[Saloon-lovers] Really bad oil pressure as engine heats up

Saloons
1

For the last few weeks I have had a very bad oil pressure
problem and so have not driven my car.

When the engine is cold, I have wonderful oil pressure:
about 45 at 800 RPM.

When the engine heats up to normal operating temperatures
of about 70 C, the oil pressure becomes about 5 at 800
and raises to about 40 at 2,500.

I hope that there is a simple fix rather than replacing all
the bearings! For example the compression is still quite good:

155, 160, 165, 165, 165, 155;

and these are at 7,000 ft where I live.

Could there be something as simple as a defective oil
pressure relief valve?

Any simple tests that I could make?–
Lowell Brown
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to


// list policy dictates that messages be trimmed

2

In reply to a message from 1958 Mark I sent Mon 16 May 2016:

Lowell,

The spec for oil pressure is 40 psi hot @ 3000 rpm with
SAE 30 oil. There is no idle spec, and idle pressure is
largely irrelevant. Oil pressure is not like money in the
bank, more is not ‘‘better’’. Oil viscosity varies with
temperature and it is normal for the pressure to be lower
when hot. If you have 40 psi @ 3000 rpm, you probably do
not have problem.

The original gauge/sender is often inaccurate, the only
way to diagnose an actual problem is by fitting an
accurate mechanical gauge. The temperature gauge is also
suspect, and if your 70C is really 95C, pressure would be
lower. If you are paranoid, my advice would be to fit a
gauge to one of the galley plugs, change the oil and
filter, making sure you have all the correct parts in the
filter assembly, drive the car for 10 miles and verify you
have 40 psi at 3000 rpm.

I recommend you keep the original filter, the spin on
conversions all have issues and you can inspect the
contents with the original.

Paul–
The original message included these comments:

When the engine is cold, I have wonderful oil pressure:
about 45 at 800 RPM.
When the engine heats up to normal operating temperatures
of about 70 C, the oil pressure becomes about 5 at 800
and raises to about 40 at 2,500.
I hope that there is a simple fix rather than replacing all
the bearings! For example the compression is still quite good:

–
PS
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to

// list policy dictates that messages be trimmed

3

In reply to a message from PS sent Tue 17 May 2016:

My oil fill cap still has about 90% of the sticker that says
‘‘Engine Initially Filled with Premium Oil 20W-40’’
I can’t ever recall using 30 in an XK…but maybe.
Most of the recommended oils in my Service Manual are 20W-40
and 20W-50.–
1964 MKII 2.4L 1950 Ford Tudor, 1950 Ford F-1, 1949 Willys
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to


// list policy dictates that messages be trimmed

4

In reply to a message from 1958 Mark I sent Mon 16 May 2016:

When the engine gets good and hot and you have it idling,
look in the oil filler cap and confirm that there is plenty
of oil up in the cam galley. That will reassure you that
there is oil flow, even though you don’t have much or any
back pressure.
This concern has been raised several times here and Paul’s
answer seems to be the general consensus.
You can blip the throttle once in a while when you are stuck
idling at a red light, the pressure will rise nicely when
you do. The real answer is of course to never slow down.
P.–
Peter J. Smith, 1966 3.8S MOD
Carson City Nevada, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to


// list policy dictates that messages be trimmed

5

In reply to a message from 1958 Mark I sent Mon 16 May 2016:

I agree with Paul completely. More oil pressure is not
‘‘good’’ oil pressure’ in fact it leads to major
inefficiencies. In fact, many modern cars (some Caddies, for
example), are actually lowering oil pressure (and viscosity)
in pursuit of gas efficiency. What matters more is whether
oil is getting where it needs to go. And if it sounds good &
runs ok it probably is. Drive it.
David
'62 mk 2
'52 MGTD
'61 R 69S
& assorted other old junk.–
ukdavo
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to


// list policy dictates that messages be trimmed

6

In reply to a message from 1958 Mark I sent Mon 16 May 2016:

I became so concerned about low OP readings, cancelled a
couple of trips, so installed a Digital Gauge for $40 to get
some answers.

They seem very accurate indeed, and give an instant output.

(My) older senders were consistently innaccurate, and a
needle gauge is not instant.

Question; I have noticed one peculiarity in particular, that
is at idle, if the car is at a reasonable uphill or downhill
angle, the OP drops quite a lot

All measurements are commensurate with my expectations, with
14psi being lowest on a low 600rpm idle, BUT on a slope, as
low as 9psi. (oil hot)

My dipstick shows full.

@ the OP, does your car have a lot of miles, suggesting
wear? I have mate 60yrs a mechanic, an engine builder, and a
bottom end genius. He can tell by listening, if bearings are
worn. If you know someone like that, let them listen/drive
your car.

does your crankshaft have excessive freeplay?–
The original message included these comments:

Any simple tests that I could make?

–
Tony
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to

// list policy dictates that messages be trimmed

7

In reply to a message from awg sent Sun 22 May 2016:

The oil pressure gauge in the '58 MkI is not electrical.
It does stick a little when the car is started, and only
after the oil pressure rises to 30 or 40 does it become
unstuck. Perhaps it does not read low pressures correctly.
I have a friend who has an arrangement to check this, and so
I shall.

The bottom end of the engine is a transplant from a 3.8
E-type. The odometer reads about 35,000 miles, but who knows
what the mileage on the engine is.

I have no indication that the crankshaft has excessive
freeplay, but I do not know how to check this.

I have adjusted the valves, and the cam bearings look good.–
The original message included these comments:

couple of trips, so installed a Digital Gauge for $40 to get
@ the OP, does your car have a lot of miles, suggesting
does your crankshaft have excessive freeplay?

–
Lowell Brown
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to

// list policy dictates that messages be trimmed

8

In reply to a message from 1958 Mark I sent Sun 29 May 2016:

you should be able to temporarily substitute your mechanical
gauge with an electronic one, by an adaptor in the oil
gallery hole, total cost less than $40 ebay, the electric
gauge does not need to be fitted in the dash.

To check crank end play needs a dial gauge, and lever the
damper back and forth…if it moves more than spec, the
thrust washers may be worn, and issue with the main centre
bearing.

I am intolerant of faulty instrument readings, must have
watched too many ‘‘Aircrash Investigation’’ TV shows–
The original message included these comments:

The oil pressure gauge in the '58 MkI is not electrical.
I have no indication that the crankshaft has excessive
freeplay, but I do not know how to check this.

–
Tony
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

[Commercial use of subscribers e-mail addresses prohibited.]

To remove yourself from this list, go to

// list policy dictates that messages be trimmed

9

The pressure can be turned up at the pressure relief valve, not a cure, but maybe a stretch in time to tear down. A MotorBook Manuals explain the procedure, not easy, patience, help ( watch gauge ) wrenches and long wide blade screwdriver.

10

Thanks for the information.

Actually, the engine in my Mk1 is a 3.8 liter E-type motor.

Could you point out where I can buy the needed book that explains how to change the pressure?

Thanks again,

Lowell

11

I’m not sure this would address his issue with low oil pressure at idle, unless the oil pressure relieve valve is defective, ie leaking by under all operating conditions. “Adjusting” the relief valve might raise the pressure some on start up when the oil is thick and the pressure is up against the relief valve’s release figure but once the oil heats up, from my experience with XK engines the relief valve is already closed. What say the XK engine brain trust??