oil pressure relief valves

oil pressure relief valves

Author
Discussion

PAUL GOTTS

Original Poster:

4,103 posts

269 months

Thursday 11th July 2002
quotequote all
After experiencing a stuck oil pressure relief valve for the second time in two years at Zolder recently (unfortunately coupled with the breakage of the distributor shaft drive to the oil pump gear) on my 4.3 Wedge, I can understand why some see this as something of a design fault. Heat seems to be a contributory factor in the steel valve sticking in its alloy housing. It may also be possible for a small piece of debris in the oil to have the same effect. Now I know that people like JE use a modded tadpole valve to overcome this potential seizure, but I remember at least one member of the national e-group warning me off using them the first time this happened to me, citing this as the cause of a wrecked engine. Does anyone have experience of the effectiveness or otherwise of these valves, or any other mod. to the housing itself to overcome this problem, as I'm now getting a bit paranoid.

Paul and a 400SE which has arrived back in UK today from the Zolder meeting, courtesy of the wonderful AA Five Star Recovery service - just under two weeks to cover 200 miles……….Won't be using them again.

JMorgan

36,010 posts

291 months

Thursday 11th July 2002
quotequote all
Mine was replaced during a little work I had done and was recomended by the builder.

Danny Hoffman

1,617 posts

269 months

Thursday 11th July 2002
quotequote all
Don't do it - I had a nightmare with the tadpole mod, wrecked engine etc. Just get an original new pump cover and valve. You may want to fit the modified end plug which allows you to adjust the oil pressure.

If you want a backup to get you home in the event of the pump becoming un-primed, I suggest a tool to wind up the pump through the distributor drive and an electric drill (battery job)

Danny

JMorgan

36,010 posts

291 months

Thursday 11th July 2002
quotequote all
Just checking my report and it seems the base plate was uprated as well. Does that improve things?
As I understand it it it allows oil in certain conditions to return to the sump, not via the motor, as in very high pressure situations?

Wedg1e

26,875 posts

272 months

Friday 12th July 2002
quotequote all
Paul:
I rebuilt my 390s engine a few weeks ago and contemplated the pressure relief valve whilst it was stripped! I used a slipstone to take the sharp edges off the valve plunger and the casting, but there were some score marks in the housing where debris had obviously been swept around by the vanes. I couldn't work out whether the pump's internal mesh filter would be effective at keeping crud out of the relief valve though. I guess the only truly effective fix for a scored housing is a new one, but at 400-odd quid, I left mine on!
ONe other mod you can make to the valve is to fit an uprated spring from Rimmer Bro's et al, that's supposed to up the pressure by 10 psi. Worth every penny of the three quid they want!
Incidentally, are you the same Paul Gotts as featured (with 350i) in Autocar in August '92?! I have the article reprinted by Transport Source Books, and the name rang a bell... ;-)

Ian

danny hoffman

1,617 posts

269 months

Friday 12th July 2002
quotequote all
For base plate upgrade, I think you mean machine away as much of the casting as possible (just leaving enough to stop the valve dropping out completely). The thinking is, I believe, less surface area for the valve to rub against = less chance of it jamming.

A new cover which included the valve housing isn't that expensive (less than £100 from memory), I think Ian is referring to the pump housing which is normally "reconditioned" by polishing the internal surface with very fine sand paper. Also go for the adjustable pressure mod, it's only a few £s more than the uprated spring - or if have access ta a lathe you could make one yourself in a few minutes. In fact didn't you say picked up a lathe recently Ian?

Danny

PAUL GOTTS

Original Poster:

4,103 posts

269 months

Friday 12th July 2002
quotequote all
quote:
One and the same - we ran that car for 7 years, mostly as our only car - more reliable than the 4.3 but definitely not as much fun to drive or to listen to as the bigger wedge. Last time I replaced the pump cover, gears, valve etc. (with new parts) it was about £35.
Paul:
I rebuilt my 390s engine a few weeks ago and contemplated the pressure relief valve whilst it was stripped! I used a slipstone to take the sharp edges off the valve plunger and the casting, but there were some score marks in the housing where debris had obviously been swept around by the vanes. I couldn't work out whether the pump's internal mesh filter would be effective at keeping crud out of the relief valve though. I guess the only truly effective fix for a scored housing is a new one, but at 400-odd quid, I left mine on!
ONe other mod you can make to the valve is to fit an uprated spring from Rimmer Bro's et al, that's supposed to up the pressure by 10 psi. Worth every penny of the three quid they want!
Incidentally, are you the same Paul Gotts as featured (with 350i) in Autocar in August '92?! I have the article reprinted by Transport Source Books, and the name rang a bell... ;-)

Ian


Wedg1e

26,875 posts

272 months

Saturday 13th July 2002
quotequote all
The housing I referred to is the main timing cover; this is what the pump gears spin in. Obviously they need to be a good fit in their chambers to be efficient, mine has some scores that 'must' reduce the efficiency to some extent. But it still works.
Yes, Danny, I bought an ancient lathe last year. Then the wife decided to evict me (and the lathe, TVR and everything else! ;-) so it's been in a pile of bits in the garage since January. I will put it back together some day. First I need to decide which bit of the garage is sinking the slowest so I can best site it...!
Paul: what's the old saying.... I know the name, I just can't think of the face.....

Ian