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Hole in oil pressure relief valve

Ian Slade
Wise Man
Wise Man
Posts: 791
Joined: Sat Feb 13, 2016 9:54 am
Location: Sevilla Spain

Re: Hole in oil pressure relief valve

Post by Ian Slade »

Not ft/lb just lb working on a 3" diameter bowl.
Owner since the 70's, Genghis is slightly to my left.

Christopher Storey
Helpful Person
Helpful Person
Posts: 404
Joined: Wed Mar 16, 2016 6:40 pm
Location: Cheshire

Re: Hole in oil pressure relief valve

Post by Christopher Storey »

I'm sorry, Ian, you need to explain this in words of one syllable to the simple like me :D :D

Tennant
Posts: 69
Joined: Sun Jan 20, 2019 7:13 pm
Location: Herne, Germany

Re: Hole in oil pressure relief valve

Post by Tennant »

Dropped the sump yesterday with excellent instructions from the Forum, including lifting the body off the subframe by about 5cm. Easy!
Took off one big end and one main bearing to check the size. Both are - 010.
Surprised to find the big ends like new but the "skinny" mains very worn.

Thank you for all your help so far.

Barry

Ian Slade
Wise Man
Wise Man
Posts: 791
Joined: Sat Feb 13, 2016 9:54 am
Location: Sevilla Spain

Re: Hole in oil pressure relief valve

Post by Ian Slade »

I can see no sense in increasing the oil pressure at the pump unless the pump is faulty, the pump is designed to produce about 50psi between 400 and 6000 engine rpm, the pressure is relieved to the sump at 50psi at a known flow rate, the filter is by-passed to the bearings again so as not to crush the filter, if the bearings are worn then the pressure at the bearings is unknown especially as the centre main wears first, it could be that the bearings after the centre main will have reducing pressure to possibly zero. The correct method of testing the pump is to run it at its slowest operating RPM with the outlet dead headed to a gauge, if it produces 50 psi then change the bearings and if needed a regrind, if it doesn't it's a worn pump and then remedial action can be taken at the pump to increase the pressure which may be blocking holes or increasing spring pressure, better still refurbish.
Owner since the 70's, Genghis is slightly to my left.

Tennant
Posts: 69
Joined: Sun Jan 20, 2019 7:13 pm
Location: Herne, Germany

Re: Hole in oil pressure relief valve

Post by Tennant »

Just a frustration update.
So, I removed the sump and heads. Took out one piston and was able then to order rings and bearings with gaskets etc at SNG Barratt in Holland.
That was about a month ago and SNG Barratt seems to be having - Brexit - problems and I have had to cancel today because they have not been able to deliver about half the parts.
However David Manners are also giving me a 6 week delivery on piston rings +20, but they are at least working on a solution.
A bit frustrating and the delay has meant that I have to move workshops.

I need a vacation!!

Barry

DaimlerDave
Posts: 30
Joined: Tue Mar 21, 2017 7:53 pm
Location: Wiltshire

Re: Hole in oil pressure relief valve

Post by DaimlerDave »

Hi, I was concerned about low oil pressure on my 250 saloon, I replaced the shell bearings which did help to some extent. At the same time I replaced the oil pump relief valve and spring, the old one had the drilled hole but the new replacement had no hole, part number c22756 £9.50 from David Manners. I fitted a new sender unit and gauge and checked reading against a mechanical one. I am using Moss 20W-60 engine oil. Every little step I took increased the oil pressure reading a bit. I now get 20 psi at hot idle but on a run on a hot day it will still drop to 5 psi sitting at the traffic lights, I always take it out of drive while waiting to let the revs pick up a bit.
1967 Daimler V8 250
1979 Honda CBX1000z
1974 Suzuki GT750M

Tennant
Posts: 69
Joined: Sun Jan 20, 2019 7:13 pm
Location: Herne, Germany

Re: Hole in oil pressure relief valve

Post by Tennant »

Hi Dave,
I have now ordered all parts by David Manners who seem to be very competent. They recommended also a new spring and plunger and I am gled to hear it will not have a hole. I am just waiting for the delivery, which should have been on Monday, and have spoken with DHL 8 times in the last 3 days to clarify custome problems that did not really exist, because the detailing on the Manners Invoice was perfect!!
I think that couriers and customs are just overloaded.
As you say, every liitle action helps, with the Oil Pressure on these engines.
I hope to get it back running by the end of next week (If the parts come this week).

Barry

Tennant
Posts: 69
Joined: Sun Jan 20, 2019 7:13 pm
Location: Herne, Germany

Re: Hole in oil pressure relief valve

Post by Tennant »

Wellness cure update,

So, with the help of a 3 armed dwarf with 10 inch fingers, and my son, I stripper the engine in the car and replaced the pistons, big end bearings and center mains. With a set of wonderful pair of heads that Robert Grinter overhauled for me.

I must say that if I did this again, I would remove the engine!! It would be quicker and easier.

After about 100 Km I can say that the engine seems to be oil tight, it has given up smoking and the oil pressure seems to be better and is super smooth.

However I have the feeling that a crank grind will be necessary in the not too distant future because the center mains were well worn, but for the 1000 Km / Year I use it, it should be a while.

Barry

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