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MG TD TF 1500 - Self Destructing Distributor

This thread is a continuation on Car Club Roadside Heroes. I've attached a pic of the inside of my self-destructing distributor. Three questions:

1. What would cause my distributor to self destruct?
2. Does anybody have a good TD distributor for sale?
3. Has anybody tried the replacement 45D distributor that Moss offers?

Side question: As best we can tell, the helical gear that used to be at the bottom of my self-destructed distributor is now rolling around in the bottom of my oil pan. I have Tom's magnetic drain plug which may have caught to foul thing. Having just put the motor back in the car, I'd really rather not pull the oilpan to retrieve the darned thing. How dangerous is just leaving it in there until I have another reason to pull the motor?


1953 MG TD

J K Chapin

Personally, I wouldn’t leave it in there.
W A Chasser

I've seen this exact thing happen before. Did you remove the center screw to oil the shaft? The screw doesn't need to be removed to oil, but a lot of people do it anyway. If removed, the cam can pop up a little and it's easy to miss. Then when you tighten the screw back down, it won't push the cam back down all the way because the guts have moved. Then things start to come out of place and WHAM! The fact that the pin shears off is a safety feature, not a flaw. If not, the damage would be far worse!

I had it happen on my Y-Type once. I had removed the cam to check the weights and after the fact realized what I had done. The other possibility is if the weights and pivots were heavily worn and the weights moved enough to jam.

In any case, I don't think the gear can cause any problems since it can't get through the intake screen, but you can get it out. Get one of those magnets on a thin telescoping rod. Then stick that down the distributor hole. It took me a while but I did get it. You might be able to remove the drain plug and use some bailing wire to push it over there, or even jack the car from one side.

As for the distributor, it can be rebuilt. Send it to British Vacuum Unit and he will make it like new.

Good luck!
Steve Simmons

Would have thought that using a an inspection camera (very useful tool anyway)and a magnet attached to a piece of wire would be worth a try. Just needs draining the sump, have a look with the camera which hopefully would locate the part and allow to direct the magnet. Infact a very strong magnet outside the pan may even move the part nearer the drain plug-that's assuming that it doesn't even come out with the oil anyway. A great challenge and one I hope you solve.
JK Mazgaj

From experience, the skew gear will be on top of the baffle plate. It may or may not have the bits of pin still with it.
I was unable to get the bits out so removed the sump.
It is only an hours work but you get peace of mind.
I have had a replacement dizzy for around 10 years and am very happy with it.
Ray TF 2884
Ray Lee

The advance weights fail due to metal fatigue!
In my case the shaft was also bent > not useable.
The CSI 23D looks like a Lucas distributor.
Rob @ British vacuum doe not recommend a 45D!
I sell the CSI 23D for a LOT less money than the Moss 45D or Moss CSI For MGB!
Add a new drive gear installed and shimmed still less money!
CSI curves tor XPAG XPEG normally aspirated and Supercharged in stock.

Len Fanelli

To be fair, the weights would have to be really old and worn to fly apart and break the distributor. If you're running a distributor with that much wear then you probably have other issues as well, like erratic timing from worn bushings and thrust faces. A rebuild would certainly be in order long before that point.
Steve Simmons

Steve it was professionally rebuilt & recurved about a 2 years before the advance weights failed. And the advance weights were not re bushed but not as badly worn as others.
Len Fanelli

Well whatever caused that, I'm sure it was a a bad day! Unlucky for sure. When it happened to me on my YB, I realized afterward it was my own fault, and fortunately no damage was done because the gear pin sheared. Makes me wonder if the guys putting hardened pins in there aren't doing themselves (or others) a disservice. In the event something internally does fail and the pin doesn't shear, bad things will happen. Would be interesting to see hat kind of pin was in Jud's dizzy.

I haven't kept very good records but from what I can see my TC dizzy has been rebuilt about every 30-40,000 miles or so.
Steve Simmons

Steve, I'm pretty sure it must have been the correct soft pin because it sheared off nicely without (I think) doing any further damage..

I've sent the broken off dizzy off to Jeff at AD in hopes that he can rebuilt it and I've ordered a new CSI dizzy from Len. I expect to get the CSI installed before Jeff returns the rebuild original dizzy and I'll carry the rebuild one as a backup. I'll let y'all know how that goes.

You can read the whole tale in my earlier post at the end of Over Heating ... and so It Begins.

J K Chapin

Hardened roll pins shear just like the original solid soft pin with no other damage except for possibly the bent shaft in my case.
Len Fanelli

That's why I question it. The gears I've seen shear off with original pins had no other damage. Jud had damage to the plate, which is understandable if something came apart in there, but what about the shaft?
Steve Simmons

after installation and setup of the CSI fully electronic distributor, to take full advantage of the improvements and consistency, you want to adjust your carb mixture.

Even before installation and setting timing Len or others might have suggested a wider spark plug gap to again reap the full benefits. If the spark plugs are old treat yourself and the car to a new set as they can continue working way passed their optimum into their well below par.

Of course you'll need to confirm all this by giving the car some spirited runs, and then a few more just for the fun and joy of it.

Nigel Atkins

Spirited runs are what we do. Eighty miles today in the MGA.

New plugs for the TD are a fine idea. The ones in there are at least 5,000 miles old.

J K Chapin

if you enjoy spirited driving in the TD you definitely want any the fully electronic dissy and adjustment of settings as required.

For the plugs a wider gap may be better but some have plugs very wide which may not - and even I wouldn't change plugs at 5,000 miles unless the plugs were years old or showed signs of damage. Spray/blow clean, check/adjust gap and refit.

Having said that last year I swapped a set of plugs that I knew weren't very old or much mileage on them and glad I did. The benefit to cost was sufficient to me. I don't like waste so I offered the used plugs to a mate but he said he'd get new plugs as they were so inexpensive to buy.

I gave them to a neighbour but I know they'll probably be put in a toolbox to roll about until they get damaged then thrown away or worse still fitted to soon play up.
Nigel Atkins

Happened to me, once. A bit more dramatically, as the weight smashed the whole distributor casing - when I raised the bonnet the dizzie cap was just dangling on the plug wires.

Pity my new wife and I were just setting off on our honeymoon. A day late, too, because I'd had to go to Court on a speeding charge that morning.
D A Provan

Well, this seems to have worked pretty darned well. The new CSI distributor from Len arrived about midday. It's made in Holland which thrilled my partner in crime - a Dutch marine engineer who lives about 1/4 mile down the road (Peter, TD 10879).

Out of the box, simple clear installation instructions and the implant was completed in about 45 minutes. Probably half of that was spent searching for a nut off of the coil that we dropped and searching for my crimping tool to connect the Black wire to the coil (AFTER doing all the following).

Set the motor at #1 TDC, put the dizzy in, rotated it 'til the blue light flashed to tell us the selected advance curve, selected curve 8, another slight rotation to get a steady blue light (0 at TDC), put the cap on, connect the Black wire, turn the key and ... Varoom!!!

Runs like a champ. We'll have rain through Thursday so the first test drive won't be 'til Friday. In the mean time, the Holley two barrel on my '77 F-100 (302 V8) needs rebuilding due to a leaking accelerator pump so no time for idleness.


ps: The rotor turns anti-clockwise. Please don't ask me or Peter how we know.
J K Chapin

Well Done Jud.

And well done on reading the instructions, a rarity for many males, er, anti-clockwise, well, cough.

Also thanks for the true installation time details, I have to wait for my wife to find any dropped fixings, I look on the ground for ages, as obviously it's always one I don't have a spare of, yet my wife points it out on the ground in seconds. I also spend ages looking for the tools that I was using just minutes ago.

Be interesting to know if you find any difference between the old mechanical and new fully electronic.

Forget carrying round the old dissy in the boot there's no need for it, if you can't use it then pass it on to a mechanical dissy enthusiasts. Or you could swap it back in for comparison tests.

By coincidence(?) 123 Ignition are also from The Netherlands.

Enjoy your drive, and don't for a moment worry about us that can't drive our cars any distance because of Covid restrictions, I think I might have square tyres by now. 😊

Nigel Atkins

I've put about 200 miles of good mountain driving on the TD since installing the CSI distributor and it's mostly running great. The first problem I had was a bad sputtering like it was out of gas. This had nothing to do with the dizzy but was directly related to the totally clogged fuel filter preventing almost all fuel from reaching the fuel pump. A ten minute clean out of the filter fully resolved this problem.

I know my tank needs to be cleaned and flushed but the filter is doing its job well if I can just remember to clean it out about twice a year.

I haven't pulled the plugs to check but I think I'm running a bit lean. Mostly when the engine is still cold but occasionally even after it's fully warm I'll get a single spit back through the carbs. This happens under moderate load at ~3.5k rpm. Slightly pulling the choke seems to eliminate this but, because it is just intermittent I'm not sure. I think I'd rather run slightly rich than slightly lean so I suspect a carb adjustment is in my future.

I've not yet drained the oil to search of the dizzy gear and bits of shear pin but that is on the agenda. Hopefully all the little pieces have sunk to the bottom or become attached to Tom's magnetic drain plug. My informal polling yields about a 50-50 split on the necessity of dropping the pan to retrieve the bits and pieces.

I don't want to drop the pan because, like Nigel, I'd rather drive the car than work on it. On the other hand, if I don't work on it I may end up not being able to drive it.

To drop or not to drop - that is the question.

J K Chapin


I've had a very similar dilemma.

I'd make it an opportunity for a thorough hot oil (and filter) change (and clean and flush).

Depending on what sort of flushing fluids you get out your way I'd use one and if it's the type that needs the car to be driven even better.

I always try to drain oil as hot as possible/sensible for as long as possibly. Getting the oil hot means driving the car, a reward for having to do the work for me. Getting the oil as hot as possible and leaving it to drain for as long as possible gets as much old oil and muck out as possible with just a drain. I also tip some new warmed (by standing in the sun or hot water) fresh oil in during the draining to act as a slight flushing too.

When you take the pan off you could photo it and the magnet to show how much oil and muck stays in after even a thorough hot drain.

And perhaps the underside of the bottom of the engine and its bits, again to show how much muck and oil remains there even after a hot thorough drain.

All before you clean the pan and bottom of the engine of course. 😁

Just imagine how much more oil and muck is left in on a quick cold drain as many do, especially garages.

It all soon gets mucky again but at least you get a slightly better ratio of clean fresh oil replacing old oil and muck for a good few change forward - and you know it's done so feel justified in exploiting the new fully electronic dizzy's performance more.
Nigel Atkins

Before you remove the pan, you have to drain oil so why not look for the gear and likely save yourself a lot of extra work.

Chances are, it dropped down to the bottom of the sump and once below the windage tray, the only way it'll get up in the engine is if you roll the car onto its roof.

As pointed out before, you could use a powerful magnet to sweep under the pan and drift any iron back towards the drain hole. Drift the magnet from the center and over to the edges and then back as it likely would be blocked by the oil pickup in the center. It won't come out in one piece but you may have more peace of mind knowing it is stuck to the plug's magnet.

Maybe you could do a few burnouts so the high G forces shove it to the back. You think? Disregard that suggestion.

It used to be borescopes were expensive, but not only have the prices dropped about an order of magnitude with cheap imports, the USB borescope/endoscope adapters are another small fraction of the price on my Harbor Freight scope.
I recently acquired one of the USB kits for around $10 and my cell phone is far better than the dedicated mini-screen on my Chinese borescope. I can use it with my laptop if I want the "big screen." You'll still have to contend with that oil pick up in the middle but you might get a birdseye view down the distributor hole if it is still on the windage tray, then use a magnet or whatnot if you spot it.

Good luck!

I'm not against Jim's ideas especially if you're certain you're engine isn't that dirty as you've had it rebuilt recently, or quite recently done a thorough oil change/clean.

This assumes the pin will be attracted to the magnet and can be dragged to drain hole as I wouldn't fancy planning or fishing through the old oil that comes out by that's just me, I wouldn't see it with my wonky eyes and uses the magnet to fish for it in the drain pan too which would royally piss me off too, but that just my attitude to car 'fun'.
Nigel Atkins

Somewhere there may still be a 2.4L straight 6 old Nissan Maxima engine out there with an extra valve cover bolt in the sump. Likewise, a 350 small block with a distributor hold down bolt in the pan. While the gear is a little bigger, I go with the leave it alone until you have to pull the sump for something else. George
George Butz III

I agree with George. There are plenty of Chevrolet V8 engines that had lifters & cam worn out. The lifters were mushroomed so much that they were just hammered into the sump after the cam was removed, then a new cam & lifters were installed!
Len Fanelli

Just realised I had a total brain fart in my last post (and no doubt many others) and was thinking of another thread and thought Jim was referring to looking for a dizzy clip pin (don't ask, don't wonder), thinking that's going to be difficult to find.

Would the gear fit through the drain hole?

With my car luck i'd never get away with leaving anything in oil pan.

Not following my own dictates I added a quick job, and without proper preparation, to an otherwise successful afternoon doing something on the car as things were going so well and it was a quick job I could do before losing the daylight. As it was only a couple of weeks after the annual service oil change I di think about just leaving it or putting some magnets on to hold it until 12 months later but I just could risk it in my mind.
Nigel Atkins

This thread was discussed between 08/03/2021 and 24/03/2021

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