[Healeys] Car dies suddenly
WILLIAM B LAWRENCE
ynotink at msn.com
Tue Mar 19 20:57:58 MDT 2019
Sounds like a bad coil. The problem they have is temperature related with one or the other of the windings having a broken wire which is in contact at lower temperatures, but loses continuity when the coil warms up. I drove my old Range Rover classic 300 miles with this problem once with the coil cutting out every 20 miles or so. It is seared in my mind.
From: Healeys <healeys-bounces at autox.team.net> on behalf of Bluehealey <bluehealey at gmail.com>
Sent: Tuesday, March 19, 2019 9:36 PM
To: Michael Oritt
Cc: Austin Healey
Subject: Re: [Healeys] Car dies suddenly
Are you using a black rotor arm? I had a similar problem that was resolved by changing to a red rotor with no rivet.
Apparently the black colour of the plastic is created by using carbon - which can be an HT conductor if a crack appears usually from the rivet.
Keep us all in the loop.
Alan - from my iPad
On 19 Mar 2019, at 17:45, Michael Oritt <michael.oritt at gmail.com<mailto:michael.oritt at gmail.com>> wrote:
Yesterday morning I went out for a drive and after about five miles the car suddenly died. There was no rough running, sputtering or missing leading up to it—the car simply died. I coasted to the side of the road and after about 30 seconds since the key was still on I pushed the start button. To my surprise the car started immediately, revved freely and idled smoothly. A bit perplexed I decided to drive on to see what would happen now that I was paying close attention. The car accelerated smoothly and ran fine for about 1/2 mile and then it died again in the same manner as earlier. I shut off the key, popped the hood and examined the ignition system. Everything seemed fine—all spark plug leads were firmly in place as was the lead from the coil to the distributor. The power wires to the coil were tight and the harness/connector to the distributor (see below) seemed fine.
After scratching my head for a couple of minutes I got in the car, turned on the ignition and pushed the start button. Again, the car started right up and ran normally. With fingers crossed I headed for my shop/garage, about ten miles away and got there without any further event. Though the problem did not seem to be fuel related I decided to verify that this was not a fuel delivery issue. I have a double-headed SU fuel pump wired to a switch mounted just behind the driver’s seat which allows me to switch between pumps as well as turn the fuel pump off. While I was running the car at highway speeds it ran perfectly on either pump and when I selected the “off” position it slowly lost power as I expected it to—but in no way like it had suddenly twice died 15 or so minutes earlier. This indicated I was not dealing with a fuel issue but rather something related either to the ignition system or to the primary wires that run to it.
This morning I dove a bit deeper to try and diagnose the problem. The car has a Mallory Unilite ignition system tied to an MSD coil which has been in place and performed faultlessly for a number of years. I removed the distributor cap and everything appears to be okay, at least visually. The interior of the distributor was clean and dry as was the cap, leads, carbon contact, optical reader, etc. Mallory specifies the use of a ballast resistor in the lead from the power source to the coil and with the engine fast-idling I tested 12.5 VDC to the resistor and about 5.5-6 VDC out of it and at the positive coil terminal.
I have a large low-oil pressure light that is mounted in the dash in place of the original overdrive switch. It is wired from the ignition switch through a 10 psi normally-closed switch mounted in the oil pressure gauge sender line and then to the light. I point this out because both times when the engine shut down yesterday the light immediately came on, from which I conclude that the ignition switch itself is not the source of the problem. And though I did not remove the ignition key switch the wires to and from it seem tight and intact.
So my question is: What do I do? I hate to throw parts at it without finding something that appears to be defective but I don’t know where to start any further tests, etc. I also don’t want to simply wait for the issue to happen again. BTW over the weekend I drove about 150 miles with no issues whatever. Beyond installing four new plugs last week I have not performed any work related to the ignition system. All suggestions/questions welcome….
Best--Michael Oritt, BN1
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