Lehman temp sensors

[Marco Flamingo]

There appear to be two heat sensors on the Lehman underneath the coolant tank, one on each side of the thermostat (removed in the picture). The one one the right goes to the gauges and measures temp. I assume that the one on the left is a high temp warning? The multimeter didn't show any voltage from the lead with the ignition on and grounding the wire did nothing. Is my high temp warning out? (That explains why I have my engine torn apart.) I don't have a coolant temp warning light, so it would be a buzzer only (if still attached). I'm assuming that I'm looking for a buzzer like the low oil pressure buzzer.

 

[RT Firefly]

Greetings,
Mr. MF. Brian @ American diesel.

 

[SoWhat]

It's a normally open switch that closes at 205F. On my boat the buzzers are located behind the flybridge steering. Hard to hear when I'm at the helm below. Someday I will change it over to a relay and a piezo alarm and probably add an exhaust gas temp sender. I shredded a fan belt once and didn't notice it until I glanced at the temp gauge pegged at 250F.

Check the continuity of the wire and then test functionality of buzzers. It could be the same one used by the low oil pressure sender.

 

[Nick F]

I agree exactly with SoWhat

 

[Chuck34]

Greetings,
Mr. MF. Brian @ American diesel.

Yep, any questions/issues you have with a Lehman, that’s the go to guy. Get to know him and buy your Lehman parts from him.

 

[mike66]

Didn't know there is a 4 cyl Lehman. One question, are those injector pump outlets covered to keep dirt out?

 

[hytedin]

I changed mine to a 200 degree switch. And, I added a bigger alarm. In doing so I am able to get an earlier warning. American Diesel carries both 205 and 200, or at least did a year ago.

 

[bgillroy]

The 'buzzer' are at helm station not near engine.

 

[socalrider]

The stock wiring for the FL's is to run the oil pressure and temp alarm in series to a buzzer at the helm & another at the flybridge. Neither of my buzzers worked when I bought the boat, so I re-wired new loud BlueSeas piezo alarms at the helm and flybridge. With these there will be no doubt about missing an alarm. Way more important than the temp/pres gauges in my opinion as you're unlikely to be looking at the gauges at the exact moment something goes wrong.

I have a hand drawn diagram I got from somewhere on the internet but I can't find it at the moment.

 

[Choices]

I just wrote this up on my blog, grandbankschoices.

On my 135, the GB alarm panel was wired wrong from the factory and never worked.

Without going into detail both panels were wired the same.

There should be a buzzer at each helm. Check wires, someone may have pulled one to silence it.

The buzzer works on high coolant temp, high tranny temp, and low oil prs.

The GB wiring schematic was wrong. Way wrong.

It is easy to trouble shoot, just short out sender terminals with wire or a screw driver. Make sure all bulbs work first with a meter. If LED read my blog! They also use a blocking diode to keep them from back feeding each other. All mine were bad but one.

I also added an exhaust temp alarm. It's in the blog also. Had it made for genset and main engine.

Any questions PM me your number and I will call you to answer questions.