Merak SS getting hard to start

Oneball

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11,075
Stampings on Lucas coils are usually threefold:

2 letters 2 numbers - coil type
6 numbers - part number
4 numbers - month and year

Of course it could be a modern Indian one in which case no idea what the numbers mean.

There’s only really two types of 12v coil when you’re talking about being compatible, ballasted or non-ballasted.
 

Phil H

Member
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4,107
Does the other coil have any additional/different markings?

As Zep says, Lucas should be able to help, but if not the following thread recommended Andrew Brodie as a 'go to' man for SM's and Meraks, albeit some years ago.

I believe he passed away but the company still seems to be around

ES might also be able to help.

Update:
Google searches suggest that the original coils were Bosch (possibly 0221122001).
 
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Belfry

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Messages
184
Thank you for the link for the replacement Lucas coil, I will contact them on Monday. I’m not sure what the symptoms of a faulty ignition coil and it will be interesting to see if a new coil fixes the issue.
 

Belfry

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184
Apologies, I missed a couple of messages.
Here are the pictures of my faulty coil. Not much info to go on. Only LUCAS on the top and 0754 on the bottom. These replaced the original Marschal ones. 9197891979
 
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Oneball

Member
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11,075
I reckon that’s a modern Indian made one. But to check if it’s a ballasted or not. Measure the LT voltage at the coil with the ignition on you can also measure the resistance across the coil

ballast 6v and 1.5ohm
Non ballast 12v 3 ohm
 

Oneball

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11,075
If it is ballasted. Check the voltage at the coil when the starter is turning. It should go up to 12v
 

Belfry

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184
I reckon that’s a modern Indian made one. But to check if it’s a ballasted or not. Measure the LT voltage at the coil with the ignition on you can also measure the resistance across the coil

ballast 6v and 1.5ohm
Non ballast 12v 3 ohm
Both coils show 4.6v with ignition on across the 2 stainless nuts on the top. When cranking the coil in question drops to 3.2v and the other rises to 9v.
 

Oneball

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11,075
Sorry should’ve been clearer. You need to measure the voltage between the +ve coil terminal and earth (assuming the car is -ve earth) not the two terminals on the coil (that’ll give you a reading that’s affected by the ignition module/points, coil, and the type of gauge you’re using).

But you have got an idea now that one side of the ignition system is doing something odd.
 

Oneball

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11,075
It’s a ballasted ignition system the two boxes to the right of the Luminition units are the ballasts.

Was wondering how they’d do it, they’ve done it how I thought. So you’ve basically got 6 plugs, 1 distributor, 2 coils and 2 electronic ignition boxes. Each coil/ignition box will give spark to 3 cylinders.

With a ballast ignition system when the engine is running the low tension side is at 6v and the LT power to the coil passes through the ballast resistor. But to give an extra boost at start up when you turn the key 12v is supplied to the coil from the starter solenoid bypassing the ballast resistor.
 

Oneball

Member
Messages
11,075
Also check the voltage between the LT terminal and earth when you’re trying to start it. The one gave a funny reading before (when you did it between the two terminals) could have been a broken coil but might not be.

So voltage between positive on coil and earth should be:
Ignition on 6v
Starter turning 12v
 

Belfry

Member
Messages
184
On a reluctant first start does it splutter when it eventually fires?
It always splutters for the first 10 seconds with a dead cold start.
There was some exhaust smoke but I guess I’ve been trying to start it while testing the wiring over the last couple of weeks so there will be unburnt fuel in the system
 

Belfry

Member
Messages
184
It did start almost straight away with a set of jump leads from the land rover. With 14 volts it starts easily.
Once started it will restart straight away with no problem and the car seems to run and pull well.
Even 4 hours later if starts on the button. Could there be something sticking on the starter motor solenoid? If assuming that no that it starts immediately that the coils, resistors etc are all working fine.