Okay... I am calming down now, but boy do I feel like a complete idiot.

I was having issues with my '99 E300 Turbodiesel running very cold over the last week. Temp gauge would not climb over 55C, no water weeping out of the pump, plenty of coolant in the system, and not much heat in the cabin.

Upper and lower hoses warm, but not hot on 30-50F days.

This makes me think that the thermostat must be stuck open. I do a bit of research and yes, the thermostat fails open as it should, low temps are indicative of a filed thermostat on this car.

So I order a new thermostat and gasket and think that I'm read to go.

Car on ramps, cowls off, coolant cap off, vinyl drain tube on radiator drain into a nice clean bucket. Try to loosen radiator drain plug and plug head simply falls off in my hand.

Okay... minor setback right? Order new drain plug, wait two days for drain plug, loosen remaining old drain plug, coolant draining.

Is thermostat stuck? Drained about 7 liters out of radiator drain plug. System holds a little over 7, guess that thermostat is stuck open and block drained through the thermostat.

Cover alternator with plastic bag, put drip pan under engine, remove heat shield from exhaust manifold, remove thermostat bolts, just a little fluid drips out. Try to pry out thermostat from housing....

Darned thing is in there tight!! Loosen hose clamp and pull housing from hose. Now have housing and thermostat out of car.

Compare new thermostat with old... HUH!!?! What the heck (rated G version)?!? What kind of "blippity-blipp-blipp" design is this?!? The thermostat is designed as part of the housing or vice-versa!! In order to replace a failed thermostat, you have to order a new housing!!

I swear Gottlieb and Karl are rolling in their graves, or at least I would if this design made it into my project(s).

Now I have to wait for a new housing to come in so that I can put my car back together.

The more I work on this '99 the more I feel that the '77 240D is the keeper and the '99 will be traded in on a Toyota.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

That's odd that your 99 doesn't have the updated housing. My 98 has the new one. Or, at least I think it does. It was a standard setup when I replaced the thermo. a couple years ago.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

LOL

__________________
Jim

It would bother me so much, but what is typically an hour long job with the W123, turns in to weeks with this car due to all of the little "gotchas" involved.

Just frustrating.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

There have been posts on here for years saying that you had to replace the housing along with the thermostat if the OE one was still on there. In fact just a week ago I reminded someone of that fact. You need to be like some of us losers who have no life and spend more time here.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

I agree. Spending more time here might mean less time under the hood.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

I did not know this, but do now. I plan coolant & hose replacement soon, but will wait on WP and tstat failures before replacements.

I should aspire to being a better loser, and spend more time here.

Don't give up on the 99 it is a great car.

__________________
Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW

But once you change the OE housing out, thermostat changes after that are just like the old days. No need to change the housing again.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

I plan on doing this change this summer with a coolant flush. Is there a way to tell if its the original housing unit or updated already before removal?

__________________
1999 E300 TD 190,000
1996 Passat TDI 225,000-sold
1996 E300 120,000-sold
1998 Jetta TDI 186,000 -sold
1983 Chev Suburban C20 6.2-sold

The original thermostat/housing unit on mine had a 606 203 stamped on one side of the housing and Wahler stamped on the other side. Too dark outside now to go look at the new housing, but it is part #603 203 04 74 and is under $20.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

Here are photos of the original and the replacement housings from my '99 E300D.

Attached Thumbnails

   

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

Thanks, mine has 606 203 on it and "made in Germany". I must have the original as well.

At least I can learn from your pain.

__________________
1999 E300 TD 190,000
1996 Passat TDI 225,000-sold
1996 E300 120,000-sold
1998 Jetta TDI 186,000 -sold
1983 Chev Suburban C20 6.2-sold

Sokoloff,

At what mileage did you replace the Tstat & housing? Did it fail, or did you replace in preventative manner ?

Mine must not be original, as I have no writing on top side of housing.

__________________
Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW

Yea, but in the end when both are running, the '99 is such a nicer car. Of course, nothing can be done with that Taurus-looking rear end, but the smoothness and creature comforts do make a difference....

A thermostat made into the housing???? What German guy over-thought that one??

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

...and then get that '99 "chipped", maybe defeat the EGR, and you'll never go back. A few surprise like this are worth it when it can throw you back in the seat and still get 30 mpg!