Oil pressure problem

From: abarbou@ista.fr
Date: Thu, 19 Nov 1998 15:27:59 +0100
Subject: [imps] Oil pressure problem.

When I got my 66 MK2 Imp witha sport engine ,the seller told me "the oil electric pressure gauge indicates a low pressure but the engine run well"
That's right . In fact, when the engine is cold, the pressure grow up to 3bars then after 3 minutes it fall down to 0.5bars. No strange noise, no pressure light on .
I use Elf competition 10/40 oil.
I thank that it was the gauge in case . At St.andrew's national , I buy to Malcolm Anderson 's workshop a new mechanic gauge . After installed it on the car, it's always the same , no pressure !! ! !.
This year, I'd done many rallies,without any problems , but I know, it's not normal
I measured the oil pump clearances, all is OK.
With the electric, the warning light and the oil pressure gauge were fitting on the connection point n7 like it's draw in the wokshop manual page 15
Now with the mechanic the gauge is always onthe point n7, and the warning light on the point n°8.
Never the warning lignt on even at low rev, 800r/mn.It 's light just when I start the engine.
When the engine is warm, even at 6000r/mn, the pressure is 0.5bars ! I wonder where is the disfonctionnement !
If one of the readers as any idea, please answer me using no so complicated words, I just learn English , when I was student.
Thank 's for advance
The poor alone french Imper ! don't cry !

Date: Thu, 19 Nov 1998 07:17:43 -0700
From: Dave Edge
Subject: [imps] Re: Oil pressure problem


I suggest you buy a new oil pressure warning light to prove that you are doing no damage. I can only think of one reason for your low pressure: Because the pressure never increases above 0.5, this must be where the relief valve in the oil pump block is letting it go back to the sump. I don't know how you check the pressure relief valve.

Good Luck
(Votre Anglais est meilleur que mon Francais)

From: Hawes
Date: Thu, 19 Nov 1998 20:17:33 -0000
Subject: [imps] Re: Oil pressure problem

Bonjour Alain

You put us Brits to shame. My sons would never try to write in French or German even having got their GCSE's in both languages, let alone speak!!!!!!!!

From: Gary Henderson
Date: Fri, 20 Nov 1998 09:02:46 +1300
Subject: [imps] Re: Oil pressure problem

Hi Alain

I haven't had this with my Imp, but I did have a similar mystery on my Series 5 Humber 80 (=Minx):

The oil-pressure relief valve, in the oil-filter base, had its body-sleeve break away from its head. (The head is the solid part with the hex and the screw-thread. The sleeve, with the valve-port and the spring-retainer, was slipped into the head and soldered.) Fortunately, the body-sleeve couldn't escape completely, because its end reached the other side of the filter-base casting first. This resulted mainly in the spring of the relief-valve being allowed to extend by about 50% longer than it should be, plus the port in the side of the sleeve moving along also. As a result, my recently rebored beautiful engine had a steady, controlled 20 psi instead of its proper 55.

I suggest you have a look at the relief-valve.

Good luck & bonjour

From: Nickcleak@aol.com
Date: Thu, 19 Nov 1998 16:31:20 EST
Subject: [imps] Re: Oil pressure problem

Hello !

I think Dave may be right , check the pressure relief valve , it screws into the top of the oil filter housing .. it may be stuck open ...
It is very quick nd easy to check , the piston in the centre should slide in and out under spring force ..

I had a problem with one in the summer , it was sticking shut , resulting in a burst oil cooler !

Nick ...

Date: Fri, 20 Nov 1998 01:07:06 +0000
From: Graham Begley
Subject: [imps] Re: Oil pressure problem

Everyone is correct about the most likely cause.
To quote from a home-servicing book by C.J. Beddall-Smith published by Pearson's in 1964:
There are at least four possibilities:
  1. Low oil level in sump.
  2. Pressure relief valve open due to dirt under seat or sticking.
  3. Choked oil filter
  4. Choked oil pump inlet filter.
If you need to work on number 4, e-mail me before you start.
There are some dangers in doing this job! I will scan and send you the pages (24 & 25) from the book.
Au revoir,

From: Gary Henderson
Date: Fri, 20 Nov 1998 16:50:42 +1300
Subject: [imps] Re: Oil pressure problem.

Hi Graham

Do you know if my Minx situation (i.e. valve 'readjusted' itself to a low setting by coming apart but in confined space) can apply to the Imp? (I'm not taking mine apart just to look.) This syndrome gave instant 'light out' etc but a nice, well-regulated 20 psi . If the spring failed, it would do the same.