MD2B original rev counter

Katouf

New member
Joined
15 Oct 2004
Messages
168
Location
Essex man, Thames @ Leigh
Visit site
Katouf is fitted with the original VDO analogue rev counter supplied by Volvo in the instrument panel introduced in 1972/73. It reads up to 3000 rpm with max engine revs about 2500 on a good day, more usually 2200. It's recently been playing up; sometimes working, most times not.
The signal for the revs comes from the crankshaft via a magnetic pickup (my engineer friend said it's the 'Hall' effect) and then via 2 wires that go to the W and G terminals on the rear of the unit.
I've performed the following maintenance:
1)tested continuity of the wires with a meter between the pick up and the 2 terminals;
2)checked the + and - supply from the electrics - there is 12v going to it and the circuit is complete with no loose wires that I can see.
3)removed and cleaned the pickup head of oil and cleaned the spade connections for the two W and G wires;

Is there anything obvious I've missed or is there a way of testing the rev counter on the bench?
I don't really want to buy a new one because I aspire to be like the Tightwad sailor, and anyway a new one wouldn't fit the big hole in the instrument panel.

Alan
Katouf Centaur CR505
 

Searush

New member
Joined
14 Oct 2006
Messages
26,779
Location
- up to my neck in it.
back2bikes.org.uk
The pickup failed on mine & I had a sense of humour failure when I was told the cost of a replacement. I managed quite well without for about 10 years when I replaced the then 30 year old engine.

BTW, do not run the engine for long periods with the sensor removed, the flywheel carries some oil & this sprays off inside the engine casing as it rotates. With the sensor removed, some of this oil will spray out of the hole & your engine will run out of oil & could seize, possibly on passage . . .

We completed the journey under sail, but it took us an extra 6 hours to enter Douglas harbour as we couldn't sail against the wind & tide. That was my first engine rebuild, but I never replaced the sensor, I just put the old one back to fill the hole.
 

VicS

Well-known member
Joined
13 Jul 2002
Messages
48,334
Visit site
You can relax about the cost of the sensor, if that is what has failed. It is out of production.

maybe you can find one on a old engine
 
Top