Temperature Alarm Switch

[PSR]

I have a Universal 5411 diesel in great shape on board my Catalina 27. The switch for cooling system temperature alarm seems to have malfunctioned (goes off when engine temp is in the normal operating range or cooler). Anyone know exactly which temperature switch is the right one for my engine?
Thanks!

[Snore]

First welcome aboard!

Second google is your friend. There are several universal dealers with extensive on line inventories and even parts manuals. They can get you the newest relevant part number.

[GordMay]

Greetings and welcome aboard the CF, PSR.

SEE
http://www.cruisersforum.com/forums/...sting-645.html

[dohenyboy]

these gauges are based on resistance (ohms).if the threads are gunked up or someone used teflon tape it will be off just as you describe. cheap fix possible. take it off, clean it good and reinstall.

[Marqus]

Originally Posted by GordMay

Greetings and welcome aboard the CF, PSR.

SEE
http://www.cruisersforum.com/forums/...sting-645.html

Gord

Reading your beautifully summarized thread about temperature and oil pressure sender testing and the resistance values, I have a question regarding impact of voltage level.

If we take an engine Temperature gauge, its momentary resistance value (and thus current flow) will determine the gauge reading.
Let's assume a temperature sender's resistance is 20ohm (and no other ohmic losses).

If I run engine with alternator off (voltage 12.6v), the current through the meter would be 630mA.
If I run engine with alternator on (voltage 14.4v), the current through the meter would be 720mA.

Does the 15% difference in current mean my gauge displays a 15% different temperature value depending on the voltage feeding the sender?

Or do VDO instruments (and equivalents) have a built-in voltage regulator/compensation to avoid this variance?

[PSR]

Sorry I did not introduce myself before posting something else, and thanks for the welcomes! I am 69 & was a faculty member at UC Davis for 35 years before retiring to build acoustic guitars 8 years ago. My 50th guitar is in progress.

A Catalina 27 ("Surprise" berthed at Glen Cove Marina, Vallejo, CA) is my first cruising boat, though I've sailed small boats and other people's big & bigger boats since my first memory (looking down the centerboard box of an old Cape Cod knockabout at that mysterious blue deep). So far, Surprise and I mostly go out alone, and we haven't cruised anywhere for an overnight. People tell me there are lots of places to cruise to around SF Bay, so eventually I'll get out. I hope to do at least one blue water cruise to the south while I'm still fit and when Surprise has proven herself strong enough to do that. She's 33 yrs old....

Thanks for your notes! I will check the sensor to see if the mechanic used teflon tape. Otherwise it is a new piece, so probably not gunked up. Gord-Thanks for the link to your gauge testing post.
PSR

[dohenyboy]

are you sure engine is not getting too hot? I use a laser gun to check the temperature at the thermostat case.
the sender is not expensive, and easy to change. so switch it out and see.

[sanibel sailor]

Originally Posted by dohenyboy

these gauges are based on resistance (ohms).if the threads are gunked up or someone used teflon tape it will be off just as you describe. cheap fix possible. take it off, clean it good and reinstall.

There is a difference between a gauge SENDER (variable resistance) and an alarm SWITCH (open/close at defined temp). You have a switch for an alarm. If you have a sender, that might explain the problem. Cleaning may help if it is a single wire N/O switch and cannot ground.

Knowing your thread size (typically pipe thread), number of wires and what you want the alarm setting, you can pick one out from here:

eCatalog

and go to the auto parts store for it.

[PSR]

DohenyB & SS-
Thanks for the thoughts. I know the engine is not overheating and that it is a temperature switch that is the problem. There is no P/N for a warning switch in the Universal 5411 parts list, so I thought someone else might have found one that is correct and could give me a reference to that part. The alarm would be useful since the gauges are not at a convenient place to monitor easily (they are low in the cockpit), so I would like to have the thing work. What's more, my lovely new engine instrument panel has the idiot light and alarm for the temp switch, and I just like things that are there to work. Catalina Direct sells the panels supposedly for my motor, but they do not have info on the alarm switch for the motor.
Thanks again--always nice to have folks look and respond!
PSR

[sanibel sailor]

Originally Posted by PSR

DohenyB & SS-
Thanks for the thoughts. I know the engine is not overheating and that it is a temperature switch that is the problem. There is no P/N for a warning switch in the Universal 5411 parts list, so I thought someone else might have found one that is correct and could give me a reference to that part. The alarm would be useful since the gauges are not at a convenient place to monitor easily (they are low in the cockpit), so I would like to have the thing work. What's more, my lovely new engine instrument panel has the idiot light and alarm for the temp switch, and I just like things that are there to work. Catalina Direct sells the panels supposedly for my motor, but they do not have info on the alarm switch for the motor.
Thanks again--always nice to have folks look and respond!
PSR

Do you know what size thread it takes? One wire or two? Spade or ring connector? What temp does your engine typically run before you get concerned?

[dohenyboy]

TOAD Marine Supply.

water temperature sender is part no. 35109. or 299066.probably the first is correct. temperature switch is 30125.

carpindu is a seller on ebay of this item. send it a photo of yours and it probably will get out to you asap

or discountmarinesource.com
look under westerbeke
http://discountmarinesource.com/p-23...25-030125.aspx