New Thermostat failure possible?

ALIKA T3 · Posted: Sat Oct 18, 2014 8:00 pm Post subject: New Thermostat failure possible?

Aloha all!

I have a newly rebuilt engine (by me) that is running hot.
Its a syncro engine with all coolant componants from the syncro put into a 1983 Vanagon.

I thought the coolant pipes under the van were crossed while I did the conversion, but no, I quadruple checked out everything.

I have a brand new Wahler 80°C thermostat ( 035121113 ): the engine and expansion tank get hot real quick, while radiator stays cold for a while, then gets real hot. It is not plugged and is fairly recent.

The cold pipe from radiator to T-stat cover is cold, for a while, then gets hot all of a sudden, making me think the thermostat doesn't close properly. Is that possible, or new failures usually never happen on this type of part?

(On vanagons,it is open at rest when cold, and closes when it gets hot, correct?)

Thank you Wink

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dhaavers · Posted: Sat Oct 18, 2014 9:03 pm Post subject:

I'd say you've got it backwards - the operation you're describing sounds normal.

When the engine first starts, the t'stat is closed until the engine gets up to operating temperature.
(Even before the t'stat opens, coolant is available to the heaters.) Once at at it's set temperature,
the t'stat opens completing the circuit to the radiator to cool the engine.

Pretty standard automotive theory...
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Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

As soon as you installed the rebuilt engine, you immediatly also installed a new radiator--right?
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kamzcab86 · Posted: Sat Oct 18, 2014 10:05 pm Post subject:

hans j · Posted: Sat Oct 18, 2014 10:06 pm Post subject:

How are you measuring how hot? By touch or with an infrared heat gun?
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rubbachicken · Posted: Sat Oct 18, 2014 10:12 pm Post subject:

find an test old german thermostats, i'd not be trusting a chinese part.
i test every german thermostat i find, the good ones get bagged up for that rainy day Wink

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IdahoDoug · Posted: Sat Oct 18, 2014 11:20 pm Post subject:

A thermostat is a shockingly simple product. Yet I hear of people mentioning defective ones out of the box once in a while on other auto groups. I personally have never run across one even though I change mine out early and thus have installed way more than my share. Though I actually am picky about the source now that I think of this. When I had a Subaru, I got the part from the dealer, I get my Audi ones from an Audi parts source, etc. So perhaps because I may never have used a chain store one, I've never had an issue.

If you are out of options or causes, I'd consider swapping it out as a cheap check. Then label as a spare if it turns out to be good. What else is on your radar as a possible cause? Sometimes if you yak a bit about it, something will jump out.

PS - fully closed when cold, fully open when hot. In a pan, they don't open as much as you'd expect.
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 50332

You need air flow over the radiator to get cooling, no air flow/no cooling. This is where the cooling fan comes in to give you air flow at idle and at lower road speeds. Without air flow the return from the radiator will be just a few degrees cooler than the coolant as it leaves to engine heading forward to the radiator and thus the engine will slowly overheat.

An 80°C thermostat should start to open at 180°F +/- which is hot enough to burn you if you hold your hand against the block.

devesvws · Posted: Sun Oct 19, 2014 5:51 am Post subject:

this is why I like to use behr, the whaler 80' I had in mine with less than 12k failed... and its not the first time a whaler tstat failed on me...just saying...
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ALIKA T3 · Posted: Sun Oct 19, 2014 1:02 pm Post subject:

Hi Everybody Smile

Thank you all for your input!

T-stat is NOT installed backwards.
It is not a chinese knock off, it's a Wahler made in Germany.
It's been raining here for 3 days, hurricane outside the islands, so it's hard to test anything right but it's definetely getting too hot too quick, no matter if it's idling or not :/
I read on another site that t-stat works reverse of what we think, therefore removing it would cause coolant to not flow to radiator.
So since I live in hot climate, can't I modify it to keep it open at let's say 10mm?

Thermo switch, I don't know, I didn't think about it...I'll put in the AC vanagon model , since the van doesnt have AC, big chance it's the wrong model.

Radiator is definitely not new but looks like it's been replaced.
It's the Behr model for later vans.
Cold outlet going to t-stat is the vertical one connected to the elbowed rubber hose from what I saw on the Bentley book.
Maybe I should replace it anyway... I'll go get a Behr one monday locally.

Aloha!
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 50332

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

Hit the area surrounding the radiator sender to the fan, then get a couple of readings from other areas on the face of it.

See what you come up with.
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ALIKA T3 · Posted: Sun Oct 19, 2014 7:52 pm Post subject:

Ok, I'll have to get an IR gun, mine is reading all over the place on an even surface at room temperature Sad

Hurricane rain is still quite strong, I might off tomorrow and this I will let you guys know following your instructions.

Cluster gauge might read unaccuraty too, bit fan turns on easily and coolant expansion tank is hot as sh%t... That's where my concern is from, it was never that hot on the previous shitty 2.1L engine running with 1.9L injection :/

Stay tuned Smile

Goodnight!
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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

ALIKA T3 · Posted: Mon Oct 20, 2014 10:38 pm Post subject:

Alright folks,

I got an IR gun.

Those things are stupid, they read all over the place.

After 1 minute of idling from starting the engine, top hose that goes from radiator to thermostat was cold but reading way hotter than the pipe below, that was barely becoming warm.
I tested it on the firewall, same thing, hotter than the "hot pipe" that goes to the radiator.
So I did it my way, since I worked as a plumber in France and I'm working into solar installations (hot water and photovoltaic)
I held my hand onto the pipes and hoses to feel them. Metallic pipes under the van, the hot one particularly, at idle, gets hotter on the top than on the bottom, due to slow flow from water pump at idle.
They are definitely not crossed.

I didn't take accurate measurements with the gun on the radiator, but I used it to confirm my understanding of the flow.
When you face the radiator, both hoses from the engine come in from the left (passenger side).
I could feel with my finger that there is a notch half way up the radiator, on that side, telling me the radiator is actually split in half: bottom half across the whole width, and top half.
Coolant comes in bottom left, travels across towards the right (driver's side),goes up to the top half, right side, then travels across radiator towards the left (passenger side), where the bleeder sits.
then it comes back down from the (left) side of the radiator.
IR gun measurements confirmed this theory. I measured also each "fin" that goes across the radiator, on the driver's side to see if a few were clogged.Nope.

I guess it's all fine and I was worried for nothing.

I then by passed the thermo switch, which is gray and new as well in order to run 2nd speed fan.
I then went back to the engine back and accelerated by hand a little bit over idle to bring (incrrease flow) cold coolant from radiator to engine.
Temperature seemed to drop at before and after thermostat.
Temperature on the long metallic pipe were lower (120's) on the middle than by the thermostat (150's) , then WAY HOTTER (200's) prior to the water pump flange inlet.

Right underneath is the exhaust pipe (Tencent's old exhaust pipe from many years back).
This makes me think at idle increases the inlet temperature to the water pump a lot.
I will have to make a shield of some sort.

I went driving the van mostly in neighborhood hills and temperature was steady 3/4 of the gauge.
I'm so used to the Subaru or M-Tdi's temperatures, I guess that's why I'm freaking out….

All seem ok I guess.

Thank you all for the help.

Mucho aloha!
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

Wildthings · Samba Member Joined: March 13, 2005 Posts: 50332

All right you have me confused. The coolant leaves the coolant manifold on the right side and goes forward to the radiator, it enters the upper of the two ports on the radiator and then crosses the rear set of tubes in the radiator, enters the tank on the thermoswitch (left) side and then returns via the front tubes to the right side again. Hence it leaves by the lower port and returns to the thermostat.

crazyvwvanman · Posted: Tue Oct 21, 2014 6:34 am Post subject:

Since both hoses are on the same end of the radiator the coolant has to flow back and forth through the core. As Alika noted above, Vanagon radiator back and forth flow is by upper and lower halves of the core. The end tank is divided in half on the hose end, upper half and lower half with a hose to each half. Hot coolant flows from the hose end of the rad through the bottom half of the rad core. Then it goes up the tank on the temp switch end and comes back the other way through the top half of the rad core.

One of the ways that Vanagon radiators fail is that the wall between the tank halves on the hose end can crack inside the tank. This lets coolant come in one hose and go back out the other without having to pass through the radiator core. Then the coolant leaving the radiator is hotter than coolant in the radiator core.

Mark

ALIKA T3 · Posted: Tue Oct 21, 2014 10:20 am Post subject:

danbar · Posted: Tue Oct 21, 2014 10:41 am Post subject:

Just an FYI that I had a new Wahler fail after 3 weeks earlier this year. I just got in one day and the temp shot straight up. Swapped it out and all is good. I've heard of one or two others doing the same recently. Maybe they had a bad batch?
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ALIKA T3 · Posted: Tue Oct 21, 2014 10:56 am Post subject:

hans j · Posted: Tue Oct 21, 2014 11:55 am Post subject:

We only use dealer thermostats. I've had too many Whaler and Behr go bad. And when some of the thermostats are behind timing belts (modern Audi's), you make sure that the one you put in is going to work correctly!
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1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181


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