MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Oil Pressure Issues

Hi

I bought my TD about 18 months ago from USA via a Dutch dealer. It was my intention to get it ready for its Contrôle Technique test ( required for registration in France). Once the registration was completed and the car roadworthy I intented to take out the engine and gearbox and send the car for painting which it badly needs due to poor previous paint prep.So far I have done the following:

Changed back axle ratio.
Refurbished rear springs.
New floorboards and sidescreen box.
Refurbished and renewed brake system.
Refurbished steering.
Cleaned and sealed fuel tank.
Fitted spin on oil filter adaptor from NTG.
Plus other small jobs.

Unfortunately this took time and autumn/winter was upon me, this combined with work that was needed on my other cars/projects, so the car went to the back of the garage. Now the better weather is here I intend to get the necessary and register the car.
OK that's the history, now the question. When I start the car it fires up immediately but the oil pressure is down at 40psi, when it gets warm it drops to 20 psi. I have fitted a known good oil gauge same result. The take off is from the bottom banjo not the head. I have new oil (Millers Classic 20/50)and filter. There are no funny noises or knocks from the engine other than the usual rattle that emits from an EXPAG engine. The oil pressure will not rise above 40 and 20psi even when revved. The engine is the earlier type #XPAG/TD/LHX952. I want to be able to drive the car to the test station but have reservations re. oil pressure. I thought about taking out the oil pump and refurbishing it in the hope that it will help to get me by. As I said I intend to remove the engine and strip it in the near future while the car is at paint.
Am I wasting my time, is it a forlorn hope that as if by magic my oil pressure will improve with a refurbished oil pump, or can the community think of a better course of action.
Sorry for the long winded post but there is no MG enthusiasts near here so I have no-one to talk to.

Barry
B Bridgens

Barry, What was the oil pressure when you got the car? I would check the pressure relief valve on the pump for a worn ball or weak spring, which would allow oil to bypass at a lower pressure. Just a suggestion, not knowing that's your problem, but worth a check. PJ
Paul161

Have you checked for wear on the rocker shaft and rockers? They can get badly worn and will reduce the indicated oil pressure. Most of the wear is usually seen on the rocker shaft itself. If so you need a new rocker shaft and rocker bearings (need to be reamed to fit). Which part of France are you in?
Dave H
Dave Hill

I think that you would be able to drive to the test station on 20 psi and try to improve it afterwards.

The suggestions of Paul and Dave are good starting points.
Willem van der Veer

I agree with Willem,, just don't push it too hard,,How far is it to the station??

steve
Steve Wincze

Hi

Thanks for the quick replies.

Paul, when I got the car I changed the oil and put in the spin on oil filter plus I moved the oil pressure gauge take off from the head to the block. As I remember I felt that the pressure was low but I didn't run the engine for long, only to verify the new installation. I feel it will be easier to remove the oil pump to check the relief valve and I can do the gear and cover measuremant at the same time. The effort will not be wasted as I will know the state when I come to do the engine refurb.

Dave, doing the rocker shaft would be the next move after the oil pump I think, once again effort not wasted as this would be covered in the engines refurb. I had an idea that for a short period I could block off the head oil feed and see if it made a difference. Obviously this would only be for a few seconds. I live near le Mans on the east side.

Steve/Willem I kind of thought that myself, having read many articles on the internet of engines being run at 25psi with no problems for long periods of time. However, something inside me just can't bring myself to do it. The station is 8km away so 16km plus running at the test station. I am so used to my MGA and Porsches at 50-70psi.

I'll pull the oil pump and see what it's like.

Barry
B Bridgens

I would block the head oil feed off first. There have been instances where the rocker shaft end plug was left out or fell out, and that was the only problem. George
George Butz

No need to remove oil pump to get at pressure relief spring. You would need to remove (pump) to get at the bypass valve, but there is no indication that is faulty. The pressure relief spring controls the pressure available to the engine, and these springs do not last forever before they go soft. MG actually offered an auxiliary spring that went inside the main spring to boost the pressure for racing, etc. Abingdon spares still sells them. The original spring should have 13 winds. The ball should be in good shape.

Check the spring to be sure it is not broken or something, it will take 5 minutes. Stick a coin or washers in the cap base to increase the pressure on the ball. If your pressure does not go up, you have a faulty gauge or feed to gauge, or your pump is not working right. I have heard of flexible oil lines vs solid lines effecting oil pressure some. Running thin synthetic oil could lower the pressure. Moss and other's sell an adjustable pressure relief valve which does the same thing as washers. When yo find the right combination of washers leave them in there. Or, try a new spring.
Pic shows regular (larger) spring, and an auxilliary spring. Washer or coin would go in cap base to the right in pic.


D mckellar

Hello Barry,
First, geographical confusion, Le Mans is more about the west side of France.

Another idea could be to replace oil for a higher grade. Just to go the "controle technique".

Are there any play on the rockers when just moving them by hand when valves are in the closed position ?

Easy inspection : just remove the valve cover and inspect at tick over if oil is gushing great flows or just squirting above the rockers.

But I agree that only 16 km with this low pressure will not dammage anything more. Furthermore, the engine will be cold for this short trip hence 40 PSI to go and maybe 30 to get back home.


Laurent (Toulouse)




LC Laurent31

Hi

I'll try the coins first.

Laurent I meant I live to the east of le Mans, I'll take of the cover and check with the engine running.

Barry
B Bridgens

Best of luck!
Dave H ( Carcassonne - sometimes )
Dave Hill

I have run my TD for several years with oil pressure at a max of 40 psi, although it can drop to 10 - 15 psi at a hot idle. So running with those pressures, assuming that is the only symptom, is not likely a problem. Oil flow volume is much more important than actual pressure, both from a lubrication and cooling standpoint.

Having said that, there are a number of issues which can result in low pressure, especially in a worn engine. Oil pump wear and rocker shaft wear have already been mentioned. But the more likely culprits are worn main and cam bearings. Any wear beyond the factory spec will allow oil to flow too freely through and around these bearings resulting in a low indicated pressure. The same goes for the rocker bushings.

So have no fear to drive the car with those pressures, knowing you will soon have the time and budget to rebuild the engine.
Lew3

Barry,

My '50 TD had exactly the same symptons as you describe. Until now I do not know the cause of these symptons. But my guess was that with a modern car the control light would not come up as long as pressure is not at zero all the time. So why bother?

The good news is that after appr. 5000 kms of happy driving the gauge suddenly started to show the right values, and until today that's still the case. As I said I do not know the cause nor the solution. Maybe something was just clogged...

Jasper
JL Nederhoed

Barry,
I agree with Lew and J L. Those pressures would have been a welcome sight in my first TD. Drove it across the US and also New York to Florida with no ill effects. When hot it would idle at about 10 lbs. and get up to 30 lbs. at 4000 RPM.

Good luck with the registration process.

Jim Haskins 1953 TD (The second TD in 50 years)
J M Haskins

The presssure is tolerable, especially if you intend to go through the engine soon.

Could your oil be too thin? Heavier oil may bump the readings more to your liking.

You said you moved the gauge from the head to the lower banjo fitting on the block. Verify your lower banjo fitting has a large hole, as opposed to the top banjo with a small hole. I discovered a wierd banjo bolt (to gauge) on one of our TDs with a small orifice in the block thread. This requires that fitting be installed in the head.

JRN JIM

There are a few things to check prior to pulling the pump. The spring is one as mentioned.

First thing to do is pull the valve cover and start the engine (may want to put some rags or paper towels around the outside of the head).

If you see oil spurting out of the rockers, you have adequate pressure to take it to the Station.

Next is to check the gauge. Unlikely, but the gauges sometimes get gummed up and don't allow correct pressure readings. Try an aftermarket oil pressure gauge.

Bruce TD4139 Cunha

Hi

Thanks for all the advice and tips. I'll be working on it over the weekend to see if I can improve matters, if not then I'll make an appointment with the test station and throw caution to the wind.

Barry
B Bridgens

Modern, higher revving, higher compression modern engines don't even turn on the idiot light until 11psi. As hinted at by above posters..oil pressure change over time can be an indicator of wear as pressure drops.
I would just drive the car, monitor the pressure for change over time, and not worry about it. Regards, tom
tm peterson

Here's a picture of a worn ball. With it it gave 50 psi pressure. The new spring and ball produced exactly the same 50 psi....

So don't count on a higher pressure with coins or heavier springs. If the systems leaks too much pressure or the pump produces too low a pressure, no amount of spring action will up the psi's?

Willem van der Veer

Hi

I blocked the feed to the head and there was no difference.

So out with the oil pump and radial clearance on the drive gear shaft was 0.13mm and the end float was 0.09mm both in spec. BUT the driven gear was a rattling good fit on its shaft so I did some measuremnts and the shaft is 13mm and the bush i.d. was 13.56mm. It really does move side to side despite the clearance being so small. I guess once these bushes start to wear it is all downhill. I kind of feel that just renewing the driven gear bush might be false economy but I can feel no play in the drive gear shaft so I might just renew that bush on its own. I can only find NTG that sell just that bush most other places sell the 3 bush set.
The ball, seat and spring all look good and the spring measures in spec. NTG sell the auxiliary spring so I might just order one of them at the same time.
So a good clean, lap the cover mating surface and then sit back and wait for the parts to arrive.
I'll report when it is all back together.

Barry
B Bridgens

This thread was discussed between 31/03/2016 and 03/04/2016

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now