Low oil Pressure

Technical advice Q&A

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Taff
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#1 Low oil Pressure

Post by Taff » Mon May 24, 2010 10:28 am

Hi All,

New to the Forum, and already gained a lot of information. How did we manage before the Internet??

I've recently acquired a 1969 S-2, 2+2 white in colour. Its my first ever, so still finding out all the info I can.

The first problem is low oil pressure. the car was laid up for a while, but did have good pressure. Already taking off the oil filter housing to check the valves. What I can see of it all looks OK with my limited knowledge of them.

Can somebody help me understand how it should work. My guess is that the oil flows into the left camber and through the central hole in the middle
into the filter. Then if the filter blocks it would flow back to the sump though the pressure relief valve.

Having gone through the filter, the oil will then return into the right camber.
What I'm not sure of is why the balance valve. What does this do?
Also, I've been on the SNG parts catalogue, but can't see any for sale.
Can you still buy them should it be needed?

Having only just found this forum, I now reliese that maybe I should have replaced the sender and garage with the JEC first to see if that would work. Will be ordering one very soon.

Hope this 1st post is not too long winded, my apologies if so,

Many Thanks,

Art

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Heuer
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#2

Post by Heuer » Mon May 24, 2010 11:26 am

Art

Easiest way to test the by-pass valve is functioning is to clamp the by-pass hose and run the engine. If the pressure rises the spring is probably weak.

SNG have a lot more parts than they have on the web site or catalogue. Just give them a call with the Jaguar part number and they should be able to supply.
David Jones
S1 OTS OSB; S1 FHC ODB

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keith andrews
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#3

Post by keith andrews » Wed Jan 12, 2011 3:16 pm

[quote="Heuer"]Art

Easiest way to test the by-pass valve is functioning is to clamp the by-pass hose and run the engine. If the pressure rises the spring is probably weak.

SNG have a lot more parts than they have on the web site or catalogue. Just give them a call with the Jaguar part number and they should be able to supply.[/quo

It may well be the dreaded oil pressure sender, the round one about the diameter of 10p and sat on top of filter housing, they are unreliable and fail frequently, this is the first point of renewal. Not easy to see or get at, 7/8" o.e. spanner as terminal lug on top for feed to o.p.gauge.
Just been down this path and this was solution after pulling many bits out.

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christopher storey
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#4

Post by christopher storey » Wed Jan 12, 2011 7:24 pm

Art : how low is low? anything equal to or better than 20 at idle hot is perfectly acceptable particularly if it rises with rpm. The only reliable way to check pressure is to use a mechanical gauge ( any generic type will do) which can be screwed into one of the blanking plug holes which run in the main oil gallery along the RHS of the engine at about filter level - it is that slight bulge in the block which runs the length of it . It is IMHO essential to do this before chasing round the sender/gauge/pressure relief valve route which can all too easily become expensive but inconclusive

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rfs1957
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#5 Balance Valve Assembly

Post by rfs1957 » Sat Jan 15, 2011 3:07 pm

Hello and sorry for arriving 8 months late on this topic.

Has there been any further info posted about the function of the balance valve assembly, and can anyone indicate where there is a diagram of how the flows are routed through the filter block ?

I gather that excess oil-pressure overcomes the relief valve (118261) spring and is bled south via the hose into the sump .......... but what of the balance valve itself ?

Many thanks in advance.
Rory
3.8 OTS Cream 877393 Built May 28th 1962
1978 Mini Van
(plus bevel and belt single-cylinder Ducatis)

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skiday
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#6 Re: Low oil Pressure

Post by skiday » Tue Jan 23, 2018 6:11 pm

Hi Guys

Perhaps this thread should be moved to technical??

I am now looking at my low oil pressure. My pressure is high on starting - over 40 psi, but drops with driving to 20 or less whilst cruising and revving it makes little difference. I have noticed this since its last oil change and therefore suspected the problem may be in that department. I have the oil filter head off. The relief hose is clear (incidentally I fitted a silicone oil pressure hose from a Fiat Coupe (new), which I had lying around spare and fitted perfectly. I used this because the one supplied by SNG was so rigid it did not clamp down properly). I ordered all gaskets and a new relief spring but found the old spring to be just as strong as the new one.

In the picture below you can see that the hole in the Balance Valve has its hole seemingly half blanked off due to the position of it, but the manual does not go into details how it should be and I'm wondering if that might be wrong. I can't think it will have moved and pressure has never been low before so I'm not sure about that. I can't think that either the pressure sensor on the top or the dashboard gauge can be at fault or the pressure would always be low rather that as it is, starting high and becoming low when warm.



Image

Any Ideas

Thanks - Andrew
Andrew Day. Former owner of S1A 4.2 2+2. Current cars; Aston Martin DBS 1968, Ferrari F355 & Fiat Coupe 20vt. Flag of choice; EU

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Series1 Stu
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#7 Re: Low oil Pressure

Post by Series1 Stu » Tue Jan 23, 2018 6:40 pm

Maybe it's the oil you used. Seems to be the lowest common denominator.

Regards
Stuart

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

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mgcjag
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#8 Re: Low oil Pressure

Post by mgcjag » Tue Jan 23, 2018 7:33 pm

Moved to Technical..the only way to be sure is to test with a mechanical guage....the electrical are notorious for incorrect readings
Steve
1969 S2 2+2 & Building a C type replica

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skiday
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#9 Re: Low oil Pressure

Post by skiday » Tue Jan 23, 2018 9:46 pm

I used Halfords Classic 20/50.
But what about the position of the Balance Valve, is it good?
Andrew Day. Former owner of S1A 4.2 2+2. Current cars; Aston Martin DBS 1968, Ferrari F355 & Fiat Coupe 20vt. Flag of choice; EU

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politeperson
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#10 Re: Low oil Pressure

Post by politeperson » Wed Jan 24, 2018 8:19 am

I agree with Steve,

I looked at a friends 4.2 roadster last week that was reporting 19psi at 3,000 rpm on the dash gauge.

I unscrewed the sender and screw in a mechanical gauge witch accurately reported the oil pressure at 45 psi @3,000 rpm and 20psi at idle hot. They only cost a few quid.

https://www.ebay.co.uk/itm/Wave-Box-Oil ... SwcUFZpVbf
James

L.J.K. Setright was right.
"You just cant beat a good E-type"

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