What causes HIGH oil presure in a V8?
grinder01
cause low pressure but what causes high pressure? I was driving home last
night, when I noticed, just after I started the engine, the oil pressure
gauge in my beloved '82 Range Rover (3.5L Stromberg carb) was going almost
off the scale, regestering 50 PSI when going gently along the road and only
dropping to 40-45 PSI when idling. The reading seemed to fluctuate slightly
when idling but remained in the 40-50 PSI range. This was from a coldish
engine (10 mile run 6 hours before). Needless to say, I droved the 7 miles
home very gently. I thought I could hear a new noise that sounded like a
maching metal on a lathe, but it was quite faint and I could be mistaken.
Can anyone give me any ideas on what to check? I did a google search, but
only came up with the oil pump pressure relief valve being metioned. Where
is it, and how do I check it?
Tom R-H
Austin Shackles
<grin...@btinternet.com> enlightened us thusly:
It's on the pump top, adjacent to the oil filter. Big hexagonal cap which
undoes, then there's a spring and valve inside. Facing towards the sump
side of the pump top, IIRC.
Dunno whether you can gain any useful insight by taking it out in situ
though. The only thing that'd cause high pressure is if it had stuck
closed, and I can't see that being solvable without taking the pump top off
to look at it. Having done that, you have to pack the pump gears and space
around them with vaseline (petroleum jelly) in order to make it prime again,
before putting the top back on. Amazingly, this works.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"My centre is giving way, my right is in retreat; situation excellent.
I shall attack. - Marshal Foch (1851 - 1929)
Tanuki the Raccoon-dog
<aus...@ddol-las.fsnet.co.uk> said
>On or around Sun, 19 Jan 2003 23:29:29 +0000 (UTC), "grinder01"
><grin...@btinternet.com> enlightened us thusly:
>
>>What are the possible causes of HIGH oil pressure in a V8? I know what can
>>cause low pressure but what causes high pressure? I was driving home last
>>night, when I noticed, just after I started the engine, the oil pressure
>>gauge in my beloved '82 Range Rover (3.5L Stromberg carb) was going almost
>>off the scale, regestering 50 PSI when going gently along the road and only
>>dropping to 40-45 PSI when idling. The reading seemed to fluctuate slightly
>>when idling but remained in the 40-50 PSI range. This was from a coldish
>>engine (10 mile run 6 hours before). Needless to say, I droved the 7 miles
>>home very gently. I thought I could hear a new noise that sounded like a
>>maching metal on a lathe, but it was quite faint and I could be mistaken.
>> Can anyone give me any ideas on what to check? I did a google search, but
>>only came up with the oil pump pressure relief valve being metioned. Where
>>is it, and how do I check it?
>
>It's on the pump top, adjacent to the oil filter. Big hexagonal cap which
>undoes, then there's a spring and valve inside. Facing towards the sump
>side of the pump top, IIRC.
>
>Dunno whether you can gain any useful insight by taking it out in situ
>though. The only thing that'd cause high pressure is if it had stuck
>closed, and I can't see that being solvable without taking the pump top off
>to look at it. Having done that, you have to pack the pump gears and space
>around them with vaseline (petroleum jelly) in order to make it prime again,
>before putting the top back on. Amazingly, this works.
I've seen a Rover V8 with a "high pressure high capacity" oil-pump burst
its oil-filter canister when the relief-valve stuck shut after a
rebuild!
Is your gauge mechanical or electrical? If it's an electrical gauge,
then failure of the instrument voltage-regulator can make the gauge read
worryingly high, though it generally also affects the fuel-gauge and
engine temperature gauge (which are also fed off the instrument
regulator).
--
!Raised Tails! -:Tanuki:-
"Microsoft .NET is more than a suite of software products - it's a marsupial-
filled popcorn-machine rolling down a hill out of control and smashing into
a bingo parlour full of crossdressing kleptomaniac vampires."
Gary Sutherland
(grinder01) wrote:
> What are the possible causes of HIGH oil pressure in a V8? I know what
> can cause low pressure but what causes high pressure?
Might be a blocked oilway somewhere in the engine causing a bottleneck.
This could cause as much damage as low oil pressure so it needs tracking
down quickly.
Could be worth draining the oil and putting flushing oil through a few
times to see if it will clear.
Cheers
Gary