Replaced Thermostat now no heat - Advice?

I replaced the thermostat in my 2005 Passat SW TDI now I have no heat, or should I say continuous heat, it comes and goes. I have bled the system at the heater core 5 times. Four times by raising the expansion tank up until fluid came out of the bleed hole. The 5th time I did it, call me stupid but I was fed up, I pulled the heater core hose back, clamped it and ran the car letting the fluid spray into a rag. All 5 times same result, heat in the beginning then after 3-4 miles no heat. I would downshift to get the RPMs up and can hear the heater core gurgling, the heat would return for a few seconds then cold again. Also while in Park I loosen the expansion tank cap and ran the engine just over 2000 RPMs hoping to circulate the air out.
Am I still not getting all of the air out?
Is my new thermostat faulty? (ESC Tunning P/N 044121113) Genuine VW
What to do next?
Thank you in advance for any helpful advice.

just thinking... is it possible to put a thermostat in
upside down?

I'm very confident I installed it correctly, but stranger things can happen.

Did you put G12 (purple/pink) antifreeze back in when you were complete? People have clogged their heater core by mixing incompatible antifreeze.

passat05wagon said:

I replaced the thermostat in my 2005 Passat SW TDI now I have no heat, or should I say continuous heat, it comes and goes. I have bled the system at the heater core 5 times. Four times by raising the expansion tank up until fluid came out of the bleed hole. The 5th time I did it, call me stupid but I was fed up, I pulled the heater core hose back, clamped it and ran the car letting the fluid spray into a rag. All 5 times same result, heat in the beginning then after 3-4 miles no heat. I would downshift to get the RPMs up and can hear the heater core gurgling, the heat would return for a few seconds then cold again. Also while in Park I loosen the expansion tank cap and ran the engine just over 2000 RPMs hoping to circulate the air out.
Am I still not getting all of the air out?
Is my new thermostat faulty? (ESC Tunning P/N 044121113) Genuine VW
What to do next?
Thank you in advance for any helpful advice.

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Yes I did use G12, thanks for responding.

Just drove 50 miles to work, the heater core hoses are not hot, the upper radiator hose still somewhat soft, not much pressure. The temp gauge was right at 190. I'm going with a faulty thermostat.

passat05wagon said:

Just drove 50 miles to work, the heater core hoses are not hot, the upper radiator hose still somewhat soft, not much pressure. The temp gauge was right at 190. I'm going with a faulty thermostat.

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If the temperature guage is reading 190 that tells you the thermstat is working ok.
Did you bleed both heater hoses?

when you pulled the heater hose off you may have sucked air into the system. contrary to logical thinking, the b5.5 sucks water through the heater core, so opening a hose at the heater will allow air to enter system, not expel it. I would again raise the coolant tank as high as possible, expose the bleed hole ,and allow enough time for the air to escape, perhaps "milking" the top rad hose. What happens is the water pump is attempting to pull on an air bubble in the heater core and cannot pull coolant through it.

Peiphil and thundershorts, thank you for your response. I just finished bleeding again. I ran a tube off the bleed hole into a container. Ran the car and pushed a little over quart of coolant into the container. The upper radiator hose was hot and the lower hose was cold. Wouldn't that mean the thermostat isn't opening? Still no heat. I'm going to try your advice but this is my last bleed then I'm starting over again and replace the thermostat again. Fed up! Thanks again I appreciate your help.

if you know any mechanic friends, a coolant vac may be your best bet on getting all the air out, it will pull the system into a vacuum and refill, leaving no air in system. we do this all the time on semi trucks, and it works flawlessly. it attaches to reservoir, and you need shop air to create the vacuum, and a hose into a bucket of coolant. another name for this is a coolant lift. works great and no spillage if you reuse coolant that was drained into a pan.

Thanks dangerrange, that's a great option, wish I knew someone. Amazon has an Air Lift II for $75.00

passat05wagon said:

Thanks dangerrange, that's a great option, wish I knew someone. Amazon has an Air Lift II for $75.00

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Like I have already said your thermostat is fine.
Try finding a hill and get the car pointing uphill then rebleed the heater hoses

I'll try bleeding again

You can also try to fill the heater core separately by detaching both tubes and injecting coolant straight into the core.

Thanks Mikey2, I did that today.
So I put a piece of cardboard if front of the radiator, heat worked great. Took the cardboard away got cold again. Temp gauge stayed at 190. I'm going with a faulty thermostat.

Use a handheld Mityvac on the overflow bottle hose to help burp all the air out of the system.

FWIW the temperature gauge is an analog idiot light. Use a SGII or VCDS to see what your ACTUAL coolant temperature is - mine still shows straight up full heat at 75ºC per the SGII, far less than 90ºC where it should be. My thermostat got lazy and was opening too early, holding a steady 77ºC maximum. Replaced it and now I get proper coolant temperature.

passat05wagon said:

Thanks Mikey2, I did that today.
So I put a piece of cardboard if front of the radiator, heat worked great. Took the cardboard away got cold again. Temp gauge stayed at 190. I'm going with a faulty thermostat.

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What does the temp guage read when the car is first started?
What did it read when you had the cardboard in place?
Do you still have your old thermostat?
If you do throw it into a pot of water on the stove with a thermometer and watch to see what temperature it opens at.
Maybe it was not at fault in the first place
Maybe you have apartial blockage in your heater core.
Are the hoses hot?
You have to answer all of these things to get help.
Check all of these things first as it may be a waterpump missing fins etc.

peiphil I'll answer your questions in order
1. zero, goes to 190 in a few miles
2. 190
3. yes i have to old thermostat, temp was reading 165 with the old thermostat. the dealer troubleshot it and determined the T-stat needed replacement for $300.00+
4. 5. as stated above engine temp at normal operating conditions was low.
6. don't believe the heater core has any issues
7. lower radiator hose is cold, upper hot, heater hoses warm, depends on OAT
8. Had no heat issues until I replaced the thermostat just operating temp was low below 30 deg OAT

did you use an aftermarket thermostat?

No I did not thundershorts, OEM

Which thermostat did you buy from ECS? They list 4 or 5 under the VW part number and some of the items ECS sells are junk.

Did you buy the $50 OEM item, the $20 Wahler or possibly the $4 MTC item?

If you had heat prior to changing the thermostat then begin your search there.

I bought the $50.00 OEM, I'm changing it tonight with one I picked up at the dealer. I already called ECS Tuning, they said to return the one I bought from them.

one member had recently used a French stat, probably Chasson, and it worked fine. It will be interesting to hear if the dealer supplied one is same as estuning one

Update, not fixed! Very frustrated.
Friday I replaced the T-stat again to satisfy myself. I bought an Air Lift Cooling System refiller and use it to replenish the coolant. No heat.
Today I attached a hose to the bleed hole in the heater core hose, attached my vacuum hand pump and sucked out over a gallon of fluid, yes I refilled the tank as I went. Still no heat. Drained the coolant again and used the Air lift tool again to replenished the coolant. No heat. The upper rad hose and both heater hoses get hot, the bottom rad hose stays cold. Temp gauge reads 190. I guess I'll give up and take it to the dealer.
Thank you all for the great input, I appreciate all of the advice you have given me.

passat05wagon said:

Update, not fixed! Very frustrated.
Friday I replaced the T-stat again to satisfy myself. I bought an Air Lift Cooling System refiller and use it to replenish the coolant. No heat.
Today I attached a hose to the bleed hole in the heater core hose, attached my vacuum hand pump and sucked out over a gallon of fluid, yes I refilled the tank as I went. Still no heat. Drained the coolant again and used the Air lift tool again to replenished the coolant. No heat. The upper rad hose and both heater hoses get hot, the bottom rad hose stays cold. Temp gauge reads 190. I guess I'll give up and take it to the dealer.
Thank you all for the great input, I appreciate all of the advice you have given me.

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If both of your heater hoses are getting hot that means you do now have flow through the heater core.
Question is how much flow!
Maybe you disturbed some kind of crud that has partly blocked off some or most of the heater core tubes
A rad shop could do a heater core flush cleaning and test is an idea?
I would guess the dealer would be selling you a new heater core$$$$

Peiphil
Low volume of flow is exactly what I was thinking.
I just done, laying in the driveway in the cold was easier in my younger days. I'll post what the dealer comes up with some time this week.

I HAVE HEAT!!!!!!!
Let me bore you with my story today with this issue.
1st thing this morning I went to the Hardware store and bought 3/4" hose and a garden hose fitting with all thoughts of flushing the heater core... but I didn't. Instead I spent the day as I explained 3 post above, never did the core flush and had no good results so I gave up. After an exchange with Peiphil I just sat here thinking I need to go out and flush the core as I intended to do 1st thing this morning. Well 1/2 an hour out in the dark, I have heat.
Just like the school days, ALWAYS GO WITH YOUR 1ST ANSWER... HA HA. I could have saved my Sunday afternoon enjoying the day.
Thanks Peiphil, you may not know it but you lit a fire under my butt.
I intend to get the cooling system flushed.
Thanks again everyone!!!!

passat05wagon said:

I HAVE HEAT!!!!!!!
Let me bore you with my story today with this issue.
1st thing this morning I went to the Hardware store and bought 3/4" hose and a garden hose fitting with all thoughts of flushing the heater core... but I didn't. Instead I spent the day as I explained 3 post above, never did the core flush and had no good results so I gave up. After an exchange with Peiphil I just sat here thinking I need to go out and flush the core as I intended to do 1st thing this morning. Well 1/2 an hour out in the dark, I have heat.
Just like the school days, ALWAYS GO WITH YOUR 1ST ANSWER... HA HA. I could have saved my Sunday afternoon enjoying the day.
Thanks Peiphil, you may not know it but you lit a fire under my butt.
I intend to get the cooling system flushed.
Thanks again everyone!!!!

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Thank you for the compliments but dont do that!
Only do the rad flush on your heater core not the rest of the engine and main rad Somewhere on this forum I did a write up on how to do that with a pail with 2 fittings with an in line block heater 2 hoses and a gallon of rad cleaner hooked to just the heater core alone.
Something I have done several times to several vehicles while living out in northern Alberta Canada for several years.-45c
They clog up faster than you think because of heating and cooling cycles turn the coolant into acid which makes the silicates want to make deposits all over.
That is the ONLY reason they recomend changing your coolant every so many years
The rad flush stuff is hard on the newer aluminum engine rads and the block for that matter so I just flush the heater core by its self rather than the whole system
Now is your butt warm because I lit a fire under it or because your heater now works?

In above freezing conditions, I"ve successfully cleaned the entire cooling systems of many cars by running just water and Tide for several days, then draining, rinse, refill with coolant.

Great advice peiphil, I'll do them seperatly. As far as the butt warm, it's a little of both. This mornings ride into work was a lot warmer.

thundershorts, Tide, never thought of that.