High oil pressure

Talk about the E-Type Series 3
User avatar

Topic author
Pgxxl
Posts: 43
Joined: Tue Sep 29, 2020 9:23 pm
Location: Bristol
Great Britain

#1 High oil pressure

Post by Pgxxl » Thu Aug 18, 2022 7:15 pm

My baby is now showing very high oil pressure constantly after start, 80. Using a test gauge their has confirmed the dash good reading to be good. The realease valve has now been replaced but the problem is still the same . Any thoughts guys ??
1972 OTS
Opalescent silver blue
Purchased Oct 2020

Link:
BBcode:
HTML:
Hide post links
Show post links


MarekH
Posts: 1394
Joined: Wed Jul 21, 2010 8:30 pm
Location: Surrey
Great Britain

#2 Re: High oil pressure

Post by MarekH » Thu Aug 18, 2022 7:42 pm

Others report that the big relief valve caps the pressure at somewhere between~70-90psi and that is what you are reporting, so why is this "very high" and what exactly is "the problem"?

kind regards
Marek

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

abowie
Posts: 3645
Joined: Wed Sep 07, 2011 9:15 pm
Location: Australia
Contact:
Australia

#3 Re: High oil pressure

Post by abowie » Thu Aug 18, 2022 10:45 pm

That's exactly the oil pressure my XJS has cold.
Andrew.
881824, 1E21538. 889457. 1961 3.4l Mk2. 1975 XJS.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

lowact
Posts: 532
Joined: Mon Oct 09, 2017 10:05 am
Location: Canberra, Australia
Contact:
Australia

#4 Re: High oil pressure

Post by lowact » Thu Aug 18, 2022 10:52 pm

And have you changed anything? Is the gauge still being supplied an average 10V from the voltage regulator? Is the sender the correct type, with twin lugs in the centre? If the gauge is being supplied 12V (= 13.6V) and the sender is the type with single lug on the side, rectify both of these, should be ok.
Regards,
ColinL
'72 OTS manual V12

Link:
BBcode:
HTML:
Hide post links
Show post links


MarekH
Posts: 1394
Joined: Wed Jul 21, 2010 8:30 pm
Location: Surrey
Great Britain

#5 Re: High oil pressure

Post by MarekH » Fri Aug 19, 2022 8:47 pm

lowact wrote:
Thu Aug 18, 2022 10:52 pm
Is the gauge still being supplied an average 10V from the voltage regulator?
This may become a point of confusion.

The circuit diagram shows the gauge and sender are supplied by a non-regulated green wire supply. This is because the original senders were of a bi-metallic strip construction. In effect, they had their own built in voltage regulator and the oil pressure signal floated on top of this. An old style sender like this makes an LED "strobe" on and off rapidly if it is fitted as a substitute for the gauge.

It is also possible to buy replacement senders which are simply resistive in nature, just like the fuel level sender is. An LED fitted inline with one of these would stay solidly illuminated if fed by the same white wire.
The (resistive) fuel sender circuit is fed by a green/black wire from a regulated supply.

Another way to differentiate the sender type would be to simply hook up an air compressor to the sender and bench test it on its own. The resistive sender will vary in resistance (between the lug and the case) in proportion to the air pressure, but the old bimetallic type of sender won't.


Cold oil is thicker (more viscous) than warm or hot oil. That's why oil pressure on a cold engine is high. The relief valve caps this at its pop-off pressure. It's reasonable to expect the working pressure to drop below the pop-off valve value once it is both warmed up and revs are low. A freshly rebuilt engine with new bearings typically has a higher oil pressure than an old engine.

I wouldn't consider oil pressure to be "high" unless it is higher than the cap value.

kind regards
Marek

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

chrisfell
Posts: 1389
Joined: Tue Oct 06, 2009 9:52 am
Location: Salisbury
St Lucia

#6 Re: High oil pressure

Post by chrisfell » Fri Aug 19, 2022 9:10 pm

If this was my engine, then unless I had a very non standard oil pump or the crank had been fitted with bearings that were exactly the same size as the crank ( ie no clearance for any oil), I probably wouldn't have 80 psi oil pressure. I would have a faulty oil pressure sender.

I already have several faulty oil pressure senders. They are a thing, not a myth.
Chris '67 S1 2+2

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

malcolm
Posts: 2239
Joined: Fri Jan 03, 2014 10:44 am
Location: Fleet
Great Britain

#7 Re: High oil pressure

Post by malcolm » Sat Aug 20, 2022 8:41 am

I get 70-75 when cold on my series 2. Accurate, as measured in a workshop on a capillary type guage and now on my fitted mechanical guage. Runs at 65 when hot.
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S

Link:
BBcode:
HTML:
Hide post links
Show post links


Paul Buckley
Posts: 84
Joined: Sun Jan 24, 2016 7:41 pm
Location: Northwich, Cheshire
Great Britain

#8 Re: High oil pressure

Post by Paul Buckley » Sat Aug 27, 2022 5:34 pm

80psi (full scale) on a cold start is quite normal and is what my unrestored V12 has always shown for the last 50 years!
However, last year I had the engine out and took the opportunity to install a 'wet' mechanical gauge.
The new gauge is scaled to 100psi and the engine still records 80psi on startup; no change!
When fully warm it records 25 to 30psi. at idle and circa 65 at 3000rpm.
Cheers
Paul

1972 S3 OTS, 32k mls, a survivor.

Link:
BBcode:
HTML:
Hide post links
Show post links


cunpr
Posts: 19
Joined: Mon Jan 24, 2022 10:52 am
Great Britain

#9 Re: High oil pressure

Post by cunpr » Mon Aug 29, 2022 4:25 pm

Dear All,
My unrestored 47K miles has 70psi cold started on choke, 20 psi warm on idle and 60-70 warm motoring.
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic