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Metal Thermostat Housing Upgrade; An Essential Modification
Topic Started: Sat Nov 14, 2009 2:34 pm (21,284 Views)
Neil
Newbie
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As many of you know, the standard Thermostat Housing fitted to the W201 when new was made of a Plastic/Polycarbonate-type material, and is susceptible to cracking and leaking in old age.
The worst case scenario is that a hairline crack can give way under heat, and the whole housing simply break open.
If this were to happen, you'd lose most of your Coolant. Nightmare.

Posted Image

So, for a while I had been intending to replace my original housing with the updated all-Metal unit from Mercedes-Benz.
A couple of days, whilst Andy was working on the car, Steve noticed a little limescale deposit and a drop or two of water around one of the 3 fixing points on the housing.
Looked like it was weeping, and it was this that spurred me on to get it sorted asap.

Parts required for this upgrade on an M102 8-valve:

A102 203 03 74 - Metal Thermostat Housing Cover x1 - £27.50 +VAT
A102 990 00 88/28 - Banjo Union x1 - £3.30 +VAT
N000 000 004 895 - Hollow Screw x1 - £1.70 +VAT
A015 997 23 48 - Seal Ring x1 - £1.35 +VAT
N007 603 008 106 - Seal Ring 42010103 (Copper Washers) x2 - £0.50 each +VAT
N304 017 006 019 - Screw x3 - £0.80 +VAT each (You should buy these in case you shear off the old fixing screws)

In total, you will spend about £42 inc VAT.
Obviously, you should give the Dealership your chassis number when ordering parts as some items will differ between types of W201 engine.

After removing my old Housing, I could see the crack easily:
Posted Image

Here's the tell-tale dried-up coolant/limescale:
Posted Image

Here's the new Metal Thermostat Housing, fitted to my 1.8-litre M102 engine:
Posted Image

Up close, you can see how the Banjo Union and Copper washers fit together.
The Hollow Screw holds the Banjo Union on, and allows Coolant to flow around inside it.
Posted Image

An essential modification to any W201 imo, to be quite honest I think I was very very lucky that Steve spotted the damage to mine
and if it blew in Traffic I'd probably kill the HG at the same time.

Hope this is a useful thread :)

Edited by stwat, Mon Aug 7, 2017 11:42 pm.
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Johnboy Mac
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Good info Neil, another item on the to do list, thanks! No, I reckon it's well worth doing.
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balamb37
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Handy Post Neil
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RobertE
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I've posted on this re. electric fans. There are two vital areas where the plastic cooling parts can fail - one is the thermo housing and the other is the rad. itself. Temperature extremes are not good for these parts, and they are under load all the time. I recommend that everybody swaps the thermostat housing for a new (metal) one. It takes minutes to do...
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Neil
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If anyone is doing this with an engine other than a 1.8-litre M102, perhaps they can post their Part Numbers for the various specific parts in this thread?

Cheers
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Richy190E
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Great writeup Neil, I can vouch that it is a nightmare when it grenades at 80+ MPH on the southbound M6 at 3am in the rain!
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Nathan
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On detali it has A1022000417 (£6.68) for the thermostat housing for the 2.5-16. Seems too cheep to me, anyone know if this is for the metal or plastic one?
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Will
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Nath_XPR
Sat Nov 21, 2009 2:25 pm
On detali it has A1022000417 (£6.68) for the thermostat housing for the 2.5-16. Seems too cheep to me, anyone know if this is for the metal or plastic one?
IIRC that is for the original plastic type which *should* have been discontinued by now.

I fitted a metal replacement one to a 2.5-16 a couple of years ago and it was likewise about £20 or so.

There could be the odd plastic type sitting on a dusty MB shelf somewhere I guess.

From what I remember, the M103 has used the metal type for a long while now and are quite a bit cheaper too.

Only snag with fitting these is that the retaining bolts are quite often stuck. Steel bolts into an alloy housing, combined with heat cycling and probably twenty years of sitting there can be a recipe for disaster. Proceed with care as you undo them, despite using caution I had two shear off and had to remove the thermostat housing to drill the old remains of the bolts out carefully on a pillar drill and clean the threads up with a tap.

Not the end of the world, but it can make a ten minute job a bit more tricky ;)

Similar problems can be had with the distributor cap retaining bolts.

Will
Edited by Will, Sat Nov 21, 2009 2:34 pm.
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Neil
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Will
Sat Nov 21, 2009 2:34 pm
Only snag with fitting these is that the retaining bolts are quite often stuck.
Steel bolts into an alloy housing, combined with heat cycling and probably twenty years of sitting there can be a recipe for disaster.
Proceed with care as you undo them, despite using caution I had two shear off and had to remove the thermostat housing to drill the
old remains of the bolts out carefully on a pillar drill and clean the threads up with a tap.

Not the end of the world, but it can make a ten minute job a bit more tricky ;)
I got lucky, bolts and threads in perfect condition.
Good job too, as MB had only 1 spare bolt for me to buy.
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Will
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NEIL
Sat Nov 21, 2009 2:38 pm
Will
Sat Nov 21, 2009 2:34 pm
Only snag with fitting these is that the retaining bolts are quite often stuck.
Steel bolts into an alloy housing, combined with heat cycling and probably twenty years of sitting there can be a recipe for disaster.
Proceed with care as you undo them, despite using caution I had two shear off and had to remove the thermostat housing to drill the
old remains of the bolts out carefully on a pillar drill and clean the threads up with a tap.

Not the end of the world, but it can make a ten minute job a bit more tricky ;)
I got lucky, bolts and threads in perfect condition.
Good job too, as MB had only 1 spare bolt for me to buy.
I luckily bought three new bolts as I had an idea that they'd be tricky. I guess it could have gone worse, all three could have snapped! :lol:

I think the heat cycling makes the bolts soft and the steel-alloy probably causes them to sieze.

This was during the cylinder head overhaul on my 2.5-16 auto and was the only snag I had on the whole job. Every other bolt and fixing came apart with absolute ease despite being twenty years old. The bits I expected to cause trouble didn't (eg, the downpipe bolts, nuts/studs on the manifold etc) and then just two easily accessible bolts like this let go!

Will

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RobertE
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Those bolts could be of better quality, I must say. I had the same issue with the 2.5 and I'm anticipating more of the same. It's electrolytic corrosion, which is weird, because despite effectively bonding two different metals at a tiny temperature (compared to welding) it also weakens both of them. The Alloy goes cheesy and horrid and the steel goes brittle and I know, having run several Astons, how damaging it can be in all departments.

I dislike thermoplastic intensely - it works until it doesn't, and then, when parts which are light (v.good) and cheap to make in volume (v. good) let go, the result is a wrecked engine (v.v.v. bad). I'm considering commissioning some all metal radiators along the lines of those alloy ones they (Marstons) built for E type Jags.

Hence my mini-crusade re. auxilliary fans..
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Richy190E
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When I did mine I replaced the bolts with stainless, not sure whether it will have a great effect but I had a packet of them on the shelf.
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RobertE
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I think that's a sound idea, if only because it's a total p.i.t.a. to have to sort it all out when the bad thing happens. I was going to change the thermostat anyway, so what I ended up doing was breaking the plastic cover with the Irish spanner (which scrapped the old thermostat anyway) and then using the Faithful Fluid to lubricate before hoiking the bolts out the next day. But what a performance!
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kentronix
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I'm only really here for the Kitchens

And remember folks, there is a rubber inside, there is no need to do the bolts up too tight.

I learnt from my scirocco's catastrophic coolant failure that its important to have a weak point so any problem and you dont blow every single element in your system at the same time but it clearly shouldnt be this part. Hopefully there is a plug somewhere. Will add this to the tutorial list thread.
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shariffe
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i had it plastic one go on me when drove to slovakia, i was stuck i traffic when i noticed the coolant light came on and that part broke into two parts. problem was they dont have 2.6 190s there so i had to get 300e 1 which fit, untill i got back to england.





So change it......
Edited by shariffe, Sat Nov 21, 2009 7:51 pm.
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chrismatheou
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Worth noting that on the diesel engines the thermostat housings are all metal.
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G3MAW
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Hi Neil,
A signal service to the forum,indeed. Can I just add a rider for anyone purchasing this mod. from an MB dealership - the two copper washers ( N007603008 106 - Seal ring 420103 ) don't show up on their database as part of the mod. They are essential to provide an effective seal on both faces of the banjo fitting when the hollow screw is fitted. The failure of the plastic cover, however, has become legend on their side of the counter.
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Neil
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G3MAW
Sun Nov 22, 2009 11:18 am
Hi Neil,
A signal service to the forum,indeed. Can I just add a rider for anyone purchasing this mod. from an MB dealership - the two copper washers ( N007603008 106 - Seal ring 420103 ) don't show up on their database as part of the mod. They are essential to provide an effective seal on both faces of the banjo fitting when the hollow screw is fitted. The failure of the plastic cover, however, has become legend on their side of the counter.
True - was the case when I went to collect my parts.
Somebody else had prepped my order over the phone, and when I went to collect the sharp-eyed fella on the counter spotted the washers were missing, and got straight onto the EPC to find them.

MB Colindale are good, no probs from them so far.
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Karlos28
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just been and bought this mod, just copied all those part numbers and all seems good so far, but iv not fitted it yet!

only thing diffrent was the prices, i paid about 60 quid for that lot!!!
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Richy190E
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karlos...£60 is cheaper than a head gasket mate :)
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Tim29
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They must have just gone up in price, I had it all fitted on the 23/12/09 it came to £34.80 for the parts. All genuine Mercedes...its like the jacking point rubber that's approaching £20 now, it used be just a couple!

Tim
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Karlos28
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Richy190E
Fri Jan 8, 2010 4:15 pm
karlos...£60 is cheaper than a head gasket mate :)
very good point!

its not getting up to temp properly so i needed to change the thermostat anyway!

im quite impressed how i can turn up to a dealer and walk away with parts for a 20 yearold car! i go to stockport but if they havnt got it about 10 mins down the road is manchester who usualy do have it!
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stwat
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Tim29
Fri Jan 8, 2010 4:18 pm
They must have just gone up in price, I had it all fitted on the 23/12/09 it came to £34.80 for the parts. All genuine Mercedes...its like the jacking point rubber that's approaching £20 now, it used be just a couple!

Tim
I think mine cost me about £18 all in for everything!!
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MadMike
Therapy Needed
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Just checked mine.


I paid £48 92 for all of it, and the receipt is dated,5/11/2007.


So I think that price ic about right.
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Karlos28
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god! how is there so much diffrence!?
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aemt
Serial 190E Owner
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Ok checked the part No with MB Colindale at weekend and the one supplied for my 2.6 is correct even though the part No is strange ( 104). Part No is 1042030274

Price paid to MB Oxford £8.57. The part No ordered was A1032030774. MB Colindale say it is one and the same part.

Other bits and pieces to go with it came to about £2.5 (seals new bolts etc)
Edited by aemt, Mon Mar 1, 2010 7:14 pm.
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Nathan
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I think this should be pinned.
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Neil
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Information from member PARI:

these are what i bought for my 2.6, not a 2.0

copper seal ring MN007603 008109 x 2 @ 0.80p each
Banjo union MA102 990 0088/28 x 1 @ 3.50 each
Housing Screw MN304017 0060019 x 3 @ 0.90 each
Hollow screw MN000000 004895 x 1 @ 1.90 each
Thermostat MA110 200 05 15 x 1 @ 14.30 each
Metal Housing MA103 203 07 74 x 1 @ 8.10 each
^^ that was part number on invoice but part number on the actual housing was 104 203 0274

Like i said before you can probably source cheaper copper washers and and housing screws. plus i also used washers for the housing bolts which were not included.
If you are not changing thermostat with the housing then you will need a searl ring which is around 0.60p from merc
But if you are not really bothered about using MB Genuine parts then GSF and ECP could be cheaper,
every little helps. This is a doddle, and you should find changing it no probs.

I changed the poly thermo housing to a shiny metal one with a new thermostat.
total time it took was 15 mins so a very easy job and one that should be done if you currently run with a poly housing, mine wasn't craked but was weeping somewhere.
Tools for the job a flat screwdriver for jubilee clips, 10mm socket or T key for 3 housing bolts and a 12mm spanner or socket for the hollow screw.
Oh and do it when the engine is coolant cold not like me when its piping hot lol, otherwise you will scaled your hands.
Must admit it looks better now, just remember to put a washer between the housing and bolt, MB didnt provide any but its good practice to do so.


Posted Image

Posted Image
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balamb37
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Next time I go in to Carlisle mine is on the agenda, could order by phone as they deliver post free but prefer to collect myself to be sure I get all the parts.
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Nathan
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Parts and prices for the 2.5-16;

Thermostat       A1102000515 £15.23
Cover               A1022030374 £30.24
Union               A102990008828         £4.12
Top Screw       N000000004895         £2.17
Base Screw      N304017006012         £1.00 each 3 required  
Base Washer    N000137006204         £0.42 each 3 required

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Richy190E
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I thought I would mention that FEBI have added this item to their catalogue.

Housing - 30080 - thermostat housing, replacing part number A102 203 03 74 £13ish


Fittings - 30076 - mounting kit For thermostat housing with screw kit and gasket, replacing Mercedes Benz part number A102 203 99 74 £11 ish

Thermostat kit - 9671 is about £14,
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unforgiven
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Hi friends. I'm new to the forum members. Thank you to everyone who played a part in the forum. my 91 model 190 e 1.8 you have a car. thermostat cover and I were welcomed with the result of cracking. I have provided a metal lid from a second hand. I add paintings. Remove the metal cover instead of the old plastic cover alone, I wear only when you need any other track, Will? at the beginning of the subject

"A102 990 00 88/28 - Banjo Union x1 - £3.30 +VAT
N000 000 004 895 - Hollow Screw x1 - £1.70 +VAT
A015 997 23 48 - Seal Ring x1 - £1.35 +VAT
N007 603 008 106 - Seal Ring 42010103 (Copper Washers) x2 - £0.50 each +VAT
N304 017 006 019 - Screw x3 - £0.80 +VAT each (You should buy these in case you shear off the old fixing screws)"

friend, he gave a list of part number. Remove the plastic cover instead of metal parts for attaching the cover to the above list, do I need? If the screws used a plastic cover, will you? Sorry for the English is broken. Thank you.

Posted Image
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jamaks
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Greetings Everbody, just replaced the thernostat housing myself and think the price was reasonable compared to some of the prices I've seen mentioned.
Febi Bilstein part No 34700 comprising thermostat housing 102 203 03 74 52 and the banjo joint copper washers and hollow bolt 102 203 99 74. Thought it may be beneficial to pass on the link:
Code:
 
http://www.micksgarage.com/
Based in Dublin but parts arrived within two days.
Regards. Jim
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Nastynick
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Where can I get the part numbers for all thes parts, BUT for a 2.0 non aircon, engined W201?
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RobertE
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I think that they are all the same; certainly, valvers and 2.6s use the same one...
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stwat
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Nastynick
Mon Aug 5, 2013 6:14 pm
Where can I get the part numbers for all thes parts, BUT for a 2.0 non aircon, engined W201?
The very first post has all the part numbers needed.
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Mark_P
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Once again I am indebted to my fellow lovely W201 people.

I changed the drive belt today and noticed the thermostat cover was leaking.

Popped on the forum and within five minutes I have all the info I need to sort it.

Marvellous :D
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kentronix
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I'm only really here for the Kitchens

Make sure you get new bolts and dont over tighten, they snap very easily and are a pain to drill out if they do.
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Mark_P
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kentronix
Wed Sep 10, 2014 5:55 pm
Make sure you get new bolts and dont over tighten, they snap very easily and are a pain to drill out if they do.
Ordered the Febi kit today; will report on how good it is.
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Parisien
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So the numbers listed at the start will also do the 2.0 litre engine?

P
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