F26 Gauge Replacement Summary

[The Dog House]

Over the last year I have been working on replacing the gauges on my 1971 F26. When I purchased the boat only three of the seven gauges were working (see list below).

Tachometer - working
Port Fuel Gauge - not working
Oil Pressure Gauge - working
Temperature Gauge - not working
Ammeter - working
Starboard Fuel Gauge - not working
Hourmeter - not working

The gauges were mixed and looked like this.



I replaced the gauges with Faria Chesapeake White SS gauges (American Standard).



After replacing the gauges the status was this.

Tachometer - working
Port Fuel Gauge - working backwards
Oil Pressure Gauge - working backwards
Temperature Gauge - not working
Ammeter - working
Starboard Fuel Gauge - working backwards
Hourmeter - working

I'll detail each gauge and how I fixed it separately.

[The Dog House]

The oil pressure gauge was the easiest to fix. The oil pressure sensor was replaced with a Faria oil pressure sensor matched to the gauge. The old sensor was blue, was located between the distributor and the coil, and had a 1/8 NPT fitting.



The new sensor was purchased with a 1/8 NPT fitting. I simply removed the wires from the old sensor, unscrewed the old sensor, screwed in the new sensor, and then connected the signal wire. The old sensor had a floating ground so it had a wire going from the sensor to the engine block. Since the new sensor ground was through the threads there was no need for this wire and I only connected the sensor wire. The new sensor is brass colored.



After replacing the sensor with a matching sensor the oil pressure gauge worked fine.

[The Dog House]

The new temperature gauge was still not working which led me to believe that the sensor was bad. I grounded the sensor wire to the engine block and the temperature gauge went full scale confirming that the wire was good and the sensor was bad. The sensor in the intake manifold/thermostat housing was 1/4 NPT and only had 1/8 inch from the tip of the sensor to the start of the threads. The shortest American Standard temperature sensor I could find was from Sierra (part no. TS26611) which was 3/8 inch from the tip of the sensor to the start of the threads. This was still too long. The threads could not grab the housing.

The engine hose from the engine to the thermostat housing was already split and connected with a 1 1/8 inch copper pipe (see below).



I found a company that would make hose connections that include sensor fittings (Jaguars That Run, http://www.jagsthatrun.com) and they manufactured a 1 1/8 inch hose connection which included a 1/4 NPT fitting and ground fitting. It was easy to take out the copper pipe and replace with the Jags That Run connection (see below).



After replacing the hose connection and installing the Sierra sensor I had a leak at the sensor. Since the ground was through the threads I had to be careful with how I sealed it. I first tried teflon tape leaving the first half of the threads bare. This slowed the leak but it still leaked. I then removed the teflon tape and carefully applied pipe dope to the sensor leaving the first half of the threads bare. This stopped the leak and the temperature gauge still worked.

My boat is raw water cooled and has a 140 degree thermostat. So far the running temperature is slightly above 100 degrees. The water is still cold and the sensor does not have the thermal mass of the manifold to heat it, so I'm not concerned. I do know if the temperature ever gets to 175 degrees I have a problem, so the gauge and sensor are getting the job done that I need them to do.

[The Dog House]

The only thing left was the fuel guages. With the American Standard gauges, 1/4 F was full and F was 8 gallons remaining (they worked backwards). Replacing the fuel tank senders would be much more difficult than replacing the oil pressure and temperature senders. The American Standard resistance values for fuel gauges are E = 240 ohms and F = 33.5 ohms. The European Standard resistance values for fuel gauges are E = 10 ohms and F = 180 ohms. Assuming a linear relationship I calculated that 1/4 F on the American Standard gauge was equal to 178 ohms. This led me to believe that the European gauges would work for my application. I installed two European Standard gauges to replace the American Standard gauges.



The only difference is instead of an E and a F they have an empty circle and a full circle. I guess this is because of all of the different languages that are spoken in Europe.

The gauges are no longer working backwards. They go the correct direction. 3/4 F is full so they don't work perfectly. 1/4 F is 10 gallons remaining, so I believe that each 1/4 is equal to 10 gallons but I don't have that much experience yet to be sure (I have 30 gallon tanks). I believe E will equal empty but I probably will never test it to be sure. While not working perfectly, the gauges are working close enough for me to be happy with the outcome. It was much easier replacing the gauges than replacing the fuel tank senders.

That's the summary of my gauge replacement adventure. My boat now has functioning gauges that allow me to feel comfortable when I'm on the water. If anyone has any questions feel free to PM me. I learned a lot from this project and I'd be happy to share any wisdom I gathered.

[yorklyn]

Great post! Great troubleshooting to get them working! They look nice, good job!

[gordd]

Looks great The Dog House .. I will be doing similar soon . Half don't work , other half not reading right so time

[The Dog House]

Great post! Great troubleshooting to get them working! They look nice, good job!

Thanks. It took a lot of time figuring out what size the sensors were, what size the engine hose was, finding Jags That Run, etc. I figured I could save others a lot of time by posting what I did.

[mikeandanne]

Great post-- thanks--- it seems many people are having the same gauge issues---- I had the same problem with temp sender on small block mopar and ended up drilling and tapping a new larger hole to accommodate the only senders you can get now---- my stuff is the same ,some work and most I don't trust--the PO changed the gauges on the bridge and they still are suspect----- Mike

[32pacemaker]

Looks great, I love your US made choices

[The Dog House]

Looks great, I love your US made choices

Great minds think alike.