faulty condensors

[anaxemurderer]

Hello all

I seem to be having more trouble with my rrc. Its a 3.5 on SU carbs and old fashioned points distributors. Been laid up for a little while with a broken diff but was running okay last time i touched it.

Howver when i went to start it nothing happened. Went through the usual checks and came to the conlcusion the condensor had failed. Changed it and then tried again. She started up but only on a few cylinders. After i had stripped out the plugs (to clean out the gunge and hopefully get some more going) it refused to start again.

Apparently my spare condensor has also failed!

Am i missing something? Why should my condensor keep failing (this is the third in 12months). I only bought britpart ones, should i try a better brand?

Thanks

Nick

[Loz V8 Capri]

I upgraded to electronic ignition - never have to worry then. Someone else on here might be able to tell you why your condensers keep failing...

[ged]

Hi Nick,

Have you had a plug out & checked for spark? If you have & it's a crisp blue colour then your problem lies elsewhere. You said it started on a few cylinders which makes me think it could be a fuel problem. Have you checked for fuel flow?

Ged.

[anaxemurderer]

definately got fuel and the problem is now theres no spark at all

[RoverP6B]

Hello Nick,

Go through a process of elimination.

Try a different coil and see what happens.

Make sure that the carbon contact on the inside of the distributor cap is free to move within its sleeve. Try and start the engine in the dark and look for arcing along the leads and around the distributor cap. If so replace parts as required.

The capacitor (condensor) is there to prevent the points from burning, and runs in parallel with the points. Should it fail (develop a short circuit) the engine will be difficult to start, and will begin to missfire after several miles of running. Check the points for signs of excessive burning.

To check if the condensor is at fault, switch ignition on and separate points by hand. If this is accompanied by a flash, then this indicates condensor failure.

Ron.

[anaxemurderer]

Yeah i've been through the elimination process and as i say reckon the condensors failed. Was just wondering if there is any reason they keep failing (other than them being cheapo ones).

I shall buy a genuine part version but i'd rather not kill that aswell

Nick

[RoverP6B]

As the condensor is connected in parallel with the points, the same voltage appears across both.

The condensor will fail if the voltage across it exceeds its voltage capacity.

With engine off, switch on the ignition, check that the points are closed. With a voltmeter connected between the coil positive terminal and earth.

The voltage reading should be between 6 and 7 volts. If it exceeds this figure then you have found the cause.

Ron.

[IanT]

Did I read somewhere that Mallory often found that 'condensor problems' were down to a coating on new condensors - it needed to be cleaned off with emery cloth to get a good contact?

Found it (on the RPi site):

First, we have seen problems when a customer replaces a condenser. If he continues to reuse the old bracket or does not tighten it properly, he may not be getting a good contact with the housing. The condenser has a coating to prevent discoloration on the outside of it.
When the bracket is tightened down, it scratches through the coating and make a good contact. I suggest the customer take a new condenser, scuff off the coating with a very fine sandpaper, then install it using the new bracket we supply with the condenser. Make sure he tightens the bracket and not just snugs it enough that the condenser will not fall out. Quite often, the problem will disappear.
As for a replacement that can be used, there really isn't a more heavy duty piece available. The rating needs to be .28 mfd.
If you are having failures like you are describing, I would check for a bad or poorly matched coil, bad plug wires, and bad grounds. Condensers, once they are functioning, do not normally just fail on their own.