual seat is pressed into the block during the manufacturing process and some have found it has come loose.
Always check the valve bore for anything unusual.
The first S I had back in 66 had low oil pressure at idle when hot from new, almost zero psi. The dealer, or dealers in this case, fitted new oil pumps, relief valves, springs etc and whatever else dealers do and the only way it was fixed was when I did the first rebuild.
The valve was not sealing all the way round as the wear mark was only on one side of the valve. No wonder it didn't have any oil pressure. I lapped it in and all was ok. 50 psi hot and 85+ psi when cold.
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