Losing spark when hot

[Clean]

Hi peeps,

Our 1971 Crossover starts first time, every time, and run's as sweet as you like. Particularly after a great overhaul by VW Restorations of Halifax.

However...... she was recently borrowed by some friends, and on a couple of occasions they had difficulty restarting her when warm, notably when stopping for petrol after an hour or so of trucking.

The RAC attended and claimed that the spark was weak. Having stood for an hour waiting for the RAC to turn up, everything must have cooled down, and she started first time, much to their embarrassment! This happened on their way home, too, in almost identical circumstances.

So, here's the question, can the coil / HT leads / Distributor break down when the engine compartment is hot, and if so, what should I change?

Everything?

Costs to change the lot are not great, but if this is a coil specific problem that people know about that would be helpful to understand.

Thanks in advance to any ignition-meisters out there who can help....

Clean.

 

[Hubs]

If you have an electronic contactorless (no points) ignition then that could be its way out. They seem to fail gradually which makes them pita to fault find. Generally playing up more when hot. Most of the budget replacements in the last year now have improved the electronics. Get one that turns it self off after 1 second if the engine is not running. This prevents you cooking them when you leave the ignition on.

 

[Clean]

Thanks for the reply, but we have a standard distributor with rotor arm etc.. I am increasingly convinced it is the coil breaking down when the engine compartment is hot.

 

[Hubs]

Worth having a spare coil anyway. If your confident the spark is weak and points are set right then as they are just a switch to ground I can't see what else it would be electrically, other than the coil.

 

[Tofufi]

I had a coil begin to break down while hot before. I did 80 miles, stopped and switched off, and it wouldn't restart.

New coil solved it. Buy stock/good quality, not a shite pertronix flamethrower or similar

 

[Clean]

I had a coil begin to break down while hot before. I did 80 miles, stopped and switched off, and it wouldn't restart.

New coil solved it. Buy stock/good quality, not a shite pertronix flamethrower or similar

Bingo! That will do for me as a vote for the thought.

Now to try and work out which coil I need!

I will buy Bosch, and might even get a full kit (coil, HT Lewds and Dizzy) from JustKampers. I have a pretty standard single port 1600; any tips on how to pick the right Coil?

Thanks,

Clean.

 

[Tofufi]

I had a coil begin to break down while hot before. I did 80 miles, stopped and switched off, and it wouldn't restart.

New coil solved it. Buy stock/good quality, not a shite pertronix flamethrower or similar

Bingo! That will do for me as a vote for the thought.

Now to try and work out which coil I need!

I will buy Bosch, and might even get a full kit (coil, HT Lewds and Dizzy) from JustKampers. I have a pretty standard single port 1600; any tips on how to pick the right Coil?

Thanks,

Clean.

Just a standard one will be fine. I normally use Bosch blue coils, but even that can be a bit of a minefield these days - I normally buy secondhand ones. I think one of my cars is currently running a coil from an 80s Volvo :msn4:

This link may help if you're buying a new one:

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

 

[StefansBus]

A new quality coil won't hurt and won't break the bank either but hot start issues may also be carburetor related and are not uncommon.

I use a Beru blue coil. However, just like the Bosch coils, there are different ones out there. Try to find one which is actually made(!) in Germany, if possible. I had a cheap blue Beru which also said Beru Germany but not made in Germany. It was filed with oil which you can feel/hear when you shake the coil. The better one has a more solid insulator which is also immediately obvious when you shake it as you don't hear/feel anything.

Stefan

 

[Tofufi]

Just as an aside, yesterday I had to go and rescue a friend who has a Lotus Europa. It'd start and run fine, but wouldn't re-start when hot due to a weak spark. New (secondhand) coil solved it

The failed coil was oil filled...

 

[Clean]

Bosch Blue Coil ordered from VW heritage following the advice from the “ratwell” link shared by Tofufi.

Cheers, all; I will let you know how we get on.

 

[Clean]

Bosch Blue Coil ordered from VW heritage following the advice from the “ratwell” link shared by Tofufi.

Cheers, all; I will let you know how we get on.

It was the coil; she now starts first time, every time, again.

8)

 

[Tofufi]

Good stuff