Water temp guage not working

[danfinn]

1994 Monterey with 4.3LX

I could've sworn this was working at the beginning of the season when I bought the boat but lately it hasn't been working.

I tested the gauge by jumping to a ground and it works fine.

I tested the wire coming from the sender by jumping it to the negative terminal on the battery and it made the gauge go full hot so that's working fine.

This past weekend I replaced the sender with a Sierra 18-5897 Temperature Sender purchased here at iboats.

little more info here:
http://forums.iboats.com/showthread.php?t=346747

I'm still getting no reading on my gauge.

 

[sdoomaha]

Re: Water temp guage not working

Have you been running the boat on muffs in the driveway or in a lake? How long have you been running it and how hard? A thermostat stuck open can have the result of your boat never reaching a temp that would register on your guage. Also, if your guage is moving but only slightly....your thermostat could be stuck closed. The guage sending unit is in the thermostat housing, "on the cool side" of the thermostat...it is not in the block or manifold. If the thermo is stuck closed, the heated water circulating your engine never reaches the sending unit, and will not register the temp increase...mine only registered a slight increase from the thermostat housing itself slightly heating up.

I would check your thermostat next....I had the same issue until I changed mine.

Good luck.

 

[danfinn]

Re: Water temp guage not working

Have you been running the boat on muffs in the driveway or in a lake? How long have you been running it and how hard? A thermostat stuck open can have the result of your boat never reaching a temp that would register on your guage. Also, if your guage is moving but only slightly....your thermostat could be stuck closed. The guage sending unit is in the thermostat housing, "on the cool side" of the thermostat...it is not in the block or manifold. If the thermo is stuck closed, the heated water circulating your engine never reaches the sending unit, and will not register the temp increase...mine only registered a slight increase from the thermostat housing itself slightly heating up.

I would check your thermostat next....I had the same issue until I changed mine.

Good luck.

I've been running it in the lake. I let it idle for about 10 minutes and didn't see anything on the gauge. Took it out wakeboarding for about half an hour, still nothing.

If memory serves me correctly, when I did used to get a reading on the gauge it always seemed to read on the cool side, maybe somewhere around 140.

Is there an easy way that I can check to see if the t-stat is functioning correctly. Shouldn't some hoses be hot while others are the temp of the outside water?

 

[totx]

Re: Water temp guage not working

1994 Monterey with 4.3LX

I tested the gauge by jumping to a ground and it works fine.

I tested the wire coming from the sender by jumping it to the negative terminal on the battery and it made the gauge go full hot so that's working fine.

This past weekend I replaced the sender with a Sierra 18-5897 Temperature Sender purchased here at iboats.

little more info here:
http://forums.iboats.com/showthread.php?t=346747

I'm still getting no reading on my gauge.

Your gauge can still be bad!

Check the range of your sender unit in the manual, think it is 240-33 ohm

Get a 100 ohm resistor (approx halve range of sender)
Connect the sender wire to the resistor and other end to engine (ground).
The you should have approx halve scale on gauge.

 

[dodgezilla04]

Re: Water temp guage not working

put the tstat in a pot of water on the stove with a thermometer in the water.... as the water heats up, you'll see the tstat open. check the thermometer......

 

[danfinn]

Re: Water temp guage not working

put the tstat in a pot of water on the stove with a thermometer in the water.... as the water heats up, you'll see the tstat open. check the thermometer......

Where's the t-stat and how do I remove it?

Doing some reading up of old posts on here it sounds like I SHOULD NOT have used teflon tape when I installed the new sender as it needs the contact from the threads for a ground. I only used the teflon tape because I noticed it had been used when installed in the past. I'm going to re-install w/o teflon tape and report back. If that doesn't work I'll be looking at replacing the t-stat so any help with how that is done would be really appreciated.

 

[totx]

Re: Water temp guage not working

Where's the t-stat and how do I remove it?

Doing some reading up of old posts on here it sounds like I SHOULD NOT have used teflon tape when I installed the new sender as it needs the contact from the threads for a ground. I only used the teflon tape because I noticed it had been used when installed in the past. I'm going to re-install w/o teflon tape and report back. If that doesn't work I'll be looking at replacing the t-stat so any help with how that is done would be really appreciated.

Take off the wire on the sender, and touch the wire on the side of the sender.
If this give you full gauge, your grounding is good.

 

[sdoomaha]

Re: Water temp guage not working

Thermostat is easy. The "adults only" section at the top of this forum should have the manual if you want to see it in writing.

Thermostat housing is right at the front center of the engine. Has the 4 hoses running into it, with a flat cover on top of the housing with two bolts holding the cover on. Remove the bolts and the cover and you should be able to see the thermostat. There is a "sleeve" that slides in above the thermostat that holds it in place. Remove the sleeve and the thermostat will come out. Mine sleeve and thermostat was pretty well rusted in, so I just pulled the entire housing (disconnected all of the hoses and unbolted it from the intake) and gained access to the thermostat from below and hammered it and the sleeve out.

New thermostat goes in, sleeve goes in, replace the gasket for the cover and bolt the cover back on.

Good Luck.....hope you get it figure out....

 

[danfinn]

Re: Water temp guage not working

It's so nice when things are easy fixes. It ended up being the teflon tape on the sender. I took it off and I can now watch the temp gauge heat up to 160 and then stay there. I took a look at the t-stat and it looked kind of old and crusty but it seems to still be doing it's job so I'll put off replacing that until next spring.

Does 160 sound about right for where the temp should be?

 

[sdoomaha]

Re: Water temp guage not working

Yup, 160 is where mine sits when running hard.

Glad it was an easy fix...wish mine all were that easy : )

Take care.