High temperature alarm

IMO many older boats were built with exhaust sized for lower powered engines than become options later. I see some mighty small exhaust ports in the yard. If those were connected to a turboed engine they may just be too small and indicate the raw water system may be undersized.

I dont think an engine should get too hot at wot regardless of how long it is run. To me that indicates something not right.

SKS said:

I've come to the conclusion that some independence and redundant sources of temperature information plus a bit of work to insure what I have works correctly before making any changes is the most prudent course.
Thanks again!

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I think you have come to the correct conclusion. Also, your alarm should be set to 203 as per Cummins and not 190. As everyone has stated, 190 is not particularly "alarming" as far as temp goes. You just don't want it to go any higher than that.

I have 330Bs in my boat and have had similar issues. I do not know the "flow diagram" of your exhaust system but I would think the first spot your impeller vanes would get hung up is your transmission cooler since you do not have an aftercooler.

As far as Murphy Gauges go...I did purchase one. They are mechanical extremely accurate gauges. I used it as a compliment to make absolutely sure all of my other indications were correct(OEM gauge and IR gun). I screwed it into the port where the temp sender is. And that confirmed to me that my engine was NOT running as hot as indicated.

My issue with IR guns is that you can hit one spot(ie near temp sender) and it show 178. Then move it a millimeter and it shows 243. That is a just an example but you can basically get whatever temp you want out of it based on where you point it. I guess my point here is I do not get a lot of confidence out of the reading of an IR gun. My most consistent temps are on the pipe leading to thermostat and on the expansion tank. I was told to hit the beam at the head just right next to the sender. I cannot get a consistent reading there.

Anyway, a Murphy gauge is cheap and easy to use and will answer a lot of questions for you....mainly is your gauge correct.

I even went so far as getting another heat exchanger(I am not advocating this....only exemplifying how far I was willing to go to get to the bottom of the issue). It is not installed but I was damn curious....$860 curious....and that is not OEM parts. The OEM Cummins part was something like $1800. A Company called Mr. Cool sells them cheaper and they are made by the same people....Sendure and...I forgot the name of the other one. Very excellent customer service people at Mr. Cool.

So Ski and David, I have a question. When I took the sending unit out of the hole and screwed in the Murphy Gauge, was I also disconnecting the alarm??? IOW, is the alarm on the same wiring/circuit as the gauge??? I assumed it was and acted accordingly. ANd I never saw anything over 185.

Bayview, Thanks very interesting point on exhaust sized for lower powered engine.

Baker,
Thank you. Having a very accurate mechanical gauge does seem to be an excellent, inexpensive and simple "add-on".

I do have a question about your Murphy gauge, you said..."I screwed it into the port where the temp sender is. And that confirmed to me that my engine was NOT running as hot as indicated."

Did you relocate the temperature sender so that you still have working temperature gauge(s) on the helm(s)?

Baker- If your alarm system uses the Cummins pcb at the helm and if you removed the electric gauge sender from the engine, yes you have disabled your high temp alarm.

There should be two port on front right of cyl head so you can keep the sender and the murphy gauge at the same time.

SKS said:

Baker,
Thank you. Having a very accurate mechanical gauge does seem to be an excellent, inexpensive and simple "add-on".

I do have a question about your Murphy gauge, you said..."I screwed it into the port where the temp sender is. And that confirmed to me that my engine was NOT running as hot as indicated."

Did you relocate the temperature sender so that you still have working temperature gauge(s) on the helm(s)?

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It was a temporary set up to test indications. Murphy gauges use a "diaphragm" tube with gas in it. The expansion of the gas moves the needle on the gauge. I tell you this because there is a limit to how long that diaphragm tube can be. That limit for a Cummins B engine is 20 feet I believe...since the temp sender port is 1/4 inch...both figures going by memory. So if you want to have a permanent murphy panel, they have to be within 20 feet of the engine...and that tube cannot be bent at a very sharp angle. Once it is kinked, it will not work properly. I have a flybridge helm and not sure 20 feet is enough.

But back to your question, it was temporary and had no helm instruments while this test was in progress.

Ski in NC said:

Baker- If your alarm system uses the Cummins pcb at the helm and if you removed the electric gauge sender from the engine, yes you have disabled your high temp alarm.

There should be two port on front right of cyl head so you can keep the sender and the murphy gauge at the same time.

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Ok thanks. That is what I thought.

Nice.
Thank you Baker and Ski.
I noticed that spare, plugged, port just to the right of the sender next to a bracket (for lifting the engine I guess). It's appears to be almost an inch across.
Two questions come to mind.

1. do you need an adapter to install a Murphy gauge there since the hole is bigger than the sender hole (or at least it seems so to me)?
2. Are there other spare ports, say, to install a switch for a separate alarm?
Triple redundancy, all different.

SKS said:

Nice.


1. do you need an adapter to install a Murphy gauge there since the hole is bigger than the sender hole (or at least it seems so to me)?
2. Are there other spare ports, say, to install a switch for a separate alarm?
Triple redundancy, all different.

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I installed mine where the original sender is. So if it is a different size, you will need a different sized murphy gauge adapter. With that said, the one I have came with a few different adapters....and you likely could find the one you need at a hardware store if it is not supplied by Murphy.

Thanks Baker,
I noticed Seaboard Marine has a VDO 120- 250° sender with a 205° switch.
Maybe by replacing my current sender with this one allows me to keep my helm gauges and maybe even the current 190° over temperature light as an "early warning". Then I disconnect the 190° buzzer feature on the circuit board. Next I wire a new buzzer to the 205° switch on the new sender.
I could install a Murphy mechanical gauge to the extra port.
(BTW: I appreciate the info. on the limitations of the Murphy gauge. I think I might be able to mount it on the flybridge without any kinks in the run.)

See any errors in my thinking? I'm new to this and learning so, please, don't hold back.
Thoughts, input anyone?

Thanks again!