Ford 1600 crossflow high tension ignition problem diagnosis
Discussion
The problem is no spark at the spark plugs but let me give you some background to what happened.
The engine is a Ford 1600 crossflow from the late 60s/early 70s. I can't tell you which distributor is fitted but it has the Lucas side entry plug leads on the distributor cap and standard 12v Lucas coil from that era. It has some form of Hall effect electronic ignition module.
Driving along the motorway, the car had been running fine, not missing a beat. I slow to enter the services and as I'm about to park up, the engine starts to misfire and at this stage I have no idea whether the problem is fuel or spark. I leave the car for 10 mins to do usual service station stuff.
On getting back to the car, it starts and runs fine so I set off, only for the car to misfire and die before re-joining the motorway.
I check all the usual stuff (fuel and spark which all looked good) and when I try the car - it starts and is running fine again.
Back on the motorway, the car is bowling along - no problem, that is until another half an hour passes and then it misfires and dies.
There's no spark at the plug leads and when I check the spark from the coil, it's weak so I diagnosed a failing coil.
I fitted a spare coil (yes of course I had one in the boot) and I've now got good spark coming from the coil but none at the spark plug end of the plug leads.
I checked the distributor cap and rotor arm, they all seemed fine from what I could see, plug leads look fairly new and in any case, there is a good strong spark coming from the coil to the earth when I take the HT lead off and allow it to spark to the block.
So it sounds like it is either a rotor arm issue or distributor cap, neither of which I had spares for so I ended up being recovered home (Startrescue were brilliant other than dropping my car off the back of the truck when unloading and dragging the car off with all the weight on the exhaust).
The rotor arm and dizzy cap were replaced 4 years ago but the car has done less than 1000 miles since then. Obviously I'm going to order replacements of both but I've never known either to suddenly fail with no spark getting to any of the plugs or have the misfortune for that to happen just as the coil is failing.
I've even tried turning the engine over in the dark to see if I could see spark escaping from leads or on the outside of the dizzy cap but can see nothing.
In over 40 years of old car motoring, I've never had a complete failure like this, there's always been some sign if examined closely.
Has anyone had a rotor arm or dizzy cap suddenly fail like this when there is no signs of tracking, damp or other obvious signs of failure? The engine was running really well - until it wasn't.
Any thoughts of what's caused the failure on parts which have seen so little use?
The engine is a Ford 1600 crossflow from the late 60s/early 70s. I can't tell you which distributor is fitted but it has the Lucas side entry plug leads on the distributor cap and standard 12v Lucas coil from that era. It has some form of Hall effect electronic ignition module.
Driving along the motorway, the car had been running fine, not missing a beat. I slow to enter the services and as I'm about to park up, the engine starts to misfire and at this stage I have no idea whether the problem is fuel or spark. I leave the car for 10 mins to do usual service station stuff.
On getting back to the car, it starts and runs fine so I set off, only for the car to misfire and die before re-joining the motorway.
I check all the usual stuff (fuel and spark which all looked good) and when I try the car - it starts and is running fine again.
Back on the motorway, the car is bowling along - no problem, that is until another half an hour passes and then it misfires and dies.
There's no spark at the plug leads and when I check the spark from the coil, it's weak so I diagnosed a failing coil.
I fitted a spare coil (yes of course I had one in the boot) and I've now got good spark coming from the coil but none at the spark plug end of the plug leads.
I checked the distributor cap and rotor arm, they all seemed fine from what I could see, plug leads look fairly new and in any case, there is a good strong spark coming from the coil to the earth when I take the HT lead off and allow it to spark to the block.
So it sounds like it is either a rotor arm issue or distributor cap, neither of which I had spares for so I ended up being recovered home (Startrescue were brilliant other than dropping my car off the back of the truck when unloading and dragging the car off with all the weight on the exhaust).
The rotor arm and dizzy cap were replaced 4 years ago but the car has done less than 1000 miles since then. Obviously I'm going to order replacements of both but I've never known either to suddenly fail with no spark getting to any of the plugs or have the misfortune for that to happen just as the coil is failing.
I've even tried turning the engine over in the dark to see if I could see spark escaping from leads or on the outside of the dizzy cap but can see nothing.
In over 40 years of old car motoring, I've never had a complete failure like this, there's always been some sign if examined closely.
Has anyone had a rotor arm or dizzy cap suddenly fail like this when there is no signs of tracking, damp or other obvious signs of failure? The engine was running really well - until it wasn't.
Any thoughts of what's caused the failure on parts which have seen so little use?
E-bmw said:
Is the rotor arm turning?
Yes, the rotor arm is correctly attached to the distributor and with the cap off, can see it rotating. The spring and carbon brush are also correctly in place in the distributor cap and in contact with the top of the rotor arm.
As there is spark going into the dizzy and the carbon connector is touching the brass part of the rotor arm, either spark is tracking from the rotor arm to earth or from the dizzy cap to earth.
I think my solution lies in the replacement of these parts which I'm going to try to get today but I'm surprised by the very quick deterioration.
Take the coil lead from the top of the dizzy cap, remove the dizzy cap & hold the end of the lead about 3mm or so above the centre of the rotor arm using suitable measures to prevent you getting a shock.
Crank the engine & see what happens.
If a spark jumps from the lead to the rotor arm the rotor arm is faulty & allowing the current to earth via the dizzy centre shaft.
Rotor arms can be a problem on the Rover V8 (Land/Range Rover Classic). Some pattern parts on these have the metal strip riveted to the plastic of the arm & should be avoided. Type with the strip moulded into the plastic are the ones to use.
I don't know if this would be the case for the rotors available for your Ford, but worth checking
ETA Tracking on the dizzy cap can also be a problem & I've met that on other cars. Usually more of an issue in wet/damp weather & often the 'crank in the dark' check you've done will show it up - but if it's all dry it might not be noticable.
Crank the engine & see what happens.
If a spark jumps from the lead to the rotor arm the rotor arm is faulty & allowing the current to earth via the dizzy centre shaft.
Rotor arms can be a problem on the Rover V8 (Land/Range Rover Classic). Some pattern parts on these have the metal strip riveted to the plastic of the arm & should be avoided. Type with the strip moulded into the plastic are the ones to use.
I don't know if this would be the case for the rotors available for your Ford, but worth checking
ETA Tracking on the dizzy cap can also be a problem & I've met that on other cars. Usually more of an issue in wet/damp weather & often the 'crank in the dark' check you've done will show it up - but if it's all dry it might not be noticable.
Edited by paintman on Thursday 3rd February 10:25
paintman said:
Take the coil lead from the top of the dizzy cap, remove the dizzy cap & hold the end of the lead about 3mm or ......
That's a good point trying the spark directly on the rotor arm, thank.Edited by paintman on Thursday 3rd February 10:25
The rotor arm is the nasty riveted type.
jeremyc said:
These are the guys for non-nasty distributor parts: http://www.distributordoctor.com/
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