1800s ELECTRICAL QUERY
 

Hello - I am new on here having just joined the VOC. I have a 1968 1800S which I drive regularly and it has been incredibly reliable - until just recently.
What happens is this: It will be contentedly ticking over when suddenly the rev counter needle starts to jump about and then the engine just stops.
Usually it will re-start when I turn the key and after a few seconds of steady running, the problem repeats itself.
Mysteriously, it will often then run for a couple of days without any problem - then suddenly do it again.
The other day I was driving along at about 50mph when it suddenly started happening - the rev counter started to jump and the car kept hesitating and struggling to go, then it righted itself again and was fine after that.
Any idea what may be causing this? Have wiggled all the wires on the coil and the distributor (while it was running) without any effect. Someone suggested it might be a faulty coil?
Any help would be welcome.

I had a similar thing on my Amazon a while ago, which turned out to be the electronic doings I had replaced the points with. Put points and condenser back and everything fine.

R55;

Welcome to this forum!

First question(s) must always be: Has any work recently been done, especially on the system exhibiting issues, and if so, what what it.

If none, symptoms you are describing could be ignition or fuel supply, but more likely ignition, particularly because of action of the Rev Counter just prior to complete loss of function. [Point of info: Rev counter monitors Ign Coil primary current, which Points (should) break relatively cleanly because of the quenching action of the Condensor.] ...but Condensors available in recent years, even Bosch labeled, have been less than reliable...no, worse than that: Horrendous!...and a failing Condensor allowing the primary current to break noisily would manifest itself as multiple hits in the Primary current, which in turn would be interpreted as a high RPM and indicated as such. I believe this would explain the symptoms and cause, but component replacement will confirm this.

I recommend you replace the Ign Condensor with new, Bosch labeled one (probably still the best available), replace nothing else(!) and seeing if symptoms remain. Please be acutely aware of the centering of Pointsbolt. See also: http://www.sw-em.com/Volvo%20Ignitio...ition%20System

Yes, the ignition coil is failing to provide a spark, but not because it has failed, symptoms are a result, not a cause.

Good Hunting!

Thank you very much for your suggestions. However, I now think the problem may be solved (fingers crossed).
My mechanic was certain the problem related to ignition. So what he has done is bypass the ignition switch on the dashboard and replaced it with a direct feed (fused) via a small toggle switch.
Now when I turn the key, the dashboard lights up and if I turn the key a bit further it will crank the engine, but the engine will not start until I flick the switch.
This has bypassed the ignition switch behind the ignition key barrel which he believed had a fault on it and which Brookhouse Parts tell me is no longer available.
So far today I have driven the car without any problems. I am hoping this has therefore solved the problem – and gives me the extra benefit of a hidden cutout switch which adds extra security to the vehicle, so I am very pleased with the result.
I am planning a longer journey tomorrow in it so hopefully I won’t have any problems. Thank you again for your help.

R55;

There is little arguing with success, but you might want to undertake a shorter shakedown drive in order to build some confidence in the repairs (as I recall, your symptoms were intermittent!)...and if you are still using the Key turned into Pos 4 against the Gorilla Spring to start, beware it will eventually succumb to fatigue (Ref. http://www.sw-em.com/ignition_switch...ch_article.htm ). The recommended modification is to install a momentary "Start" switch to take the place of Pos 4 of the key to prevent future key breakage.

From your description of function, I expect your mechanic has made other changes, that may even include an electronic ignition module.

Cheers

The problems described by the poster were encountered on my 144 with 123 dizy. The wisdom of the manufacturers when I returned the dizy for examination was that the electronics were affected by "spiking" An adjustment was made to the soft ware to make it less sensitive and the problem was solved.

Riddler55,

Another 1800 in Stockport; I know of five in the town (including mine)! There is a black '62 on display in the new main dealership on St Mary's Way; have you had a look at it yet?

Happy motoring!

Mr Thirsty

You mean this one? Yes I have - it may be up for sale I believe - belongs to one of the technicians.
I am only aware of one other in Stockport - Davenport area. Where are all the others and how come I never see one? Always out in mine!