Vitesse said:

I was going to comment that they only appear to sell the dodgy Brazilian ones I decided to look on mine first before I make a fool of myself and it is Brazilian

Just went and got it in from the garage and it measures 2.97Ω when cold, it was a bit chilly in the garage, stuck it on the radiator for 20 minutes to warm it up and it only rose slightly to 3.04Ω. I would imagine that, that figure would rise to somewhere nearer to 3.2Ω in a nice hot engine bay and after producing a few hundred thousand sparks. That’s measured on a meter that I have recalibrated once a year so it’s really accurate.

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Very wise to check your facts first... not something I usually do. [emoji16] This is where my original decision was made ..

http://www.ratwell.com/technical/BlueCoil.html.....

It's quite informative. The proof of the pudding etc. Mine is no longer blue as the label came off and it got some black overspray but that doesn't affect its performance.[emoji16]But my ultimate customer review of the company I bought it from and the coil itself is that despite a short period of overheating when my voltage-control went faulty and doing me proud for, I guess, at least 20,000 miles, I haven't got the slightest misgivings that it it won't go on forever. [emoji16] PS. I've never checked the internal resistance or measured it's temperature.

Did it have “Prince of Darkness” under the label? :devil:

I think I have seen that page before, no doubt spoken about it before in the dim and distant past? ��

I was confused, it looks like those dodgy Mexican’s you need to be wary of , not the poor Brazilian’s. Which I suppose makes sense as they continued to make the Beetle for years and it uses the same coil, so there was probably not a shortage of demand.

fiat500 said:

I recommend this company for the blue coil HT leads, spark-plugs and anything relating the ignition system; they really know their stuff.
https://simonbbc.com/bosch-blue-ignition-coil-0221119027/

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I spoke with these guys yesterday. It's where I got the Viper coil from. Their website states the blue coil as 3.4ohm. However when I spoke to the chap, he said no, they are 3ohm. He went and measured some and confirmed all showing as 3ohm.

So I've ordered a Beru 172 which a lot of the VW classic guys use. Rated at 3.3 on the primary. Due tomorrow. Shall see what the meter shows.

If not, I'll get another Bosch blue and irrespective of the reading, will plumb it in and see how it performs.

What a faff I'm having. But will get it sorted :slayer:

Right for me at least, problem solved. I’ve fitted a Beru Blue 172 coil and it does still get hot but not as burning hot as other coils I’ve fitted.

It seems that the higher resistance of the primary has done the trick (3.3 ohm). This coil used by a lot of the VW air cooled bunch has lower amp to the points so they don’t burn out. According to their adverts. Early days, but post long drives and touch test, all is where I’m want it to be.

Got mine of the bay of e by company called machine7. 2 day delivery. No affiliation etc.

Cheers
Rob

Any chance of an update Rob?

i fitted (sequentially) several dry Viper 2.7Ohm (primary) coils with and without an "auxiliary" resistor to bring up to 3Ohm and still had the engine cut out after 20 mins with each.

i am still not decided between ignition problem or fuel vaporisation on my car.

cheers
RDS

As in another post I put on here check all ignition parts from dizzy to plugs I found it was one of my plug extensions that had a much higher reading than the other. I thought they were solid but on cutting one open it has a sort of spring inside , so check yours.

I did see that post but didn't realise it was the cure!!

I already checked lead resistance and all were within a tolerance so no cure for me yet....


cheers

RDS

Hi RDS, so as per my post above. I've fitted a Beru Blue 172 coil and so far, post drive, its not hotter than the surface of the sun. It's hot, but not as bad as the other coils. It has a primary resistance of 3.3 ohm.


But to be honest, even with my Viper coil at 2.7ohm, I never had an issue with regards to the ignition. Just that I was not happy at the high heat the unit contained.

Cheers
Rob

Cheers Rob
I hope to get to a show at the weekend in a different car and plan to feel as many other coils that I can for comparison purposes!
I get a slight warning of impending cut out when the rad fan starts but it is immediate really hence the thought that it's ignition.

Further thought and testing required....

Ttfn
RDS

Hi guys, I'm having a similar issue and just got done having a friendly disagreement with the mechanic about the problem being with the coil, the starter, or both. Like the original post the car stutters and stalls after running for about 20 minutes. At this point, when trying to restart, the starter grinds slowly, if at all, as if the battery is dead. After cooling off (for a while) it will start again like normal.

Car has new battery, distributor, plugs, leads.

The mechanic measured the resistance at the coil and got something like 1ohm (well below the 3.4ohm min as I told him). I reckon that we need to check the resistance in the leads next but he seems to think the starter is bad.

So the question to you all: does this overheating coil problem cause the car to slow crank/no-crank? Or do I need to investigate the starter?

I personally would take the starter out and have it checked by an auto-electrician. I had a problem where the starter was sometimes 'lazy' when cold, as if I had a slightly flat battery, but it was fine when the engine was warm. The electrician checking it found a duff section on the armature--cleaning it and cleaning out between the segments has sorted the problem---starter spins the engine over fine, cold and hot.

RDS said:

Cheers Rob
I hope to get to a show at the weekend in a different car and plan to feel as many other coils that I can for comparison purposes!
I get a slight warning of impending cut out when the rad fan starts but it is immediate really hence the thought that it's ignition.

Further thought and testing required....

Ttfn
RDS

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felt a few coils (!) at the weekend and pleased to say that they are all uncomfortable to hold for more than a few seconds, just like mine and just like a 40w bulb wold be. Those cars ran ok so I am going down the fuel vaporisation/delivery route as the cause of my problems for the next phase of this.

RDS

Stevemode said:

So the question to you all: does this overheating coil problem cause the car to slow crank/no-crank? Or do I need to investigate the starter?

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Cranking ability (as distinct from getting the engine to fire up) is not dependant on the coil. As the Hobbler says, it could be the armature but also brushes, solenoid, or high resistance/poor contact of feed wire or earth.

fiat500 said:

I can confirm that after at least 3 years regular usage the Bosch coil is still sparking well. Me and it tend to keep our distance and I suspect that Mr Bosch is not keen on me touching him as I have been given no indication that he has the hots for me.[emoji16]

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I am still struggling with the heating issues in spite of going for the Blue Bosch Coil. Can drive at the most 3-5 Miles and the coil gets heated.

Can anyone advice what else is needed for me to check. It is very annoying. Have replaced 5-6 coils upto now :-(

sidkhona said:

I am still struggling with the heating issues in spite of going for the Blue Bosch Coil. Can drive at the most 3-5 Miles and the coil gets heated.

Can anyone advice what else is needed for me to check. It is very annoying. Have replaced 5-6 coils upto now :-(

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Have you checked the voltage from the generator? If the regulator is faulty you could burn out the coil.

check voltage supply as stated above with Multimeter when engine off but ignition on and also when running, to both sides of coil.
you should have approx 12.5v when not running and 13-14v when running, to the + side of the coil, a little less to the - side of coil.

test the primary resistance of the coil: is it nearer 1.5Ohm or 3Ohm - should be latter for non ballasted ignition. 1.5Ohm coil will get hot and fail quickly.

Is coil too near exhaust and absorbing heat, rather than generating it? If so, move it or try a heat shield around it.

Are your points properly set (gap and mating properly) and the capacitor working?

Is your ignition timing correct?

Have you checked the valve clearances?

However, as I found out on my other project, the "coil" issue, was actually none of the above but a carburettor issue. After a deep clean no more cutting out after 20 minutes....