1996 B4 Passat... where's the thermostat?

The Turtle

Veteran Member
Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
Had a look under there and cannot really figure out where the thermostat is. There's a plastic fitting near the #3 injector, there are some other coolant hoses that don't seem to have enough space to fit the thing. I am pretty sure mine is stuck mostly closed and am getting no heat, but it'd help if I could figure out where to put the new thermostat!
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
La Conner, WA
TDI
... None :S
It's under the watter pump, above the power steering pump. You'll see a plastic elbo that bolts to the bottom of the water pump. That's where it lives.

-Jason
 

darkscout

Grammar Scout
Joined
May 28, 2006
Location
Michigan
TDI
2003 Golf
No heat? How far are you driving? Did this just start (as in you were getting heat before on the same duty cycle)?

The thermostat is under the waterpump. Stand in front of your car and point straight down from the alternator... it's down there.
 

The Turtle

Veteran Member
Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
Ah, fark. Does anything else have to be removed to replace the stat? This could be an unreal PITA. As far as the heat... yeah, started out the drive with heat, then noticed the heat went away and the temp gauge went to about 195, where it's usually around 180. Got off the interstate and it spiked up to about 220 briefly and then settled down. Some bubbly sounds when I turned it off, like the stat was stuck shut.
 

darkscout

Grammar Scout
Joined
May 28, 2006
Location
Michigan
TDI
2003 Golf
yeah, that doesn't sound like a t-stat. If the t-stat was busted then you'd be running cool all around.
 

The Turtle

Veteran Member
Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
It does provide pulses of heat from time to time. Correct me if I'm wrong, but every car I've ever owned had the cabin heat on the "other" side of the thermostat... in other words, no heat until the engine warms up and the stat opens to let the coolant flow.
 

The Turtle

Veteran Member
Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
And if the stat was stuck shut (that's the usual failure mode I've seen over the years) then the engine would be hot and the radiator and heater cool. In emergencies, I've occasionally removed thermostats entirely and run without them. If the water pump is failing, how bad is that to replace? I think I did one in my 1.8T Passat but can't remember now. On the B4, does anything else have to be removed to get at the stat?
 

darkscout

Grammar Scout
Joined
May 28, 2006
Location
Michigan
TDI
2003 Golf
The Turtle said:
And if the stat was stuck shut (that's the usual failure mode I've seen over the years) then the engine would be hot and the radiator and heater cool. In emergencies, I've occasionally removed thermostats entirely and run without them. If the water pump is failing, how bad is that to replace? I think I did one in my 1.8T Passat but can't remember now. On the B4, does anything else have to be removed to get at the stat?
The heater core comes straight out of the head, however if you don't get any flow, then no cool air will be pushed through. The temp gauge is right at the exit of the head also, however given it's higher position, convection could easily heat this up. To the range you're seeing.

This is how I'd diagnose it:
Heater Cold, Engine Cold = Thermostat
Heater Cold, Engine HOT HOT HOT = Water Pump


You have to take the TB off to get to the pump. You you don't have to take the whole thing off, the impeller part bolts to another body and if you're good and don't break any of these bolts you can just pull that out.
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H, the other oil burner: 1967 Saab Sonett II two stroke
Be aware of where the sensors are located. An engine coolant temperature sensor might not necessarily be in the engine.
You could have a cool "engine" temperature sensor reading, yet still have an overheated engine, if the hot fluid in the engine doesn't circulate past the sensor.
 

The Turtle

Veteran Member
Joined
Jul 24, 2006
Location
rural Maryland
TDI
1996 B4 Passat wagon, SpeedTuning chip, 360,000+ miles, 1996 B4V, 306,000 miles on original engine
Thing is, the temp sensor is by and large entirely normal. Engine isn't blowing steam or anything. Heat comes and goes and never gets very warm. Coolant level is normal. Since this is the second engine in this car I can't say whether it's still got the original impeller assembly. Might as well just have Mark rip the whole thing out and do it all at once, rather than guessing.
 
Joined
Apr 27, 2003
Location
Stafford Virginia 22556
TDI
96 glx variant tdi
The b4 does require you drop the power steering pump which is easily done by removing 5 bolts. Two bolts hold the bracket going underneath the crank pulley to the rear of the motor, two vertical bolts holding the pump up into the block next to the oil pan, and a single bolt holding the power steering back to the air conditioning bracket. I also remove the small bolt holding the ps pressure hose underneath the radiator. Drop that mess down out of the way and there is the thermostat housing. It's still somewhat hidden above a piece of the block and of course vw made it so the thermostat hangs downward which means it's a pain to get back up there. Draining the coolant is accomplished by loosening the thermostat housing a little bit or just remove the house fitting by pulling out the horseshoe clip once you get the ps out of the way. Once you pry the thermostat out of the housing, you'll get a flood more of coolant so beware.
 
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JungleMan

Veteran Member
Joined
Oct 9, 2005
Location
North York, Ontario, Canada
TDI
2001 Jetta TDI
Turtle,
here is a diagram that may help you, the thermostat is item #12.
Part # b 044 121 113 (87C-102C/188F-215F)
I Hope this helps. If you need part #'s, let me know.

 
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Mike out west

Well-known member
Joined
Aug 7, 2007
Location
Washington State (usually)
TDI
96 Passat Wagon (B4V)
Alright, guys. Help me replace the thermostat in my B4 by helping me drop the power steering pump. I don't have any experience with this side of the engine compartment, so I'm having a hard time figuring out how the PS pump will swing out. After I removed the two vertical bolts into the block near the oil pan, nothing moved, and so I started to remove a few more bolts, and still no movement. Then I found this:
ninedee_golf_tdi said:
Two bolts hold the bracket going underneath the crank pulley to the rear of the motor, two vertical bolts holding the pump up into the block next to the oil pan, and a single bolt holding the power steering back to the air conditioning bracket. I also remove the small bolt holding the ps pressure hose underneath the radiator. Drop that mess down out of the way and there is the thermostat housing.
two vertical bolts...check!
single small bolt holding the PS pressure hose under the radiator...check!
two bolts underneath the crank pulley to the rear of the motor...help!
single bolt holding the power steering back to the air conditioning bracket...help!
Here's a photo:

The bolt I labeled "I" might couple with the air conditioning bracket, but it's kind of hard to see for sure. The bolts labeled "B" "C" and "D" each need to be removed before the PS pump will swing down, or am I missing something?
 

starrd

Veteran Member
Joined
Nov 24, 2003
Location
Canada
TDI
1996 Passat
Loosen bolt A and J and rotate the larger hex part at A to loosen belt tension and remove belt. The remove bolt A, J and I. Also remove the 2 10mm head bolts holding the power steering lines to the front bumper area. Remove the nut holding the other power steering to the transmission. Lower complete power steering assembly with lines connected and swing it out of the way towrds the rear of the car - clockwise looking down from the engine compartment. Then remove the 3 bolts holding the bracket the power steering pump was connected to and remove. The thermostat housing is now in the open and can be removed.
 
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Mike out west

Well-known member
Joined
Aug 7, 2007
Location
Washington State (usually)
TDI
96 Passat Wagon (B4V)
The new thermostat is in, and the temperature gauge now behaves a lot differently. It now goes up to 195°F (90.5°C) and stays there instead of wandering around 120°F (49°C). Which is itself a little bizarre because I put in what I thought was a 180°F (82°C) part. Question: is there a significant chance the engine will overheat or otherwise be damaged in case I installed a 195°F part? It's a Stant Superstat from Napa Auto Parts.

I tested the old German thermostat in a pint of 150°F water, and it was already starting to open. I should have tested the new one at 180°F, I guess.

Concerning which bolts to play with to get the power steering pump off, I did as starrd suggested and removed bolt "I". This was probably unnecessary, since bolt "I" couples the power steering pump with the bracket that I needed to remove anyway. But I did need to remove bolt "F", which is the one that couples the bracket to the air conditioning bracket. Loosening bolt "I" might be helpful in swinging the pump up to remove the belt, but removal is not necessary.
 
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TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
71, 80, and 87C thermostats are listed at Autohausaz.com. So, I would expect them to be all standard available thermostats.

Keep in mind that the water temp guage is dampened. What that means is the gauge will read 195F, but the water temp can be anything between 175F and 205F. I don't recall the actual values, but you get the idea.

The only real way to read water temp would be to use VCDS.

Your water temp sounds normal to me.

Tony
 

starrd

Veteran Member
Joined
Nov 24, 2003
Location
Canada
TDI
1996 Passat
Mike out west said:
Concerning which bolts to play with to get the power steering pump off, I did as starrd suggested and removed bolt "I". This was probably unnecessary, since bolt "I" couples the power steering pump with the bracket that I needed to remove anyway. But I did need to remove bolt "F", which is the one that couples the bracket to the air conditioning bracket. Loosening bolt "I" might be helpful in swinging the pump up to remove the belt, but removal is not necessary.
Sorry - I had trouble with the picture, Bolt "F" instead of "I"
 

CentrlFLtdi

Veteran Member
Joined
Jan 25, 2005
Location
Central Florida
TDI
1996, Passat Wagon, Deep Purple
JungleMan said:
Turtle,
here is a diagram that may help you, the thermostat is item #12.
Part # b 044 121 113 (87C-102C/188F-215F)
I Hope this helps. If you need part #'s, let me know.

Interesting. On my Bentley it shows the thermostat in the opposite orientation. Can anybody shed any light as to which side goes where? I'm getting ready to do mine right now because my car won't get above 140 degrees, but want to make sure I install it in the right direction.
 

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
My Bentley shows the thermostat 'pointing' towards the radiator. i.e. the pointy end of the t-stat points down, towards the elbow.

That's the way I installed mine; cooling just fine in 110-115F summer heat with AC running and absolutely NO cooling issues.

HTH

Tony
 

Mike out west

Well-known member
Joined
Aug 7, 2007
Location
Washington State (usually)
TDI
96 Passat Wagon (B4V)
The thermostat I removed--quite possibly the original--had the springs on the inside, which appears to be opposite of what is depicted in JungleMan's diagram.

Photo courtesy of user lupin..the..3rd's post here.

 

riofrio

Veteran Member
Joined
Apr 14, 2006
Location
New Haven, CT
TDI
96 Passat, 2002 Jetta Wagon
I'm getting ready to do this as my car won't get any warmer than ~140 it seems.

Just 2 quick questions:

1) Do I need to drain all of the coolant? Can I reuse that same coolant afterward?

2) When putting everything back together, do I just re-tighten the belt by tugging on the PS pump body? Or need I mess with the tensioner?
EDIT: Should have checked before posting... just realized there is no separate tensioner on the acc belt but it's rater done by the PS pump itself.
 
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Beowulf

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Joined
Jan 17, 2000
Location
Lovettsville, VA, USA
TDI
A3 Jetta, 1998, Green
I'm hoping for some advice. I'm trying to replace my thermostat (it's failed open and my car never reaches operating temp now).

I removed the belt, and removed bolts A and J. I removed F, but that did nothing to loosen the power steering pump. I then loosened I. THis allowed the power steering pomp to rotate down out of the way and I could remove the 2 bolts that hold the bracket in place. However, I could not remove the bracket or completely drop the power steering pump because bolt I was too long for me to remove completely. IT would hit the timing belt and I could not push up or pull down on the timing belt to get it enough out of the way to pull the bolt all the way out. Because bolt I was still in place, it was holding the power steering pump and the bracket in place and I could not get a clear angle of attack at the thermostat housing (I could see one of the bolts on the plastic thermostat housing but the bracket was still in the way).

Was I working on the incorrect bolts on the power steering pump and bracket? Or is there a trick to getting bolt I out past the timing belt? Or am I just unlucky and other owners haven't run into this problem with the long bolt I running into the timing belt when trying to remove it?

Any pointers will be appreciated. At this point I'm leaning towards having to do the thermostat when I do the water pump during the next timing belt change.
 

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
Looking at the picture, you need to remove Bolt 'B' and 'D'

Tony
 

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
Loosen bolt A and J and rotate the larger hex part at A to loosen belt tension and remove belt. The remove bolt A, J and I. Also remove the 2 10mm head bolts holding the power steering lines to the front bumper area. Remove the nut holding the other power steering to the transmission. Lower complete power steering assembly with lines connected and swing it out of the way towrds the rear of the car - clockwise looking down from the engine compartment. Then remove the 3 bolts holding the bracket the power steering pump was connected to and remove. The thermostat housing is now in the open and can be removed.
Hi Tony, Thank you very much for the reply. Is that in addition to A, J, and F, or instead of?
So, rereading and reviewing the picture...As well as looking through http://www.jimellisvwparts.com...

A-sets the bent tension - Remove this bolt and the belt
Remove B, C, D, and maybe J.

Tony
 

Yblocker

Veteran Member
Joined
Sep 1, 2010
Location
Oakland, CA
TDI
1997 Passat
Do remove J. The big through bolt B can be persuaded to clear the serpentine belt if you twist the belt a little.

After you drop the bracket, then get a big pan to catch as much coolant as you can. You'll likely end up removing the hose from the adapter and a quantity of coolant will drain. Then when you remove the t-stat housing and t-stat itself, more will drain so be ready- its a mess. You can re-use the coolant if its looks good, but you won't catch it all so have more G-12 on hand.

I would purchase the t-stat, housing, adapter and both o-rings from the dealer. The price reasonable and the vendors on the club don't seem to carry the adapter. It's recommended that these parts all be changed because the old plastic parts often leak when disturbed then re-assembled.

I connected a shop vac to my coolant bottle when re-installing the t-stat. It's a handy way to keep it in place while you position the housing over it during installation. Otherwise the t-stat wants to fall out or move and can be a source of frustration.
 

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
There is also only one way the thermostat will fit, it won't seat in the other direction due to its design. While you're there, replace the o-ring (16) since it often doesn't come with the thermostat and you are in there already.
 
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