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MG MG Y Type - Oilpressure Question

Gentelmen

The engine of my YT had been completely overhauled some 4390 km back - including new oil pump gears.
After running the engine in, the gauge showed unsatisfactors (low) reading. Thus I fitted an additional spring and I now get the following readings on the oilpressure gauge:
with cold engine = 80 psi
with warm engine = 40 psi
with engine idling = 18 psi
Somehow, this does not feel right, even though the compression rate is perfect at 8.5bar on all four cylinders.

Regards
Anton
Anton Piller

Hi Anton, I reconditioned the engine on my YT last year. I didn't replace the gears in the oil pump, but it did need new balls for the relief and bypass. It has since done about 4500 km. I get a maximum of about 50 psi cold and it holds around 40 psi when hot with around 20 psi at idle. Your cold reading seems a bit high - due no doubt to the additional relief spring.
I would be interested in other members' readings.
Regards, Ewan
E.J. Ward

Anton
Where are you taking the pressure gauge pipe from the upper or lower banjo - it makes a difference to oil pressure readings.

My YT's TC engine is currently (over 2 mths) in pieces whilst I wait for new over 0.040 size rings to arrive from the USA and unfortunately I cannot remember what reading I had previously.
Stuart
Stuart Duncan

yep. the banjo can be an issue-
Big difference between hot/cold what oil have you got in there----
William Revit

Willy's point is very important. If you are taking the pressure from the top banjo, on the head, the pressure will read lower than it should. If the valve gear is worn, it will read a lot lower. If this is the case, beware that the "real" oil pressure at the outlet side of the pump will be too high. That 80 psi on the gauge, might be 100 or more! High oil pressure can quickly damage teeth on the oil pump drive.

Even if your pressure take-off is in the correct (lower) position, 80 psi is a bit high in my opinion.

Bob Schapel
Bob Schapel

Friends

Thank you for your replies. I am aware that 80 psi might damage the teeth of the oil pump drive in the long run - this is why I posted this thread :o)

I am using the lower banjo for the oil pressure pick-up, as it is, see photo.

I am using mineral oil 15W-40 / API SL.

I will remove the extra/additional spring, I had fitted to the pump and I will go for two new balls (for the engine).

The Swiss driving season nears its end and the mods will be a winter job. I'll keep you posted, but please be patient.

Anton






Anton Piller

Nice colour Anton - looks fantastic

Your oil choice is good- I think you are on the right track with removing the extra spring and checking/replacing the balls

One little thought is that--because these cars have been about for quite a while and fiddled with by many, it might be an idea to remove both the banjo bolts and just check that the restrictor is in the end of the 'top' one , not in the bottom one

willy
William Revit

Willy

Thank you for the flowers regarding my YT. Attached please find a photo of the car, when I bought it some 35 years back.

Regarding your remarks about a restrictor: excuse my ignorance, but I am not aware that there should be one! Attached please find a copy of NTG's catalogue. I used the two hexagon types shown in the bottom halve, but do not remember, to ever having seen a restrictor.

Best, Anton




Anton Piller

Wow, you have done an incredible job of restoring that car! It is beautiful! I agree, it is a great colour.

NTG's labelling does not look right to me. As far as I know, TB and TC had the almost round (two small flats) bolt in the top fitting. TF and Wolseley 4/44 had the smaller (thin hex head) bolt in the top fitting. However, I am not sure when they changed over, or what was used in Y Types.

I don't think there was any restrictor originally, but so many owners fitted them that they became almost standard. Good thinking Willy. If there is a restrictor in the lower banjo bolt, it could be causing the pressure symptoms.

Cheers,
Bob
Bob Schapel


Guys

The top banjo bolt on the head of my YT is used to feed oil into the thin flexible hose that automatically lubricates the vanes of the Shorrock Blower. Thus both the top and bottom banjos must be unrestricted.

The first of the attached photos shows an old type round head banjo bolt that was eventually replaced by a hexagon one with BSP connecting thread.

Cheers
Anton




Anton Piller

OK-nice setup

The top banjo bolt won't effect the oil pressure at all much unless the rocker gear is badly worn
If it has a restrictor in the top it will only restrict oil to the rocker gear-theoil feed to your supercharger off the bajo fitting would still be at full pressure
But
By some chance, if there has been a restrictor fitted in the bottom banjo bolt then it 'could' be playing with your oil pressure at different temps
Don't trust what 'should be' -For your own peace of mind I'd be pulling the bottom banjo bolt out and just make sure it hasn't been fitted with a restrictor in the end of it-
willy
William Revit

Willy

At the time of fitting the blower, I also fitted two new "union bolts with take-off" from NTG. They definitely had no restrictor fitted and were unobstructed.

Anton

Anton Piller

All good Anton---It was just a thought, but if you're sure it's unrestricted then all is good there-
Cheers
willy
William Revit

Hi Anton,
Can you measure the operating temperature of the oil ?.

As you know the Y-Type had a plain un-finned cooling sump, while the TC had a finned sump for cooling the oil.

Perhaps the oil is not being cooled enough before reuse in the engine.

I have had similar issues for a few years in Australia, particularly after longer drives on the motorways. I think these modern multi-grade oils are just not able to handle the heat (or we are not cooling it enough?).

Safety Fast

Tony Slattery
The Classic Workshop
Black Mountain
Australia
A L SLATTERY

Hello Tony

I would not know, how to measure the oil temperature without an appropriate dash-instrument, but:

On my YT, I am using a big (10.5 pint) finned sump. The only draw back being the lack of a recess in front of the sump, which makes it difficult to dropp the engine into the chassis - I had to lower the engine vertically down to its fastening position and the gearbox had to be added from inside the car.

cheers
Anton

Anton Piller

Anton
I agreed earlier with your oil choice 15/40 and with a fresh engine you'd think that would be fine, but most people here seem to run 20/50 in their MG's
I've been running a 15/50 diesel mineral oil in a friends semi competition MGA with good results for maintaining oil pressure under stress/hot
Might be worth chasing up some 15/50--but you'll definately need to remove them relief valve washers if you were to do that

At one stage I tried 15/50 synthetic but when nice and hot the oil pressure was terrible, -it probably lubed ok but looked scarey on the gauge

willy
William Revit


Thank you Willy

Thank you for the extra oil grade 20/50 data. I am a bit hesitant because of the moderate temperatures over here in Switzerland - I might consider with the next oil change in spring 2023.

I had modified my water pump set-up to 6 vanes when fitting the Shorrock. This actually should do the trick :o)
The only photo, I have of this modification is a Christmas Greeting of 2016....

Be good
Anton


Anton Piller

This thread was discussed between 23/10/2022 and 13/11/2022

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