1992 300d thermostat
 

Hi, can anyone give me some directions on how to change the thermostat on my car. I want to change the coolant and the thermostat also because the car is getting hot very slow, it reaches 85 C in about 10 minutes of driving. Any advice and pictures are appreciated.

Thank you

Does it go any higher with the A/c on and getting on the turbo?
 

Might be the thermostat?
How many miles on the car. Still the original fan clutch (viscous coupling) on the fan? Still have the original radiator? Just did both of mine not too long ago, very common. Do a search there are many posts on the subject.

May want to check for residual pressure in the top hose after you shut the car down (the hose should go soft). Also check the fan clutch. Start'er up then have someone shut'er down while you look at the fan for excessive spinning (1 to 2 spins and should stop). Grab a hold of it also and make sure the bearing is good(no play or slop).

More info
 

Sorry about that, I forgot the details. The car has 260000 miles and I bought it 3 months ago and no history. The fan clutch is working and I don't see any problems with the radiator (no leaks). Now with the cold season coming I just want to change the coolant (last change unknown, current coolant looks like distilled water) and the thermostat so I can check them off my TO DO list and get ready for winter. Also the temp gets a little higher with the AC on but I never reached 90 C so that's why I was thinking about the thermostat. As for heat inside the car I have hot air blowing inside in about 5 minutes after starting in the morning and driving.

All I wanted to know is the location of the thermostat and if any special precaution in changing it.

Thank you.

Clean the radiator fins, flush the radiator thoroughly, change the thermostat as well as the VDO temp sender and also check the ground of the vehicle.

It's located on the lower passenger side of the block (towards the front of the car). I just changed mine out when I got my car back in April. It's a straight forward job. Just make sure to tighten the housing bolts evenly and not too tight. Watch for leaks after you install the new t-stat.

Any recommended chemicals for cleaning the fins and for flushing the radiator, or any product will work. Also where is the VDO temp sender , I could change that also if I am working on it.

Thank you

Thank you SW, I kind of figured it was there I was not sure thaw.

I use Castrol degreaser which removes dirt and grime quite well from the fins. The temp sender is on the right side of the engine block close to the firewall.

Thermostat
 

Thermo and it's O-Ring are # 77
(Make sure you use a new O-Ring)
10 Newtonmeters Torque on the bolts that secure the Thermostat housing.

So,It's on the right (Passenger) side of the Water Pump Assembly.

Thank you compress ignite, that is a great picture.

If there's a temp sensor just ahead of the thermostat, it might help to remove the temp sensor so you can remove the radiator hose fitting more easily. In some applications there's just enough room to slide the radiator hose fitting forward and out. No room to pull it directly away from the block. Mind you remove only radiator hose fitting bolts, not the thermostat housing bolts. Doing so you might upset the gasket between the thermostat housing and the block.

Sixto
87 300D

Coolant
 

I do have the temp sensor just in front of the thermostat housing, I did not start on changing it because I a still waiting delivery on the thermostat and the o-ring so I haven't looked in detail at the housing , but after looking at the diagrams that compress ignite sent I see only 2 bolts that hold the t-stat housing, but I will go tomorrow and take a good look and see if there are any other bolts. Also I found that for coolant I can use Zerex G05 from Pep Boys, is it gonna work or you have other suggestions for coolant fluid.

Thank you

Zerex G05 works for me.

All the sites say you need an o-ring and all the sites send you a thermostat with an o-ring in the box. Go figure.

I've never worked on a 602 thermostat. 603 has 2 bolts.

Sixto
87 300D

Change time on Sunday.
 

Thank's everybody for the input. This weekend I'll take it off.

Finished
 

I got the t-stat out and replaced it, no wonder the temp was not going up, somebody drilled 2 holes in the old t-stat.

Until now works ok, I'll see how it behaves in the next days, after I hit some traffic and see how much the temp will go up.
Also I use the original mercedes benz coolant , it's only 23 $ a gallon.

Thank you