[Snoopinrob]

Hello everyone,

I have a 1996 Shabah Z200 5.7L Alpha 1 with just over 100 hours and can't get my water temperature gauge to read right. I've replaced the impellar and of course serviced it while it was apart and replaced the thermostat as well. With an IR temp gun it's reading about 160-165 at the thermostat housing and I've checking the overheat alarm so I know it's not running hot. But, the gauge likes to hang around 200-225 and every once in a while it'll move back towards the 175 mark where it should be then right back up. Also, when you turn on the Nav/Dash Lights the temp gauge pegs and it's the only gauge that won't light up and I checked the bulb and it was fine and even tried another one just to be sure but no change. I've been up under the dash and behind the dash through the headrest and don't see anything unusual to me but it's hard to see/trace everything in there as well. I don't know if I have a faulty gauge or a wiring/grounding problem but if anyone has any ideas that could help me or a diagram for the gauges I sure would appreciate it because this is driving me nuts! I've been trying to fix it since I got the boat a little over a month ago, other than that I LOVE the boat! Also, I am new to this site and haven't gotten much feedback on this problem so please let me know if I'm posting in the wrong place. Thanks for any help everyone!

[mosky]

Although i've never had a problem with my gauges or had to troubleshoot them i'll throw out that i suspect that your problem would be most likely associated with a bad ground connection. I believe that the gauges are simply reading the voltage coming back from the sending unit and thus a faulty ground or any additional resistance in the ciruit will result in inaccurate readings. The fact that the gauge pegs when the lights are turned on is the biggest clue in that the 12V from the lighting circuit is now also trying to 'share' this ground and the resulting increase in resistance on the bad ground will make the guage 'peg'. Like i said i've never actually had to troubleshoot my gauges but i've given it my best guess.
The good news is that Faria gauges are guaranteed for life and if it is in fact the gauge you can alsways get it replaced but i would suggest that you try the easiest troubleshooting methods first. try to hook a ground wire up directly from the ground connection on the gauge directly to a known good ground and see what happens.
Here's a link to the Faria website's troubleshooting guide for their resistance type gauges:

http://faria-instruments.com/site_ma...MiscGauges.pdf

Hope this helps.

[Snoopinrob]

Thank you so much for your input and the link mosky! I hate electrical type problems and I'm not always the best in the world at tracking them down, especially when there's a small space to work in and a ton of wires to sort out! Your advise and thoughts on it made a lot of sense and I will definitely try grounding that gauge to a for sure good ground and see if there's any change! Why I haven't thought to try that yet is beyond me but as soon as I can get my boat back to my house I will give it a try! Unfortunately it may be the first of the week. Thanks again!

[Duke]

Originally Posted by Snoopinrob

Thank you so much for your input and the link mosky! I hate electrical type problems and I'm not always the best in the world at tracking them down, especially when there's a small space to work in and a ton of wires to sort out! Your advise and thoughts on it made a lot of sense and I will definitely try grounding that gauge to a for sure good ground and see if there's any change! Why I haven't thought to try that yet is beyond me but as soon as I can get my boat back to my house I will give it a try! Unfortunately it may be the first of the week. Thanks again!

I have nearly the exact same problem...let me know what you come up with. I purchased a new Temp Sending unit as I noticed the Temp Sending unit installed on my motor has pipe dope on the screw teeth and I have read that can inhibit the readings. Mine will typically read 175 after it has warmed up then at some point spike out to 220-230 and stay there. Laser shows 146 on the therm and alarm test works and does not indicate overheating. Very annoying problem.

[Snoopinrob]

I'm with you Duke, very annoying! Especially on your temp gauge, that one's kinda important! When you say "pipe dope" are you speaking of teflon tape or something like that on the threads? If so, I've recently heard somebody say it's ok to have some on there as long as you leave enough off to where the threads can ground to the housing. I've thought of replacing mine too but I've only got a little over 100 hours on my boat and I wouldn't think it would be bad. Even if it was it wouldn't explain the pegging with the Nav lights on and the gauge light not working. Frustrating! Good luck with yours and I'll post any progress with mine!

[darkcalling]

Would have to agree with Mosk the light switching pegging the guage sounds off the ground alarm big time.

[Duke]

You're right on with the Pipe Dope. I had initially heard same as you, but then heard that any dope on the threads can interfere and the dope is unnecessary for this application. My boat has about 360 hours so it may be time to replace, just a knuckle busting operation given the placement on my 98 merc 4.3.

[Snoopinrob]

Well, throw on some gloves to protect your knuckles, I always seem to forget and let me know how it turns out! I'd be interested to know if that fixes your problem because if my ground situation solves the lighting/pegging situation but not the temp reading I'll be heading in that direction next! Hopefully that's all it is if everything else is acting normal!

[Snoopinrob]

Problem solved!!! It was a bad ground as Mosky originally said, I appreciate that advise and everyone else's very much! This problem has been driving me nuts for almost 2 months now! I just took a piece of black wire and jumped off the defrost ground and grounded it to the back of the temp gauge and bingo! The temp gauge is accurate, the light works and no pegging when turning on the Nav/Dash Lights. I just need to go back in now and secure all the connections like they're supposed to be. Thanks again everyone!!!