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Volkswagen EuroVan: 1992-2003 (T4) 93 MV Engine Coolant Temperature Sensor


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Last Post: Aug 17, 2012 3:28 PM Last Post By: FKH161
willysburg

Posts: 9
Registered: 08/12/12
93 MV Engine Coolant Temperature Sensor
Posted: Aug 12, 2012 4:02 PM
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I have a 93 Eurovan 5 speed running rich along the lines of a malfunctioning engine coolant temperature sensor. I am an idiot, but fairly handy. I was able to re-solder the relay to make my gauges work again by following the instructions linked to on this forum (Thanks!). And since this part was only $10 online I figured I'd give it a shot replacing it. Does anybody have any tips on the repair, or is it pretty much plug and play? Will engine coolant start streaming out when I remove the old? Is there any special knowledge required?

Thanks for any help.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 12, 2012 5:38 PM   in response to: willysburg in response to: willysburg
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  • Engine cold.
  • Remove & Install coolant expansion cap to bleed off any stored pressure

The blue sensor is on the top of the front flange... leaving the reservoir cap in place helps minimize coolant loss when the sensor is removed (system maintains a vacuum holding coolant).

The o-rings sometimes get stuck, so be sure to fish it out if it does not come out with the sensor.
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 12, 2012 8:35 PM   in response to: FKH161 in response to: FKH161
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Thanks a bunch for the quick reply. I'll give it a go.
swim4au

Posts: 171
Registered: 12/17/04
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 12, 2012 8:43 PM   in response to: willysburg in response to: willysburg
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Ensure you have a new O-ring and retaining clip available. The old clips have a tendency to break.

Bob W
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 12, 2012 8:55 PM   in response to: swim4au in response to: swim4au
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'93 should have the metal clips... which last longer, but yes, new clip couldn't hurt.
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 13, 2012 1:44 PM   in response to: FKH161 in response to: FKH161
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Uh-oh. Couldn't find the engine coolant temperature sensor from the top. I found a thread on another forum about a 2001 saying you get to it from underneath by taking off the cover. Easy enough, except I am a true curbside mechanic, no driveway, no jackstands. Do I assume correctly that this means I am paying my mechanic for this one?
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 13, 2012 2:06 PM   in response to: willysburg in response to: willysburg
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Attachment evtemp.jpg (120.3 KB)
Picture attached... you might want to move the radiator forward to service position for more room, but should be doable without.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 13, 2012 2:51 PM   in response to: FKH161 in response to: FKH161
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The use of a scan tool such as VCDS (with 2x2 adapter) is an investment that will pay for itself quickly by letting you view engine sensor inputs (temp, map, o2 etc).

If she's running rich, also check the vacuum hose to the engine computer map sensor... very common that they break, causing the ECM to over fuel.
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 13, 2012 5:08 PM   in response to: FKH161 in response to: FKH161
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Golly I love the internets. Things are sure easy when you have people drawing you pictures. I got it replaced in less than 15 minutes, didn't have to tilt the radiator. Thanks so much.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 13, 2012 5:38 PM   in response to: willysburg in response to: willysburg
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Pure luck that I had a EV on the hoist...
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 14, 2012 12:56 PM   in response to: FKH161 in response to: FKH161
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Yeah, me again. Do I need to reset the computer somehow? I did the repair with a turned off cold engine, but I am still experiencing stalls along with good cold start/bad warm start, and the gas smell seems to be a little worse. I also recently replaced the idle air control valve if that makes any difference (and duly noted with regards to the scan tester). Thanks again.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 14, 2012 1:02 PM   in response to: willysburg in response to: willysburg
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Should need to reset anything when swapping temp gauge.

Did you check the vacuum hose going to the ECM?

The ECM is to the right of the battery mounted against the inside of the fender.... look for a small diameter vacuum hose and follow it to the intake manifold. If it looks frayed/broken, replace it.

Without scan tool, I'm guessing as much as you are (with regards to what the cause could be).
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 17, 2012 2:35 PM   in response to: FKH161 in response to: FKH161
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So, with vacation nearing I decided to punt. The hose you mentioned was frayed, so I took it to my mechanic, pointed to the hose, and told him the repairs I had done. He checked the hose and the MAP sensor and found them full of gas - apparent culprit the fuel regulator. VW told him to just blow out the MAP sensor and replace the regulator. I picked it up: smooth running and no fumes. Problem is the ice cold AC is now luke warm. I check the fuses and find it's the same one as the engine fan - hey the fan wasn't running when I stopped like always - but the fuse is fine. Back to the shop. With the hood open to check the AC (told him it was Ice Cold two days ago, but whatever) a coolant hose blows cause the engine is so hot. Now they say the AC probably wasn't working because of a over-heating safety shut off (makes sense, but then why didn't the AC work before the temp got high), overheating because the fan didn't switch on, and now they are trying to find out why the fan didn't turn on (thermostat, fan motor...).

I guess my questions are; am I barking up the wrong tree thinking the fan/ac prooblem is electrical because they share a circuit? does the ECT sensor control the fan and could I have screwed it up some way? and is there another common problem I am unaware of that covers my pain?

FKH161 you have been a great help. I hope you can hit this ne ut of the park (no pressure though, did I mention our vacation is riding on this :)
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 17, 2012 3:00 PM   in response to: willysburg in response to: willysburg
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It's been a while since I've seen a broken regulator like that... good that they found that.

Check the fuses for the rad fans... 2 fusible links in front of the battery, mounted against the radiator support.

If those links are OK, remove the harness plug for the rad fan thermo switch (left side of radiator) and bridge 2 pins out of the 3 (the two outer pins should activate high speed, one inner & outer should activate low speed).

If nothing happens, first make sure one of those pins has power... using a test light.

There are 2 resistors that control high & low speed... if those resistors are burnt out (common), then you will not be getting low speed.

I don't deal with ac, so you'll have to let the shop diagnose.

Deal with the rad fan issue first.

Apply power directly to the rad fans individually to make sure that the motors are still ok.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 17, 2012 3:05 PM   in response to: FKH161 in response to: FKH161
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Resistors should be under driver headlight... you'll need to move the radiator forward to service position so that you can remove the metal trim under the headlight.

Resistors look like this:

http://tech.bentleypublishers.com/servlet/JiveServlet/download/48-22933-304696-5089/EVresistors.jpg

Edited by: FKH161 on Aug 17, 2012 3:06 PM
willysburg

Posts: 9
Registered: 08/12/12
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 17, 2012 3:14 PM   in response to: FKH161 in response to: FKH161
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You called it. I just called to tell them where to find 'em, and they said they traced the wire and tracked it themselves. Fusible link. Where are you located FKH161? I owe you at least a six-pack.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: 93 MV Engine Coolant Temperature Sensor
Posted: Aug 17, 2012 3:28 PM   in response to: willysburg in response to: willysburg
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Good stuff... I like easy/simple fixes!

I'm on the west coast of Canada... can't be more specific, not sure who else is reading along! :-)

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