Gear Reduction starter question

My freshly built 4.2 is outside of the car and on a wooden dolly. I want to test the starter and build up oil pressure before starting the break-in process. I have a Limora gear reduction starter from Terry’s, a brand new Optima battery with 910 cranking amps.

I connected the little terminal to the big terminal with a small jumper wire (per Moss’ video) and the big wire to the + terminal on the battery. I connected the - battery terminal to the starter case and bellhousing with jumper cables.

The starter barely turns the engine a little at a time, waits a second, turns a little more. The jumper cables got very warm. Terry’s says this sounds like a bad ground/earth. I agree, but what is a better ground than straight to a brand new, unpainted starter and a very clean bellhousing?

I removed the starter and used the same connections and the starter jumped to life like it’s supposed to.

The engine rotates easily by hand, so it’s not binding or has too much compression, or anything like that.

So, what do I try next?


Try loosely bolting the starter up almost tight but enough that it can wiggle, then try it.
It may be that the gear teeth are to tightly meshed into the flywheel teeth, and the starter just needs move outwards a tad.
Also, once you bolt the starter in place ,can you rotate the engine by hand.
It may need a 1/8th shim to take the starter away from the bell housing.

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I can easily rotate the engine by hand with the starter bolted up. I’ll try shimming it out a bit or leaving it loose. I ordered the correct starter for the teeth count on my flywheel, but you’re right, it may need a shim.

Are the spark plugs removed?

I just don’t know why people fit such devices :thinking:
I love the sound of my old starter motor , when the engine is cold
When hot , my engine starts instantaneously , just can’t see the need :roll_eyes:


I’m inclined to agree with Ian.

Original spec devices were designed to last for 80-100,000 miles when the car was being used as a daily driver so, as long as they are in good order, they should be more than good enough for us.

An exception, which mught be a reason in this case, is that on some (all?) models removal and replacement of the starter motor is extremely difficult due to lack of space and I’m guessing the new motor is smaller than the original.

I needed a new petrol pump for mine and bought a wonderful, better than the original, never have any trouble with this, will last for ever electronic masterpiece which didn’t even fit :rofl::rofl:

Dont just trust that you have the correct starter…measure the distance from the bellhouseing face to the flywheel…then measure form the starter mounting face to the toothed pinion at its rest position and when the pinion is thrown out…also count the teeth on your flywheel and on your pinion and contact the starter manufacturer to ensure they are compatable…do you have the original starter…does it have a spacer plate attached to it…typically the 4.2 starters attached to the bellhouseing with a spacers and 2 ring dowles…the bolts went through the ring dowles to fix the starter in the correct position to the bellhouseing…if its slightly out of position it could jam… Steve

The starter is matched to the flywheel, but I will count the teeth on the starter to be certain. The flywheel and bellhousing are from a 3.8 so I can run the manual trans I have. I know they all work together, but there might be a problem with spacing. I’ll measure the distances you suggested, Steve

The spark plugs are in, just like they would be if I was trying to actually start the car. It turns over easily by hand with the plugs in.

Regardless of why I chose to use a modern starter, I have a simple problem that needs a solution. Since you asked, I have the original starter. It works, but is a bit slow. The gear reduction is stronger, lighter, does not require a separate solenoid and cost less than rebuilding the original.

Hi…ok so you have a 3.8 flywheel and 3.8 bell houseing…so you should be useing a starter for a 3.8…the bellhouseing fixing bolt holes are in a slightly different position to those on a 4.2 bellhouseing…a 4.2 starter on a 3.8 bellhouseing will bind…Steve

In my case, the nut on the end of the original starter’s Bendix came off while I was driving and got between the ring gear and the bell housing, so now there is a hole in the side of the bell housing where the nut made its escape.

Steve, it is a 3.8 manual trans starter and a 3.8 104 tooth flywheel and a 3.8 bellhousing.

I measured the distances and they line up correctly. About 1 inch from flange to flywheel and 1.5 to the other side of the flywheel, and that’s how far the starter gear moves outward when engaged. The marks on the gear suggest it is engaging fully. It looks like shimming the starter out would cause less tooth engagement. It doesn’t sound like the starter is slipping or skipping teeth. It does seem like it’s not getting enough electricity, but the battery is fully charged. I suspect there is a simple solution here, but it escapes me.

Hi Joe…try jumping with another or battery…you battery may read good on volts but not enough cranking amps…how old is it?..ok just read its a new battery…pull out your spark plugs and see how ot turns over with no compression…that will prove that its engageing well and spinning the engine… you want the plugs out anyway so the engine spinns easily and pumps the oil around…Steve

I’ve had exactly this problem with using jumper cables in this situation.

The jaws don’t provide enough surface area for the current required to turn the engine over.

What you need to do is use a battery cable with an eylet fitting, and use that to bolt the cable to your earth. Use a bell housing to engine bolt.

Your engine will now turn properly.

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Did you bench test the starter to make sure it works?

That starter case looks broken.

Have you checked whether yr brand new 910 CCA battery is a dud? Try it in another vehicle? Can you measure the resistance in the cables battery + to starter + and from batt - to starter case? Is yr original starter usable ATM, can you compare performances?

I haven’t read all the posts in detail so if I’ve covered the same ground as others, then please ignore.

I had the same problem several years ago and the engine was too tight for the starter. I connected two batteries in series and hit the starter. (Spark plugs removed). Spinning for no more than about 2 seconds on 24v was enough to free it up. This is made as a closed circuit with just batteries, starter, and an in-line switch. The push button starter solenoid can be used, but everything else at the solenoid must be removed.

It does not damage the starter because of the very short duration. It is imperative that whichever way you do this, you must have healthy cables with tight and large connections - eyes, clamps, etc. The starter current draw can be a few hundred amps.

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I used a 12V battery on a 6V VW Karman Ghia to start it.

I would spin the engine long enough to start heating it up by friction, the rings would seat, and the engine would start.

It would ‘run fine’ until I shut it off. Engine didn’t use much oil, just was worn out and didn’t have much compression until it warmed up some.

Solution! I was using jumper cables which must have been too small of a gauge for starting purposes. I switched to actual batter cables and it cranked normally. It still seems a little sluggish, but I’ve never started an XK engine before. I also realized that the trans is in gear, so I need to get it into neutral and try again. Of course it’s not playing nicely.

Colin - yes, I tested the battery and it was confirmed to have 910 cranking amps.

Jerry - yes, I bench tested the starter. That image was taken from the Limora website, and you’re right, that particular starter looks broken, but not mine.

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Good outcome.

All it needs when eventually set up right is to get to compression once or twice and then it should start.

We start in neutral and do not touch the clutch for starting.