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MG TD TF 1500 - Smoke and Oil consumption

HI all


I now have the carbs sorted out, had a floating float and a swimming one. Replaced both floats and had the throttle shafts and bushings done with all new seals etc. And new jets and needles. I haven't noticed any performance improvement but have only taken it on a short drive. The big change is when going down hill with the weight of the car driving the engine it used to go pop pop pop out the exhaust and now that has been GREATLY reduced.

So now the smoke I thought was over rich mixture is something else. I think it is oil but I am not sure. It is a white grey color. I don't see any evidence of oil in the radiator or on the dipstick but will look more closely when I change it which will be soon. Consumption seems high as well as I have to add a half quart or so over the driving season which for me is maybe 1-200 miles.

I am hoping it is something simple like leaking valve seals. Something that can be repaired without disassembling the engine. Is there a way to test this? The car smokes cold or hot.

Also I read that the INTAKE valve guides can have the MG 1275 midget Seal, Valve Stem, Umbrella Moss # 297-635 fitted. Would this be instead of the regular TD O-rings or in addition to?

If a top end is required looks like the parts for the valves and rocker shaft with bushings is only around $300. Not bank breaking. Finding a qualified shop here in the Lehigh Valley might be difficult though.

UPDATE

Just checked the compression today:
Cold 1: 130 2: 145 3: 145 4: 145
Hot 1: 145 2: 145 3: 150 4: 150

The plugs are pretty black. pic attached.






S Grimm

After the car has been standing for several hours, take off the rocker cover and look at the tops of the valve retaining washers and cotters. Although on a slight slope, they should have a pool of oil on top. If the oil has all run through the valve cotter gaps (down the valve guides), the oil seals were assembled wrongly. If this is the case, there are ways of fixing it without removing the head.

Properly assembled original system will work as well as any "umbrellas" in my opinion because the original system effectively does that job with the original shrouds.

Bob
R L Schapel

If it's been running rich all the time from the carbs being out of whack maybe it was washing the bores a bit and with a good run all 'could' come right
William Revit

I would do a leak-down test. Chances are good that you'll figure out what is wrong by the results. If the smoke is only on start-up then you'll probably find that the valves are the problem. If it's al the time then it's likely rings.
Steve Simmons

To add to Willie's and Steve's post, you may want to change the oil as it could have "thinned out" with the fuel dumping in the cylinder bores.

Also a fresh set of spark plugs would help may be in order

Cheers

Gary

79 MGB
gary hansen

If your plugs fouled up as show in the photo after only 1 to 200 miles then you have big problems, I hope that you just didn't clean them after working on the carbs. For the cost involved you should change them. If you stay with NGK you should buy a set with protruding electrodes, they are less prone to fouling.
I suggest that you change to BP6HS, it seems that yours are B6HS (non protruding electrodes).

John





J Scragg

Bob

Here's a pic of the valve tops. No oil after sitting overnight. I also ran it for about 15 - 20 minutes going as high as 2000 RPM. Oil pressure at 2K is about 62 PSI. After the run there was no change in oil pooling on the top of the valve springs.

Steve

I'll try to get to Autozone and borrow their leak down tester and see what that reveals.

I did not clean the plugs after fixing the carbs.

John

Thanks for the BP6HS suggestion. I'll pick up a set. They're cheap.

Gary

oil change is next on the agenda.

I'll keep everyone updated.

Stuart



S Grimm

Looks like it's going to need valve stem seals from that
If the seals are working properly there should be oil held there so it must be weeping down through the keepers
Unless it has modified seals further down the stem
I'm 100% with Bob on this, nothing wrong with correctly fitted original seals
If you've still got the cover off is there any chance of a nice close up pic. from the sideof a valve spring showing the valve stem in there, matbe from a couple of different angles

Also with the plugs I'd be tempted to go for a 5 instead of 6
NGK's are very forgiving in there heat ranges and because you are only doing low mileage and not revving the nuts off it ,it would give better running for you

willy
William Revit

Willy

I’m going on a trip tomorrow. I’ll get those pics when I get back.

Took the car on a 30 minute drive this afternoon. Seemed to run OK. Can’t see any smoke while driving, just after starting and during idle.

Stuart
S Grimm

Willy can you email me at pjbm (at) bigpond (dot) com please? Cheers
Peter TD 5801
P Hehir

Peter-you have mail
William Revit

While I’m on the road I have time to look into the tools for the job. Sanders clued me in on a valve spring compressor. I might try to borrow one from AutoZone or Advance Auto down the way. They both have tool lending programs. Get a compressor spark plug adapter too.

So is there a preferred brand or type of valve seals to get or something to steer clear of?

Are they a standard size, something I can get locally? Moss has a whole set for a whopping $0.99! But shipping would be crazy.

Thanks

Stuart
S Grimm

It may well have modified valve stem seals fitted to the top of the guides or umbrella type already
You need to check first by having a look through between the valve spring coils to see what's there -probably nothing or the little O ring sitting down there in the wrong place


I get a bit of stuff off these guys and they're really good,they've got everything you'll ever need--and are quite happy to hunt out the best postage-- If you ask they'd post them in an envelope to you ,and not far away from you really

https://www.englishparts.com/

Looked the seals up, they're a whopping $1.52 for the set of 8

here---

https://www.englishparts.com/productSearch.aspx?ukey_make=8&modelYear=1952&ukey_model=39&ukey_trimLevel=0&ukey_driveline=0&ukey_Category=19619&numResults=100&sortOrder=Relevance&isOnSale=0&isAccessory=0&isPerformance=0&searchTerm=valve%20stem%20seals
William Revit

I have changed the plugs in all my XPAG's to NGK 5 from 6. You need a hotter plug for the modern fuel to burn off the deposits. Hard to start when cold & plugs failing & black fouling on a regular basis are pointers to a need for a hotter plug.

Lean needles in the carbs will also transform your XPAG in combination with modern fuel !.

Good Luck

Tony
The Classic Workshop
A L SLATTERY

How far from gray and how close to white is the smoke? Coolant leaks are pretty close to white, oil darker and overly rich mixture black. Perhaps this was sorted out in the thread and I missed it.

Regards, Tom
tm peterson

Soooo. I know I was going to replace the seals over the winter but I just couldn't do it. Between the cold and my fear of dropping a valve down into the cylinder I put it off.

The time has come for me to change these out. I gathered up the courage and pulled off one of the springs and I got a bit of a surprise. I didn't find any o-rings but I did find this.

I think these are modified but don't know the part # or where to get them.

Your help is greatly appreciated.

Stuart





S Grimm

Stuart

Are you familiar with stuff the cylinder with rope via the spark plug hole to negate dropping valves into the cylinder?

Graeme
G Evans

Stuart

I neglected to add this as an alternative:


https://www.youtube.com/watch?v=h5nhTOsj53c

Graeme

G Evans

Stuart
That is one of the Mini or Ford seals
Many people run them but some have trouble with them coming off the top of the guide and running up and down with the valve

For my money I'd just run the original 'o' rings like you have in the bag there, the others sound like they weren't working anyway---

To fit--
No need to tell you how to get the spring off, that's done---so-

With the valve held up (by air or whatever method chosen)
Then compress the valve spring down past the valve ,then fit the 'o' ring towards the bottom of the groove where the keepers go, then fit the keepers, you might have to push against the 'o' ring a bit to get them in then release the spring compressor
The spring cap comes up against the 'o' ring and the keepers and the taper inside the cap tightens everything up against the stem

DO NOT FIT THE O RING ONTO THE VALVE STEM BEFORE FITTING THE SPRING---It's spring and cap first then the 'o' ring

The springs have been fitted incorrectly on some cars as well with the oil shroud on the bottom instead of the top, if the shroud is on the bottom it holds oil against the valve stem and causes smoke
Proper order is tin washer for spring location on the head first then springs then oil shroud then cap then 'o' ring then keepers
I've had a couple of cars where the shroud is completely missing and doesn't cause an issue, so if they've thrown yours out or cut them down to fit them other seals don't worry it will be fine without them
Would you have a pic of your springs, cap etc in the order they came off---?

cheers
William Revit

Just had another look at your pics and yeah it looks as though your shrouds are missing but don't worry about them it will be fine without
Found this pic for you of the spring stack and the seal in the correct position under the keepers but inside the cap
Unfortunately even this pic on the rh side shows the seal unerneath the cap which is WRONG , it's cap down first then o ring then keepers then release the assembly up against the o ring and keepers as is shown in the drawing in the circle


William Revit

I had not realised the subject of valve stem seals has been flogged to death.

http://www.mg-cars.info/mgtd-mgtf1500-bbs/question-about-valve-seals-2014010522030727289.htm

Seems there is little consensus on best solution.
G Evans

Also a way to tell if it is piston rings or valve seals / guides is as follows. Driving down a long hill with throttle closed have someone drive behind you watching the tail pipe, as you get back into the throttle if lots of blue smoke come out of the tail pipe it is valve seal / guide related. Blow by from worn or broken piston rings can also be watched from someone following you when under a heavy load, have throttle wide open looking for smoke from under the car as it will be puffing out of the road draft tube.
Len Fanelli
Len Fanelli

Also when running correctly I recommend NGK 4085 plugs
NGK (4085) BPR6HIX Iridium IX Spark Plugs

https://www.google.com/search?q=NGK+4085&rlz=1C1CHBF_enUS781US781&oq=NGK+4085&aqs=chrome..69i57j69i59.8447j0j7&sourceid=chrome&ie=UTF-8
Len Fanelli

Those rings look like they are thicker than the originals. To assist in fitting them, cut the cone tip off a plastic nozzle at the same diameter as the valve sten and chamfer the inside. Use a small ring spanner to push the ring over stem.
saves damaging the rings and your fingernails.
If you are using compressed air to hold up the valves. Put the engine at TDC, put in gear handbrake on,The valve can only drop to the piston then.
PS definitely handbrake on or the car will run over your foot, don't ask me how I know!!!
Ray TF 2884
Ray Lee

Thanks for all the comments. I went ahead and ordered 4 of the 1275 A-series (297-635) umbrella seals from LBCarCo. I decided to use both types on the intake and just the O-ring on the exhaust. Looks like it's a bad idea to put the 'hat' type on the exhaust side.

William, thanks for the assembly order. That was one of my next questions.

Steve Simmons suggested a leak down test in this thread last October. Not sure how to do that but with the piston at the bottom and about 80 psi in the spark plug fitting I can hear a definite hiss of air passing the rings. Should that be done with the piston at the top?

Len, thanks for the plug recommendation. I'm currently running NGK B6HS.

Ray, If the piston is at the top and a valve does fall will the stem still be in the guide? If so then I could just slip in my magnet-on-a-bendy-thing and pull it back up. So Ray, how do you know the car will run you over? ;)

Later

Stuart
S Grimm

<<Also when running correctly I recommend NGK 4085 plugs
NGK (4085) BPR6HIX Iridium IX Spark Plugs>>

Len,

These plugs are 1/2" reach. For 3/4" would you recommend NGK 6637 BPR6EIX IX ? Comparing the specs they are the same heat range.

https://www.ngk.com/product.aspx?zpid=9476

Frank
TF1414

Frank Cronin

Yes the valve will be in the guide,it will only drop the depth of the combustion chamber.
As to the car running over your foot,the answer is in the exclamation marks. The first time I did it it was on a 1967 Midget which rolled back onto my foot.I had to disconnect the airline before I could get it off my foot.
Before I got an air compressor I used to feed a length of pyjamas cord into the cylinder at BDC and then turn the engine to compress it into the valves
Ray TF 2884
Ray Lee

Yes Frank! And in the US Rock Auto has the best price, about $ 23 includes shipping.
Len Fanelli

As has been mentioned, it is easy to buy or make a tool for removing the valve springs/seals with the head in place. I use this tool with several of my own modifications. It is adjustable so the spring compressure screw can be exactly aligned with the valve guide/stem.

Compressed air works, but I simply make sure the piston is at the top of the cylinder and insert 1/4-inch soft, clean nylon rope to hold the valve. A friend was using air pressure when his air hose ruptured and the piston had moved from TDC (his fault). Not fun.

Good luck.



WHT

WHT

WOW and I thought mine looked good

Ray TF 2884


Ray Lee

While I'm waiting for the umbrella seals to arrive, I'm looking for the torque settings for the rocker tower bolts. The 10mm bolts go to 43 lbft, but I am getting conflicting information on the 8mm bolts. Some sources show 16 lbft while others show 29 lbft.

16 lbft:

http://www.ttalk.info/Clark/Torque%20Settings%20-%20XPAG.htm

http://www.mg-tabc.org/library/torque.htm

29 lbft:

see page 13:
http://www.iot.ntnu.no/users/oddk/mg3/downloads/XPAGEngine.pdf


Your thoughts.

Stuart
S Grimm

Stuart

This contradicts the sources you have identified, from my experience values are also a factor of threads being lubricated or dry.

www.fastenermart.com/files/metric_tighten_torques.pdf
G Evans

Found it in the archive here: https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=200412251442506705

16 for the 8mm and 43 for the 10mm.

Stuart
S Grimm

So this was supposed to be a fairly easy job right? Well not so fast there young man.

The umbrella seals I ordered were for the early A-Series 1250 which I had read would fit the XPAG. The ones that I got are considerably smaller than the ones that were already on the engine (see pics).

So I decided to just go with the O-ring only on all the valves instead of the O-ring and umbrella seals on the intake valves and just O-rings on the exhaust.

New problem. I can't compress the exhaust valve springs to get the keepers out. I have a feeling it's because there are dual springs on the exhaust and the spring compressor I have (see pic) won't play nice together.

Your thoughts please.

Stuart






S Grimm

Here's the spring compressor I have.



S Grimm

19 F/P for the 8 MM rocker stand bolt IS correct.
Oh and 25 F/P for the Gudgeon pin or wrist pin bolt!!
Len Fanelli

Stuart,

Do yourself a favor and pull the head...it makes the job so much easier.

Gene
Gene Gillam

Gene

I really don't see how pulling the head would make things easier. Sure changing the valve stem seals would be a breeze but all the time and work of draining the cooling system, removing the carbs, exhaust manifold, cooling system etc would take hours. And don't forget the carb setup after putting everything back together. Plus the expense of the parts to do the job would top $100 easily.

So I did the next best thing and made a tool. I took inspiration from the ones WHT and Ray Lee posted. Only took a few hours and didn't cost anything as I already had everything on hand. This thing combined with the spark plug / compressor adapter worked like a charm. It's a little tight getting the seal in place but not too bad. I admit I did lose one to the Black Hole behind the carbs. Oh well. You lose some and you lose some ;)

BTW, there were no seals on the exhaust valves. Can't tell if they were never there or if they just disintegrated.

First pic is a rear view, second is more of a side view.






S Grimm

Here's a view showing the springs compressed and the keepers loose enough to grab with my magnet-on-a-stick.

Not sure why all the pictures are 90 degrees out as they are fine on my computer.

Stuart


S Grimm

Stuart I use a wind up spring compressor just like yours ,it's a Meco brand, I welded a bit onto the ends of the claws so they poke through to the second spring----I'd say they've thrown the inlet inner springs away to fit them big seals, best if you can get some more to replace them
William Revit

This thread was discussed between 18/10/2019 and 28/05/2020

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