Too much pressure?
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
By using this site, you agree to our rules. Please see: Terms of Use
-
- Minor Legend
- Posts: 1460
- Joined: Sun Sep 25, 2011 6:32 pm
- Location: Clacton On Sea, Essex, ENGLAND.
- MMOC Member: Yes
Too much pressure?
Hi Folks,
After renewing the oil pressure relief valve system using ball bearing and spring instead of the bullet type that came out I notice on startup that the oil pressure reading is off the scale on the gauge but does drop back on warm up.
Is this acceptable or should I go back to the original bullet and spring system?
After renewing the oil pressure relief valve system using ball bearing and spring instead of the bullet type that came out I notice on startup that the oil pressure reading is off the scale on the gauge but does drop back on warm up.
Is this acceptable or should I go back to the original bullet and spring system?
-
- Moderator
- Posts: 7679
- Joined: Fri Nov 01, 2002 2:55 pm
- Location: LEAMINGTON SPA
- MMOC Member: No
Re: Too much pressure?
The relief valve is there to limit the max pressure when the oil is cold.
If you're going off scale, then it needs to be fixed.
If you're going off scale, then it needs to be fixed.
Ray. MMOC#47368. Forum moderator.
Jan 06: The Minor SII Africa adventure: http://www.minor-detour.com
Oct 06: back from Dresden with my Trabant 601 Kombi
Jan 07: back from a month thru North Africa (via Timbuktu) in a S3 Landy
June 07 - back from Zwickau Trabi Treffen
Aug 07 & Aug 08 - back from the Lands End to Orkney in 71 pickup
Sept 2010 - finally gave up breaking down in a SII Landy...
where to break down next?
2013... managed to seize my 1275 just by driving it round the block
Jan 06: The Minor SII Africa adventure: http://www.minor-detour.com
Oct 06: back from Dresden with my Trabant 601 Kombi
Jan 07: back from a month thru North Africa (via Timbuktu) in a S3 Landy
June 07 - back from Zwickau Trabi Treffen
Aug 07 & Aug 08 - back from the Lands End to Orkney in 71 pickup
Sept 2010 - finally gave up breaking down in a SII Landy...
where to break down next?
2013... managed to seize my 1275 just by driving it round the block
-
- Minor Legend
- Posts: 1092
- Joined: Sat Mar 14, 2009 2:50 am
- Location: Red Deer, Alberta, Canada
- MMOC Member: No
Re: Too much pressure?
What's the top of scale on your gauge?
Have you checked your gauge for accuracy against a known good gauge?
Have you checked your gauge for accuracy against a known good gauge?
Talk slow, think fast!
-
- Minor Legend
- Posts: 1460
- Joined: Sun Sep 25, 2011 6:32 pm
- Location: Clacton On Sea, Essex, ENGLAND.
- MMOC Member: Yes
Re: Too much pressure?
Max reading on the gauge is 80psi,
pressure relief should operate at 60psi although I have read on this forum of engines running at 80psi fully warmed up!
Just need to know if excessive oil pressure would cause damage.
pressure relief should operate at 60psi although I have read on this forum of engines running at 80psi fully warmed up!
Just need to know if excessive oil pressure would cause damage.
Re: Too much pressure?
One night the pressure relief valve jammed shut on mine. The engine felt laboured and the gauge, up to 100 psi, was as high as it could go. I stopped the motor and on restarting it was ok again. Drove home, keeping a close eye on the gauge.
The next day the results were a small bit of grit in the valve and a leaking gasket between the oil filter housing and block.
The next day the results were a small bit of grit in the valve and a leaking gasket between the oil filter housing and block.
Re: Too much pressure?
If the gauge has been pushed beyond the top reading - it will no longer be accurate. Why did you fit the ball?? This is a competition modification (I did it on my race/rally engines) - but yes the spring needs to be shortened - simply because the ball is 'thicker' than the bullet when installed. 70 psi is plenty pressure when hot - the ball should be able to dump enough oil to have no more than 90/100 psi when cold - but of course - you must never 'rev' a cold engine.
-
- Minor Legend
- Posts: 1460
- Joined: Sun Sep 25, 2011 6:32 pm
- Location: Clacton On Sea, Essex, ENGLAND.
- MMOC Member: Yes
Re: Too much pressure?
Thanks Roy, Got the ball from ESM thinking that it would seat better than the bullet, as you rightly say the ball puts more pressure on the spring which was why I had a bit of a job refitting the valve system.
I have now ordered a new bullet to replace the original one and will be refitting the valve when time and weather permit.
I have now ordered a new bullet to replace the original one and will be refitting the valve when time and weather permit.
-
- Minor Maniac
- Posts: 10907
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Too much pressure?
When using the ball bearing instead of the standard plunger (Pt No: 12H865) you should use shorter and stronger spring (Pt No: AEA536) which has a free length of 66mm. Original oil pressure relief valve spring (Pt No: 6K853) has a free length of 73mm and is much weaker.
If finer control of the max oil pressure is required then use an adjustable pressure cap instead of the standard cap (Pt No: 12A1851). Adjustable pressure caps are available from the majority of 'A' Series Tuning Firms
If finer control of the max oil pressure is required then use an adjustable pressure cap instead of the standard cap (Pt No: 12A1851). Adjustable pressure caps are available from the majority of 'A' Series Tuning Firms
Last edited by philthehill on Sat Jan 26, 2013 4:59 pm, edited 1 time in total.
Re: Too much pressure?
The AEA 536 spring was specified for the S - but it will still be too strong for a ball..... Just cut a coil or two off the standard spring. it works !
-
- Minor Maniac
- Posts: 10907
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Too much pressure?
If you are determined to cut the spring make sure that it is the remaining correctly formed end that sits on the ball bearing and the cut end sits inside the cap.
Re: Too much pressure?
Indeed yes - I should have added that! Thanks Phil. I have tried the S spring in the past - and it still put the gauge off the clock when cold - which of course ruins the gauge.....
-
- Minor Maniac
- Posts: 7845
- Joined: Thu Jan 25, 2007 3:18 pm
- Location: South East London
- MMOC Member: No
Re: Too much pressure?
Just use the standard bullet, it works fine.
Remember if it ain't broke ..........
Remember if it ain't broke ..........
"Once you break something you will see how it was put together"
Re: Too much pressure?
I agree for a road car. But I used the ball in my comp engines because there is virtually NO chance of it ever sticking....
-
- Minor Maniac
- Posts: 10907
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Too much pressure?
Idealy when fitting a new oil pressure relief valve it should be lightly lapped in. Great care should be taken to ensure that the lapping paste DOES NOT get into the oil ways. BMC reccommended using Oil Pump Relief Valve Grinding Tool Pt No: 18G69 specificaly for the lapping of the relief valve but a piece of suitable hose pipe inserted into the valve will surfice. Make sure that all traces of lapping paste are removed from the valve seat, the valve and housing before fitting the valve and not forgetting to put a new washer under the cap.
Re: Too much pressure?
The dowel handle of the valve grinding tool - with a twist of tape added - fits tightly in the valve.... Ball saves all that hassle!
Last edited by bmcecosse on Sun Jan 27, 2013 11:40 am, edited 1 time in total.
-
- Minor Legend
- Posts: 1460
- Joined: Sun Sep 25, 2011 6:32 pm
- Location: Clacton On Sea, Essex, ENGLAND.
- MMOC Member: Yes
Re: Too much pressure?
I agree, I believe I will just clip the spring!bmcecosse wrote:The dowel handle of the valve grinding too - with a twist of tape added - fits tightly in the valve.... Ball saves all that hassle!