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TR4/4A Symptoms with bad condenser


Jedi Knight
Country flag
I now know what the symptoms are when a condenser goes bad. It happened yesterday while on a scenic drive. Fortunately we were able to figure it out and was able to drive home.
The problem started when the car gave a couple of backfires as I drove down the road at a fairly slow pace. Then about 1/4 mile later it did the same thing. About another 1/4 mile it did the same thing followed by a powerless stumbling of the engine. The engine would start and run but only stumble along. Pushing on the accelerator I got a slight increase in rpm but still just a stumble with no power.
Replaced coil, cap with plug wires and plugs with no help. Points looked good in this recently rebuilt distributor. Last to be changed was the condenser and it started right up to the delight of all.:wink-new::friendly_wink:


Senior Member
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I have an old 250 inch Chevvy in my swamp buggy. Couple years ago I took the carb apart three times to clean it out for what was obvious carb failure. It turned out to be the condenser.


Country flag
I never realized what a bad condenser could do for you.

My Woodmizer saw mill was running rough partly because the 18HP motor is old and not been run much lately. Worked on the carb and ended up getting a new one from e bay. Still did not run well. Had changed the points and gone through the timing several times with little improvement. Finally thought the condenser is the only thing I have not changed. I was in fact looking at up grading the motor to a 22HP motor. Went to a lawnmower shop and got the condenser.
Do not need a new motor the condenser was the problem all along. It runs like it did when I bought the mill.



Jedi Knight
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Well Got All 4,
The reason I am running a points dizzy is that the car came to me with a Crane electronic unit. That worked well for several years and then the it started missing some under load. Eventually the coil died . But even after that I still got the missing under load. I finally replaced it with a points unit.
Meanwhile I had built up a second TR4 and used a TRUE SPARK electronic unit. So I was operating with both cars having electronics. Thennnn one fine day the TS unit just flat died and left me about 200 miles from home. I then replaced both electronic units with points units. So been there done that. This time I was able to drive away on my own.
Thanks for the info. I used them before when there was a problem with the rotors. I will contact them again.


Great Pumpkin - R.I.P
My experience has been similar to Charley's : Every single aftermarket ignition I have ever owned has failed at least once, sometimes in strange and mysterious ways.

One of the most entertaining ones (in retrospect) was a MSD unit that would simply stop working, only for a minute or two, only in morning rush hour traffic while sitting at a stop light! How it managed to do that, I have no idea; apparently something to do with warming up. It would run fine the rest of the day, nary a cough on the way home or going out to lunch.

IIRC, that was the one that MSD said they could not repair. But there was another one before that, which would quit working only going up a long hill. That one I sent in for repair, got back, and failed again within a year.

Anyway, in all cases, switching back to the OEM ignition was more reliable.

Yeah, in 40+ years of TR ownership, I've had two condenser failures. But spares are free (you get one with every tune up), and it only takes a minute to change a condenser. Changing out an electronics module is a lot more hassle, and replacements tend to be a lot more expensive.

One conundrum I haven't quite run to ground yet: I bought a capacitor tester just so I could see what was wrong with my most recent failure. Funny thing is, according to the tester, there is nothing wrong with it! Haven't figured that one out yet, but it's got to be something like heat or vibration (that doesn't happen on the bench) making it go intermittent But I've tried tapping on it and even hitting it against the bench, with nary a flicker on the meter. Same for heating with a heat gun. Still not sure what's up with that.


Country flag
I'm using a Mallory dual-point with vac advance in my TR3 only because I got the thing really cheap and it was brand new. Mallory had a lot of problems with condensers around the time that I got it, and even Mallory owned up to it and shut things down until they came up with a fix. I haven't had any problems with the condenser yet (maybe 12k miles), but carry a spare (along with other spare parts for the distributor), and it's actually a common Chevy condenser. They work just fine in place of the Mallory, and are available anywhere.


Luke Skywalker
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One common denominator I hear here is everything eventually will fail. Being a driver mechanic our responsibility is to be prepared when a problem arrives especially if your on a trip far from home. If you have Petronics you must carry an extra set or a set of points and condenser. Even says that in the operation instructions. If your running points carry at lease 1 extra condenser if not both and a feeler gauge. If your using a Mallory ignition and it goes out your probably out of luck or better to carry a spare distributor and coil.
Obviously all these are made buy humans so they won't last forever. You have to decide what fits your situation and thinking. I have points and Petronics (also a Hot Spark in a TR250 that broke a Valve spring after I installed it) and got to say the Petronics made my distributor run like it was new and what a joy to drive.
One nice advantage with the points replacement is you don't have to every couple of thousand miles readjust the points or retard the timing to make up for wear. I do carry spare points and condenser just in case. Another is faster starts for sure. I also have a spare set for the 250 too but have zero miles on the Hot Spark until I get the valve springs replaced.


Jedi Knight
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When my True Spark died it was still under warranty. They offered to replace the component . I opted for a new points dizzy though it was a cheaper model. I then found an original dizzy for my car and had it rebuilt. So it is like new all except for a possible defective condenser. I note that the bad condenser that started this thread was in my other TR4. And it also had a recently rebuilt dizzy, following the removal of the Crane unit.


Country flag
One of the most difficult fixes I ever had turned out to be a bad condenser. 67 Midget I had just bought. It ran ok when I bought it, but would die occasionally. Soon it turned into a situation where it would idle, but wouldn't accelerate and would barely rev up in neutral. I messed with carbs, fuel pump, points, wires, plugs, coil, just about gave up, then changed the condenser and it was instantly fixed.

At the time I had been fiddling with old British cars for 20 years or so and never had one fail, so I didn't think they did, but they do.

As stated, replace when you do a tune up, keep the known good part as a spare.


Several years ago Steve Maas (Sarastro on this board) started 2 threads discussing quality issues with modern replacement condensers. In one thread he recommended an equivalent industrial capacitor that will function the same and offer longer life.

You can read over Steve's experiences and recommendation in the two threads linked below.


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