troubleshooting overheating issues

[Paulbeard]

This seems to be a longstanding issue for me and I'd like to get it resolved.

What I seem to have is an overheating problem compounded by a malfunctioning gauge. Symptoms are high temps as read on the oil temp gauge, no fan coming on when it's hot (like idling after a good hard run). I can turn on the fan via the no-op A/C's controls. But I get no feedback from the gauge. The heater works so I know there is hot coolant being moved around.

I have a new temp sender to drop in and I already replaced the voltage regulator that seemed to be failing. Maybe that fixes the gauge.

What I haven't done (never thought of it) was to hit the radiator with an IR gun and see if it's getting hot evenly. So that's on my list. I'm not opposed to replacing that, if needed, but I want to be sure.

If I do replace the radiator, it sounds like replacing thermoswitch is a "while yer in there" task?

What other steps should I pursue to isolate this?
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Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[Ahwahnee]

A through examination with the IR to see what gets hot when is a logical approach.

[Paulbeard]

So some quick research items after a short runabout…
• the radiator was 88°F on one side, 122°F on the other
• the coolant (and oil) temps at the block and the hoses leading to the radiator were closer to 190°
• The pressure tank is full, so I don't think there is any air. The fact that the heater works also points to an airless system, I think.

I think the radiator might not be working well.

I may have found my oil leak as well but that will wait til things are cooler. Looks like it's weeping from the oil temp sender. Not sure if I can use any teflon tape or anything there as it gets its ground from the threads it screws into. I'll see if it can be snugged up any tighter.
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Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[oceanair]

Drop in a new radiator and be sure all of the hoses are in great condition -- if it's old, it's clogged.
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84 Vanagon Pop Top Conversion from Tin Top, 1970 Ghia - all sweet rides! Love em!
Previous: Green 72 Tin Top, White 72 Westy, Blue 64 Beetle, Yellow 71 Squareback, 2014 Jetta TDI Wagon - wish I could have them all back!

[Paulbeard]

[crazyvwvanman]

Remove the lower grill.
Do the jumper test at the rad temp switch wires.
If the fan runs on both speeds during the test you should replace the rad fan temp switch with a new correct one for 2.1 vans.
It can be done quickly with little coolant loss.

Mark

[oceanair]

Not if there is restricted flow in a clogged radiator. But yes, test that the fan works! But it does require hot coolant flowing over it to trigger.

[oceanair]

It's an easy and cheap sensor to replace, right on the back of the engine.

[VicVan]

This might be obvious but since you didn't mention it: is your system bled properly? Could be air in the radiator.
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[crazyvwvanman]

With the lower grill off he can feel the radiator temp in the area where the temp switch is, after a drive when the engine seems fully hot. No reason to just guess the radiator isn't flowing. FEEL IT!

Mark

[Paulbeard]

If this is the switch, I'll just do it at the same time. Odds are, the radiator and switch (and fan, etc) are all original equipment, ie, on borrowed time.
_________________
Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[crazyvwvanman]

Again, no reason to use guesses. With the upper grill off you can see the date code molded into stock radiators. The two digit year will be inside of a round emblem in the black plastic side of the radiator, passenger side. It it say 86 or 87 then probably original on an 87.

Mark

[Paulbeard]

I'll look for that, but I think it won't change much. The IR gun test was enough to convince me it's past its prime. I'll know more tomorrow, once I change out the sender and do some more testing, hands on or otherwise.
_________________
Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[crazyvwvanman]

Yes if you drove it enough to get the system fully warmed up you should see higher readings than you did at the radiator. But there is a lot of coolant in the system to get warm and the thermostat opens and closes a bunch of times in that warming process.

[dobryan]

And you checked that the thermostat is operating correctly?
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Dave O
'87 Westy w/ 2010 Subaru EJ25 (Vanaru) and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[VicVan]

[Paulbeard]

[tjet]

Not wanting any overheating issues on a 2.2 high compression WBX I was installing, I made some cooling system changes on my '87 Syncro:

1. Lower temp engine thermostat installed;
2. Lower temp "fan-on" radiator switch;
3. 10c oil cooler with fan (& retained the factory oil-wtr heat exchanger);
4. Removed AC condenser from in front of the radiator (along with the entire AC system);
5. Advanced engine timing about 8 deg;
6. Gutted original catalytic converter (to help lower exhaust / compartment temps).

Side note: I discovered that the skid plate I installed where the spare tire used to live was getting pretty warm from the air leaving the radiator. To help the airflow escape, I cut some slots in it. The factory radiator fan blows the air straight thru it now.

It's overheat proof, IMO. I can let it idle forever. I only use VW G12 coolant (or G13?) & distilled water, 50/50. My pressure cap is an OEM black version (not blue). It has a slightly higher operating pressure value. My temp needle hovers just below or over the bottom part of red LED. Doesn't matter if it's hot or cold outside, if I'm stuck in traffic, driving in low gear off-road, or driving up to the mtns.

Other mods include extended scoops at the pillar vents & a propped license plate lid. Also, not sure if it makes any difference in engine compartment temps, but the rear aftermarket bumper I'm using doesn't cover those little vent openings above the cat/muffler like the factory bumper does.

The only issue I've had was a plastic water manifold cracking. It didn't get hot, but the water loss caused the LED light in the temp gauge to blink. I replaced it with a s/s one. I think this is a Syncro only part.

One more thing, I really like the pressure bleeder that GW sells. Works great on my van, and I've also used in on my Golf & Jetta.

Hope this helps

[Paulbeard]

The oil cooler is an option, if none of the other stuff gets me there. I expect a new rad will solve this, especially if this one is as trashed as I suspect. The exchanger very acceessible too.
_________________
Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[oceanair]