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Is my temp sender faulty...dead?


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Got the car back together after a cambelt change. 

Refilled with coolant.

Never had a problem doing this before as in trapped wind  air in the system.

Got no movement on the temp needle.

Checked the earth on the ally pipe and seems ok. If I touch the wire onto the terminal of the sender the gauge springs into life. So am guessing the gauge is ok and the wiring too?

 

As a side note I have a low battery warning light on. Ive been trickle charging but doesnt go out? The car sat for a while so could be a flatish battery but was wondering if it could be Ive know an earth somewhere?

 

buddsy

 

"Belief is the enemy of knowing" - Crrow777

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I know when I fist got my car back on the road I was listening to everything kept and eye on the engine bay...and almost rear ended someone. Being an engineer isnt always a good thing. I had to m

Wahoo fans back working. A bit too much corrosion on the terminals.  That al larn me not to drive her round for a few months. Thanks for your help Fabian saved me a lot of agro!  Next i

Good stuff, nearly fixed. Luckily I am a fan expert now as well as electrics after 6.5 years of issues!  Assuming the fan control is the two wires at the front on the stat in the curved bit of pipe.

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Can’t help with your problem Buddsy, but I can recommend the use of one of these battery isolators instead of trickle charging the battery. I’ve killed more batteries over the years trying to condition them than I’ve ever done since getting one of these. Simple screw it down when you use the car and unscrew to disconnect when not using the car. I can leave mine for months and go back to it and it’s starts first time every time.

https://www.electricalcarservices.com/battery-isolator-switch-the-original-richbrook-rb100003-/p-3016?gclid=EAIaIQobChMIkbbj8_Dt6wIVh6ztCh0yyAKKEAQYAiABEgKXH_D_BwE

Standard Batteries prefer this instead of constant trickling it seems. Lithium batteries are different which is what I have in the Exige but the isolator is a great solution for an old-school standard battery. If you have an alarm on your Esprit that you want to keep functioning, then you may want to ignore the above - if not, get one bought😉

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Hi Stephen.

 

I always disconnect the battery from the terminal and its always been ok.

Battery is fine to start the car but just when I connect it up I have a red battery warning light come on?

Thats why I wondered if ive knocked an earth off when clambering in the bay?

 

buddsy

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"Belief is the enemy of knowing" - Crrow777

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Do you mean a red battery symbol on the dashboard? That's not a low battery warning, but a charge warning light. It should go out when you start the engine and the alternator starts working. It could be a wiring problem, best check voltage on the battery with engine running or even better current from alternator to battery.

As for the temp sender, a bad or broken connection will mean the gauge stays at zero. Do I understand correctly the the gauge works if you wiggle the wire? Than it's obviously a bad connection, probably caused by unplugging it to do the cambelt. You can use pliers to squeeze the connector a bit so it's a tighter fit.

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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4 hours ago, Escape said:

Do you mean a red battery symbol on the dashboard? That's not a low battery warning, but a charge warning light. 

Yes thats the one it comes on when i connect the battery and stays on until i put the key in and turn the ignition on

 

4 hours ago, Escape said:

 Do I understand correctly the the gauge works if you wiggle the wire?

No. I was checking the earth connection so removed it from the coolant pipe and touched it on the body of the temp sensor.

 

buddsy

 

"Belief is the enemy of knowing" - Crrow777

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Has the lead come off the alternator? Think its brown and yellow, If so it won’t charge? I have knocked this off before whilst working on other parts. Temperature sender must be the connection. Check the alternator and temp sender leads have been connected correctly. Then see if there is coolant in the temp sender pipe, by unscrewing the sender. Might be an air bubble. Problem getting air out is the thermostat (three way one) needs replacing. It may not be opening at the correct temperature. You can easily check the sender and temp gauge. Put the sender in a beaker of boiled water with a lab thermometer. Note the temperature and compare it with the gauge. This is really easy to do. Hardly any coolant leaks outbwhen the sender is removed.

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Cheers Fabian.

 

I have checked the leads but will check again. I think the lead you are talking about, the small one to the alternator I seem to remember I crimped on a new terminal as the old one was loose.

 

Thanks for the tips on the sender I will give those a go too.

 

buddsy :thumbup:

 

"Belief is the enemy of knowing" - Crrow777

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Hi Buddsy,

Yep the small one to the alternator. I am pretty certain you will find its not making contact. It controls the charging and I think the battery light stays on because the battery will not charge if its disconnected.  

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Well it looks like a mistake I made about 5 years ago.

Fabian your talk of the small wire stirred a memory. It was this wire which the connector had fallen off so I crimped a new connector back on.

From my picture I took this morning it all looks ok but then ~I remembered the wire doesnt connect to the terminal as would seem obvious but to some where else!

119672463_329030701876499_4438370781163723277_n.jpg

I found this old pic and yes I now remember it goes to a bolt post!

IMG_6063.JPG

 

I will change the fitting tonight and connect to where it used to be and see how that goes!

 

Cheers for the help.

 

 

52 minutes ago, Lotusfab said:

How did you tension the belt?

What on the Alternator? Im guessing thats what you are talking about as its not easy to get it tight. I had a piece of wood like a 1 1/2" X 1 1/2" about 20" long that I could get between the alternator and lever it to tension.

 

buddsy

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"Belief is the enemy of knowing" - Crrow777

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That alternator is different to mine. Normally the brown yellow wire goes to the spade inside the black bit. This controls the battery light and charging. 
 

No I meant the cam belt. Did you use a clavis gauge or Burroughs?

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For the blue cam belt I noticed it was tighter than the standard belt with the tensioner set as light as it would go. I tightened a bit until I could twist the long run just a bit.

That felt about right. I then tested with the frequency phone app.

I think 120 was deemed to be correct. Mine was consistently reading as 117. As that felt right slightly tighter than the standard Ive left it at that.

 

buddsy

 

"Belief is the enemy of knowing" - Crrow777

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I use a similar gauge on my belts without issue but will try the frequency check to confirm accuracy.  
Hope you get the temperature issue sorted Scott but sounds like you have the issue sorted now. 👍🏻
Dave :) 

Do or do not, there is no try! 

 

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I used a Burroughs gauge. I found this and will download an app and see what frequency my belts are, as a double check. Trouble is the apps I have found need belt info input and I am not sure of some of the parameters.9C7F85DA-0FCC-4B41-A29E-46DE8FFDC9F1.thumb.png.e57a35f8f683de9e8e68b787f1492c06.png

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The burrough and other gauges work fine for the normal belts.

Personally I wouldnt bother double checking with the frequency on those.

The blue belts are just harder and I dont think gauges work hence the frequency test.

 

buddsy

 

"Belief is the enemy of knowing" - Crrow777

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Good stuff, nearly fixed. Luckily I am a fan expert now as well as electrics after 6.5 years of issues! 
Assuming the fan control is the two wires at the front on the stat in the curved bit of pipe. 
1. pull wires off, short them and check fans come on. If they do go to 2.

2. Put multi meter across stat and check resistance goes to zero when engine is at temp. If it doesn’t there are two possible problems. The stat is broke(very unlikely) or there is no coolant in the pipe due an air bubble. This is much more likely. Air bubbles or coolant boiling out that can’t be easily bled out from the rad bleed in my opinion are all cause by a faulty thermostat. They don’t open at the correct temp (after forty years they have reached end if life) and the coolant boils before it reaches the full circuit. I posted a new stat on my blog that works perfectly and costs about £70.

One of the simplest tests that I overlooked was the temp gauge. My car was working perfectly but my gauge was reading 110c. The temp was really 90c.! The gauge calibration was wrong. The test is simplicity. 
 

Buy a school lab thermometer thats about a foot long. Stick it in a beaker with the stat in(hardly any coolant comes out when you unscrew it) then pour boiling water from a kettle in it. Record the thermometer temp against the gauge all the way across the scale. If its off recalibrate the temp gauge by making a small gauge tool(Really easy with a file and some studding). 
You should get it accurate to within 5 degrees across the range. Job done.

You don’t want to know how much effort the above took to figure out.

Oh, by the way its most likely the oil stat is also not working properly if its original. Mocal make a new one thats quite cheap. See my blog.

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Well I shorted out accross the 2 wires on the stat at the front and my fans came on.

Was a bit of a job getting them going due to corrosion on the terminals.

Im going to clean up and make sure I get a good contact and try again.

 

buddsy

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