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MG TD TF 1500 - Oil pressure (again)

Hi all
Changing oil and filter for the summer I then noticed a weep from the pipe from pump to filter.


Decided to renew all pipes with flex pipes (block to head renewed with flex pipe two years ago)

So new oil filter pipes from pump to filter and filter to block renewed result 20 psi drop in oil pressure from 45 to 25.

All pipes primed oil pressure gauge removed and bled for air locks. Plenty of flow to the rockers where has my 20 psi gone. Don’t want to drive it on the road!

Thoughts please
J A Davies

Hi
If the new flexis are bigger I/D than the ones they replaced I think that would reduce the pressure. I replaced mine a couple of years ago with specific for XPAG flexis and saw no difference.

Barry
B Bridgens

It’s possible that when the soft lines were made up and the fitting was inserted into the hose it cut some rubber with it and it is partially occluding the orifice. Personally if the hardline was leaking at insertion of the fitting I would probably braze it or replace with another hardline. If it was the copper seals I’d replace them.

Bill Chasser
TD-4834
W A Chasser

Maybe the old pipes were almost clogged and their ID reduced. Inspect them carefully...


In case, 45 psi was the erroneous value and 25 is actually the pressure that reflects the wearout of your engine.

I hope I'm wrong !

Laurent.
LC Laurent31

Hi Barry
Purpose made kit if anything the new pipes look slightly smaller the banjos certainly are.
Bill
I will look at the bores when I strip the flex pipes out tomorrow
Old pipe was split and had been rebrazed in the past so not happy to repair again
Laurent
Old pipes were clean thanks lt was something l hadn’t checked until you mentioned it. Thanks
I will report back tomorrow when i check everything again Thanks for the comments
John
J A Davies

Was the flex pipe from the block to the head replaced as well or left alone

Where is your oil pressure gauge plumbed in
William Revit

May be silly, do you have a modern filter canister inside a lookalike casing? If so check whether the filter has a drain back valve. Some conversions pump oil the wrong way through the filter and you need one without a drain back valve.
Ray TF 2884
Ray Lee

Like Bill asks, have you moved the oil pressure line from down on the block up to the head? That would display the reduced pressure feed to the rockers and not show the real oil pressure.

Should we assume you have an older style oil filter that uses banjo bolts rather than a newer spin on? If you added a spin-on filter, the lines could be backwards like Ray mentioned.

No matter what you did from the pump feed through the the filter should cut pressure significantly because the filter relief bypass would direct the flow right into the block.
JIM N

Put old lines back on and check pressure. If fine, likely a blockage in the new line. Yes, the wrong spin-on filter will kill pressure. George
George Butz III

Hi William

Flex pipe from block to head replaced two years ago. Oil pressure gauge plumbed in from the block connection.

Hi Ray,

Not silly at all. It's a modern filter - see image. How do I check if the filter has a drain back valve - see image of top of filter

Hi Jim

It is a modern adapter for a spin on filter - see image - but it has banjo bolts!!!! Sorry I don't understand the pumping oil backwards. Does the image help?

Hi George

That's my intention - to renew the pipes - see image - I've started bending already. New lines appear to be clear. I've put compressor air through them. Spin on filter supplied by the same people who supplied the flexi pipes (who I have the greatest faith in)

Thanks everyone for your helpful comments.

John


J A Davies

And again

J A Davies

Again

J A Davies

Sorry computer says file too big to allow any more photos....
J A Davies

Hmmm
A few observations

To me the lines appear fairly small in diameter, but having said that 'if' it is a bought kit you would imagine that it is ok, a lot of modern hoses are very thin walled so maybe inside dia. is ok-----?

With the oil filter return valve----bit hard to pick in the picture, but if it has a valve it will be a flap type arrangement that checks the flow back out of the 6 outer holes and easily seen through the holes-With it sitting like it is there the holes should be shut if it has a valve,- basically,if you filled them 6 holes with oil with it sitting like that if the oil stays there it will have a check valve ., if it drains into the filter it hasn't

Not sure how that filter head is plumbed inside but if it's as it looks externally, -- normally the oil supply from the pump goes to the outside of a filter ,through the 6 holes , passes through the filter and back out the centre
This is reverse to how yours is set up so it would be "very" important to have a filter without a check (anti drain) valve

If that were my car, if there's nothing stopping the filter housing being turned 180deg., I'd spin it round and put the hose from the pump onto the side and then the top outlet off to the engine oil gallery, by doing this it would eliminate the risk of having a filter with a check valve with the oil trying to go backwards through it
Another point here is that most filters have a blowoff valve built into them so that if the filter gets blocked or can't cope with the flow of cold or thick oil ,the valve opens to allow some unfiltered flow to prevent oil starvation---With the filter hooked up in reverse as in your picture this valve will not work -not ideal

William Revit

Another little possibility is that the new banjo bolts "might" be longer and blocking a port--probably not but worth checking

The layout of the pipework for the spinon conversion was probably done to copy the layout of the old paper element filter housing for an orignal type look and with a filter with no check valve then that is fine but if you happen to get a filter with a valve it's disaster, I'd really consider spinning that housing if possible
William Revit

Looking down into the filter, it does not appear there is a rubber flap to resist oil draining back down into the engine where the pump has to refill the filter and all the channels at startup before pressure builds up. The pump may even lose prime. I would expect a new filter package to utilize it. I just had to spend quite a few minutes repriming a TD that set for a few years.

If the lines were reverse, the flow would be backwards where the flap would block the flow. I looked at one of our engines and see the line from the pump feed the top of the the canister and the banjo fitting on the side runs to the engine, like yours.

Even if the flow through the filter were blocked, oil would flow into the engine via the filter bypass valve and likely display full pressure, assuming that valve is functioning.

I'm going to make a suggestion for you to reposition the top banjo fitting towards the engine for a gentler bend for a couple reasons. For one thing, there is a small rubber tube inside that external steel braiding and that small radius bend may closing the tube down a touch. For the second reason, let me relate a true story... once upon a time, there was a new steel braided hose much like yours running from the bottom banjo fitting up to the brass fitting feeding the pressure gauge. It made a nice graceful bend. I installed a blinking red LED light in the instrument cluster for an oil pressure "idiot light." One day, I received a call from my wife because there was this funny red light blinking on the dash. I looked into the phone and screamed "SHUT IT OFF!" I drove to her with a gallon of oil; she wasn't hard to find since I could follow the black oil line on the road. Even though the engine compartment was dripping with oil, it took quite a few minutes to discover a very fine oil spray coming from that new line. One wire in the braid had broken and punctured the tube. I have a hydraulics business so this didn't come as a big surprise.

I'm curious why they made an adapter for the pump rather than just match the original dimensions for the banjo fitting. They must've had a reason.

The first photo gives a hint the oil gauge line runs to the bottom banjo fitting, like you said. One of our TDs has a banjo bolt with a restricting orifice on the end that fits into the head rather than the block. That provided good readings before the filter upgrade.

Air in the lines would change the gauge reading.

Coincidently, for the past week, I've been trying to get one of the old canister filters to seal in the middle because it is missing a steel band that locates the seal. I brought home another handful of different seals to try this weekend.

Good luck and let us know what you find.
JIM N

Oops, too late to edit my goof.

Air in the lines would NOT change the gauge reading.
JIM N

TC engine? Has micro adjuster on dizzy and TC type oil pump fitting.
George Butz III

I resolved my oil filter cannister joint leak using a combination of "fabric and rubber V seal" and a 3/16" O-ring in the V. Then discovered drips off the oil pump and oil line. It was determined that the line was leaking at the pump banjo fitting solder connection. No wonder, the joint was never soldered. There was only a superficial fillet on the end of the fitting. Totally inept.

After extensive cleaning, the tubing was tinned and some of the banjo fitting socket. I have a lot of confidence in that solder joint but no confidence in the other 3 joints for the two lines.

I have a remote filter fabricated for one of our other TDs and will likely fabricate another for this '51. The filters will mount beneath the front apron for cooling.



JIM N

Hi All

William

sorry not to reply earlier weekend at Prescott watching the hill climbing.

I agree the lines appear to be fairly small and I think this could possibly be the cause of the problem. Looking down into the filter there appears to be no flap valve and I am pretty sure I can see the filter through the six holes. From what I can tell ?? The oil from the pump goes down the centre of the filter, thru the filter and exits via the six holes, I.e. The side connection onto the block/gallery. I will strip it out again in the next couple of days and check it all again. I can't seem to see a blow off valve. I'll spin the housing and report back further and will also put a new filter on.

Jim

Hi I am in the process now of making new copper pipes (instead of the steel that were original) and silver soldering the same to the banjos. Clearly these will have a much bigger ID. The reason for the adapter on the pump is because it is an early type pump. Sorry just me - are you happy with soft solder joints??

George

You're just too good - it's a TC engine!

Thanks for all the help. Once I've made new pipes and installed same I will report back.

Again, many thanks for all your help.

John
J A Davies

John,
the blow off valve (filter bypass) is in the block behind the oil pump. It discharges directly into the oil gallery. As you did not touch it, that should have no effect.
Just check the pressure relief valve under the oil pump does not have crud under it after the oil change.( a little tap with a brass drift helps to seat them)
Ray TF 2884
Ray Lee

All good john, Prescott would be my choice-just a bit jealous-!!
Yeah, if you can see filter down through the holes, the filter should be ok to run with reverse flow as you have it
I tried to research your filter but couldn't find the required specs-BUT-I did manage to find the specs of the Mann W712 equivelent listed on your box for it and that has neither the anti drain valve or relief valve so all being fair your filter should be the same and have neither and be ok
It will be interesting to see if the pipes do the trick

Just out of interest
To check if a filter has a blowoff valve you can look down through the centre hole to the far end of the filter--Right down there if it has one you will see a little housing about the size of the end of your finger with a valve in it - if it hasn't got one the end will be smooth
Even if your filter had had a relief built in, by running the flow backwards through the filter prevents that valve from working as it is directional and would act as a filter without a valve so that part of it all cancels itself out--------on your setup

Now- It is my understanding that TC's after engine No 14224 had a oil flow (filter ) relief valve in the block which opens in the case of a blocked filter or blockage in the pipework etc and redirects the oil direct into the main gallery as a safety precaution-
I believe that early TC engines prior to engine No 14224 did not have an oil filter bypass valve in the block and if anything gets blocked there is a resultant drop in oil flow/pressure ---If your engine No. is less/earlier than this then I would imagine there is definately a blockage there somewhere
William Revit

John,

I'm not familiar with the details of the TC engine if that's what you have so you may not have the oil filter bypass, so your all the oil pressure must come through the filter; if there's too great a pressure drop through that circuit, the relief valve is dumping oil right around to the pump inlet through the pressure relief valve, starving the engine. The filter bypass on the TDs would short circuit the excess oil directly into the block feeding the bearings, etc. with good pressure. I think we're all on that same page.

Does the filter adapter have a bypass built in? A lot of filter housing do so they directional. You'd have to think they figured that out ahead of time.

It is remarkable my tubes held up this long with such a tiny sliver of solder sealing the edge of the fitting. Hope that's not the norm.

It won't matter if you use tin/lead solder or silver solder. I preferred the soft solder for lower temperature. I would not use anything hotter than an air/propane torch. The oil will make resoldering impossible so you'll have to remove the fitting from the tubing to clean it thoroughly. Make sure you scribe marks before separating because position is critical- there's no tweaking when you go to reinstall them. I used acetone to chemically strip as well as possible, sanded the tubing easily and then used a drill bit to scrape the inside of the brass banjo fitting (don't go crazy and open up a larger gap). The tubing was pretinned easily. The fitting took some time to tin the socket where it was reachable; fortunately, the angled cut gave access to quite a bit of surface. A small screwdriver was used to scrub the ID to coax it to tin. The end of the fitting was sanded to clean metal so it was easy to build up a nice fillet of solder to the tubing.

I like to use "tinning flux" in cases like this. It has granulated solder in suspension so it might help. Of course it was hiding on me so regular plumbing flux was used. Not a big deal.

Goodluck!

Jim
Welding Engineer
Ann Arbor Hydraulics
JIM N

Just thought of something
The sealing washers on your banjo fittings
The washers on the bolt head side of the fitting isn't an issue BUT the washer on the housings side can be an issue--If the washer is a snug fit to the thread size the oil flow can be restricted/blocked
The washers need sufficient clearance on their inside diameter to allow flow--Good purpouse made washers fit the bolt to locate them but have cutouts to allow flow or alternatively the banjo fitting has a recess to locate a larger inside dia. washer
Just thought that if two different styles of washer were in your kit it could be easy to get one or two mixed up
willy
William Revit

Sorry - Disregard that--overthought it
I've been playing with SU overfow pipes today and got myself a bit excited about nothing
On the SUs they need clearance to breath but not on them oil lines ,sorry to confuse things there
willy
William Revit

Hi All did you get my latest messages and photos?
J A Davies

See photo in this thread. This is the problem with the flex lines. https://www.mgexp.com/forum/t-series-and-prewar-forum.46/mg-tc-oil-filter-adaptor-and-pipes-change.3955804/ George
George Butz III

This thread was discussed between 22/05/2019 and 12/06/2019

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