Anyway to calibrate a VDO water temp gauge?

[Evans Ward]

I suspect my VDO water temp gauge is not calibrated correctly as it shows 25 degrees higher temps then my SM 2.1 does across the range. I'm trusting the shown temps on the Scanmaster. It's about a year old and has always been this way. Anyway possible to take it out and calibrate (move needle counter clockwise)? Or would it be better just to purchase another since they aren't that expensive? Anybody tried this or have any words or wisdom here?

 

[NASSTY]

Me Too...

I got a VDO water temp gauge that is off by 15* from my scanmaster readings.I tried a different sending unit,it didn't help.I hope there is a solution besides buying a new one.

 

[T-top87GN]

You know mine has always done this also. Only thing I can figure is the fact that the ECM and the gauge are both correct. Remember, they are not using the same sending unit. They are in different places.

I've always thought, but never tried, that maybe soldering a resistor inline with the feed wire would maybe make the gauge read what the ECM sees. Never tried, just a thought. hehe I just always subtract 15 from whatever the gauge says. Figured that was easier than messing with resistors.

 

[SuperSix]

I'm REALLY starting to dislike my VDO guages. Oil pressure guage is very erratic, water temp is 20degrees too high (According to TLink), and last night I notcide the temp gauge does up 10 degrees when I turn on either the parking lights or headlights! WTF??

Hate to do it, ($cost$) but I think there's Autometer units in my future.

 

[Evans Ward]

I suupose my question now is: does anyone have a VDO water temp gauge that reads close to (within 5-10 degrees) OR the same as reading through the ECM via SM, TL, etc??

 

[Hognose]

I got a used VDO Oil Pressure and Water Temp gauges and installed them a couple of weeks ago. They both work pretty well. My Water Temp gauges is only a couple degrees off from what my Scanmaster reads.

Needless to say I am happy with the results. My biggest complaint is finding the correct light bulb for those gauges.

 

[mark b]

They have been historically noted for being high, usually 10 degrees is the most cited figure.

Ron's Custom Auto used to sell a pipe kit that extended the area where the sensor mounts and provided accurate readings.

I'm not sure if it's actually the guages or the location of the sensor that causes the problem. I never bothered to test the guage independently of the car.

 

[gnnovas]

My VDO gauge read 20-30 deg's high when I had a ground problem. Called a placed that worked on them and they suggested to solder all connections and run a ground from the gauge directly to the engine block. I fixed my ground problem and solder all conections and now it reads 10 deg's high. Have not run a line directly to the block yet. The sending units on my car are both in the front of the intake in the same pasage on oppisite sides of the thermostat. Its hard to believe that there would be that much difference in tep's

Ken
87 GN

 

[mark b]

> The sending units on my car are both in the front of the intake in the same pasage on oppisite sides of the thermostat. Its hard to believe that there would be that much difference in temp's


Supposedly that is one the issues, since water flow from car to car can be different. Kinda like the technical aspects of using a surficant to reduce air bubbles in small passages like the heads that can reduce overall cooling.

Personally, I'm not sure if I believe it. But effectively that's what Ron's kit did. It move the reading spot to a more "stable" point for lack of a technical term.

FWIW, I bought it but never installed it. I lived with the 10 degree diff.

 

[NASSTY]

Originally posted by Evans Ward
I suupose my question now is: does anyone have a VDO water temp gauge that reads close to (within 5-10 degrees) OR the same as reading through the ECM via SM, TL, etc??

Yes I have one of those too.In my GNX clone I have VDO gauges in a GNX dash and the temp reads 162*-164*when the weather isn't extremely hot and humid .The funky temp gauge is in my 86GN which usually reads 180*.I've also tried a couple different 160* thermostats to verify I had a good one.The problem is I would have to take my GNX dash apart to test the other temp gauge in my 86 .I think I'll just buy another temp gauge if moving the ground to another location doesn't help.

 

[MSDGN]

I have VDO Temp guages in both cars...according to Tlink one is right on...other is 5 degrees off...can't remember if it's off high or low...I have the sending units screwed into the drivers side of the block in place of the brass plug...

 

[turbofrank]

VDO temp gauge always read 10 deg coolr than turbolnk and needle moves whenever i hit the brakes.

 

[T-top87GN]

Originally posted by turbofrank
VDO temp gauge always read 10 deg coolr than turbolnk and needle moves whenever i hit the brakes.

If any of you guys are getting needle movement when you use a part of the electrical system then you need a better ground for your gauge. Period.

 

[Weazel]

Whew, I'm not the only one. Mine's routinely 25°-30° high. I was ready to rip out the TStat before I got DirectScan, which I trust more than a $35 gauge I wired myself. I'll go with AutoMeter from now on I think, even though my VDO Oil gauge seems right on.

 

[TurboDave]

Originally posted by Evans Ward
I suspect my VDO water temp gauge is not calibrated correctly as it shows 25 degrees higher temps then my SM 2.1 does across the range. I'm trusting the shown temps on the Scanmaster. It's about a year old and has always been this way. Anyway possible to take it out and calibrate (move needle counter clockwise)? Or would it be better just to purchase another since they aren't that expensive? Anybody tried this or have any words or wisdom here?

Problem with the VDO gauges (and the reason I hate mine so much) is that they are incredibly cheap (internally). They have no voltage compensation what-so-ever, and the slightest fluctuation in the voltage that they reference and the reading will vary considerably. Just a volt or so, and your temp reading will likely change more than 20º.