Mortortest Exhaust Gas Analyzer

[v8s4me]

I've been given an old Mortortest Exhaust Gas Analyzer, model number 9030. It runs off a car battery.

When switched on the needle swings about halfway across the dial. Does anyone know how I can check whether is is working or not. I suspect it is faulty but it would be nice to check. Thanks in advance.

Edited by v8s4me on Saturday 6th February 10:38

[v8s4me]

Thanks for the response.

Mroad said:

...The two plastic pipes attach to the nipples on the respective corresponding clear window below, it looks like these have broken off?..There should be a paper filter element inside somewhere (probably behind the clear window),....

Yes, it looks like they have gone. The paper filters are there and clean though.

Mroad said:

...There is a membrane pump which should pull the gases through the detector, that needs to be checked if it's working (it should make a definite pumping noise when turned on).....

When I switch it on, there is a 'hum' but no pumping/sucking noise.

Mroad said:

...Turn on and zero the scale in clean air (away from exhaust), use the knob on the right of yours to zero CO on the scale.......

When I switch it on, the needle swings to the middle of the gauge, but turning the adjustment knob fully anti-clockwise will not re-set the needle back to zero.

Mroad said:

...Yours has two scales, 0-2% and 0-10%, the scale is use is indicated by the green light, it might be auto scaling or the light might be a push button to switch between scales....

Push-button on this one.

I'll try to ascertain why the pump isn't working, but it looks like this one might be heading for the scrap pile.

Thanks again for your help.

[v8s4me]

The pump works and the two tubes do connect to the front of the filter housings. But the air flow is a bit confusing:-



Exhaust gas flows (red arrow) into a plastic bottle and from there to the front of filter A. From there to a glass bottle (vapor separator?) and then to a T-piece. Fresh air appears to be drawn from inside the casing (green arrow) through filter B and then to the other side of the T-piece. The mixed gas (blue arrow) then goes to "can" 1, then out of "can" 2 and to atmosphere, out of the back of the unit.

Is this correct? Why is the exhaust gas being mixed with fresh air before it goes into the analyser?

[v8s4me]

Mroad said:

.....Does it zero in fresh air? It's possible the small white line on the meter is the zeroing point although it's sitting on 4.5% or 0.9%, neither of which make much sense.

Here is a better picture of the dial.



As you can see, the white line in the middle is actually a '1' on the '0' to '2' scale. This is where the needle sits when the unit is switched on. Turing the zero adjuster anti-clockwise will not make it move back any further.

[v8s4me]

kev b said:

....Mine needs a new sensor and as far as I know they are unavailable, rendering it useless..

How would I know if the sensor on mine is faulty?

Here is a picture of the dial with the unit switched on and "breathing" fresh air.

[v8s4me]

kev b said:

...Mine has a knob on the front to set the display to zero whilst sampling fresh air, when it is no longer possible to achieve zero then it is likely the sensor is u/s.....

Mine does that, so it looks like it is scrap then?

[v8s4me]

Krikkit said:

Some pictures of the sensor circuitry may yield results, worth a go!

Any help?

[v8s4me]

I've tweaked the component (variable resistor?) pointed out here....



... this has zeroed the gauge.



So I suppose the only way to test it is to stick the tube up the exhaust pipe. What sort of reading should I expect from a warmed up Rover V8 (7000 miles on a full rebuild).

[v8s4me]

kev b said:

I would expect a properly tuned Rover V8 on carbs to show around 3% at idle.

Mine is a fuel injected 3.9. What would you expect on that please?

[v8s4me]

StevenB said:

Can you compare it with the last MOT reading ?

Good idea

[v8s4me]

This is the reading on a hot engine at 3000rpm



The reading on the last MOT was 0.66% so that's looking good.I'll check it on some other cars now to see whether this is coincidence.