Morgan +4 Forum

Greetings...Does anyone have any experience with this device? https://www.spiyda.com/fuel-gauge-wizard-mk3.html It looks like it should cure all the worlds ills.

Tim(D.Y.M.)

Not to worry. You don't have to. You have options.

1. The very top world guru for your instruments is Hedwig Rodyn. He is situate just north of Brussels and owns a company called BelMog. If he chooses to deal with you, he can restore ANY instrument of that era. If he chooses NOT to deal with you, get back to me.

2. The second company would be the ofttimes supplier of instruments to Morgan and the owner of many instruments names and technology, including Smiths. The are in Wales and called Caerbont. https://www.caigauge.com/ They have a division called SpeedyCables the refurbishes, repairs and handles ALL sorts of old instrument problems and conversions. https://speedycables.com/

gmg



Edited 1 time(s). Last edit at 2019-02-10 05:54 PM by GoMoG.

STLMike on the google Morgan forum bought one a couple of years back to try, but I don't know how he made out with it. Will probably work fine knowing the reputation of that small company. Fred

By the way, Dave Dubois who's signal inverter design inspired me to breadboard a universal positive/negative earth version passed way recently. He was a legend in the MG community especially with his improvements to SU fuel pumps. We've lost a really good man there. Fred

Greetings... And then there is this fix supplied by Bob Nogueira and presented on the pages of GOMOG (and I believe Freds Bookl)

http://www.gomog.com/allmorgan30.html#TEMPERATURE

Uses a TR6/GT6 gauge and sender.

Tim(D.Y.M.)

Yes, but that method modifies the gauge with the inherent risk involved. Also, one of the charms of the old gauge is that it reads hot when there is no power to it. A sharp eye will see the difference. Fred

An old thread but my 1960 gauge reads near hot far to early anything I can try to recalibrate?

Good thread. Of course, there is a tendency of different nations to focus only on solutions found in their own country, even
if the car and parts are designed and made elsewhere. Happily, China is resolving this for all of us!! (Bless them).

The most common problem with Morgan instruments until the VDO era is the voltage stabilizer. Can you check that before
anything? Voltage stabilizer reduce voltage to a more reliable specific. I believe hope was that the readings will be more accurate if
the voltage is reduced to a more reliable level, thus eliminating a reliance on a voltage that varies. In driving (for a decade) two almost
identical Morgans, one with Smiths and the other with VDO instruments, I can attest to the greater accuracy of the former and the
value of a voltage regulator.

But what is the effect of the voltage stabilizer partially or fully failing, or its earth/ground being compromised? (They used to screw the
ground wire and other electrics&electronics needing a solid connection. But wherever or how it is screwed, over time the holding screw
loosens and the gauges and even the signals to the later car's computer become very sad for the owner. I have seen post 1990
EFI people look for a cause for their Morgan's misbehavior for years when all that is needed is to tighten the transducer screw!

The sign that people notice with a stabilizer fault is the gauges attach run high, high temperatures, and high fuel levels... So test that first.
http://www.gomog.com/allmorgan/voltagestabilizer.html After that, we can cherry-pick which of the other fine solutions in this thread may
apply if still necessary.

gmg



Edited 3 time(s). Last edit at 2019-04-07 05:01 PM by GoMoG.

There are adjustments that can be made to the gauge. Google that method and something should pop up or maybe a member here has done it. I haven't done it myself so I can't offer any warnings or advice on doing so. I also assume that with the ignition switch OFF, that your gauge pegs to the hot position indicating the early type of electric gauge using the electro-mechanical bimetallic sender? Your old sender ( Smiths bi-metallic type with contacts inside) is likely on its way out as they tend to give hot readings when there is less average current flow.
If you had the type of sender using a thermistor, I would suggest putting a diode (never a resistor) in series with the sender to reduce the voltage ( almost independent of current flow, which is why to never use a resistor for that purpose), but since you most likely have the older style sender, I do not have a solution other than converting your system to use a modern thermistor style sender. Fred.

I doubt a 1960 Morgan has a voltage stabilizer. My 56 doesn't. Everything floats with charging voltage on my car. (Even my 66 Volvo 1800 with Smiths instruments does not have a voltage stabilizer). Good call though, but I don't think it fits this situation especially if the sender is the early type that works backwards to what we are used to on more modern cars. Fred

Lorne and Fred:

I have attached a couple of pictures that might help you out for the Smiths TT1200. This unit was one I just took apart this weekend to repair that came out of a 53 Rolls. Again the repair is not simple and in some cases just not worth it.

In picture "nichrome wire contam" you can see where the nichrome wire insulation is wearing away due to age. The metal arm is actually part of the circuit and this unit had intermittent shorts. As the the arm deflected the wire would short out on the arm

In picture " sender adjustment screw" you will see where oil had gotten into the unit ( Rolls had the sender in the oil flow, not water flow) and there was build up at the contact point of the screw and the arm. This is the adjustment screw to adjust the sender output duty cycle. Very minor adjustments are all it takes.

The problem is to get to the screw you will have to take apart the sender, and this is a real pain in the ass to do and not damage the unit.

Yes you can adjust the gauge but this is not at all straight forward. If you go this route, suggest you send the gauge into a repair shop, however remember if the sender is on its final legs then you will be back adjusting your gauge in no time.


Couple of notes:

This type of sender & gauge combo do not require nor should they have a 10V regulator. It is of no value. If for some reason some one decides to use one ( can't think of why anyone would) please only use a newer semiconductor regulator from Moss or Caerbont. Please so not use the old original bi-metal 10 v regulator.

The original 10V regulator is essentially the same basic concept as the temperature sender. You can actually use some of the parts out of the 10V regulator to repair the infamous Smiths TT1200 or the TT1800 series of senders.

Important to remember, this combo requires a clean ground. Please do not use teflon tape on the sender and make sure the radiator is properly grounded. There is a generation of Smiths sender/gauge combo that was a floating design, but not this design.

Also check for contamination between the union bulb and the sender itself. The design of the TT1200 is actually two parts. Cleaning the sender in CLR (soak it a couple of days) , or even vinegar/water solution and then using a common polish such as Brasso will sometimes put your sender back in working order. Especially if it is just reading high but otherwise seems to work. This design is a PTC format meaning in theory the unit increases in resistance as it gets warmer, whereas newer designs for the most part are NTC. Note please the Smiths temperature unit does not actually change in resistance but rather the duty cycle changes.

Now for the diode. Yes a silicon diode will have a forward drop of 0.6V to 0.9V (dependent on the diode construction, the average rule of thumb is 0.7V for most common diodes, 1N4005, 1N5403, etc). Please also note diodes have a current rating. Dropping the voltage in this design is of no value.

You can use a resistor provided you calculate the wattage you expect to go through the resistor, otherwise it will get very hot and burn up. Most later generation coil driven ignitions used a resistor to drop the voltage when in running mode.

I hope this info helps you guys out a bit. If you need more info contact me directly.

Regards, Larry

Larry, Thank-you very much for that. Your post should go into the achives or whatever this forum has. It's a jewel. I've never seen or worked on the original type of sender. I have experimented with the thermistor type that came later. The reason I do not suggest using a resistor with a thermistor type of sender is that it adds proportionately to the resistance of the thermistor. In doing so, it greatly reduces the span of the gauge such that a large increase in temperature results in a small increase in needle deflection. A diode by comparison reduces the voltage and thus an amount of current irrespective of the thermistor resistance. This allows the span of the gauge to be maximised to an extent almost as great as if there was no diode in the circuit. Lots of folks use a resistor to bring the gauge back into mid scale without realizing that if the engine overheats the gauge will not respond to the fullest extent that it could (IE reduced span) Fred

Picking up on this
My 1960 smiths sensor 9shows H when switched off) quickly reaches hot but engine is 60/70*c.
What should I do?
I guess putting a potentiometer in the line wont work.
The bulb looks to be right but maybe its not.
Thats the solution?
Thanks

I think you are scuppered. The gauge having a heating element for its action and the sender also having a heating element, means that both would respond equally to a reduction in current flow. In theory (from my armchair) the gauge and sender should stay in calibration for all charging system voltages. Reducing the voltage by any means probably won't work. BTW, with a thermistor type sender never use a resistor. You can drop the voltage with a diode successfully with only a minor affect on the gauge's span. Using a resistor reduces the span by an unacceptable amount. With the bi-metallic sender, I do not think that a resistor would affect the span, but there is no point in doing so from what I can see, except perhaps to slow the frequency of the sender which might make the contacts last longer. (also an armchair diagnosis, so take with a grain of salt!) Fred