FL-120, Water Temp when off > 170 degrees F

Lehman 120's. Port gauge (upper and lower helm) reads 150, STB reads 170. The engines have been off for almost a week. This is a new to me boat and this anomaly was written up in the survey during the sea trial when the gauges were reading, Port = 180, STB = 195 while running at 1600 rpm. I am assuming this is the coolant temp. I have purchased a temp gun and, after checking its accuracy against known sources, shot the block at the temp sensor. The Port side is 69 and the STB is 71 (a light source had been shining on it for a while). The question is, could this be a new problem that is just now showing up and what would cause it? If the problem is old it could indicate a mismatch between the sensor and the gauge that the PO just ignored and made a mental compensation for. Tomorrow I'm going to be cruising for about 3 hours with a training captain and will shoot the temps again when they reach op temp. I expect the gauges will be close to the temps seen during the sea trial. If so, and the temps found with the gun are, as I expect, about 180, and within 5 degrees or so of each other, what would I need to do to correct the gauge readouts?

There are basically 3 things in the gauge system, the sender, the wiring and the gauge itself. Since you have a bridge and lower helm the senders should be for 2 gauges. That can cause a misreading if the sender is for 1 gauge, but probably not the problem here. A loose connection or dirty connections can cause a problem. Or the gauges themselves could be the problem. An easy thing to do is verify with the non contact temp gun which gauge is correct and then swap the sender wires between the engines and see if the problem follows the gauge or the engine. That can tell you if the problem is the sender or the gauge and the wiring. You can swap the wires at the gauge if the problem follows the gauge to see if it is the wiring or the gauge. If you need support the guru is Brian at American Diesel 804-435-3107. He is wonderful and very willing to help.

Is your hot water heater connected to coolant flow or it it strictly electric?
That would account for a difference. Make sure all your connections are bright and shiny. A worn water pump, old impeller, or simply gauge accuracy could all contribute to difference. Temp gauges are not adjustable.

Another question is does your high temp alarm go off at correct set point.
One engine was pegged at 250 and I missed it. Eventually buzzer sound broke through the background noise and I shut down. No harm done but red warning lights and shrieking alarms (with mute) will be added this winter.

Check the above items first. If the problem isn't found, you could also check your thermostats. They are usually stamped as to what temp they open. They may be mismatched. If not, put one in a pan of water on the stove and use your IR heat gun to see when it opens. Same with the second. They could open at 15 degrees difference.

Obviously more work than just switching the sender wires, checking your impellers, etc., so this would be well down on the diagnosis list.

The gauges read 150/170 with cold engines - off for two weeks. They are clearly a big part of the problem, notwithstanding to good advice above.

Greetings,
Some gauges will remain at the last reading (150/170) when the ignition is turned off and will reset to ambient when the ignition is re-energized.

Good point. Have you turned the keys of energized the ignition circuit in the last two weeks?

rgano said:

Good point. Have you turned the keys of energized the ignition circuit in the last two weeks?

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RTF and you have nailed that mystery. All the temps are now reading a little under 130. And, yes, the hot water tank is heated by both electricity and engine coolant. The cruise tomorrow should show discrepancies, if any, when the engines are at normal speed of 1600 rpm.

The engine that heats the water heater tank should not warm up as quickly but eventually it should come up to the correct temperature. It will just take a bit of time to heat the water.

Relying on gauges of unknown accuracy as an indicator of a problem is a venture in flying blindly. The starting point is using an infrared temp gun pointed at the thermostat housing. If the gauges read differently then, and only then, should one begin troubleshooting the gauges.

As Commodore said, the water heater cannot be the cause of a disparity. But, one of my engines always runs 5 degrees warmer than the other because one has a hydraulic pump for the stabilizers bolted to the front of the engine. My gauges read accurately (upper and lower VDOs with dual station senders) according to an IR temp gun.

catalinajack said:

But, one of my engines always runs 5 degrees warmer than the other because one has a hydraulic pump for the stabilizers bolted to the front of the engine. My gauges read accurately (upper and lower VDOs with dual station senders) according to an IR temp gun.

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While I do not have a lot of experience with these bolted-on hydraulic pumps, the last boat I ran with one had an electric clutch for the pump which relieved the engine of the added load when the fins and/or windlass were not required. Dose yours have such a clutch, and when the fins are not running, do you see a closer agreement in temps between the engines? Enquiring mind....

5 degrees difference isn’t unusual, mine are always off probably due to the lack of gauge accuracy.

Also in reality no two engines are exactly the same. Even two that came off the line one after the other. They have and develop differences as do the guages due to their own construction and also age.

If the differences keep developing then there may be cause for concern.
With the low cost of these IR temp guns it is easy to check. Just be sure to read and understand their own limitations and pick one or two spots on each engine for comparisons. Do not just blindly shoot all over the place. The best place initially is literally right at the thermostat base and or the existing temp. sensor mounting.

As a few people have commented before expecting two engines to be exactly the same is the curse of two engines.

Become familiar with the engines, keep track of them and then when something changes pay attention.

Nope. No clutch. The interface is a rubber thingy with teeth. The pump is always running unless I manually pin the fins in the centered position and turn the system off which I never do.

rgano said:

While I do not have a lot of experience with these bolted-on hydraulic pumps, the last boat I ran with one had an electric clutch for the pump which relieved the engine of the added load when the fins and/or windlass were not required. Dose yours have such a clutch, and when the fins are not running, do you see a closer agreement in temps between the engines? Enquiring mind....

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catalinajack said:

Relying on gauges of unknown accuracy as an indicator of a problem is a venture in flying blindly. The starting point is using an infrared temp gun pointed at the thermostat housing. If the gauges read differently then, and only then, should one begin troubleshooting the gauges.

As Commodore said, the water heater cannot be the cause of a disparity. But, one of my engines always runs 5 degrees warmer than the other because one has a hydraulic pump for the stabilizers bolted to the front of the engine. My gauges read accurately (upper and lower VDOs with dual station senders) according to an IR temp gun.

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Actually, I was not relying on the gauges for anything. I mentioned buying the gun to use after insuring its accuracy. I am gathering information in order to troubleshoot the cause of the discrepancy. Also, I mentioned using the gun to confirm the discrepancy. I suppose your pedantic tone is meant to be helpful but it feels condescending. Weather precluded taking the boat out to run up the engines. I'll post again when I have found and corrected the problem.

As you will come to know, very few people here are trying to be condescending but rather helpful. Maybe you are reading something into it but I doubt it was meant to be there.

Comodave was quite correct. I certainly did not intend to be condescending. With respect, sir, if you felt my remarks had a pedantic tone, if you intend to continue to seek advice on this forum, prepare yourself for more. You see, folks here are always trying to be helpful but sometimes overlooked nuances of a particular problem, however small and pendantic as they sometimes might be perceived, turn out to be not so small especially to new boaters or to someone not particularly versed in a singular issue. For example, why is a failed heat exchanger not nearly as potentially catastrophic as a failed oil cooler?

Try as we might, and I always do, the written word sometimes fails to convey true intent.

jbloyd said:

Actually, I was not relying on the gauges for anything. I mentioned buying the gun to use after insuring its accuracy. I am gathering information in order to troubleshoot the cause of the discrepancy. Also, I mentioned using the gun to confirm the discrepancy. I suppose your pedantic tone is meant to be helpful but it feels condescending. Weather precluded taking the boat out to run up the engines. I'll post again when I have found and corrected the problem.

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catalinajack said:

Comodave was quite correct. I certainly did not intend to be condescending. With respect, sir, if you felt my remarks had a pedantic tone, if you intend to continue to seek advice on this forum, prepare yourself for more. You see, folks here are always trying to be helpful but sometimes overlooked nuances of a particular problem, however small and pendantic as they sometimes might be perceived, turn out to be not so small especially to new boaters or to someone not particularly versed in a singular issue. For example, why is a failed heat exchanger not nearly as potentially catastrophic as a failed oil cooler?

Try as we might, and I always do, the written word sometimes fails to convey true intent.

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I'll take the blame here. I apologize. I'm very grateful for all of you who are trying to help and appreciate that you are basically flying blind when trying to interpret the questions and concerns when I, and others, don't fully articulate the circumstances that are causing our angst. I've had our Defever 44 for about 3 weeks now and it seems every time I "solve" a problem it uncovers a new one. The survey missed a lot. That observation should bring a chuckle from you experienced hands. Most of you seem to really enjoy your boating experiences so, I'm going to assume I'll eventually glimpse a light at the end of this tunnel. Hopefully, it's not the headlight of an on-coming train.

James, thank you for recognizing that, to the extent we can, we do try to help, that our intentions are good. Ironically, our boat is a DeFever 44 also. We have lived aboard full time for nearly five years. I will send a private message as to our DeFevers so as to not get this thread going off on a tangent.

jbloyd said:

I'll take the blame here. I apologize. I'm very grateful for all of you who are trying to help and appreciate that you are basically flying blind when trying to interpret the questions and concerns when I, and others, don't fully articulate the circumstances that are causing our angst. I've had our Defever 44 for about 3 weeks now and it seems every time I "solve" a problem it uncovers a new one. The survey missed a lot. That observation should bring a chuckle from you experienced hands. Most of you seem to really enjoy your boating experiences so, I'm going to assume I'll eventually glimpse a light at the end of this tunnel. Hopefully, it's not the headlight of an on-coming train.

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Yes, most surveys miss quite a bit. Boats are there to keep you busy. Keep asking and we all will keep trying to help.

Greetings,
Mr. jb. "...seems every time I "solve" a problem it uncovers a new one." I call that project creep. Welcome to the world of boating! Yup. Clean up that teak on the bulkhead and it makes the bracket look messy. Clean up the bracket and now the upholstery is the wrong colour. Re-do the upholstery and the curtains don't match. Replace the curtains and "Dag-nabbit! should have put in Venetian blinds..." There are no problems, only solutions. It will take time and patience to get to know your new mistress. Be patient.



"That observation should bring a chuckle..." I, for one, am NOT chuckling at all. I feel your pain and frustration. Boat maintenance seems like a never ending series of "Oh no. What now's" BUT, it does get better. Trust me on this one.


Take this bit of advice from a not so experienced hand. Everything will get done. Pretty well everything takes time and money. Not everything has to be done right away and when it comes right down to it, this is about the most fun you can have with your pants on.

"pedantic" I learned a new word today. I never heard or read that one before.

One thing I am a little anal about is knowing engine coolant temperature.
Always verified with a temp gun right at the sender. When it starts to be inaccurate I change sender and gauges.
Last time I made the change on my Lehman, I searched and found a gage that had a mark at 180 F because I don't like to interpolate.
But that's me. YMMV

In a new to you boat suggest a removal, pressure check and clean out of both transmission and engine heat exchangers. Also, replace both raw water impellers and check pump innards. Any clues as to age of engine coolant? If unsure or older than three years change coolant out too.

Then you can be be reasonably sure that trouble shooting the temperature discrepancy is chasing areas of lesser concern than a potential over heat situation.

sunchaser said:

In a new to you boat suggest a removal, pressure check and clean out of both transmission and engine heat exchangers. Also, replace both raw water impellers and check pump innards. Any clues as to age of engine coolant? If unsure or older than three years change coolant out too.

Then you can be be reasonably sure that trouble shooting the temperature discrepancy is chasing areas of lesser concern than a potential over heat situation.

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Thanks for the suggestions. The heat exchangers (all six) were replaced with new late last year. Hoses are new (and zincs). RW impellers have about 15 hours on them. Coolant was changed out when the HE's were done. Before I bought the gun I (under a captain/instructor's guidance) drove the boat off the lot and proceeded on a 5 hour run to the permanent slip. Concerned about the reading on the gauges, I went down in the engine room and put my hands on the hoses with no discomfort. Also, the valve covers were quite warm but not enough to create the urge snatch my hand away. Now that I have the gun, I need some good weather and willing captain to get me out of my slip to do some of the other testing suggested.

jbloyd said:

Now that I have the gun, I need some good weather and willing captain to get me out of my slip to do some of the other testing suggested.

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Dang, and here I sit with 29 years of Ford Lehman experience wanting to go to Oz, and the pandemic strikes blocking your ability to send me a ticket. Sounds like you are getting there...

Water Temp When Off

My gauges never go down to 0. But read properly while running. Best place to check actual temp is where hot water enters heat exchanger.

Ford Lehman engine

Anyone who posts here about a FL engine I ALWAYS tell them to contact Brian at American Diesel (https://americandieselcorp.com/) in VA.

I've seen people speak with great authority about parts on a FL that aren't there.

Save yourself time and aggravation.

They would also have any parts you might need.

Good luck.

Brian is a great resource. Take the time to really listen to him. Ask questions. We have twin FL125"s in our 37 Uniflite. One engine was always running warmer by 20 degrees. At a recnt haulout, Iwas cleaning out the intakes, and found a flap of sealer that had been extruded when they were installed. I removed it through the grille with a pick, and they now run within 5 Deg. of each other. It is always a learning experience.

You'll probably find out more by swapping the two thermostats.
Or just replacing the low reading thermostat.

Hi JB, Like others here - when screwing around with boats - my experience - there is always something!!


If it's electrical or electronics - it's most likely corrosion or loose connections. Water, vibration and electricity don't play nicely together!


So as not to appear "pedantic" or condescending I'm gonna give you my best quess as to the problem in short form. There are technical ways to prove it but that would take a lot of typing.


To wit: There is corrosion in the temp sensor mounting hole. Remove, clean, grease, check resistance of sensor (300 to 800 ohms), reinstall(no teflon or other sealing tape)