[Solved] 3.8 low oil pressure

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mgcjag
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#21 Re: 3.8 low oil pressure

Post by mgcjag » Thu Sep 01, 2022 6:01 pm

Hi Serge....the cork was part of the filter element i assume....have a look at the various filters available they all have some type of seal....cork, fiber, paper etc on one end........you can anneal you copper washers....not in situ.....take them off heat till cherry red then let them cool down....you can always use ptfe thread seal (thin white tape)....plus add some blue hylomar to the threads if you use copper or ptfe....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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ralphr1780
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#22 Re: 3.8 low oil pressure

Post by ralphr1780 » Fri Sep 02, 2022 9:18 am

Serge, I can gladly remove the oil gauge from my car, which is reading correctly, and lend it to you for testing.
Ralph
'69 OTS + '62 OTS - Belgium

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#23 Re: 3.8 low oil pressure

Post by paydase » Fri Sep 02, 2022 4:34 pm

Steve, thank you for the advices.

Ralph, that is very kind of you.

What I intend to do first is to reassembly the oil filter and make a first check.
I will also attempt to clamp the sump return hose.

If the oil pressure remains low, I will do a swap of the dashboard gauge with the one of my FHC, in case that instrument would be defective.

If still unresolved, next step will be a mechanical gauge (I suppose that you are talking of such a gauge).
I will then call you. :smile:
Serge
1964 (3.8) FHC
1961 OTS

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#24 Re: 3.8 low oil pressure

Post by mgcjag » Fri Sep 02, 2022 5:03 pm

Hi Serge...iv just re read you thread and previous thread on oil pressure...this goes back to March...have you not yet tried a mechanical guage?.....the electric guage and sender are just really indicators of pressure. ....you will have no idea what your real pressurevis untill you test with a mechanical guage....this should have been the first thing you done. ....in my opinion you should just reassemble your filter and test pressure with a mechanical guage...cheap enough to hire or buy....it dosnt need to be a guage that fits in you dash...just a test set.....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#25 Re: 3.8 low oil pressure

Post by bitsobrits » Fri Sep 02, 2022 5:09 pm

Given the well documented issues with the electrical sending units for the E type I would simply replace the gauge with a mechanical one (some thing I've done on all three of the E types I've owned). Then the sender/gauge is eliminated as a variable.

There has been so much documented angst by the owners with supposed oil pressure problems in so many threads over the years with countless posts by the well intentioned helping them troubleshoot the issue. And I would say so much time wasted until the OP figures out it's the sender/gauge. Just replace the gauge and if the problem persists then you KNOW (and will always know) you have another real issue.
Steve
'65 S1 4.2 FHC (early)

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#26 Re: 3.8 low oil pressure

Post by paydase » Fri Sep 02, 2022 10:19 pm

Thank you again for the comments.
I could not really address the issue since March because of very small time available.
I take note of the strong advice to test the system with a mechanical gauge.
If the OP remains low after reassembly, I will check it with a mechanical gauge.
Serge
1964 (3.8) FHC
1961 OTS

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#27 Re: 3.8 low oil pressure

Post by paydase » Sun Sep 04, 2022 11:17 pm

Just reassembled the oil filter housing and canister, putting a new filter.
No oil leak apparently, which is already a good point.
But still low oil pressure as read during the few moments that I was able to run the engine.

Because I have severe gas overflowing from the front carb, probably a sunk bowl or a stuck open needle/valve in the floating chamber.
No tapping on the float chamber could resolve the issue...
I will have to first address this gas issue before pursuing with the low oil pressure resolution.

@ralphr1780 , I will contact you when that time comes.
Serge
1964 (3.8) FHC
1961 OTS

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#28 Re: 3.8 low oil pressure

Post by paydase » Wed Sep 07, 2022 9:28 am

I have installed a "good" oil pressure receiver behind the dashboard in place of the current one (disconnected), to eliminate this possible cause of low OP reading:
IMG_20220906_183609.jpg
IMG_20220906_183609.jpg (236.14 KiB) Viewed 2929 times
In case of still low OP, the last judge will be a mechanical gauge.
I still need resolving my gas overflow before cranking the engine.
Should be done soon.
Serge
1964 (3.8) FHC
1961 OTS

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#29 Re: 3.8 low oil pressure

Post by paydase » Sat Sep 10, 2022 5:44 pm

Gas overflow issue after having disassembled, verified and remounted the float chamber of front carb. Apparently it was a stuck needle/valve.

Cold started the engine just to check if I have a good oil pressure with the new receiver on the dashboard.
Crossing fingers and ...it works!
About 35 psi at 600 rpm :P
IMG_20220910_190456 (2).jpg
IMG_20220910_190456 (2).jpg (238.8 KiB) Viewed 2889 times
No defective OPRV, no defective pressure sender, but the pressure reader on the dashboard!
I had not seen such an issue reported before.
Don't want to be overoptimistic before having driven the car with hot engine. Will do that test hopefully tomorrow.
Serge
1964 (3.8) FHC
1961 OTS

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#30 Re: 3.8 low oil pressure

Post by mgcjag » Sat Sep 10, 2022 5:51 pm

Hi Serge...now try with your original guage becaus you have had your filter and houseing apart and the problem could have been there....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#31 Re: 3.8 low oil pressure

Post by paydase » Sat Sep 10, 2022 9:36 pm

Hi Steve,
Yes you are right, it could still have been that debris within the the OPRV have been released during that disassembly process.
Will do the swap back after the drive.
Serge
1964 (3.8) FHC
1961 OTS

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#32 Re: 3.8 low oil pressure

Post by paydase » Sun Sep 11, 2022 12:07 pm

My hopes were short-lived:
IMG_20220911_120245.jpg
IMG_20220911_120245.jpg (236.98 KiB) Viewed 2844 times
Close to zero at idle when engine hot :sad:

Both the pressure sender and receiver were giving a "normal" oil pressure on my FHC.
Not the case here.

Strangely, I observed oil normally spilling down on the camshaft at hot idle, so there is at least "non rezo" oil pressure.

What would be the soundest approach at this stage:
- still trying to measure the OP with a mechanical gauge;
- disassembly and replacing worn crankshaft bearings; or,
- depending on compressions, going all-in with an engine rebuild (it has 60k miles)?
Serge
1964 (3.8) FHC
1961 OTS

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#33 Re: 3.8 low oil pressure

Post by DWW » Sun Sep 11, 2022 12:30 pm

What does your oil level show?
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR
"Experience is something you don't get until just after you need it."

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#34 Re: 3.8 low oil pressure

Post by paydase » Sun Sep 11, 2022 1:14 pm

More than enough, slightly overfilled by the PO.
I let it like that:
IMG_20220313_171544.jpg
IMG_20220313_171544.jpg (178.44 KiB) Viewed 2833 times
Serge
1964 (3.8) FHC
1961 OTS

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#35 Re: 3.8 low oil pressure

Post by DWW » Sun Sep 11, 2022 2:39 pm

Ok, because once mine read low on hot and I was 2 liter down on oil, refilled and back to normal.
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR
"Experience is something you don't get until just after you need it."

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#36 Re: 3.8 low oil pressure

Post by Series1 Stu » Sun Sep 11, 2022 5:51 pm

You should definitely check the oil pressure with a wet gauge before you start throwing time and money at the problem.

Regards
Stuart

If you can't make it work, make it complicated!

'62 FHC - Nearing completion
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109

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#37 Re: 3.8 low oil pressure

Post by paydase » Sun Sep 11, 2022 6:01 pm

Thank you Stuart, I will follow your advice
Serge
1964 (3.8) FHC
1961 OTS

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#38 Re: 3.8 low oil pressure

Post by DWW » Sun Sep 11, 2022 8:42 pm

Will be very interesting to see what a wet gauge will read in this case. I have always been curious as regards the real OP is on mine, yet to be performed.
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR
"Experience is something you don't get until just after you need it."

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#39 Re: 3.8 low oil pressure

Post by paydase » Sat Dec 31, 2022 10:54 pm

I've got my New Eve (E) gift today 31st December :santa: .
Normal oil pressure read after having installed a mechanical gauge! :bigrin:

60 psi when starting engine cold:
IMG_20221231_173013.jpg
IMG_20221231_173013.jpg (221.34 KiB) Viewed 2169 times
Still 20 psi at idle when engine hot, while electric oil gauge showing close to zero (the gauges are blurred by water vapor, I have to fix that...):
IMG_20221231_175714.jpg
IMG_20221231_175714.jpg (253.66 KiB) Viewed 2169 times
That is a mystery for me because I had replaced both the sender and the receiver of the electric oil gauge by good ones (these work on my FHC and show good oil pressure even when hot).
Maybe a weakness in the electrical circuit, I dunno :scratchheadyellow:

Nonetheless, it's very reassuring and I can now work further in improving what needs to be done, in particular the cooling circuit (my cooling fan is still the Boeing blade and my header tank is leaking).

I will post further infos and pictures to show how I installed that mechanical gauge and how I routed the cabling.
Happy new year to everybody!
Serge
1964 (3.8) FHC
1961 OTS

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#40 Re: 3.8 low oil pressure

Post by mtnjag » Sun Jan 01, 2023 1:38 am

Why don’t you put it in the dash?
Layne
Car #876005, 62 OTS

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