Temp gauge

[Ryanshepherd1]

So I just had an engine rebuilt on my 1989 21 foot Bayliner. It has a 351 Windsor 5.8 L motor. When I go to start the engine the temperature gauge flickers a little but never seems to move. How can I test the gauge to see if it is bad ? Or any other suggestions?

 

[alldodge]

First check for 12V on the gauge with key ON, and clean ground connections.

Next with ignition to ON, find the sender wire on the gauge terminal and jump that terminal to ground. Grounding the gauge terminal should make the gauge peg HOT full scale. If it doesn't peg, you have a bad gauge.

If it does peg, reconnect the sender wire and find the sender on the motor. Remove the wire from the sender and ground it, gauge should peg HOT. If gauge does not peg then the wire is the issue, if it does peg then need to test the sender

 

[kenny nunez]

Take a test light and probe the sender where the wire is attached, the light should come on dim and the needle in the gauge should move over to the high side. If it does not move then go behind the instrument panel and probe the "S" side of the gauge, if the needle moves and the light comes on dim the gauge is good and the wire is broken somewhere. If the light does not come on also check the + side of the gauge to make sure that there is current coming to it. If the gauge and the wire check out good then either the sender is bad or the thermostat is broken or not there.

 

[Ryanshepherd1]

So I went to work on the temperature gauge today and when the ignition is in the ACC position with the gauge lights on, the needle is all the way to the hot side. With it off the needle is all the way to the left. Does this mean that there is a short? I cannot find the temperature sender on the engine. It is a 5.8 L OMC cobra 351 Windsor. Any help is really appreciated

 

[alldodge]

Does this mean that there is a short?

Either the gauge is bad or something is grounding the sender wire (the wire it self or the sender).

The sender is on the thermostat housing and will have one wire going to it. Suggest starting at the gauge. Get access to the back of the gauge and remove the sender wire. The gauge should have an "S" on the back of it. With the wire removed you should be able to turn key to Acc and the gauge will stay cold

 

[Ryanshepherd1]

No Title

Does the temp sender go where I have the red arrow? I thought it was weird there is just a random Screw hole. does the temp sender actually touch moving water in the engine? no water comes out when driving

 

[alldodge]

No, that is the fuel pump leak hose. If the fuel pump leaks the hose will fill with gas and move it to the carb

The temp sender should be in the thermostat area by the blue arrow

 

[Ryanshepherd1]

Oh I was talking about the screw hole right behind that hose but now that I know where to look, I appreciate your help. You are awesome

 

[Ryanshepherd1]

OK so I finally found it and I was missing it because it has a plastic cap on it that makes it look like a spark plug. I put power to the gauge and it does not spike so the gauge appears to be good. With the wire disconnected from the temperature sender it also stayed spiked so it has to be in the wiring..... so now I'm worried because the wiring is all together and goes through a wiring harness, how do I find the "ground" can I just bypass everything all together and run 1 wire from the sender to the gauge?

 

[bruceb58]

Remove the wire at the gauge before guessing its in the wiring.

 

[Ryanshepherd1]

I did just put power to the gauge and it stayed to the left. The only combination I guess I didn't try was power and ground with no temperature sender wire

 

[bruceb58]

I did just put power to the gauge and it stayed to the left. The only combination I guess I didn't try was power and ground with no temperature sender wire

That's what you need to do.

 

[Ryanshepherd1]

Ya that figures.... I don't have the boat near me. So can I just ask if I do determine it is the wiring, can I just bypass the harness and go 1 wire from the sender to the gauge? I just want to go prepared if I can

 

[bruceb58]

Ya that figures.... I don't have the boat near me. So can I just ask if I do determine it is the wiring, can I just bypass the harness and go 1 wire from the sender to the gauge? I just want to go prepared if I can

Absolutely but my bet it is not the wire in the harness.

 

[Ryanshepherd1]

I just wanted to give an update. I ran a new wire directly from the temperature sender to the temperature gauge and fixed my issue completely . Thanks everyone for your help

 

[bruceb58]

I just wanted to give an update. I ran a new wire directly from the temperature sender to the temperature gauge and fixed my issue completely . Thanks everyone for your help

That's surprising but glad it worked out.

Could have possibly been the engine connector had corrosion in it to for that signal as well. Wish I had though about that earlier to you and mentioned it.