1800: I think I killed my rev counter - any advice?

[SteadyRolling]

Oh man, I swear this car is fighting me at every turn… Recently got back on with recommissioning the ES with its engine rebuild after a lengthy hiatus - first problem was it wouldn’t run, but eventually discovered the dizzy must have somehow changed position while disconnected. Once twisted round a bit, it was idling at 2-3000rpm but managed to bring it down near to what it should be in readiness for setting timing properly. But then I discovered the dizzy’s gasket had fallen off so I pulled it off again to refit - and this is where the ‘fun’ really started…
As I was tightening the two bolts on the mounting plate, there was a flash (having forgotten to isolate the battery). Heart in mouth I turned the key - it fired up ok, still running a bit rough, but now the rev counter isn’t working. All the other instruments are working (bar the obvious clock and also oil temp - bit annoying as I’d replaced the broken sensor) and the fuse was OK. Reconfirmed the connector on the dizzy is properly located too. So anyone got any ideas please - the world of electrics is a bit of a mystery to me…
It’s Pertronix electronic ignition btw if that makes any difference.

[SteadyRolling]

Anyone?

[powen1]

Hi,

Ron has produced a good document regarding Tacho's worth a read
http://www.sw-em.com/Smith%27s%20Tachometer.htm

I suspect there is a way to remove from Dashboard and check
I'll let someone more in the know to provide more information

cheers

[Ron Kwas]

SR;

I did see this post, the there are several things that are strange to me, so I didn't chime in at that time, fearing a response would be lengthy...but now that I've been referenced, and no one has addressed all the questions which you brought up, I guess I have to...

"dizzy...Once twisted round a bit, it was idling at 2-3000rpm but managed to bring it down near to what it should be in readiness for setting timing properly"
...twisting it around a bit is a hellova way to tune, or set the idle! If Timing is unknown, Static Time first, then set idle in the proper method! See: https://www.sw-em.com/Volvo%20Igniti...tatic%20Timing ...and: https://www.sw-em.com/D-Jet_Idle_Adjustment.htm

What a "dizzy’s gasket"?

Care should be exercised when working around Batt live wires, but the "flash" likely was caused by you inadvertently making a contact between engine (Neg return to Batt), and term 30 Batt live on Solenoid, which likely damaged nothing (but the chrome on the wrench involved), besides getting your full attention! Tip for the future: Work with higher degree of care, and/or disconnect Batt!

If "all other instruments...bar the obvious clock and also oil temp...are working"...on what troubleshooting basis did you replace the Oil Temp Sensor...or was it on speculation? See: https://www.sw-em.com/temperature_ga...er_Temp_Gauges

Non functional Rev Counter is not a directly a result of the short circuit which caused the "flash", but you should mention preconditions...like that it did, or did not, function before, and after Pertronix was installed... See: https://www.sw-em.com/Smith's%20Tachometer.htm

Good Hunting!

powen: Thanks for reference!

[142 Guy]

You did not specify a year; but, ES so assume a later 1800 ES with the Smiths current sense tachometer. Unless the wiring has been messed with, the fact that the engine runs indicates that the current sense line from the ignition coil through the tachometer to the Pertronix connection on the distributor is intact.

It would have been super helpful if we new what actually 'flashed'. As Ron notes, if this was a contact between the wrench tightening the bolts on the distributor body and terminal 30 on the solenoid, it should have zero effect on the tach circuit.

When you said the fuse is OK, which fuse is OK? The tachometer and a bunch of other stuff gets its power supply via fuse #4. If fuse #4 is good then the next step is to extract the tach and check to see if the tach is getting 12 volts with the key in the run position. Since the tach current sense line is intact, if the tach is getting 12 volts switched power then non operation suggests the tach has expired. You have provided insufficient information to speculate on why the tach has expired although sometimes stuff just happens.

Ron's excellent web site has provided the wiring diagram for the 1800ES

https://www.sw-em.com/Wiring_Diagram...iring_Diagrams

The external wiring of the tach circuit is dumb-ass simple. Study the diagram with care and you should be able to confirm whether the external wiring to the tach is intact and correct. If it is, then you are left with a dead tach. Ron provided a link to his notes on the Smith tach which may help you.

Enquiring minds need to know what a distributor gasket is.

[SteadyRolling]

Thanks guys, useful post, will attempt to decipher it properly later on... In the meantime:

Originally Posted by Ron Kwas

SR;

...twisting it around a bit is a hellova way to tune, or set the idle! If Timing is unknown, Static Time first, then set idle in the proper method! \

On first turn of the key after engine rebuild, engine wouldn't catch properly, ie really lumpy and cut out as soon as I let go of key. So adjusting the 'collar' of the dizzy was to solve that and get it running, not to sort out idle.

What a "dizzy’s gasket"?
Seemed a bit redundant to me too, but there was a paper gasket separating the block and bottom of dizzy flange. It was there when I stripped the engine, so I put it back on again. Of course, if I had my time all over again...

but the "flash" likely ... damaged nothing (but the chrome on the wrench involved), besides getting your full attention! ]
I really hope you're right, although tacho is still dead. I disconnected battery fully overnight in the vain hope it might reset, but no luck.

on what troubleshooting basis did you replace the Oil Temp Sensor...or was it on speculation?
Before I rebuilt the engine, the old one's terminals were broken off.

Non functional Rev Counter is not a directly a result of the short circuit which caused the "flash", but you should mention preconditions...like that it did, or did not, function before, and after Pertronix was installed...

It definitely worked right up until the flash, that's how I know it was idling at 2-3000rpm. Pertronix was already fitted when I bought the car.

[SteadyRolling]

142Guy: just on my way out for a day or two now, but is a 72ES. And yes, I checked Fuse 4 - was intact, as you'd expect when (most of) the other instruments are working.
Re what flashed - I'd tightened the front-facing bolt, then as soon as I went to the 'back' bolt and put the socket on it, there was a (small) flash. Pretty sure I hadn't touched anything else with the ratchet though.
Re gasket - answered above before I saw your post. It's exactly same shape as the flange of the dizzy. All the cool cars have one these days...

[powen1]

Suggest the flash was the ratchet touching the big live wire going to starter motor
mines quite close and easily done ;-)

[morwenna240]

Originally Posted by SteadyRolling

142Guy: just on my way out for a day or two now, but is a 72ES. And yes, I checked Fuse 4 - was intact, as you'd expect when (most of) the other instruments are working.
Re what flashed - I'd tightened the front-facing bolt, then as soon as I went to the 'back' bolt and put the socket on it, there was a (small) flash. Pretty sure I hadn't touched anything else with the ratchet though.
Re gasket - answered above before I saw your post. It's exactly same shape as the flange of the dizzy. All the cool cars have one these days...

So, all of us poor undizzy gasketed folks are running around in uncool base models, huh?

[Ron Kwas]

SR;

"It definitely worked right up until the flash"...I don't know how that could have damaged the Tach...what I do know is that Tach negative return current path is through its housing and car chassis, so this suggests to me that possibly the mega-current surge that you initiated found some circuitous route back to the Batt Neg which got damaged because of the high current. OR...the Tach was on its way out, as they often are at this age, and its ultimate failure with your "flash-event" was coincidental. You can try snugging the Thumbscrews and reseating the Tach Housing Clamp in the Dashboard, and inspect, clean and reconnect the Chassis to Engine Braid...or adding the external capacitor at Tach ( https://www.sw-em.com/Smith's%20Tach...lated_Problems )...without further details, I have no further ideas or tips...

"...that's how I know it was idling at 2-3000rpm." ...Tachs often are generous in their indication as a symptom of old-age and impending total failure (see above, and link!). A true idle RPM of 2-3kRPMs is an indication of a vac leak!

Good Hunting!