TheSamba.com :: View topic - Just bought my first Vanagon...temp sensor?

Sun Apr 08, 2007 11:01 am

My dash temp sensor barely makes it 1/4 up the scale...also, engine runs great but at startup it wants to stall until its warmed up. Could these be related?

Sun Apr 08, 2007 12:56 pm

It would be a big help if we knew the year of your van. There is some difference in the advice that could be given.

Sun Apr 08, 2007 1:15 pm

sorry, it's an 87 GL Wolfburg

Sun Apr 08, 2007 3:00 pm

There are a couple of issues that can cause bad warm up. The first and easiest is the Temp II sensor. It is cheap and easy to replace. If the problems persist, then you have to go a bit deeper. You need to see if your Throttle Switch is adjusted correctly (which allows the Idle computer to do its job). Then you need to set your idle properly.

The Temp II sensor is located on the tower that houses your thermostat. All the online vendors carry them, but try to stick with a Boch unit.
Read through this to see how to adjust your idle and Throttle switch:
http://www.loam.org/vw/Vanagon/VanagonProTraining/DigiFant/

http://www.van-cafe.com/vanagon_parts.jsp?pa=p&p=1258418664&pct=343148836&ct=212141836

The temp indicator is not a precision instrument, it is just a relitive indication of what is happening.
Read this:
http://www.gowesty.com/library_article.php?id=52

http://www.gowesty.com/library_article.php?id=114
Have fun!

Sun Apr 08, 2007 3:26 pm

sounds good. many thanks

Sun Apr 08, 2007 8:01 pm

The gauge error could be due to a bad sender (it's located in the thermostat housing. The gauge sender is the one facing forward; the Temp 2 sensor is the one facing left), faulty ground connection from the sender connector (the brown wire grounds the sender, since it sits in a plastic housing), or a faulty voltage stabiliser. If it is the stabiliser, your fuel gauge would read low as well. The fact that the needle responds at all suggests that the gauge itself is OK, as they rarely fail.

Once you make sure the Temp2 sensor is OK, and the Throttle Body Switch is closed at idle, then you would want to diagnose the Idle Speed Control system. It won't work at all unless the TB switch is closed at idle, and those fall out of adjustment frequently, so of course check that first.

To check if the Idle Speed Control is working at all, feel the silver cylindrical object, the Idle Speed Control Valve, located right in the middle atop the engine. It should vibrate palpably at idle. Pull the connector off of it while idling; if it is working at all, idle speed will drop. The valve is easily removed, and will often respond to cleaning with carb cleaner and blowing it out with compressed air. If it isn't vibrating at all, and you're sure the TB switch is closing, then the Idle Speed Control unit is probably gone bad. They do it all the time, and unfortunately replacements are very expensive, $250-$300. It is the double-sized relay-like unit mounted in the nook at the right rear corner, behind the plastic plate that the air hose to the filter box comes from.

Here's a run-down of what to check at GW:
http://www.gowesty.com/library_article.php?id=110

Mon Apr 09, 2007 3:29 am

good stuff, thanks for the direction. can this issue be related to a vacume hose issue? I ask since my cruise control will not stay engaged for more than a couple of seconds...and I believe this is related to a "leaky?" hose that controls the throttle in cruise mode. Read something like that in another thread....Must go shopping...need a Bentley!

Mon Apr 09, 2007 7:49 am

I'm not too familiar with the cruise used on these. If it won't stay engaged then you could have a leaking servo, but I don't know how isolated that is from manifold vacuum. There are many other possible reasons the cruise might not work right as well.

The thing is, vacuum leaks have to be pretty big to upset idle, and it would be erratic when warm as well. There's only one vacuum line in use at idle on a non-cruise late van, and that is the fuel pressure regulator line. If that were cracked or leaky, fuel pressure would go up, it would run richer, and probably have a higher idle as a result. The richness would easily overcome the small effect of the vacuum leak.

Check the small hose from the fuel pressure regulator to the manifold, right ahead of the distributor cap. It's only a few inches long. Make sure it is intact. Try removing and replacing it at the regulator while at warm idle, you'll see what I mean. Even with the open vac line, idle speed will actually rise noticeably due to the richer mixture. I imagine the cruise vac feeder tees off that line. If you want to isolate the cruise from being a possible cause, just remove and block the cruise feeder, and see how your warmup idle is then.

Thu Apr 12, 2007 3:58 pm

On my 85 Weekender, on the temp guage, the right side of the needle only gets to the left side of the warning light, and that's it, unless I am in hot weather and pushing the engine.

I also had a stalling issue after putting in new plugs, wires, rotor, and distributor cap. Make sure they are Bosch is what I was told. The stallign went away after a tune up at my local shop and now it runs great. The timing was 20 degree too far advanced.

Happy Valley huh? We Are!!
EMS '94
85 Weekender
San Diego, CA

Thu Apr 12, 2007 10:46 pm

After I had soldered in the new capacitor to fix the blinking LED problem, Winston's gauge has never gone beyond the light, either. I've only heard his fan running once or twice--but he shows no sign of overheating and is running BEAUTIFULLY.

I admit to some anxiety that the gauge's needle is hanging up on the surface of the bulb--but it's not a particularly valid fear, I think. It IS an oooold gauge, though. I do think of whiles of rigging another temperature gauge, just to be safe and have lots of advance warning if he is getting hot. One comfort is that I can turn on his vestigial Air Conditioning switch and kick the fan on at any time.

Best!

Fri Apr 13, 2007 12:41 pm

Thanks for your thoughts. Just need the weather to break here in the northeast so I can take the van out and take a close look at it. Spring has not sprung.

GoPSU
98 Geosc.

Sat Apr 14, 2007 8:03 pm

Thermostat could be something to look at too.
my van started and ran, but the gauge never got above 1/4 unless it was midsummer and stuck in traffic with the AC on.
replaced the thermostat and now the heat works!

Sun Apr 15, 2007 3:08 am

I'm glad you mention that since my heat is currnetly only luke warm at best. Thanks