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MG TD TF 1500 - Starter motor problem

I've been sidetracked. After successfully starting the engine and running it for a minute, the starter motor no longer engages. It originally was stuck engaged, but I freed it easily. Now it just spins.
I took the starter out and the sliding gear wasn't moving up and down; the spring did not have enough force. I oiled it and it now moves nicely, but I still think there is very little force in the spring. (I can easily move it up and down, when I let go it springs back into place, but not with a lot of force.
How much force should the spring be creating?
Geoffrey M Baker

Quote "the starter motor no longer engages."

The motor does not engage, the pinion gear engages.

The pinion gear is forced into the ring gear on the flywheel by the rotation of the starter motor shaft.

Once the car engine starts it turns the pinion gear at a higher RPM than the starter motor. This forces the pinion gear to disengage.

The spring is there only to "Prevent the pinion drive from being vibrated into mesh when the engine is running"

The above quote is from the WSM Page N.9

The pinion needs to be very free moving on the starter shaft. Any rust, dirt or dings that inhibit free movement will be an issue.

Jim B.
JA Benjamin

It appears to be moving very freely. I cleaned and oiled it and while it originally was not moving freely (it sat with the gear halfway down the shaft, now it moves freely up under spring pressure and you can easily rotate it up and down the shaft. So freely moving, it is.
Still, when I pull the starter, the motor spins, but the pinion gear is not engaging.
Geoffrey M Baker

Remove the starter motor and inspect the pinion teeth, and the flywheel teeth visible in the starter hole - you may have stripped ring gear teeth. Then jump the starter motor and be sure the pinion moves on the shaft with centrifugal force as the motor spins.

The starter may move sluggishly if you have no ground strap.

Tom Lange
MGT Repair
t lange

While you have the starter motor out following Tom's recommendations, disassemble the Bendix gear and clean out all of the lubricant you just pump in. If you want to lubricate anything in there, use some sort of a dry lubricant. Oil will just collect dirt and will eventually become gummed up and won't engage the ring gear. Cheers - Dave
DW DuBois

I appear to have a non-original starter motor. The manual describes a band, and a split pin and locknut on the end of the shaft. Mine terminates in a spring compressed by a large washer (I think) and no sign of a split pin or nut, nor any threading to install a nut with. It's marked "LUCAS 149D"
Geoffrey M Baker

Pictures of starter


Geoffrey M Baker

closer shot of Bendix.
PS ring gear looks fine


Geoffrey M Baker

indeed it looks different to mine, anybody else?.


mog

A look at Dave Braun's site shows his starter matches mine. Apparently you have to compress that big spring to remove the holding pin or whatever it is. Dave never disassembled it, and I don't think I have the tools to do so either.
Puzzling. Flywheel ring teeth - good.
Bendix teeth OK. Bendix is clean. Bendix moves up and down on shaft easily. Returns to open position (where gears won't engage flywheel) whenever you let it.

Install starter. Starter motor spins. Bendix gear does not engage. Not enough juice?
Geoffrey M Baker



Geoffrey get rid of the oil as expressed by Dave and myself.

Check the number of teeth on the pinion gear, I am certain this has been discussed previously, check the Archive. The length of throw of the pinion is probably correct if it started the car once.

A Google on the web will reveal the number of teeth and pinion sizes of various model Lucas starter motors, if the Archive search fails.
G Evans



Here's a video to watch that shows the Bendix like you probably have. The early TD used the nut and cotter pin.

https://www.youtube.com/watch?v=R6CR_8efA88

Geoffrey, As Tom suggested--- If you haven't already done so, its Time to resolve your ground strap issue so you have full electrical power getting to the starter motor.
Richard Cameron

The oil is gone and the unit is dry.
It's been starting the car for years without trouble so I don't think that's a problem. It started it successfully yesterday after a year long rebuild :)
Geoffrey M Baker

Think about what has altered, you now have a very tight engine. Murphy says that something that functioned before may not do so under a change in conditions.

If you are concerned about earthing as a preliminary test use a jumper lead to make a temporary connection direct to the starter motor body from the battery earthing terminal.
G Evans

This model of starter was used on a lot of cars, including the MGA, MG midget, Triumph Spitfires, etc., although the construction of the starter evolved over time. The early ones had the strap that allowed access to the brushes without dismantling the starter itself. The changes in the starter seem to have been mostly geared towards reducing the number of parts and therefore the cost of construction. And perhaps to increase reliability. :)

Your starter will have a date on the casing. Sometimes it will have a second date that indicates a rebuild.

Hard to diagnose your problem from a distance, but it does sound like you are not getting enough oomph out of it (technical term). That could be due to insufficient juice, or it could have something to do with a problem within the starter itself. I'd check your power source first. If that checks out, follow the diagnostics in the Lucas Diagnostic Manual. It is available from several sources on-line. Here is one:

http://www.gomog.com/allmorgan/LucasFault.pdf

Hope that helps!
David Littlefield

Try directly connecting with jumper cables to a different known to be good battery. Be careful, at the torque reaction can spin the case around (hold with your feet or something). If low voltage or amperage from a battery, bad switch, no ground cable from frame/block, etc., the initial spin-up rate may be too slow to rapidly force the bendix backwards as it should. The jamming is a different issue. George
George Butz

Firstly, Richard thanks for the video, I love watching John Twist at work :)
I followed his instructions and was able to disassemble the Bendix. I only had the spring fly off twice and had to spend fifteen minutes looking for it, in the process. I also resurfaced the washer that he indicated might cause a problem.
Sadly none of this fixed it. I connected the motor and same problem; Bendix didn't move.
But George had the solution. I connected the starter to a battery of known and sterling reputation (our 99 Honda CRV) and the starter motor spun like a crazy thing and the Bendix shot back instantly.
So power IS the issue.
I suspect my battery (not that old, but little used and when used probably drained too fast trying endless starts on the MG, etc) is probably just not holding a decent charge anymore.
So, starter motor problem solved. I need a new battery, and a better earth.
Tomorrow I'll see what I can to do test the battery and see if it's actually dead, or whether it's a ground problem.


Geoffrey M Baker

Goeff,
You can use a starter from an MG Midget. It looks the same, and is available from your local car parts store, and is a lot less expensive than a TD or TF starter. The only thing that must be modified, is one of the two bolts that hold the starter together,,, they are countersunk round head bolts, and one of the heads must be filed down so the starter fits flush when mounted. I’ve been using a Midget starter in out TD for many miles with out any problems.
Steve
Steve Wincze

Looks like a ground problem. Connected the starter directly to the battery and the Bendix worked perfectly.
Next step, bolt in place, add a ground directly to the starter from battery, see if that fixes all...
Steve, my starter (see pix above) is a later starter which was used in many engines. It has two bolts which have been filed down to make it fit...
I think there is probably nothing wrong with the starter (although it would be good to have it reconditioned by a specialty shop, opening up the interior showed a lot of accumulated crud).

Geoffrey M Baker

I had the same problem with my original starter (51 TD). It worked fine out of the car but hardly or not at all when installed. I purchased new brushes and bushings from Moss, thoroughly cleaned the inside of the starter and polished the armature. The starter now works perfectly for a very small investment.

Tim
TD12524
TW Burchfield

Tim, you got me motivated. Problem was, to remove the armature, I had to get off the two long screws holding the plate in. And the problem with that was the PPO had ground them down so there was no way to turn them.
So I used my dremel tool to cut a groove across both, and was able to use an impact screwdriver to get them out. I cleaned the heads as best I could and improved the groove a bit, so they both can now be screwed and unscrewed. If anyone knows of replacement screws that DONT need to be ground down (shallow hex head bolts maybe) let me know; this "fix" let me get them off but I doubt that they can be undone too many times without destroying the heads...
Anyway, fixed that so I could get the armature out, polished everything, blew out years of black electrical dust, cleaned and polished and reassembled. Tested starter directly from battery again, no problems. So the starter is back at 100% of its abilities. I'll install in the car and see what happens now!
Geoffrey M Baker

You know, I love when this stuff happens sometimes. You work on one thing (trying to start the engine) and the starter dies. You have to switch gears, get out the manual, ask questions, and get to work. After 24 hours, I know a lot more about my starter motor (non-original later model, filed down screw heads, poor internal condition, dirty) and have cleaned and fixed it.
So I put it back in the car. I also took some sandpaper and sanded around the rim of the engine where the starter is bolted in, thinking that the engine was newly painted, so the ground connection to the starter might be more tenuous than before.
Once in place, the starter started perfectly. No extra grounding needed. Just an internal cleaning, and a bit of sanding, solved the problem.
So I started the engine it again. Started right up, ran evenly for about 60 seconds, got over 40 lbs oil pressure. Stopped the engine, noticed a fast oil drip coming from (of all places) the pedal box I'd been working on prior to starting the engine. How did oil get into the pedal box?
Aha, it's dripping down from the bulkhead oil meter connection, which is obviously not tight - and probably accounting for my lower-than-hoped-for oil pressure at the meter.
So today is a good day! Unfortunately, I have to change gears and do other work for the rest of the week and weekend, I won't get back to this until probably Monday.
Thanks all for the very helpful input on the starter - esp the University Motors link!
Geoffrey M Baker

Geoffrey

Trick with the starter motor screws is to latch onto them with a pair of vice grips to get them to move initially, saves destroyed screw slots.
G Evans

Can you get replacements that don't need to be ground down?
Geoffrey M Baker

The original type and original clone/repro starters have the screws at the commutator end, so of course they do not need grinding.
George Butz

This thread was discussed between 09/12/2015 and 10/12/2015

MG TD TF 1500 index

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