Temp Sender Unit

[clynn]

I have a question about temp senders. I have twin 3208 cats and dual helms. My issue is with the port engine gauges. The lower helm temp gauge reads nothing and the flybridge gauge reads too hot.

These are the original VDO gauges and, I assime, original sender. The sender has two wires off of two two terminals. If I switch the two wires, I see no change in how the gauges behave.

Could the fault be in the lower gauge, which would then cause the upper gauge to show too hot? I guess it could be the sender, but appears to be sending some reading. Thanks for any help.

 

[clynn]

Here is a pic...

Apparently I can't post a pic with an iPhone...

 

[kapnd]

The first thing to check is the ground, then clean and grease all the connections.
Disconnect the upper panel until you get a true reading on the lower one.

 

[clynn]

I pulled the lower gauge and it had a dark semi circle on the side. I'm guessing that it's fried. Trying again to post a picture.

 

[Forkliftt]

Clynn,
Probably need to load one of the two available apps. I had the same problem. But look at me now .


1983 Present 42 Sundeck
Twin Lehman 135's

 

[clynn]

Got the app...let's see if this picture shows up now...

 

[Forkliftt]

Yessir- we got a great picture! The plastic housing has definitely seen more heat than it should have.


1983 Present 42 Sundeck
Twin Lehman 135's

 

[chiropaul]

Clynn,
The following is the procedure for testing VDO gauges and sending units. Just used this info to isolate problem to the sending unit on my 440 chryslers.

VDO GAUGE AND SENDER TESTING

VDO GAUGE TESTING: If a gauge is suspected to be faulty, the following tests can be performed on the VDO gauge and sender:

1) Turn the key on:
Pressure Gauge - pointer to .0.
Fuel Gauge - pointer to amount of fuel in tank
Temperature Gauge - pointer to temperature of engine water
2) With the key on, pull sender wire off the sender:
Fuel & Pressure Gauge - pointer will go to maximum right hand position
Temperature Gauge - pointer will go to maximum left hand position

3) With the key on, ground the sender wire to the engine chassis:
Fuel & Pressure Gauge - pointer will go to maximum left hand position
Temperature Gauge - pointer will go to maximum right hand position

SENDER TESTING:
Senders can be tested with an ohm meter that measures from 10 to 2,000 ohms.
Connect the positive lead from the tester to the sender terminal and the negative lead to a good ground. The following readings will occur if the sender is operating properly:

Temperature Sender: Cold - 700 ohms
Hot (250 degrees) - 22 ohms

Pressure Sender: Engine off - 10 ohms
Engine running 40 psi = 105 ohms; 60 psi = 152 ohms.
Fuel Sender*: Tank empty - 10 ohms; full - 180 ohms
*If the fuel gauge reads backwards, but accurate, the float arm has been installed from left to right into the pivot. Reinstall from right to left. Using a VDO 10-180 ohm gauge with a 240-33 ohm sender will also give a backward reading.

Fuel Sender Testing:
As explained before, there are many different ohm ranges in sending units. Therefore, with an ohm meter you can check to ascertain if unit is working properly.
VDO No. 226 001: E = 10 ohms; F = 180 ohms
An empty tank will read 10 ohms. As you add gas, the ohm reading will go up until tank is full and reads 180 ohms.

G.M.: Both 0.30 and 0.90. Empty tank will read .0. ohms. As you fill tank, reading will go up.
Stewart Warner & Ford: Empty tank will read high ohm range (S.W.-240; Ford- 73) and go DOWN as you fill the tank.
*All VDO electric gauge pointers peg full left hand position with the power off.
​

 

[psneeld]

The ohms for testing listed above may or may not help depending on your sender.


VDO told me their new line of instruments have completely different senders than the older senders say from more than 15 years ago.


Check your good sender on the other engine to verify if you cant on the internet.

 

[Ski in NC]

Most vdo temp sensors have only one connection. Temp sensor usually on front of timing gear case leftish side under HX. The stuff on the heads is oil pressure sensors.

Usually if one gauge works its a bad connection or bad gauge. If one does not work, other one will read off. Try swapping gauges.

 

[clynn]

chiropaul - Thank you, that is great info.

Ski in NC - I'm fairly confident that is the sending unit. I pulled the wires and the working gauge died. Once reconnected either way, the functional gauge still worked, which tells me the sender unit is sending something.

The plan is to call VDO and discuss what available gauge would be compatible and replace. I'll update once that has been done.

 

[SailorBruce]

Some time has passed....any chance you can update with the result?

Seems I’m about to go down the same path....

 

[C lectric]

Send him an email through the site.
Click on his avatar name and a drop down box will show. You can wait for him to reply through the site or include your email address.
Just post the result in this thread so others know/learn.