Re-calibrating engine gauges (after removing upper helm gauges)?

Hi all,
We've recently deleted our flybridge which meant removing an entire set of gauges from the upper helm. I've noticed that the oil pressure gauges both read at about 50% of previous pressure (in both engines) and the temps reads higher than before. This is certainly related to the removal as same behavior would occur when I still had the upper help and forgot to turn the ignition keys up there to "on" energizing the upper gauges.

I assume this is related to the change in resistance since I'm going from two to one gauge per engine but would love advice on how best to rectify the issue.

Do I need to change the gauges, or the senders, both, add a resistor, etc? Original Motorola oil pressure gauges as far as I can tell aftermarket temp gauges.

Twin Ford Lehman 120's if that matters.

EDIT - I should add that the helm gauges were wired in parallel and the engine alarms (relays and buzzers) were wired to the upper helm. The alarms appear to be a simple ground circuit relay wired to "dummy senders" on the engines. I'll be relocating those to the lower helm.

Greetings,
Mr. A. AFAIK, you are correct in your assumption that this is related to resistance. Again, from what I know, senders are specific to one or two gauge use. As to whether or not addition of a resistor of correct "ohmage" will bring your lower gauges into proper range, I have no idea. Better minds than mine most probably know.


I have tried to obtain replacement Motorola gauges for our boat but neither the gauges or sending units are available. One must replace all components of a particular circuit (sender and gauge(s)). I would be very interested in your removed gauges unless you wish to save them as spares. We have a couple of upper helm Motorola gauges that have ceased functioning. Thanks.

RT Firefly said:

Greetings,
Mr. A. AFAIK, you are correct in your assumption that this is related to resistance. Again, from what I know, senders are specific to one or two gauge use. As to whether or not addition of a resistor of correct "ohmage" will bring your lower gauges into proper range, I have no idea. Better minds than mine most probably know.


I have tried to obtain replacement Motorola gauges for our boat but neither the gauges or sending units are available. One must replace all components of a particular circuit (sender and gauge(s)). I would be very interested in your removed gauges unless you wish to save them as spares. We have a couple of upper helm gauges that have ceased functioning. Thanks.

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Winner!

Steven, the senders are calibrated fo 2 station use- so you'd have to replace the sender (as perhaps the gauges (as Mr. RT correctly surmised).

This is why I went with the Chetco setup- I was able to use the existing senders and program the Chetco unit to pout the correct reading.

As others have stated the senders were specific to dual stations, and must be replaced. There are only a couple of standard calibrations for senders, generally referred to as Euro and American standards. There are also various threaded connections to choose from. The dual station senders have half the resistance throughput their range, so I don't think a fixed resistor will work.

No personal experience with them , but I have read many favorable reports on Lauderdale Speedometer Lspeedo.com

They can probably come up with the proper senders for you.

I'm in the process of digitizing my gauges as Pau Hana has done , so that is the big $ option.

Good luck,
Brett

Greetings,
Mr. T. Lauderdale Speedometer are GREAT people to deal with and those folks are the ones that informed me of the dearth/lack of Motorola parts. Might be worth a try though.

You could hook up the old gauges and stash them under the helm. Or hook them up in the ER to see real-time when you are there

Lauderdale speedometer will also "calibrate" your compass too and leave you a correction card too.

In my opinion, I suggest getting new senders and new gages. That way you can select the gages that have the correct numbers on them.
For example, I want a 180 mark on my temperature gage. Not that easy to find, but I did. egauges.com had what I wanted.
And yes I am going downriver according to my bottle caps and the gps.

I replaced some gauges on my upper helm and was asked by my marine wholesaler whether I had dual gauges or singles. Apparently for some brands of gauges, even they need to be dual station

jleonard said:

And yes I am going downriver according to my bottle caps and the gps.

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Is there a better set up other than bottle caps? For one thing, they are difficult to see in the dark.

I don’t think you’ll be running the rivers at night

meridian said:

I don’t think you’ll be running the rivers at night

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Want some fun? Run the ICW at night from Haulover cut (FL) up to my slip area....(4 bridges) Because of the popularity fo the area, there is A LOT of light bleeding from the shore sides. Then add in the non-lighted navigational aids and our failing eyesight, boaters who do not pay attention, all adds up to an exciting experience. Makes one wish for a loud, deep sounding horn. Make them think you are a cruise liner. LOL
Yea, I am a wicked, wicked person.

meridian said:

I don’t think you’ll be running the rivers at night

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Definitely NOT.