Jammed Starter/ Siezed Engine ?

[WADunlop]

Hello All,

I am new to the site but have owned a 1968+2 (chassis No 50/0604), for a couple of years. It is a rolling upgrade, Never ending adventure! With a current MOT.

The car has been running for some of the time owned, but i have recently hit the following problem that i cannot find how to resolve. I hope that the vast experience of the List will be able to point me in the right direction.

I started with the car in running order, found that the distributor was loose, and took it out to check the condition of the unit. (I did not advance the engine to TDC, thinking that there would be no problem in turning the engine over to TDC to set the static timing, when i replaced the distributor.

Distributor cleaned and checked (Lucas 23D4) I decided to turn the engine over to TDC on the startor motor. Starter Jams and will not move.

Following removal of the starter (previously working) I found the teeth of the engaging wheel badly chewed. Flywheel checked and no apparant damage.

The starter is a different type from the one noted in the Workshop manual. It is a LUCAS unit with the number 25147 stamped on the side, with a highlighted number 123, and a highlghted 4 painted in silver just below the front face.

The workshop manual notes it should be a LUCAS M35G.

As the starter had previously worked without trouble, I exchanged it with a refurbished unit of the same type and number, from my local Motor Factors.

While waiting for the exchange starter i tried turning the engine to TDC by pushing in gear, this was not successful and the engine would only revolve a few degrees before no further movement was obtained.

I fitted the exchange starter, which appears to fit correctly, however the starter when activated does not turn the engine over.i initially suspected the Solenoid, but the starter works perfectly via the solenoid when operated outside the engine.

I have cleaned and reconnected the block earthing strap with no improvement.

I have had the starter out and refitted a few times, in both of the 180 degree opposite positions that it will mount in, wothout any improvement.

The inertia mechanism, where the pinion is drawn back up a shaft from the opposite side of the flywheel from the starter body, after its initial movement returns it of the large end spring, is not a type i have worked with before, i have tried holding the pinion drive close to the top of motor shaft, near the body of the starter, in the drive position to see if it is meshing properly (difficult to determine) put it appears to be.

I note that the pinion has ten teeth, (i did not check how many chewed teeth were on the motor I exchanged) I remember some time ago discussion regarding the correct number of teeth being either nine or ten, depending on the year and the model.

When the starter is activated, full power is getting to the motor, and there is no crunching sound (that i have always associated with teeth not meshing on other types of engines) Simply the single clunk from the Starter.

One additional piece of info is the inability to turn the engine over by way of the bolt on the end of the crankshaft, even with all plugs and thre distributor removed. the engine is still filled with oil to the correct level, and was working prior to the start of this escapade two weeks ago.

This has been a long explanation but here are the questions that i hope you can help with.

1. Is the starter moter the correct one?

2. Is there a change over date for 9 to 10 teeth or vice versa?

3. is there any reason that ht eengine would have siezed?

Any help, thoughts or wisdom would be greatly appreciated. ( And would save my sanity)


Thanks

Martin Woods

Dunlop
SCOTLAND

[gjz30075]

Hi Martin,
Welcome!

First of all, will the engine turn over if turned at the crank pulley with a wrench, gearbox in neutral? Should be a 5/8" size bolt that holds the crank pulley in place. Turn the engine clockwise, as seen from the front of the car.

Greg Z.

[WADunlop]

Thanks for the response Greg,

I had previously tried turning the engine in the clockwise direction with no movement at all.

i have now backed the engine up anticlockwise, where i can turn it with a wrench through about 340 degrees of afull revolution. it again stops dead, no mechanical noise or metal to metal sound.

From this position it will turn through the correct clockwise rotation but again only by around 340 degrees before stopping dead.

It will turn to this point on the new starter motor, ruling that out of the problem.

The engine stops around 10 degrees either side of TDC.

Any further thoughts you or anyone else has would be appreciated.

thanks

Martin Woods

[gjz30075]

Martin,
Doesn't sound as if something in the engine is causing this but not ruling that out. Sounds like maybe a bolt backed out somewhere like the flywheel and runs up against something. I'd pull the plugs, cam cover and turn it over and watch for something out of the ordinary. If nothing up there, then pull the starter and look for something out of the ordinary there while turning the engine over. If your engine has the lower dust shield over the flywheel, pull that, too. I can't remember if the 4 bolt or 6 bolt motors have the lower dust shield; it's been awhile since I've 'been down there'.

Greg Z.

[WADunlop]

Greg,

Thanks again for your thoughts, i will hopefully get a chance later today, to have another look, i feel it may relate to the starter motor i have recently replaced (possibly the pinion not disengaging fully).

If i pull the starter and still have the same problem turning it by hand i will have to look for a timing chain or backed out bolt problem. From memory the engine does not have a seperate shield on the flywheel.

I will let you know how i get on.

HAPPY NEW YEAR !!!!!

Martin Woods

[type26owner]

Sadly from your description I'd conclude you possibly have a valve to piston interference problem. Stop energizing the starter until you determine the reason the engine will not turn over freely. This just happened to be coincidental timing with the dizzy repairs and the starter swapping.

Keith

[richboyd]

I'd agree with Keith about valve to piston, but add ... it may be piston to foreign object (rather than valve) interference causing the problem. On two occaisons, I have found small bolts in combustion chambers (once on an Alfa, once on a Honda MC), but only after turning the engine by hand. As best as I can reconstruct, after coming loose, the bolts bounced around in the intake manifold for a while, never getting past the intake valve - until I slowly opened the valve by hand turning the engine. Then - dink - in dropped the bolt, the piston trapped it againt the head, and the engine would turn no further. I had the same 340 degrees in either direction, a sure sign of interference in one combustion chamber - whether caused by valve or foreign object.

[WADunlop]

I have now had the chance to pull the starter motor out again, and remove the cam cover to watch the valve actuation while turning over by hand.

I can see nothing untoward with the operation with the exception of the 'dead stop' occurring exactly when the inlet on cylinder three is reaching fully open.

It looks like my next step has to be the head off to check for either valve or foreign object / piston collision.

There is still no mechanical noise, either when turning over by hand or at the point of dead stop. The only physical stop action that i can detect appears to be felt through the water pump.

As soon as I get the chance to remove the head, i will let you know the next instalment of this Lotus Saga!!!!

Thanks


Martin Woods
DUNLOP
SCOTLAND

[type26owner]

Highly unlikely that an interference would not result in a clanging noise when metal meets metal if enough rotational velocity is achieved. There is another possibile failure mechanism which could bind the engine at the spot you've described though and not make much noise while doing so. A single link in the timing chain may have siezed and is bound up tight. If you find this to be the case then investigate the cause. Possibly the oil squirt hole is clogged in the rear timing chain cover or a sprocket(s) are worn out.

In these situations it's best not to assume anything and check everything in an orderly fashion. It still could be something simple to correct but not very obvious.
Keith

[type36lotus]

Martin,

You might want to remove the plugs and take a look. With the pistion at dead bottom you should be able to see quite a bit of the pistion crown (maybe all of it). If there is something in there you might get luck and see it lying about. A friend with a borescope would be perfect or a Doctor friend with an obsolete coloniscope (ouch!) If you see nothing you might try to fit one of those magnets on a flex rod in a run it around. Again you might get lucky and pick up the culprit. Just be sure to loose the magnet in the cylinder, then you WILL have to remove the head.

Mike G