Your Real Estate Professionals In Spain
Audifans.net: Audi Forums

www.audifans.net :: View topic - High temperature gauge reading (car not overheating!)
 
 Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
View next topic
View previous topic
Post new topic   Reply to topic
Author Message
andrewaudi
Camped on the site



Joined: May 01, 2011
Posts: 314

PostPosted: Thu Jul 17, 2014 5:36 pm Reply with quote Back to top

I have recently done a shed load of work to an a 1.8 20v ADR Cabrio that I bought as a non-runner and nursed back to life.

The car has had the following work done:

Head gasket (head skimmed)
Valves re-ground (man that was a pain on a 20v)
New Water Pump
New Belts (including timing)
New Oil Cooler (old one was leaking and likely what killed the head gasket).

So after all that work I am now running the car with no oil getting into the water and no water getting into the oil, the engine is feeling solid and pulls well.

The problem is that the temp gauge reads 115 instead of the expected 90. It jumps around a bit as you would expect these cars to so sometimes a little above and sometimes a little below. I believe that the gauge is wrong. To try and fix this problem I have done the following:

Taken the temp sensor from my 2.0E (known working and exact same part no) and tried that.

Taken the instrument cluster from my other cabrio and tried that.

I know that the temp isn't getting above 90 as I have a laser temp reader and have pulled the sensor and measured there, also measured at various other parts of the head, it never gets above 90 anywhere on the head, so the gauge is showing the wrong reading.

I have also tried soldering the voltage regulator but with no joy.

So I am confident that neither the dash nor the sender are wrong.
I am also confident that the engine is not at that temperature.
Looking to sell the car soon so that kind of reading would put off anyone who knew anything about cars.

So now I'm looking at the wiring between the gauge and the sensor, is there any common place for the wiring to go wrong?
 
View user's profile Send private message
andrewaudi
Camped on the site



Joined: May 01, 2011
Posts: 314

PostPosted: Sun Jul 20, 2014 10:02 pm Reply with quote Back to top

I was driving along today and noticed that the rev counter would bounce up and down a slight amount when holding the car at a good constant speed. That got me thinking.

I also noticed that the temperature gauge would drop slightly with the lights on and dip more when putting the roof up and down.

So it looks like my original method of testing for where the problem was wrong.

I tried another instrument cluster but I didn't actually drive anywhere first time round. So I did this time and the gauge was working perfectly. So I swapped over the voltage regulator to the original cluster and would you believe it, it works fine now.

It makes sense when you think it through logically. The regulator is there to iron out he ups and downs of an unpredictable power supply. If you or only testing it with the ignition on but no engine running well of course it will have nothing to regulate and a broken one will give the same instrument readings as a good one.

My biggest problem now, how do I get hold of one for the car I poached the good one from! Smile

The part was ITT TCA700Y, google only revealed that it's the same part they use on Holdens!
 
View user's profile Send private message
andrewaudi
Camped on the site



Joined: May 01, 2011
Posts: 314

PostPosted: Mon Jul 21, 2014 9:32 pm Reply with quote Back to top

I read on another forum (a T4 van forum!) about that part number and the £1.05 replacement component you can get from Maplin!

So I went and bought it.

Part:
TS7810CZ 1A Positive Fixed Voltage Regulator TO220 Case

The only problem with this part is that the 3 pins are reversed.

I didn't want the heatsink pointing away from the other metal that's there to extend the heatsink because these things probably run quite hot... So I put it on the wrong way round, soldered the middle pin in place and pulled the 2 outside legs away from the board, I then ran some cable so that the pins were connected opposite ways around and soldered them in place.

Happy days, it works a treat. Ebay are trying to sell the voltage regulator for £30!
 
View user's profile Send private message
v6-fubar
Audi Nut



Joined: Aug 10, 2012
Posts: 87
Location: Garelochhead

PostPosted: Thu Jul 24, 2014 3:07 pm Reply with quote Back to top

Good work on the voltage regulator mate..shame, I got rid of one on fleabay not long ago, only took a tenner for it. You could've had it for sfa. I take it when you mean they were reversed, it was just the outside pins that needed switching? A mini PC component heatshield could have also been fitted to the opposite side to save any soldering but that would mean splashing out another 2 quid or so - us scots aint up for that by nature! lol
 
View user's profile Send private message Send e-mail
andrewaudi
Camped on the site



Joined: May 01, 2011
Posts: 314

PostPosted: Thu Jul 24, 2014 5:44 pm Reply with quote Back to top

Exactly right, the two outside pins and no, I wouldn't be splashing out more! Just fixing the car up to sell to be honest, the wires are fine Smile
 
View user's profile Send private message
v6-fubar
Audi Nut



Joined: Aug 10, 2012
Posts: 87
Location: Garelochhead

PostPosted: Thu Jul 24, 2014 5:54 pm Reply with quote Back to top

If you need any other parts for your project gimme a shout, got a v6 coupe sitting in my old lockup thats being stripped for parts to sell on. Naturally it would be mates rates or freebies for people from here! Very Happy

_________________
1996 V6 Cabrio - Pearl Metallic White (Vinyl Wrap).
New burgandy mohair roof.
17 inch Dezent RE wheels, 205/40/17 Michelin Pilot Sport 3s.
BRC LPG conversion - half price fuel Wink
Twin exit custom exhaust fitted by the guys at glasgow C+C Exhausts. 
View user's profile Send private message Send e-mail
Display posts from previous:       
Post new topic   Reply to topic

View next topic
View previous topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum


Forums ©