Hi Folks,

I'm a new member from the North of England, I have posted a hello in the new members section for anyone who is interested.

I am a recent purchaser of a 1967 Daimler 250 V8, its generally pretty good, all be it in workman like rather than concourse condition, however the big disappointment is that the oil pressure leaves a lot to be desired.

At start up from cold it SLOWLY raises to about 40psi. This won't go any higher, regardless of revs. As the engine warms up it does drop fairly steadily until it reaches Zero. Revving the engine can bring it back up to 20 or so, but once everything is warmed up thoroughly, its pretty much non existent.

After some initial reading up, I managed to convince myself it was probably the sender unit. I fitted a wet gauge but this read the same as the electric one. I am pleased to report that there is absolutely no rumbling from the bearings whatsoever. The whole unit sounds strong and healthy. I am now therefore resigned to the fact that its either the pump or possibly the relief valve. Either way, its a sump off job, I will also check the bearings while I'm in there.

What I would like advice on is do I have to pull the whole engine to accomplish this, or can it (with a bit of buggering about) be done in situ? And what is the best procedure to follow? I have done a lot of Googling on this and have read the manual, but as usual, I have found differing (and no doubt dubiously inaccurate) opinions as to what exactly is involved.

I would dearly appreciate any input on this as to how to accomplish a pump swap with as little effort / heartache as possible.

Thanking you in anticipation.

mark F

 

What state is the oil in, the pump is obviously getting pressure when the oil is cold, so check the oil first, it may be too low a viscosity (wrong oil).

You should be OK working underneath, but its just not the easiest, you need to check the oil first then the pump for wear, if the pump is worn it will obviously work better when the oil is cooler, and then as the oil thins the wear in the vanes will not allow the oil pressure to get up.

 

Oil is perfect. Changed & flushed, clean as a whistle. 20/50

 

Hi, Would really appreciate any pointers from experienced owners if possible.

Thanks,

mark F

 

Umm- that counts me out. Sorry!


I do have an old sports car that has great pressure when cold, but low when warm. I have been told not to worry about it, and the few times I have been in the engine, I have seen no ill effects. I replaced the oil pump with no effect. So I just drive it and enjoy it.


Generally, there can be a number of reasons for low oil pressure, but if the engine is running well, and not clattering, overheating, or showing other signs of lack of oil, then why worry? Just drive it.


But as stated at first, I am no Jag expert, so hope you get a better answer.

 

Hi,

If you have low oil pressure the three main causes would be generally be worn bearings, faulty pressure relief valve or worn pump.

Generally the oil pump can produce much more pressure than the engine needs and the relief valve regulates this so the pump has to be quite bad for the oil pressure to drop significantly.

If the engine isn't noisy my thought would be the bearings are probably not too bad as even engines with knocking bearings usually have some oil pressure.

I would start with the pressure relief valve and see what that's like, possibly change the spring and inspect the valve and seat.

One other thing that I have seen years ago was a faulty seal on the oil pickup to the pump which caused low suction on the pump when hot. Replacement of the seal cured the problem.

I must be honest I've never worked on the Daimler engine, how difficult is it to get at the pressure relief valve?

 

Just one thought, if you need to work in the bottom of the engine, you may need to remove the front sub-frame to get the sump off (you do on the Jaguar MK2 and I assume the Daimler is the same).

Removing the sub-frame would usually be easier than taking the engine out as you only have to disconnect the steering, brakes (or remove the callipers and leave the hoses connected), the anti roll bar and the four mounts.

If everything is reasonably free removal of the sub-frame should take a couple of hours, you could take the opportunity to clean and paint it (once you have fixed the engine problem!).

Best of luck.

 

Thank you Homer, THats the info I was after, so it is possible to remove the frame & then the sump. Thats what I wanted to hear I'll let you know how it goes. M

 

Sorry should have given you that important piece of the puzzle.

Don't forget that the car is quite front heavy if you have axle stands under the chassis rails as they have to go roughly in-line with the bulkhead.

Make sure you chock the rear wheels, and keep a jack under the front axle. Once you drop the front axle the back of the car is relatively heavier otherwise it can see saw on the axle stands if you understand my waffle.

You could put some weight in the boot to help too.

 

If you have a canister filter, check the housing under the filter. I had a MK7 with low pressure and the canister was really dirty. Clean the relief valve in the filter housing.

 

Although this is an older thread I ought to reply as It may help.
Daimler V8 250 1967 low oil pressure now at a hot idle, about 15lbs. running about 30lbs. Initially when i first bought the car I had 0lbs at hot idle. I replaced sender and oil gauge and confirmed accuracy with a mechanical gauge. Dropped sump (which can be done if you remove the steering link and starter motor) and replaced oil pressure relief valve, the replacements do not have a small drilling through the centre like the original. Replaced the con rod shell bearings and refilled with 20w/50 oil although I am not sure this is a good idea after what i have read on a mini forum about oil, makes good reading though. The manual says 20 lbs idle 35-40 running. When you consider it only idles at 500 rpm 15lbs is proberly Ok. This article is good but takes some re-reading to understand it fully. High light the sentence copy and paste it into browser

https://www.minimania.com/Motor_Oils..._Misunderstood

Hope this helps some one

Dave Peters

 

As a matter of practice. Ensure oil filter is not blinded & canister is clean. Ensure pump & relief valve is on spec. Make sure all oil galleries are free of muck including crank. Ensure recommended oil viscosity is used. Plastigauge bearings to ensure correct clearance. Obviously once you have established correct oil pressure reading.

 

Hi folks, I have a similar problem with a 4.2litre engine in a Daimler C2 and have tried about all the recommended fixes, including checked oil pressure with external gauge, read higher than dash so changed sender. Also changed filter, oil Penrite, checked pressure relief looked OK. However still starts with good pressure 50psi and drops to less than 20psi when running temp and about 2500. Will drop to almost zero at 750rpm idle and has never done that before. Any advice would be appreciated before I drop the sump and check the pump etc which I currently suspect could have a split housing but is a long shot. I'll also check the O rings on pump pickup etc.

 

20 psi at 2500 is too low, you should be looking at a minimum of 40 psi, and about 20 psi at idle