Once again I'm asking a question.
I have low oil pressure issues, approximately 10psi down. I've removed the oil filter housing to see if the relief valve is stuck open.....it wasn't but I found something else. The photos below show a threaded stud/plug/grub screw and I don't know what it does or what position it should be in. I would guess screwed in.

Photos taken from under the car, front to the right and rear to the left.

This photo shows the position it was in when I removed the housing


I screwed the screw/stud/grub screw in until it wouldn't go further but not tight.


Any thoughts?

Regards

 

If the plug butts-up to something, it should be fully home, but I don't think that explains your oil pressure problem unless it was really loose in the hole. The most common cause of low pressure on the gauge is the pressure transmitter on the housing. This is electric and can deteriorate over the years so you see less pressure even though it is perfectly OK. The only real test one way or the other is to fix a real pressure gauge into the tapped hole for the transmistter and check. Other thing that can affect oil pressure is wear in the oil pump, (naturally !). You don't say what miles are on the engine, but it might be prudent to replace the oil pump.

 

Thanks, it was as per the top photo. I just thought it could impede the oil flow, I'll screw it in.....I think that must be correct.

I bought a replacement pressure sender to no avail and I've connected my mechanical test gauge, that reads a little higher but not much. The mileage on the car is 72,000, I have thought about replaceing the oil pump but that's an engine out or front suspension off job and the equipment I have isn't sturdy enough....or at least I'm not confident it would be.

I'm also begining to suspect the seller ason the test drive the oil pressure was fine, maybe he put something thickener in the oil as I changed it as soon as I got the car home.

I fully realise it's not a good idea but can I drive the car with low pressure?

 

What is the oil pressure when the engine is warm and running at 3000 rpm? Should be at least 40. Its normal for the pressure to be as low as 5 at idle. What is the condition of the oil filter? Is it the original style or has it been replaced with a screw on canister adapter?

 

The pressure at 3000rpm is about 30psi with the mechanical gauge and 28 with the electrical sender. The filter is new and it's the original style.
There were no blockages found in the filter assembly so I'm assuming, unless something miraculous happens on reassembly, I'll need a new oil pump and if that's the case I'll probably change the big end and main bearings.

I've had the car since October and only driven it about 150 miles so I'd really like to use it before I lose it during engine work. I can't use it now.....

 

What oil viscosity are you using ? Clearances were not as tight as they are on modern engines, so maybe using 20/50 or 15W40 would be better, but it does sound as though its overhaul time if the mechanical gauge shows 30 psi hot on 3000 revs, it should be more than this, minimum 40 I'd say.

 

Yeah! rebuild is what I'm thinking, I'm using 20W/50 oil from Valvoline so it's a quality brand as well. Today I'm going to re-attach the oil filter assembly and hope that fixes it (not hopefull), maybe the gasket had split between the two chambers.......clutching at straws I think.

 

On the plus side, if you have the garage and the kit/tools they are a lovely engine to work on. I've done two in my time. 74k miles is not high for a rebuild, (assuming that miles is correct), but you don't know if previous owners ignored the oil changes. The pumps do wear out, so it might be best to just try a new one first. Of course it's a big job to swap it out.

 

If you are going to the trouble of changing the oil pump, an inspection of all the bottom end bearing shells and the crankshaft journals would be a smart move; I would expect the shells at least to be quite worn to show such low pressure. If you're lucky, the crank will be ok, if not, then it's definitely an engine out job.

 

Fraser - I have the kit & tools but only suitable for smaller cars (MGB, Sunbeam Alpine) I wouldn't be happy trusting my engine crane and, whilst I have a 2 car garage, this car is so big space is limited.

Phil - I read that it's necessary to remove the front suspension to get access to remove the sump so again space is an issue. Also I see you spend time in Fougeres, is that the French one? Do you know of any classic Jaguar specialists in France? Preferably the southern half as I live in the Drome (26)

I replaced the oil filter housing yesterday and I believe/hope/prey the pressure is marginally up, maybe 2 psi. There's also an oil weep from the cylinder head so I'm beginning to believe the seller did something to the oil to thicken it for the sale. I am working my self up to getting the engine rebuilt and fitting a recon g/box. It's looking like I'll be trailering it back to England.

 

Yes #1, either the subframe must be dropped, or the engine removed to get into the crankcase. No guarantees, but your engine will probably soldier on for some time with the reduced oil pressure.
Yes #2, I am (infrequently these days) in Ille et vilaine (35), about 8 kms South-East of Fougeres. Unfortunately not, I had several Jag customers myself when living there permanently; most French garages are scared of anything petrol engined over 1.2 litres.
Although I am "retired", I have maintained most of my contacts and have a very competent French trader mate in Fougeres, if that helps at all, and a few likewise scattered around England.

Where is the oil weep from the cylinder head? Common places are from the camshaft oil feeds (usually just knackered washers), and at the front where the head, block, and timing cover meet; less simple to fix.

 

Phil - wouldn't you know it it's from the front head/timing cover joint. I'm going to buy some "stop Leak2 stuff and hope against hope that thet fixes it.

I've just put the mechanical gauge on and the pressure it higher, 38 -> 40 psi. I then re-fitted my new sender unit, which previously read low, which almost matches the mechanical gauge but takes an age to show pressure. The manual says about 20 seconds but it takes about 35-40.

I have to say I'm not fond of French "enterprises" as I find the unreliable and impolite. If I can get the carbs sorted I'm seriously thinking about taking it to https://buildingthelegend.co.uk/ as they gave me a reasonable estimate for a basic rebuild. Either trailoring it or driving, it's a bugger really as I paid to have it delivered to France rather than drive an unknown car.

 

Just to say that I took the engine and gearbox out of an XJ6 in 1992 in a UK domestic garage that took one car. Fortunately the garage had some length with a workbench at the back but once the engine was out the car had to live outside, and the garage became the workshop.

I had to install an RSJ up near the garage roof that took a wheeled trolley that had a support for a block and chain with hook that I attached heavy-duty straps to I also bought a heavy-duty engine stand suitable for an XK engine, then, once the gearbox and engine were separated, I mounted the engine on the stand and stripped it completely to a bare block, because I was rebuilding the engine around an uncracked block.

ALthough it took far too long, I did finally manage to get the engine and transmission back into the car and the car back on the road in 1996, and ran it until 2003. I had the car 14 years in total.

 

Glad you saw a 40lb read. from MVII thru the MK10 all my service manuals say 40LBs at 3000 rpm. I once fired a 3.4L and saw a reading of 60 at start drop to less than 20 on warm up. Replaced pump and restarted, got the same. Changed filter, got the same. Took of filter assembly and found a wood chip from hammer I used for installing piston assemblies. Problem cured, averaged 40lbs from then on. This was in 1974, I use plastic hammers for install now. Just finished a 3.4 MK VII and runs at 45lbs, 20 at idle.

 

EtypePhil - Funnily enough I'm discussing selling an MGB gearbox to a chap in Angers and he told me of a Jaguar specialiste in Fougere. A M TELLIEZ Laurent (spécialiste jaguar) 43 rue du Moulin aux pauvres FOUGERE 35300. I don't suppose you've heard of him have you?

Jagfixer - Your tale has brought pleasure to my heart, I don't think it's fixed but the pressure has increased and it seems the stud (photo'd above) was somewhat to blame.

Thanks to all respondants, I think I/we've gone as far as we can on this thread. It seems my engine has issues but not REALLY MAJOR ones and I will address those in the coming months. When the snow melts I intend to use the car for local journies and gradually increase the distances until I get a feel for oil pressure in use and the rate of oil comsumption/loss.

 

I haven't, but I don't spend much time there these days; if I can find the time, I may look him up next trip.