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MG Midget and Sprite Technical - Rev. counter flicks over to max on start-up

Good evening folks,

Been driving the midget lots during the good weather and noticed when starting, the rev. counter flicks over to maximum for a split second, then behaves normally when running.

Doing some experimenting (switching things off, removing fuses etc.) I found turning the radio off cures the problem.

Why would leaving the radio/cd on cause this, do I have a dodgy voltage stabiliser or something else - I could just live with it, but is damage being done to the rev counter?

Any ideas would be appreciated.

Tony
Tony G

Tony,

That's a cracker :)
It's probably "noise" transfer from the radio to the ignition/Taco circuit. Has it just started doing this or have you made a change to something and then noticed this phenomenon?
I would start by checking the aerial and radio 12v feed are kept well away from the rev. counter head and the cables to it from the coil.

After that try a suppressor on the radio feed and after that.... Just switch the radio off ;)

Best of...

MGmike

M McAndrew

I like mikes thinking

I had that happen to me also... cheap radio

What I thought the problem was the radio had a build up of residuel energy like a tv capacitor or there was a internal battry, for the digital.clock with the radio connected to the ignition and the tach inline on the ignition... I just figured it was that little release of juice on turning the key that nudged the tach

I just hooked radio up to battry with an in line fuse issue solved

But that was always a guess.

Prop
Prop and the Blackhole Midget

Stop listening to Radio 2, Tony. That'll sort it out.
Steve Clark

Hahaha

Id like to add ...NPR to the list


.
Prop and the Blackhole Midget

All I have done recently is changed the electric fan, from a naff 9" pusher to an 11" Spall puller. BTW we never listen to Radio2, always Radio 4!

Tony
Tony G

Tony,
I like the sound of an 11" puller (suction) fan but how did you find the room for it IIRC there's only about 2" between water pump and rad

try wiring the fan directly from the battery and see if you still get the rev counter flicker
Nigel Atkins

Nigel

Im guessing he had to use a 1500 shroud to make that fit

Prop
Prop and the Blackhole Midget

Hi Nigel, I used a 1500 radiator cowl from flee bay (it turned out to be a rather nice powder coated one for £15) Raised it up about 15mm to clear the steering rack, repositioned the expansion tank through 90 deg.
The crossflow rad. fits a treat and you can get to all the mounting bolts to remove the rad. without the need to extract the cowl.

The 11" Spall was the slim-line one and at only 51mm deep, there is lots of room now.

The fan is on an inline thermostat which kicks in at 90 C and drops the temp down to 83 C in about 20 seconds.

The old pusher fan had rather a large motor and covered almost 30% of the rad. surface. Now the midget runs steadily at 175F - 185F at speeds over 30mph and the fan only cuts in when in stationery traffic.

When I have resized the photo, I will post it.

Tony


















Tony G

Here is the 1500 cowl


Tony G

and the expansion tank turned through 90 degrees.


Tony G

SCOOOOOOOOOOoooooooOooooo - R !

To loud ?

Prop
Prop and the Blackhole Midget

very nice, I did wonder about bonnet clearance

had it been a couple of months back I'd have copied your idea

for some unknown reason I had a right PITA getting the rad cowl to align this time

and I prefer a suction fan apart from the more efficiency it helps to keep the front face of the rad clearer of debris and noise is in the engine bay, as I allow mine to run on after it's parked up and being on the outside it makes quite a noise
Nigel Atkins

Tony, super job; very neat and smart - a real credit to you.
Nick Nakorn

Thanks for that,

The bonnet clearance was 10mm between the top of the rad fixing bolts and the underside of the bonnet.
What would we do without bluetak?

With all my checking of fuses and wiring etc. the rev. counter flicking has now stopped! CD/radio on or off - it must have been just one of the Midget aberrations.

Tony



Tony G

yes incredible stuff, it can hold an amazing amount of weight if left for a few months

some times just disconnecting and reconnecting connections can be enough to clean them up or sort them
Nigel Atkins

This thread was discussed between 22/08/2014 and 23/08/2014

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