Club 80-90 Forums

The responses to what2do's question in "Testing hall sender - idiot's guide" were very helpful - but before I buy a new sensor, I would like to check a few more things.
I carried out the test that bigherb posted:
Remove the centre HT lead from the distributor and hold it about 5mm away from a metal part of the engine or bodywork and away from the fuel system.
Remove the three pin plug from the distributor and probe a piece of wire into the centre pin of the plug.
Switch on the ignition and then scrape the other end of the wire along a metal part of the engine this should then produce sparks from the HT lead.
If you get sparks then the rest of the ignition system is OK and the hall sensor is at fault.
I got sparks, so the fault seems to be with the hall sensor.
Next I swapped the king lead for a plug lead and earthed the body of the plug (a bit like bigherb's video) and I still got sparks at the spark plug when I scraped the wire along the engine (but now I had an extra hand free!).
Next I reconnected the 3-pin-plug to the distributor and turned the distributor shaft by hand - no sparks this time, so fault still likely to be the hall sensor.
Then I probed the back of the 3-pin-plug (whilst it was still fitted) measuring voltage between each wire and earth and found...
12 volts at the red/black wire (outside pin)
0 volts at the brown/white wire (outside pin)
4.47 volts at the green/white wire (centre pin)
Rotating the distributor made no difference to the 4.47 volts at the green/white wire.
Is this what you would expect to find?
Finally, with the distributor on the bench, I put 12 volts across the hall sensor (+ to red/black and - to brown/white). Measuring resistance from the centre pin of the 3-pin-plug to earth, I couldn't get a circuit regardless of the position of the distributor shaft.
Have I done enough to be sure that the hall sensor is the problem?
Thanks
T25 (1983) DF Engine - Leisuredrive conversion – a charmingly retro nightmare.

AlanR25 wrote: Then I probed the back of the 3-pin-plug (whilst it was still fitted) measuring voltage between each wire and earth and found...
12 volts at the red/black wire (outside pin)
0 volts at the brown/white wire (outside pin)
4.47 volts at the green/white wire (centre pin)

You should check the voltage across the two outside pins, the brown/white is the earth for the hall sender checking across the pins and getting a voltage reading checks the integrity of the Hall power supply and its path to earth.
Otherwise you have done it correctly and the Hall sender or its wiring in the distributor is at fault.

Thanks bigherb. I checked the voltage across the outside pins and found 12 volts - so it seems like time for a new hall sensor.
Info on JustKampers says I may need to re-use the connector from my old unit. Has anyone tried this? Is it as straightforward as it sounds? Is it best to join the wires inside the distributor or is it easier to try to solder the wires into the old connector?
It also seems you can pay as much as you like for one of these. I popped 034-998-065 into google and found prices from £13 to £68. Has anyone tried the offering by JP Group?
Thanks for any feedback.

T25 (1983) DF Engine - Leisuredrive conversion – a charmingly retro nightmare.

AlanR25 wrote: I popped 034-998-065 into google and found prices from £13 to £68. Has anyone tried the offering by JP Group?
Thanks for any feedback.

As they are pattern parts they could all be coming out of the same factory and reboxed, until someone buys the different types and compares them we don't know.

I would replace the plug on the end of the wiring loom to the square type
.

My son has a recurring fault with his 1980 Aircooled. On and off for some time now it suddenly cuts out while driving, usually after about 3 miles. When the engine has cooled down it starts fine.

Over time we have replaced engine electrics and fuel system and it settled down and was running well.

A new ignition amplifier was installed, we kept the old original one.

Hall sender is original. Coil is original.

Last Sunday on the Busstop run, the van stopped suddenly with the old symptoms. AA checked it out and said its probably the new amplifier failed. AA recovered van back to my son's home, he put the old amplifier back in and the engine started and runs fine again.

Am I right to suspect the hall sender is failing on and off, maybe when it gets hot. The coil is original and maybe that could be a suspect also.

mgbman wrote: Am I right to suspect the hall sender is failing on and off, maybe when it gets hot. The coil is original and maybe that could be a suspect also.

Put the suspect amplifier back on and do the above check, if you don't get a spark then it is a faulty amplifier or coil/wiring.

Thanks bigherb. The problem I have is the sudden stopping happened with the old amplifier, we assumed that was faulty and got a new one . The same has just happened with the new one. Which made me think it might be something else causing the symptoms.

Would be a bit unlucky if both were faulty.

We made some assumptions along the way when we thought fuel was the issue as the old tank was cruddy and the solex's needed refurbing and some of the tank breather was missing or leaking and my son filled up with diesel one day. So we decided it was time to renew the lot and all went well until Busstop. Its disappointing and frustrating.

But we will do the tests and maybe prove where the fault is.

As they are pattern parts they could all be coming out of the same factory and reboxed, until someone buys the different types and compares them we don't know.

Feedback - I bought J10729 from Just Kampers at £43. The label on the box said "Distributed by JP Group a/s Denmark". I followed the advice given by Tony in his review on Just Kampers and it fitted and worked fine.
However, I now have some performance issues - I don't think (hope) these problems are not associated with this part - but that's a subject for another post.

T25 (1983) DF Engine - Leisuredrive conversion – a charmingly retro nightmare.

AlanR25 wrote:

As they are pattern parts they could all be coming out of the same factory and reboxed, until someone buys the different types and compares them we don't know.

Feedback - I bought J10729 from Just Kampers at £43. The label on the box said "Distributed by JP Group a/s Denmark".

Thanks, good to know what brand the JK one is.

I really liked this thread -thankyou.
and try to give back, add useful ideas for the future.
When it was started is irrelevant.
1) if the distributor has play (most will) this fix is temporary. Eventually the rotor will touch.
2) the rotor if original is a very tight pressed on fit. Levering from the edge on biscuit tin metal will ruin it.
Start in the middle. Keep a spare.
3) there are two top dead centres as the crank and cam go at twice speed. Setting everything to TDC first like it says in the manual is correct. Idiot proofing is for clever people.
Minkey muppet saying -ohnly goos in one waayy,
slap in face required.
4)the bosch distributor can be stripped at home.
If you bought a chinese one it will break on a rainy day on a roundabout. It will run worse till it breaks. £££ money wasted. If it seems too cheap thats cause it is.
5) on type 4 engines the timing should max out at 32 degrees 3500rpm and up. A spare battery and timing light are needed/way holding throttle open.
6) the distributor rarely has maintenance. Driving it for 40 years with no oil dropped in is bound to wear something.
7 good luck!

The old dead hall sensor is useful.
Carefully remove the old wires with a good tool from the block.
Reuse the block on the new hall unit.
Make sure all is a clean v.tight fit.
No wires should be loose or allowed to touch.
Backfiring will be caused.
Do not use a 009 distributor. This is for industrial type 1 engines. It is physically a different size to type 4 (and many cheap electronic dist copy that).
Most are chinese junk anyway now.
It has no vacuum advance. This costs 3mpg or more and makes a flat spot pulling away. Emmisions are worse. It only goes to about 27 deg -not over 40 deg. The rotor points the wrong way if you have a type 4 engine. Mr.minkey muppet is wrong again. Also makes Confused next owner...