22 replies to this topic

[Spitz]

Related to a previous thread
http://www.theminifo...howtopic=119081

I had low oil pressure, so I wanted to replace the stock pressure relief valve plunger with a ball bearing.
I pull the spring out and get a magnet in there to get the plunger out....out comes a ball bearing !

OK...I think..crap. But it looks fairly small, measures .53" (13.45mm)
A stock plunger diameter is .6" (15.47mm) so I try one from another motor. Oil pressure comes up somewhat.

Someone else mentioned to use a CV ball. I try that....too big for the hole (goes in a bit then there seems to be a ridge) CV ball measures .655" (16.6mm)

What size steel ball is needed??

Thanks

Edited by Spitz, 19 March 2009 - 01:09 AM.

[Ethel]

the CV ball is right 9/16" You may well have to shorten the spring to get the pressure right.

[Spitz]

Ethel,
I tried putting the CV ball in a parts motor (in case it was going to get stuck, didn't want it in the good one).
Goes in a bit, and then held up by a ridge or something. I didn't want to push hard in case it were to get stuck.

Edited by Spitz, 19 March 2009 - 03:09 AM.

[GraemeC]

I believe there are two different sizes of 'pot joint' CV balls. One is certainly too big (5/8" I think).

[mini_turbo_pete]

It's the outer CV joint ball you want, i've used loads of these and never had a problem. there is no difference in size between the balls on drum or disk break outer cv joints so aither will do the trick

[Guess-Works.com]

9/16" is the one you want.....

Have a tray of them here which I have scavenged over the years...

[Spitz]

Thanks
Will pick up a 9/16" ball today

[Spitz]

Update.....
This is strange.

Ok..I could not find a 9/16 ball anywhere in town, so I broke down and salvaged a ball from a back-up outer CV.
I warmed up the car.
Removed the stock tapered cup and spring.
Put the ball in place......I thought I'd try it without cutting the spring first.

Started it up and my pressure is very low...lower than with the stock set-up/
What could cause this?
Thanks

[Guess-Works.com]

have you chopped loops off the spring, if so how many... ?

Sorry it's early here, and re-read the above.. you havn't removed ANY coils...

I'm very surprised you actually managed to get the dome cap back on...

And yes it's strange...

Edited by GuessWorks.co.uk, 20 March 2009 - 05:37 AM.

[Spitz]

have you chopped loops off the spring, if so how many... ?

Sorry it's early here, and re-read the above.. you havn't removed ANY coils...

I'm very surprised you actually managed to get the dome cap back on...

And yes it's strange...

Any ideas on what the problem may be?
I'd be interested to see a cut-a-way view of this area to see where the ball is going in to.
I too was surprised the dome nut went on....it didn't seem to be a problem at all. Is there something in there that may have "broken" or dislodged perhaps>

So bottom line....I'm not sure if something is up with my oil pump or the relief valve area.
After warmed up my pressure at 3000rpm is about 40lb. (when I tried the ball it was about 25lb)

Last week this motor was about 70lb
No leaks anywwhere (I know, hard to believe but true)

[Jordie]

Try an adjustable kit from minispares.

You could make one by drilling and tapping the domed nut, but the kit is fairly cheap anyway...

[Dan]

The ball sits against a valve seat which is a kind of bobbin shaped steel insert. It's there because the pressure relief tapping crosses an oil gallery tapping and the insert keeps the two tappings seperate and provides the seat. It could be that something has happened to the insert but I've never heard of that happening in any engine. It looks like this:



(image borrowed from our kind sponsors). You can see how the outer relief of the insert allows oil to flow past the outside of it to an oil gallery while the inside is the valve seat and remains a seperate channel.

[Jammy]

Am I right in thinking that there shouldn't have been a ball in there to begin with, as standard. Might suggest that a previous owner has already changed the plunger for a ball bearing, cut off a couple of coils from the spring, and now this spring is useless with this new ball?

[Spitz]

The ball sits against a valve seat which is a kind of bobbin shaped steel insert. It's there because the pressure relief tapping crosses an oil gallery tapping and the insert keeps the two tappings seperate and provides the seat. It could be that something has happened to the insert but I've never heard of that happening in any engine. It looks like this:



(image borrowed from our kind sponsors). You can see how the outer relief of the insert allows oil to flow past the outside of it to an oil gallery while the inside is the valve seat and remains a seperate channel.

Thanks for the image......not clear to m though how it works.

Heres the story.
Oil pressure was good one day...not the next.
Pulled out the relief valve spring and low and behold..there is a ball in there, but a small one..only about 1/2" diameter
Tried a stock plunger in there and it brought the pressure up a bit.
tried the CV ball with uncut spring...pressure is lower. Like Guessworks said, I should have had trouble getting the nut back on due to alot more spring pressure.

The spring is stoc length, I compared to two others (2.8" I think it is) Could something have "broken" inside?

Confused here

[Mattl]

Maybe its not the PRV?