1.4BBY the tale of two thermostats

[jonbad]

It's official, I'm stumped.
Have changed the thermostat but...
1. The old thermostat is a traditional thing.
2. I bought the "correct" thermostat but it is totally different, like a long black cylinder.
3. The new thermostat is what's shown on Audi's service software, not the one that was in the car.
4. Eurocarparts sell both types, so they don't know.
5. Oddly enough, the black cylinder thermostat does appear to locate and fit in the housing, but I cannot understand what seals it and what keeps it in place. The housing cap doesn't appear to have a way to hold it in place. It's as though the thermostat housing can take the black cylinder thermostat but there's no seal around it and the cap doesn't appear to hold it.

The car is a 1.4 BBY (petrol) first registered 1/1/2003.

I have been unable to find any reference to a traditional type of thermostat despite that having been the part fitted in the engine - I assume it hasn't, but don't know if it has ever been changed in the past.

Aside from shape,.The two thermostats have different operating temperatures.

Everything seems to point to the black cylinder type being correct for the car, but why then did it have a different sort in (and work) and have a different type available at all?!

Can anyone put me out my misery?!

 

[Peter]

I don't see how the old model thermostat (still used in my TDI) can ever fit in the housing and hoses shown in the workshop manual. The black cilinder thermostat is held in place by a clip, much like the clip used on my G2/G62 sensor, and there is an O-ring involved...

http://workshop-manuals.com/audi/a2/power_unit/4-cylinder_petrol_injection_engine_(1.4_ltr.)_mechanics/engine_cooling/cooling_system/removing_and_installing_thermostat_housing_and_coolant_pipe_(rear)/

This probably is a later model housing / hoses / thermostat.

The previous page in the workshop manual shows the "traditional" model thermostat and housing.

 

[jonbad]

I don't see how the old model thermostat (still used in my TDI) can ever fit in the housing and hoses shown in the workshop manual. The black cilinder thermostat is held in place by a clip, much like the clip used on my G2/G62 sensor, and there is an O-ring involved...

http://workshop-manuals.com/audi/a2/power_unit/4-cylinder_petrol_injection_engine_(1.4_ltr.)_mechanics/engine_cooling/cooling_system/removing_and_installing_thermostat_housing_and_coolant_pipe_(rear)/

This probably is a later model housing / hoses / thermostat.

The previous page in the workshop manual shows the "traditional" model thermostat and housing.

Hi Peter, thanks for your reply. Unfortunately, I've not managed to take a photo today, but I will try to tomorrow as it demonstrates in a split second what 1,000 words cannot! So, please bear with me and my descriptions…

1. The instructions on this page: Workshop manual Audi A2 thermostat replace show the setup I have almost exactly.

2. In the last picture on that page (showing the thermostat in situ) my car instead had a traditional style thermostat (like this: pic link ) and NOT like the one shown in the Audi manual (like this: pic link )

3. To summise, I have the conventional type thermostat installed but the setup shown with a different thermostat. However, I cannot see how the type I am 'supposed' to have would actually work, as it doesn't appear to seal the water jacket around the engine, whereas the traditional type seals the thermostat housing hole entirely and is held in with an O-Ring.

I hope that makes my explanation clearer!

EDIT: Also, looking at the page you sent, it only shows the thermostat housing being removed - NOT the thermostat itself, they've kept that on as you can see in image A19-10679. Also, there is no clip holding the thermostat in place. The O-Ring that comes with the black cylinder thermostat seals the thermostat housing cap, not the thermostat itself.

 

[spike]

Strangely, the parts list shows alternative thermostats and housings but no supersession dates or compatibility rules - http://audi.7zap.com/en/rdw/audi+a2/a2/2002-248/1/121-121075/ Don't know if it applies to the A2 but in production, parts shortages or quality problems can sometimes lead to different build specs being used

An Audi dealer should be able to quote the parts used on your specific engine from the VIN number.

Cheers Spike


Cheers Spike

 

[jonbad]

Strangely, the parts list shows alternative thermostats and housings but no supersession dates or compatibility rules - http://audi.7zap.com/en/rdw/audi+a2/a2/2002-248/1/121-121075/ Don't know if it applies to the A2 but in production, parts shortages or quality problems can sometimes lead to different build specs being used

An Audi dealer should be able to quote the parts used on your specific engine from the VIN number.

Cheers Spike

Thanks Spike - that is interesting indeed. I guess then that my car just happens to be one of those fitted with the more traditional type of thermostat rather than the black cylinder type. What's confusing is the black cylinder type does fit in the hole (it's narrower, so no surprise) but it does locate in a plastic ring at the back of the thermostat housing. However, it's not a seal, just a locator so water is free to travel all about it. The thermostat housing cap then has nothing to hold it in place either, so I guess I'll just replace like for like. My real concern was more that the thermostats run at different temps - one's 82/83º and the other 87º. I wondered if therefore there'd be any advantage to running the engine slightly hotter (perhaps more efficient?) with the black cylinder type thermostat - but looks like it's not the right one unless I change the thermostat housing and cap!

 

[Peter]

Spike's picture lists both models (metal 83 degrees 032 121 110 F and plastic 87 degrees 032 121 110 B) and also shows different covers (...G and ...K).

I see the "traditional" model thermostat being offered with both 82/83 and 87/88 degrees opening temp and both suggest they replace OEM number 032 121 110 F ...

So if your cover accepts the traditional metal model, I would get an 87 degrees version of the traditional model.

 

[jonbad]

Thanks Peter, that makes sense. Having gotten to the bottom of it, I hope this info is useful to others!

Mine definitely doesn't have the cap for the black cylinder type thermostat. I've found a picture of one here: http://www.itacua.com.br/produtos/itacua_666891081-032121121.jpg

Mine is NOT like that, so definitively the traditional type is the one for me. I can't find an 87° traditional type on first glance at the usual places though, so may end up fitting the original 82/83° type - that ran perfectly well for years, of course! I wonder if there's any advantage to replacing the actual thermostat cap in order to fit the black cylinder type thermostat.

Anyway, thanks again for your help and advice.

 

[a2a]

Sorry to dredge up an old thread here, but it comes up top on Google when you search.

I wanted to share my own practical experience:

• I needed a new thermostat
• After the uncertainty here, I wanted to order from Audi
• I rang them, gave them the VIN/Reg, they were adamant I needed to black plastic tubular type of thermostat BUT then said the metal disc type would fit my car too (!)
• Something smelled off and the thermostat was £50, so I didn't order
• I checked Autodoc both types of thermostat were less than £10, so I ordered both
• Getting the car in bits today, it was the metal disc type I needed, and there's no way the black plastic tubular type would have fitted my car
• The type that fits is determined by the thermostat housing cap. They suit one style of thermostat or the other. The thermostat housing itself appears to accept both styles.

 

[Axit]

I have a 2003 1.4 BBY, and got my thermostat from Audi. they listed both thermostats for my car but I opted for the traditional type.
On inspection the same type was already installed in the car, which I replaced with my new one and had no problems since.

 

[Tomscar]

Just sharing my experiences from a few years ago and hadn't seen this thread started by Jonbad above.

The thermostat housing supplied on the 1.4 BBY with part number 32121111AM is common to both the metal disc and the plastic cartridge type, the difference is only in the retaining cover.
The cartridge type is inserted into an internal molding in the housing and clamped down by the corresponding cover, this internal molding is redundant when using the metal traditional thermostat and is a twist fit into it's corresponding cover.

Both covers fit to the housing using the same bolts but the covers aren't interchangeable between types of thermostat.
The plastic cartridge version (87° Henschel) uses the Henschel 032121121K cover and the metal (83° Himmermann) uses the Himmermann 032121121G cover.

The widely available Topran 110350 housing is a direct replacement for the Audi thermostat housing 32121111AM and for anyone considering doing it themselves can confirm that it is suitable for either type of thermostat providing the correct cover is used.

Would recommend using original thermostat type matched to your car,
this can be checked through your VIN. Mine didn't give enough heat through the vents when using the non original metal type but sprung to life using the correct one ... live and still learning.

Hopefully added a bit of light to the subject.

 

[Joga]

Just sharing my experiences from a few years ago and hadn't seen this thread started by Jonbad above.

The thermostat housing supplied on the 1.4 BBY with part number 32121111AM is common to both the metal disc and the plastic cartridge type, the difference is only in the retaining cover.
The cartridge type is inserted into an internal molding in the housing and clamped down by the corresponding cover, this internal molding is redundant when using the metal traditional thermostat and is a twist fit into it's corresponding cover.

Both covers fit to the housing using the same bolts but the covers aren't interchangeable between types of thermostat.
The plastic cartridge version (87° Henschel) uses the Henschel 032121121K cover and the metal (83° Himmermann) uses the Himmermann 032121121G cover.

The widely available Topran 110350 housing is a direct replacement for the Audi thermostat housing 32121111AM and for anyone considering doing it themselves can confirm that it is suitable for either type of thermostat providing the correct cover is used.

Would recommend using original thermostat type matched to your car,
this can be checked through your VIN. Mine didn't give enough heat through the vents when using the non original metal type but sprung to life using the correct one ... live and still learning.

Hopefully added a bit of light to the subject.

When I checked with my local Audi dealer they could actually not deduce from their system what thermostat type my car had from factory. Can your dealer?

 

[Tomscar]

When I checked with my local Audi dealer they could actually not deduce from their system what thermostat type my car had from factory. Can your dealer?

Hi Joga, I presume so but I thought they were all linked to the same system ... they took the VIN and came up with the 87° Henschel thermostat for mine and didn't mention the other type.
I wonder if there's a cut off date for the other type on the Audi system, mine was built in July 2002.

Not sure if it influences fuel economy, can't see Audi using the more expensive cartridge without making some marginal gain but where it made a noticeable difference was the cabin heating ... metal type gave just cool air and plastic was hot.

I should also add that Autodoc's Topran housing came preassembled with the (wrong for me) metal thermostat and not as described on the website.
A bit of head scratching before realising what was going on but it works great now.

 

[a2a]

@Tomscar - While I have your attention here, do you have any tips for replacing the thermostat housing please? Access is rather tight!

I have all the pipes off (including the 3 smaller ones at the back for the heat exchanger - 7,8, 11) but I can't for the life of me get decent access to where coolant pipe 14 fixes into the thermostat housing (15):

Clip number 10 has been inserted from the bottom. Working from under the car I can get a fingertip to it but can't see a thing once my hand is in there. I'm not so confident I could get it back together with one hand!

I'm replacing it because someone's had a go a changing the thermostat before, but stripped the thread where bolt 2 keeps the thermostat cover in place

 

[Tomscar]

Hi A2A, just picked up your message.
Access is tight if you're removing that clip (no.10) and think it's near impossible to get it back in from below.
If you've already got all the pipes detached then you're heading in the right direction, I think it's easier if you leave the coolant pipe (no.14) attached to the housing.

That coolant pipe is a push fit into the back of the water pump outlet and has an O ring (no.13) making the seal.

There's a cable attached to the coolant or 'death pipe' that needs detached first and easily accessible from underneath.

Remove the C clip when the thermostat housing is out of the car, much easier to pre assemble and re fit the new housing that way.

I'll check in tomorrow if you need any more

 

[a2a]

If you've already got all the pipes detached then you're heading in the right direction, I think it's easier if you leave the coolant pipe (no.14) attached to the housing.
That coolant pipe is a push fit into the back of the water pump outlet and has an O ring (no.13) making the seal.
There's a cable attached to the coolant or 'death pipe' that needs detached first and easily accessible from underneath.
Remove the C clip when the thermostat housing is out of the car, much easier to pre assemble and re fit the new housing that way.

That's awesome help, thank you

I found the workshop manual last night (I'm new to A2s) and found it recommended taking off the driveshaft and EGR stuff. I didn't really want this to be a big job, so I'm glad I can do it without doing that!

I'll have another go at this tomorrow and will report back.

 

[Tomscar]

That's awesome help, thank you

I found the workshop manual last night (I'm new to A2s) and found it recommended taking off the driveshaft and EGR stuff. I didn't really want this to be a big job, so I'm glad I can do it without doing that!

I'll have another go at this tomorrow and will report back.

You're welcome a2a, always happy to share experiences.

Definitely no driveshaft removal involved but I think you may have to remove the two bolts from the tube that links the EGR where it attaches to the Throttle Body, this allows enough movement to remove the old housing ... more expense then as you should replace the diamond shaped metal gasket between throttle body and tube. If you can remove the housing without doing this then that's a bonus.

The tube that links the EGR to the Throttle Body is attached to the thermostat housing by a single self tapping bolt, similar to the ones that hold the thermostat cover in place.

The gear selector needs to come off for access but you can leave the two cables attached.
I marked the position of the gear selector by removing the 13mm nut from the selector shaft and painting across with tippex and marking a pen line to realign the splines when re-installing ... don't be put off as it's an easy process to set the cables again if the gears don't select properly, I do mine routinely as part of servicing and it's satisfying to end up with a nice gear change ... the process is well documented on the forum or I can walk you through it.

Another tip is to have three new bolts to hand when re-installing the housing, easily destroyed trying to get them out ... you can angle a small mirror to locate the bottom bolt (no. 16) otherwise you're doing it blind.

Just out of curiosity, do you know which thermostat is in the old housing?

Mine's a July 2002 1.4 BBY with the newer plastic cartridge type.

As mentioned in a previous post, each type of thermostat will fit the Topran housing providing you use the matching cover and if yours has been changed already then try using the VIN at the dealership to get the correct one.

Not a job I'd like to do too often and bought genuine Audi thermostat and cover for peace of mind ... although much less expensive bought from a Skoda dealership!

All the best ... Tom

 

[a2a]

I'll have another go at this tomorrow and will report back.

I'm struggling with this one a bit Tom! I'm pulling the thermostat housing as hard as I dare (all unbolted and disconnected) whilst wiggling it, but can't get the long tube (14) free from the water pump end.

It's definitely just a push fit yeah?

Also, did you find it necessary to renew the o-rings on the long tube (14)?

 

[Andrew]

I'm struggling with this one a bit Tom! I'm pulling the thermostat housing as hard as I dare (all unbolted and disconnected) whilst wiggling it, but can't get the long tube (14) free from the water pump end.

It's definitely just a push fit yeah?

Also, did you find it necessary to renew the o-rings on the long tube (14)?

Good Afternoon,

You did unclip the knock sensor wire?

A further suggestion here.

Death Pipe hanging on for grim death!

Urgent Answers please. I am replacing the death pipe and thermostat housing on my 1.6FSI. I have everything off the car, as per manual, and have even got the thermostat housing off , but I simply cannot get the Death Pipe to come out of the engine block at the Water Pump end. I can't see...

www.a2oc.net

Andy

 

[a2a]

Good Afternoon,

You did unclip the knock sensor wire?

A further suggestion here.

Death Pipe hanging on for grim death!

Urgent Answers please. I am replacing the death pipe and thermostat housing on my 1.6FSI. I have everything off the car, as per manual, and have even got the thermostat housing off , but I simply cannot get the Death Pipe to come out of the engine block at the Water Pump end. I can't see...

www.a2oc.net

Andy

Thanks Andy, it looks like I can be more brutal with it!

I'd forgotten this pipe was the same on the 1.6L too.

I've had a good look and feel around and can't see any cable clipped, just a redundant clip

 

[Tomscar]

I'm struggling with this one a bit Tom! I'm pulling the thermostat housing as hard as I dare (all unbolted and disconnected) whilst wiggling it, but can't get the long tube (14) free from the water pump end.

It's definitely just a push fit yeah?

Also, did you find it necessary to renew the o-rings on the long tube (14)?

Hi A2A, just double checking that you've removed the self tapper that fixes into the housing through a tab on the metal tube that connects between EGR and Throttle Body ... I'm sure you have.
Definitely a push fit and sealed with a square section O ring into the water pump housing ... it's possibly never been removed before but it's only the rubber seal that's holding it, should give way.
I replaced the tube (14) along with the housing for peace of mind but sounds like you might destroy your seal on removal.
Have you tried WD40 ...maybe help to free it up?