Mystery Temperature Gauge Problem

[mrgodby]

Hello all,

I drive a 84' Vanagon and I recently have had some problems on starting up. Everything starts up smoothly, but after a few seconds pass, the temperature gauge begins to blink and the needle rises very fast.

I've posted a video of what happens below. I'm hoping someone can point me in the right direction for solving this problem.


Link


Thanks!

[Ahwahnee]

Couldn't see the video, but... if there is air in the coolant reservoir the light will flash and the needle peg irrespective of coolant temperature.

The tank in this photo should always be totally full:

If the tank is full -- a faulty sensor or broken wiring can also cause errant blinking and needle rise.

[E1]

You might remove the blue cap on your expansion tank and make sure it "bugles" either on inhale or exhale (sorry, can't recall which right now, while blowing I think).

Edit: I don't think this is your problem but it's a good thing to frequently test -- and a note to carry two of the good German ones as spares. I believe those are made by Meyle.

Next thing I'd try is making sure your alternator is putting out somewhere between 13 and 14+ volts. Overcharging from a bad voltage regulator does all kinds of weird stuff in the dash.

Good Luck!


And... Welcome!!!
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[mrgodby]

My expansion tank is not completely full, so I'll give that a try.

I assume I'll need to drain whatever is in there and fill it again completely?

By the looks of it, I just need to open the drain plug below the engine and let it fall out. Is that the only point in the cooling system that needs to be drained?

I know refilling the tank involves raising the van and opening the bleeder screw on the radiator, but I want to be sure I'm not mixing something that shouldn't be.

[E1]

You might await confirmation from others more experienced here, but I would just top off the expansion tank with the same-type coolant and also make sure the overflow tank behind the license plate is at least to the minimum mark when COLD.

NEVER use coolant that's not phosphate-free! I personally only use the VW-Audi (pink) coolant mixed 50-50 with distilled water.

In case you don't know, it's tricky to slowly bleed pressure off the expansion tank when hot so all this is best done when everything's cold -- or at least cool.

I'd still check the blue cap for the bugling effect I mentioned, but now it sounds like your issue is simply the coolant being low in the expansion tank.

Personally, I keep my cold level right in the middle of Min and Max as there is a little coolant expansion when it gets hot. You don't want it to ever go above Max when hot, it's tough on seals and perhaps even hoses.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[Ahwahnee]

[mrgodby]

Thanks for the replies!

I should mention, I have no idea what kind of coolant is inside currently. Could I potentially cause any harm by adding a coolant that doesn't match what's in there?

[Wildthings]

Regardless of the coolant you can top the expansion (pressure) tank off with distilled water. Have the engine cold and remove the hose from the pressure cap. Now start the engine and use something to hold the throttle open until the engine is running at around 2500 rpm (this doesn't need to be very exact). Now remove the cap and fill the tank completely and then replace the cap. Now reinstall the hose and then let the engine drop to its normal idle speed. You want the refill (overflow) tank behind the license plate to be about 1/2 full, there are marks on the tank to indicate the preferred range. If you overfill the overflow tank it will hurt nothing, the tank will just expel the excess coolant.

[levi]

So you have 2 coolant tanks back there.

One is overflow, that's behind the license plate.

The other is the pressure tank.

Open the pressure tank, (when it's cold, not hot ).

You'll see another cap screwed into the tank, it's the sensor, and has 2 prongs on it.
Those 2 prongs have to be clean, if they get a little slimy they can give the readings you show.
Clean them off and try again.
_________________
One of these days I'm gonna settle down,
but till I do I won't be hangin round.
Going down that long lonesome highway,
gonna see life my way

https://youtu.be/cSrL0BXsO40

[E1]

[ZsZ]

I say it is a bad temp sender or wire fault. Signal wire is shorted to ground and that is why the neeldle reacts as an overheat.
Coolant level errors wont move the needle just blinks the led if there is no connection between the level sensing pins.
_________________
Zoltan
1.9 MTdi 2wd Multivan (ex Caravelle)
Van since 2006, engine since 2008

[crazyvwvanman]

The early version of the coolant level relay DOES peg the temp needle and blink the led when coolant is sensed as low.

There were 3 versions of the coolant level warning relay installed in USA/CA Vanagons. The first version had a part number that began with 251 and this version should be replaced with one of the later versions to avoid the problem of pegging the temp needle.

Most 83/84 vans have this problematic early version but any year could have it since it plugs in the same as any other version.

The taller one of the 3 versions in this photo is the early bad one.

The tall one pegs the temp gauge hot and makes the temp led blink when coolant is sensed low in the main tank. The shorter improved later versions only blink the led and let the gauge read what the temps actually are.

Mark

[Ahwahnee]

[E1]

Yes, yes, I'm still banking on the simple, low coolant scenario.

Do the correct diagnosers get cookies? Parts? Syncro upgrade package?
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[levi]

Ha
We'll probably never know....
Most of the time when folks resolve an issue, they just fade away.
_________________
One of these days I'm gonna settle down,
but till I do I won't be hangin round.
Going down that long lonesome highway,
gonna see life my way

https://youtu.be/cSrL0BXsO40

[E1]

That's just wrong. At least send some chocolate chip concoctions.

I suspect poster may have a real job, and/or is tracking down coolant and cookies.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[mrgodby]

Thanks for the replies everyone!

I'll top off the expansion tank later today and see if that solves it. If not I'll move down the lists of suggestions.

If all else fails, I'll use my overheating engine to bake cookie cookies for everyone

[E1]

DEAL!
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[mrgodby]

So I topped off the expansion tank with distilled water and the mystery temperature gauge problem is no more. I drove around for a few miles with no problems. I'll check the level next go around.

Although, I am a little curious why the level was low to begin with. I remember it being full a few days before the problem first happened. I had to replace the hose to the overflow tank and fill it up. Maybe something went wrong there.

Thanks for the help!

[E1]

All right!

I just love happy endings.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”