Oil Pressure

[John Patterson]

Hi Gang- Question- I changed the oil and filter over the weekend and filled
the sump with 10W-40 Castrol GTX and cranked the engine with the ignition
off until I recorded a pressure reading on the gauge. I then started the
engine and found the engine was running 80+ psi. after running the TC until
the engine was at temperature it is now running a steady 80 psi. Is this too
high a pressure and will it blow out the seals at the crank ends?
John Patterson TC7024

[joecurto@aol.com]

John 80 PSI is pretty high, is it possible that the gauge is correct, perhaps
the relief valve is stuck closed, does the pressure go to 82 and the needle
drops back to 80 indicating the valve is opening? I would substitute the
gauge and if that proves to be correct than I would have a look at the relief
valve assembly? What was the oil presure prior to this oil change?

Joe


















[Non-text portions of this message have been removed]

[Mike Card]

John

That 80 psi is not of course applied to either of the crank oil seals. By the time oil reaches the front and rear oil slingers on the crank, it is out of the journals and is at crankcase pressure [at or a little above atmospheric pressure]. If your front slinger and rope seal or modern lip seal, and your rear slinger and scroll etc, are in good condition they should cope with the extra oil flow which results from the higher pressure.

However the load on the oil pump drive gear, and the gear on the camshaft which drives it, will be appreciably higher and these will wear a bit faster. There is no particular advantage in having the higher pressure on a normal road car and so better to follow Joe Curto's advice and check gauge and oil pump pressure relief valve. If the gauge is correct, look at the pressure relief valve and see if a PO has added a spacer under the spring, or stretched the spring. The spring should have 13.5 coils and a free length of 37.5-mm, 1.476-in.

Your email suggests that the indicated pressure was much less than 80 psi before the oil and filter change. Curious. Or maybe that old filter was very clogged.

Mike Card
TC8233, TC9477

----- Original Message -----
From: John Patterson
To: MG-TABC
Sent: Monday, August 19, 2002 2:37 PM
Subject: [mg-tabc] Oil Pressure


Hi Gang- Question- I changed the oil and filter over the weekend and filled
the sump with 10W-40 Castrol GTX and cranked the engine with the ignition
off until I recorded a pressure reading on the gauge. I then started the
engine and found the engine was running 80+ psi. after running the TC until
the engine was at temperature it is now running a steady 80 psi. Is this too
high a pressure and will it blow out the seals at the crank ends?
John Patterson TC7024




[Non-text portions of this message have been removed]

[Bullwinkle]

John:


80 psi.

That's the same psi. as used for XPAG racing engines when the pressure
is raised.


Is this too high a pressure and will it blow out the seals at the crank
ends?


What seals? The front carbon rope "seal" is never under pressure oil
pressure. It is only under any blowby gas pressure. The front "seal"
is more like a packing used around faucet handle shafts.

The rear "seal" really shouldn't be called a seal. AFAIK its the same
as the XPAG engine and is just a reverse scroll and a oil slinger.

Blake

[AndyJ]

John re 80+ pounds oil pressure...I had that after an oil change turns out the sock material over the filter got sucked into the oill outlet and was blocking the flow. The perforated metal sleeve that is over the socki must be at the position to keep the sock from being sucked in. Check to see if the filter got put in upside down which will misalign the metal screen Anyway check the filter. Bet when you take it out it will have a knot or protrusion where it has been sucked into the oil line.
syd saperstein


[Non-text portions of this message have been removed]

[John Patterson]

Syd Thanks, the filter replacement had a perforated shield that extended
over the height of the cotton except for about 3/4 inch top and bottom. I
would think any blockage would cause lower pressure not higher, since the
pressure reading are picked up after the filter from the block. Am I correct
in this assumption? In any case I'm going to order one of the spin-off units
from Bob Grunau.
John TC 7025

FIX THE PROBLEM, NOT THE BLAME

[joecurto@aol.com]

We used to see a lot of that filter cloging, there used to be a few
aftermarket filter housings for T series, even the original filter for the SA
used a filter element that the direction of flow was different from the
common felt filters of today. I used to make a steel sleeve of performated
metal and stuff a correct length filter in it. The felt filters of today for
TD, MGA, Austin Healey, Jaguar are made to have the oil flow from the outside
to the inside.

Joe


[Non-text portions of this message have been removed]

[John Patterson]

Hi Bob, First, congrats on your award, you deserve it. I finally got your
spin off oil unit on the car along with A flexible line from the filter to
the block. Fired up the car and drove it until up to temperature at 70 C. On
start up oil pressure was 85 psi after warm down to 75 psi. Pressure at idle
was 60 psi and the pressure gauge ran from 60 to 75 as the RPM's ran up and
down from idle to 3500 RPM's. I bought a new spring for the pump and will
check the pump in the spring as the Car is in hibernation for the winter.
What should the length of the spring be? The new one is 1 1/2" long. Car ran
great. Maybe I should run 10w30 Castrol instead of 10w40, would that lower
the pressure. I feel the cause was the old unit was restricting the flow as
the old ball of twine had a dimple at the exit port.
What is your expert opinion.
John Patterson TC 7025

[Paul Camp]

John
Re your mail to Bob Gruneau- I also fitted one of his Oil Filter adaptors
and also a new spring to the oil pump relief valve,a heavier duty spring as
recommended by NTG Services.As my oil pressure was settling at 35-40 when
hot.I also discarded the oil cooler as fitted by the previous owner.
Now on start up the pressure reaches 85-95 and once warm(70 degs.) settles
to around 60 at 3000-3500 revs at idle it drops to 25-30 . I am at present
using penrite HPR 40 a 15w50w am thinking of changing to Castrol magnatex
15w40w .I am delighted with the ease of changing the spin on filter. BTW I
am 61 and purchased my TC 3 years ago a lifetime ambition!. The MGB I have
owned for 12 years
Regards
Paul
TC3348
MGB

----- Original Message -----
From: "John Patterson"
To: "MG-TABC" ; "BOB GRUNAU"
Sent: Monday, October 28, 2002 12:40 PM
Subject: [mg-tabc] Oil Pressure


> Hi Bob, First, congrats on your award, you deserve it. I finally got your
> spin off oil unit on the car along with A flexible line from the filter to
> the block. Fired up the car and drove it until up to temperature at 70 C.
On
> start up oil pressure was 85 psi after warm down to 75 psi. Pressure at
idle
> was 60 psi and the pressure gauge ran from 60 to 75 as the RPM's ran up
and
> down from idle to 3500 RPM's. I bought a new spring for the pump and will
> check the pump in the spring as the Car is in hibernation for the winter.
> What should the length of the spring be? The new one is 1 1/2" long. Car
ran
> great. Maybe I should run 10w30 Castrol instead of 10w40, would that lower
> the pressure. I feel the cause was the old unit was restricting the flow
as
> the old ball of twine had a dimple at the exit port.
> What is your expert opinion.
> John Patterson TC 7025
>
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

[Robert Grunau]

Hi John,
I would try an old spring or grind a bit off the new spring. Aim for about
70 psi cold on start-up and 55 to 60 psi hot running. 75 psi is too much
pressure IMHO. It places unnecessary load on the oil pump drive gears and
also may erode the bearings.
I use Castro 20W-50 oil in the my TC, runs about 60 psi cold and 55 psi hot
running down the highway.
I measured the length of a new spring at 1.475". I would try a
different/shorter spring to get the pressure down.
Nice problem to have and easily solved by reducing the relief valve spring
pressure.

Yes old filters can be a problem in blocking the outlet from the filter
cannister. The TC has reverse flow on the original oil filter from inside to
the outside. Most modern spin-on and replaceable element filters are
designed for flow from the outside in toward the center. Of course my oil
filter adapter is cross drilled to allow oil flow into the adapter from the
top center and then is cross-drilled to exit the filter adapter on the
outside of the spin-on. Oil flow is then through the filter and exits in the
center. The adapter is again cross-drilled to allow side exit to the block.
Regards, Bob Grunau

Hi Bob, First, congrats on your award, you deserve it. I finally got your
spin off oil unit on the car along with A flexible line from the filter to
the block. Fired up the car and drove it until up to temperature at 70 C. On
start up oil pressure was 85 psi after warm down to 75 psi. Pressure at idle
was 60 psi and the pressure gauge ran from 60 to 75 as the RPM's ran up and
down from idle to 3500 RPM's. I bought a new spring for the pump and will
check the pump in the spring as the Car is in hibernation for the winter.
What should the length of the spring be? The new one is 1 1/2" long. Car ran
great. Maybe I should run 10w30 Castrol instead of 10w40, would that lower
the pressure. I feel the cause was the old unit was restricting the flow as
the old ball of twine had a dimple at the exit port.
What is your expert opinion.
John Patterson TC 7025





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