Oil Pressure

[peterdpps]

Not really a new subject but here goes.

My 240 has run at around 40psi under load [hot] dropping to 20psi or less on tickover.

I had a partial engine rebuild recently at which time the oil pump was replaced. This increased running oil pressure very slightly but made no change to that on tickover.

Having seen various comments about the variations in oil pressure senders I have just had this replaced. Pressure is now showing up to 60psi under load dropping to 50 when hot and 40 on tickover.

The question is. Which sender is sending the correct information? Is there anythong else which may be a problem? The car runs quietly and smoothly at all revs and there is no obvious cause for concern but I would still like to be sure......

[piman]

Hello Peter,

there is no way of knowing which of the two are correct, if either are. I know they are renown for being inaccurate but how inaccurate, I've never seen any figures? Both are showing a span of 20 psi, which is something they agree on.

The alternative is to have a mechanical oil pressure gauge fitted temporarily, as a check to see which is the more accurate.

Alec

[peterdpps]

Hi Alec,

Yes, that was my thoughts. Span of 20psi is reasonable [at least if it's not 0-20 ! ]

Any idea where I can beg or borrow a mechanical gauge?

Regards

Peter

[J44EAG]

Here are some links for purchase costs.

http://www.rapidonline.com/buy/products ... -12pc.html

http://www.thetoolboxshop.com/43054-dra ... 6393-p.asp


http://srx.uk.ebayrtm.com/clk?RtmClk&u= ... 25&pi=4340


Mike

[peterdpps]

Thanks Mike I will check these out.

[stuarthardy]

You could, of course, replace your electrical gauge with an hydraulic item. You would need to run in a pipe to the back of the dashboard and replace the sender with a suitable hydraulic fitting. Smiths do one so it should match the rest of the gauges in the dash.

A while back the club did a special deal to get around this problem where you could buy a matched gauge and sender unit properly calibrated to give reasonably accurate pressure readings. I got one for my E-Type but its never been used due to the protracted rebuild.

Don't know whether they're still available.

Elsewhere within these forums (?) there is a link to a youtube video showing a pressure test in action. Gauge on dash reads zero, wet gauge reads 60 psi.

Regards

[peterdpps]

Many thanks for the replies.

On hol at the moment but will decide options when I get back.

[J44EAG]

Mike Wilkinson sells an in car mechanical direct acting oil pressure sender kit.

http://www.ebay.co.uk/itm/JAGUAR-OIL-PR ... 45fd9215b8

Mike K

[stuarthardy]

Wow, thats expensive! Typical Jaguar specialist pricing. Exorbitant.

Buy the parts separately and save a bundle. Fitting cost won't be any different.

Regards

[piman]

Hello Stuart,

that was my original response, but I don't know if there is a proprietry gauge to match the rest of the car's instruments, which this kit does. If that's of no concern then yes it can be done for a lot less.

Alec

[stuarthardy]

Hi Alec

I bought an oil pressure gauge and sender from the club's spares scheme. These were matched to each other and provided accurate pressure readings. I haven't seen any continuation of this but perhaps if there was sufficient interest then maybe a new batch could be produced. They were produced by Caerbont Automotive in Swansea who might be able to help out on an individual basis.

If you notice, the item from Mike Wilkinson is a close match but is calibrated to 100 psi, rather than the 60 psi that our cars are marked to. Mike must be getting these from somewhere. I've seen them for around £55 each, you can get a nylon capillary pipe for around £7, or a copper one for £25 and an adaptor for under £5 from Speedograph.



Regards

[ecosselynx]

Hi

As Stuart said go to Cearbont, you could ask them to do you the 100 psi mechanical gauge with the Kg/2m scale left off if it troubles you, either that when you get it strip it down and remove/paint over lower scale. I have a 0-100 gauge and electrical system in my car and doubt if many people ever notice.

[piman]

Hello Stuart,

OK, that's useful to know. Incidentally the early cars had a 0 -100 psi gauge which were later changed to 0 - 60 psi, as it gave an impression that the oil pressure was low.

Alec

[cstorey]

Any mechanical pressure gauge will do as a cross check. I use a 1940s one which has a 1/8 bsp thread, which screws into the adaptors which Jaguar used for the oil pressure warning light ( which was described as the alternator light ) on 4.2 E types , and which plugs into one of the blanked off holes on the oil gallery on the right side of the block in front of the oil filter housing

[smiffy]

I bought a Smiths 100 psi mechanical gauge on eBay for £5, replacing its chrome bezel with the black one from my electrical gauge. Various companies will sell you the connecting pipe and fittings for around £10 - Speedograph Richfield supplied mine. The mechanical gauge does not look out of place in the dash, despite the 270 degree scale.
When cold at start up, I get pressures of around 45psi at idle and 60psi at 3000 rpm. This settles when the engine is warm to 45 psi at 3000 rpm and around 25 psi at idle. The original gauge showed around 25 psi at 3000 rpm when hot!! I'm keeping the mechanical gauge in the dash permanently, as I have much more confidence in it.
Best wishes, David