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MG MG Y Type - Regaining oil pressure.

After an on-and-off 25 year ground up resto, Y 3348 is nearly done. During a test fire-up, oil pressure appeared after we put oil down the sparkplug holes; engine ran sweetly, so we thought it wasn't necessary to burp the oil pump. But at a second test today, I aborted early when no oil pressure appeared, even after putting oil down the plug holes. Is it common to need to burp the oil pump even after pressure has initially appeared?
Thanks for any advice.
John.
J P Hall

John-
Oil down the plug holes won't affect oil pressure, it won't do any harm, probably a good idea if it's been sitting for ages but won't help oil pressure-
So if i understand what you're saying, it started and ran ok, had oil pressure while it was running, did it hold good pressure right up to when you turned it off--then restarted next day and no oil pressure---none at all-? how long did you run it for
William Revit

Sorry Willy, I should have said "oil down the plug 'oles purely for lubrication"; also squirted oil down pushrods etc before we did anything.
So last week was first attempt. We did the following:
- made sure oil level good.
- oil into plug holes and valve cover.
- with plugs out, hand cranked to make sure it felt right. All good.
- still with plugs out, used starter to crank. Initially no oil pressure, but after maybe 4 x 10 second cranks, a bit of movement on the gauge.
- put in plugs and cranked. Fired up, adjusted carb settings to get smooth idle and throttle response. Oil pressure showed about 20 at idle, 30 - 40 on gentle revving.
- a week later (yesterday), not expecting any problems, I had another go. She fired up instantly (new Bosch short-reach plugs) and sounded sweet - but no indicated oil pressure. Of course I aborted straight away. Disconnected oil gauge supply pipe at block - a quick crank with ignition off, no oil emerging from block.
- removed oil pump primer plug and fed oil in; eventually (about 250ml) it stayed full enough to refit the plug. More oil down plug 'oles and valve cover. On cranking, still no pressure indicated, so stopped until I can get some advice.

Thoughts: need to test outlet nearest to oil pump to confirm pump is operating. As I understand it, the oil should not drain out of the pump completely unless there's something wrong/missing in the pump. As far as I recall, it only needed new gears and a thorough clean - but that was 4/ 5 years ago! I can rob a pump from TD (are they interchangeable?) to compare results.
Sorry for the ramble - thanks for your input.
John.
J P Hall

PS - my pump (in fact both YA and TD) does not have the priming plug on the upper edge of the cover as shown in WSM illustrations C1 and C7. I put oil into the plug that is just visible in C7 above the pump's mounting face to block. The inset to C7 shows a priming plug that I wish I had!
John.




J P Hall

Hmm- So is this first startup of a new engine or the old engine being bought back to life, it's weird it had pressure one day and not the next-
It does sound a bit like it's picked up some rubbish in or has a stuck relief valve in the pump or the very overlooked relief valve in the block has rubbish in it or got missed during rebuild is the usual go with that one
William Revit

Hi, The problem sounds like the first start had the oil pump primed with grease or vaseline .The oil pressure was fine when it was switched off so the relief was OK ??? Over the week it could bleed back into the sump through a pick up gasket or a crack in the pick up pipe. This problem is a head scratcher GOOD LUCK
Bob Wood

Ha! - thanks Bob. Where are you in Qld?
Willy, this is a completely rebuilt engine, done by a retired motor engineer, but I can't honestly remember whether he checked over the tolerances (per the wsm) in the oil pump, as I suspect the pump was at my place while he built the engine.

So the fog is clearing just a little bit. With the help of a mate today, we checked a couple of outlets and basically found no output from the pump. Then with the top pipe removed, we peered in and could see that the visible gear did not move at all whether we turned the motor forwards or backwards. So pump out tomorrow to see what's goin' on. As camshaft and crankshaft appear to be functioning normally, I'm hoping the problem might be contained to the pump body, gears, end float maybe, etc. - I'll report findings hopefully tomorrow.

John.
J P Hall

Hi John ..Good luck with the pump drive I live in Herston Brisbane but my YT is up the coast my beach house. Will you be a the meet next week in Gympie??I will BOB WOOD
Bob Wood

Sounds a bit like someone forgot to fit the keyway into the pump gear shaft, or the circlip has come off the shaft and let the drive gear move away from the cam --there are some very very dodgey aftermarket circlips being supplied with some gearsets--if that's the issue there's a fix-

willy
William Revit

Sounds possible Willy.
I've been trying to find some kind of technical paper on something like " disassembly/reassembly of XPAG oil pump" - I felt sure someone must have done a write-up sometime in the past. Does anyone here know of anything? The WSM is helpful for parts identification and location, and it may be that's all we need. Things like correct size/type of woodruff key or whatever.
I was roped into mulching this morning (swmbo), but should have the pump out later today for examination and report.
I don't know whether this stuff is of interest to others or not - Paul B will no doubt tell me if I'm wasting BBS space!
John.
J P Hall

It's always interesting John-and don't feel alone there have been plenty of XPAG oil pump failures ,mostly because of substandard parts supplies-
Just think yourself lucky, if it turns out to be the circlip, if it happened on the road it can be a bit dramatic with the pump shaft getting itself buried into a conrod --- your lucky day in a way

willy


ps
Paul B doesn't run this BBS ,he's the International MG Y type register guy, this one is under the control of Mike Plumstead
William Revit

Some pics of your pump as you dismantle him would be interesting
William Revit

SO - pump out. Two teeth broken, the bits somewhere to be determined. Shaft bent near the gear end - that takes some doing! What looks like blue heat stress on all teeth - I'm not a metallurgist, but I'm thinking the meshed gears have seized, putting enormous strain on the teeth, heating them up and breaking at least two. The first question is WHY. I fear there will be collateral damage to camshaft gear - Willy, would that be "engine out", or might we try extracting the camshaft from the timing gesr end?
In a couple more photos, I'll try to show that when the drive shaft was tapped out say 6mm, it and the gear turned freely, but by the time the shaft was tapped out another 6mm, she was stuck again.
The drive gear end face has horrible scoring on it; the corresponding face of the pump cap is actually pretty good. Strange.
Looking st the photo of the drive gear, you can see the cutout - which means I think I've installed that gear the wrong way on the shaft?
Oh dear - not a good day.
Also Willy, you're right - although the circlip on the driven gear was in place, it broke in two just with the circlip pliers applying medium force. Unbelievable crap.

Am despondent, but grateful for any input.
John.





J P Hall

First pic, shaft drifted out a few mm., and would turn freely. Second pic - out a bit more and stuck fast. Seriously bent!
JPH.




J P Hall

As well as the scoring, you can see the cutout at 12 o'clock - am I right I've fitted that gear the wrong way round? Would that error be enough to cause the seized shaft? .
Thanks all.
John.


J P Hall

Don't feel despondent John, you've dodged a bullet, it could have been a lot worse if it had happened out on the road at speed- You're not the first to have that happen
That groove in the gear is the oil supply from the pump gears to feed the shaft bearings and definitely has to be fitted with the groove down inwards into the pump housing--bad luck there with that it must have seized just as you turned it off--It doesn't have to stick by much to get pigheaded and refuse to move at startup-I don't hold much hope for your camshaft, but you never know it might be ok
To answer your question about pulling the cam out with the motor still in the car, yep, you can do that, sump off, dizzy out, rocker gear pushrods and followers and the centre cam bearing retaining bolt-- You need it on tdc otherwise the cam lobes/journals can foul on conrods---Have a real good look at the camshaft retaining plate in behind the cam sprocket and make sure it hasn't bent or cracked. The tricky bit is fitting the centre cam bearing on the way back in--you will have to check and double check that you get that around the right way when working upside down down there under your shower cap, just make sure the dowel hole and the oil hole are orientated correctly----

Bad luck all up but yeah it could have been a whole heap worse if it'd had spat the shaft out into the wizzy bits

willy
William Revit

I would suggest the broken tooth jamming in the camshaft caused caused the bent shaft. and then you get the heat stress on the teeth, not the other way.

Camshaft will need to come out and be checked to see it's not bent or cracked - lot of crack inducers in a camshaft.

There certainly appears to have been a "meshing problem" - perhaps the pump gear and camshaft were not a "match". There are some dodgy camshafts being sold in some parts of the world in the last 15 years.

As a minimum, it's a camshaft out job. A hot running engine that loses oil pressure can survive, but a cold start with no oil pressure can lead to damage pretty quick.

Assume nothing, inspect everything you possible can. You need to look further for where & what caused the initial failure.

Good Luck

Tony
The Classic Workshop

PS - these are "tough as bulldog engines", so you just might get lucky. At least it failed at home.
A L SLATTERY

Hi John,

Apologies for seeing this post rather late.
Have you used a torch and mirror to look up the oil pump "hole" to see if the conrod has been hit by the oil pump shaft, as Willy suggested? I once had a circlip fail and the oil pump drive made very neat helical cuts into a conrod.

Hopefully that is not the case here. Your oil pump drive gear looks much better than mine, which was hammered on two sides.

Bob
Bob Schapel

Thank you Bob - I know you have a wealth of experience. I had a quick look today with the colonoscope, more tomorrow when my engineer mate comes round. We'll be looking at the cam gear or anything else, but then I'll take the camshaft out for a proper look. I do wonder where the broken tooth has gone! Could it drop down into the sump?
There is some hope, in that the circlip was in place, and the shaft/gear did not appear to have gone beyond its normal reach. Time will tell, when we crack everything open!
Thanks for your thoughts.
John.
J P Hall

John, Good to hear that the circlip was in place etc. Whatever the cause, I can't imagine broken oil-pump teeth finishing up anywhere else but the sump.

Cheers,
Bob
Bob Schapel

A quick update. Lost a week after dear father-in-law died last week (92); back in the shed for a bit of therapy today.
The portion of the camshaft that is visible from below (sump off today) looks OK, but of course there may be hidden nasties, so hopefully camshaft out in the next day or two. The other pic, if you look carefully, shows the complete broken pump shaft tooth, found sitting quietly on top of the baffle plate. Under the baffle plate, no other evidence of broken bits of either oil pump shaft or camshaft; the strainer is also clean. Interesting!
John.





J P Hall

Sorry to hear about your father in law John, my condolences to your family-

Interesting--Don't forget to have a good look up the beam of that conrod--The drive gear looks grooved in the pic to me from here, could be a reflection but yeah, big inspection when he's out

willy
William Revit

John
How's progress
I had a thought-very rare phenomenon
When you get an oil pump together, I'd consider bolting it up to the engine before you refit the camshaft and get your hand up inside and check that the gear turns properly for peace of mind, then you'll know it's all good for when you finally fit it up afterwards.
just a thought-
willy
William Revit

Ha!- now that's scary Willy - exactly what my mate and I were talking about today - trial fit the pump first, make sure she spins nicely; then with camshaft in place but before connecting anything else or buttoning up the sump, see that the pump gear meshes nicely with the camshaft. Also check conrods while we're at it.
I've ordered up new pump assembly from FTFU (seems to be the best price just now), and will add new camshaft if needed.About 500 aussie dollars each.
I so look forward to finishing the YA after so long.
In my next life I think my hobby will be ping-pong. Thanks for keeping in touch.
John.




J P Hall

Right: camshaft out, and as expected, blueing evident on every tooth face; also scoring/scratches, but very hard to see in these photos. Some fine powder in the (drained) sump, but no more actual pieces of broken teeth from camshaft or pump gear. Oil pump ordered as a unit from FTFU, plus new camshaft, cam bearings, gaskets and whatever I could think of. An expensive exercise, but honestly I don't think I could have foreseen or avoided oil pump failure, as everything looked fine, was clean as a whistle and behaved fine on test, both bench and initial startup. That's why I wanted to put the tale up here, to let others know what can happen. As Willy said, I avoided catastrophe by shutting down early.
On to other jobs while I wait for parts. Shame no-one in Australia seems to stock oil pumps; I found one supplier of camshaft, but almost double the price of importing from UK or America.
Hope this all helps someone down the track.
PS - I would prefer to re-name the thread "Oil Pump Failure" to improve archiving - can I do that?
John H.





J P Hall

John,
What sort of camshaft do you want? There should be lots of used Wolseley 4/44 cams around. They are the same timing as Y-Type but have slightly higher lift (same as TF and late TD). The cam on the left of the image is Wolseley 4/44. I have a few in my shed, but have not measured to check their condition. If you ask around the club in Queensland, you should find one.
If you can't find a good s/h pump (Y, TC, early TD or Morris 10) you could use the internals of a Wolseley oil pump and re-bush your pump body. The re-bushing would probably be the most costly bit of the exercise.
Have you checked the conrod as Willy suggested? It would be good to know what caused the problem.
Cheers,
Bob Schapel


Bob Schapel

Thanks for the thoughts Bob - if this was one of my old rattlers (TC and TD), I would absolutely be looking for a good 2nd hand camshaft, on the basis that it would probably easily last 20 years and therefore “see me back to the pavilion”. But it’s my dear wife’s favourite shopping car, and apparently that means it deserves a new camshaft. As to the oil pump, I did the sums, and by the time I’ve paid for new shaft, gears, bushes,relief valve etc., plus had the body machined,it’s the same money to buy the FTFU rebuilt item, machined to spec. with new gears, shaft and all. That’s why I’m going for the two items new or as new.
I’m blessed with a retired engine builder neighbour who had a close look at the (surprisingly light) damage to the camshaft, and he surmises that the pump gear, having shed a tooth, has jammed briefly in the cam gear, bending the pump shaft just enough to enable the two to “unmesh”, with the camshaft keeping spinning by skipping over the pump gears. That would explain the surprisingly light damage to the camshaft gear - although it is still beyond economic repair.
I agree with Willy - I may have suffered a setback (you get used to them), but I may very well have dodged a bullet.
As an aside, my penchant for “driving by the gauges” has been passed onto all three sons, who. mocked the idea when they were young, but who all now keep some form of classic, and whom I hear parroting my words of yesteryear to their less informed friends! The wheel eventually goes full circle.
Yours,
John.
J P Hall

This thread was discussed between 02/06/2022 and 23/06/2022

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