Lehman 120 Temp Indicator Issue

[kurt.reynolds]

So, took out my 42 GB MY today for a post winter sea trials. Over the winter I replaced the raw water heat exchanger and was excited to see temperatures. I have a single lehman 120.

As soon as I left the dock the flying bridge temp gauge starting rising rapidly. I was kind of freaked out as it hit 220. turned around and docked the boat. Turns out the lower helm was reading just fine. Did an infrared on engine and confirmed Flying bridge was in error and about 40-50 degrees high. So I went back out and ran it hard for about an hour and no temperature issues.

I did quite a bit of work in the ER this winter with replacing batteries, heat exchangers, changing oil, etc. I am guessing maybe I damaged a wire or something. I have never had issues with the Flying Bridge Temperature gauge.

Can some identify in the picture below which ones are temp sensors? And what are my options? I guess I can redo the terminal ends as a start. Are there any plug and play wireless temperature devices I could use? I have no idea how I would re-run the wire up to the Flying Bridge.

I plan on a two day trip later in the week and would really like to get it fixed.

 

[cdsailor]

I’m intrigued by what appears to be a remote-sensor location on your engine. Rather than having the sensors hanging off the block, it appears you have a single oil line to a hard-mounted block that each of the sensors taps into. Something to consider on our Lehmans. Good luck getting it sorted.

 

[kchace]

So, took out my 42 GB MY today for a post winter sea trials. Over the winter I replaced the raw water heat exchanger and was excited to see temperatures. I have a single lehman 120.

As soon as I left the dock the flying bridge temp gauge starting rising rapidly. I was kind of freaked out as it hit 220. turned around and docked the boat. Turns out the lower helm was reading just fine. Did an infrared on engine and confirmed Flying bridge was in error and about 40-50 degrees high. So I went back out and ran it hard for about an hour and no temperature issues.

I did quite a bit of work in the ER this winter with replacing batteries, heat exchangers, changing oil, etc. I am guessing maybe I damaged a wire or something. I have never had issues with the Flying Bridge Temperature gauge.

Can some identify in the picture below which ones are temp sensors? And what are my options? I guess I can redo the terminal ends as a start. Are there any plug and play wireless temperature devices I could use? I have no idea how I would re-run the wire up to the Flying Bridge.

I plan on a two day trip later in the week and would really like to get it fixed.

I believe those 3 sensors are tapped into the oil pressure and so have nothing to do with coolant temps. The small one is a switch for low oil pressure to the warning light. One each of the other 2 are for a gauge and to control power to the alternator field. A coolant temp sensor will be attached in the vicinity of the coolant expansion tank.

Ken

 

[Cigatoo]

If it were me.......Before I touched anything that is connected and in its proper place I would look for something that I damaged while working on the boat over the winter. Retrace you’re steps.

 

[Pete Meisinger]

Your picture does not show either of the temp sending units. They are located on top of the engine in front. There are two of them. The one on the port side is the temp alarm, the one on the starboard side is for the gauges. Now I could be backwards on the senders. To test just ground one of the wires out to the block, the temp gauges should "peg".

If you didn't change and gauges or sending units look for something you accidentally loosened or disturbed.

pete

 

[kurt.reynolds]

Your picture does not show either of the temp sending units. .....pete

Thanks Pete, I will get down on the boat this afternoon and hunt down these sensors. I did change out the thermostat, so I had the expansion tank and outlet hose off, probably over there somewhere I disturbed the wire.

-kurt

 

[catalinajack]

The temp sender on a Lehman 120 is screwed into the head close to the expansion tank. You may have neglected to ensure that the sender wire is attached securely.

Thanks Pete, I will get down on the boat this afternoon and hunt down these sensors. I did change out the thermostat, so I had the expansion tank and outlet hose off, probably over there somewhere I disturbed the wire.

-kurt

 

[SteveK]

Is there two senders? He said lower helm gauge reads correct, upper not. I thought both gauges were fed by one sensor

 

[jleonard]

Is there two senders? He said lower helm gauge reads correct, upper not. I thought both gauges were fed by one sensor

Mine has only one sender for a gauge. I would check the ground on the upper gage as a first step, then look for corrosion on the terminals.

 

[kurt.reynolds]

Mine has only one sender for a gauge. I would check the ground on the upper gage as a first step, then look for corrosion on the terminals.

When you say terminals, is there a terminal block "under" the Flying Bridge. Excuse my ignorance, but I thought the wire ran all the way up. Shows how much I know....

 

[jleonard]

When you say terminals, is there a terminal block "under" the Flying Bridge. Excuse my ignorance, but I thought the wire ran all the way up. Shows how much I know....

Any place that a connector is crimped to a wire should be checked and replaced if severely corroded. Either at the crimp or at the attachment screw.

 

[catalinajack]

Any place that a connector is crimped to a wire should be checked and replaced if severely corroded. Either at the crimp or at the attachment screw.

Many, if not all, of my bonding connectors are severely corroded. The crimp-on ring terminals are open at their ends plus the wires are untinned. I just purchased 50 feet (not enough) of Ancor 6-gauge tinned wire and will today begin replacing all of the bonding wire on the boat. Big project but, hey, nothing but time on my hands. Wife happy cuz I am not annoying her with unsolicited attention and endless ranting about the COVID-19 non-response.