C-280 heating blowing lukewarm air - PeachParts Mercedes-Benz Forum

willp621 · #1 01-26-2009, 09:58 AM

My 1995 C-280's heater is blowing lukewarm air, even when set to "hi." The tengine temp guage is also indicating lowere than normal readings when engine is hot. The blower fan and all controls seem to be functioning OK.

Any suggestions?

jlomon · #2 01-26-2009, 10:18 AM

Quote:

Originally Posted by willp621

My 1995 C-280's heater is blowing lukewarm air, even when set to "hi." The tengine temp guage is also indicating lowere than normal readings when engine is hot. The blower fan and all controls seem to be functioning OK.

Any suggestions?

Your thermostat could be stuck in the open position, which prevents the coolant from reaching operating temperature - that would explain your lukewarm heater air and the fact that your temp gauge is also reading low.

willp621 · #3 01-26-2009, 10:46 AM

Is it an easily replaceable item ( i.e. do it yourself)?

Where is it located.

TX76513 · #4 01-26-2009, 10:50 AM

Follow your upper radiator hose.

willp621 · #5 01-26-2009, 11:10 AM

OK. The hose connects to a housing at the top of which is a round cover about 2 1/2 inches in diamter with 3 bolts holding it. Adjacent to the cover are a couple of electrical plug-ins. Is the thermostat located under this cover and is there any trick to replacing it?

I see that these thermostats are available here online ranging from $13-20.00

thanks

TX76513 · #6 01-26-2009, 11:15 AM

Straightforward install. Your housing should look like this on a 104.9xx engine

willp621 · #7 01-26-2009, 11:20 AM

Yes, that is it. I presume I must let the engine cool off totally before doing it. The parts photo shows an o-ring as well.

Maybe I could look at the old one and clean it up to try to "un-stick" it......

jlomon · #8 01-26-2009, 11:41 AM

Quote:

Originally Posted by willp621

Maybe I could look at the old one and clean it up to try to "un-stick" it......

Don't bother. If you're going to go to the trouble to remove it, and the part is only $20, then replace it while you're in there.

mpolli · #9 01-26-2009, 02:31 PM

It's not repairable. Just replace it. It was easy on my car, however mine is the 4 cyl. But should be pretty easy. The new one comes with a new O-ring.

willp621 · #10 01-27-2009, 12:23 PM

I obtained a replacement thermostat. I have removed the 3 bolts from the housing. The cover is stuck on there real good. How can I best remove it without damage? It appears that there may be a gasket or some kind of sealant around the seam.

Any suggestions before I button it back up and take it to a shop?

jlomon · #11 01-27-2009, 12:28 PM

I'd try striking it with a rubber mallet. You might be able to break that seal that way without chipping or breaking the housing by using a metal tool.

Don't start with a huge whallop. Increase a bit at a time.

willp621 · #12 01-27-2009, 12:53 PM

I did try that but not very persistently.........thought I might also spray some WD-40 around the edges and let it sit for a while.

I have to go out for some errands, so I will have to let the car cool off again when I get back. It's pretty cold here so it shouldn't take long.

msethk · #13 01-27-2009, 05:37 PM

maybe one of the mechanics here can give some advice on this but you can check the old one by putting it into boiling water and see if it opens. it would be interesting to see if it is bad, other than the fact that you will know its fixed by its performance. the first thing i thought about when I read this thread was "is there enough fluid in the system." I think thats the first thing i would have checked, then the thermostat... cheapest fixes first! This would also be a good time to flush the system if you havent done it in a while.

willp621 · #14 02-05-2009, 11:34 AM

I was able to remove the old thermostat after applying some penetrating oil and a bit of persuasion. Replaced the unit and now everything's fine. Thanks

jlomon · #15 02-05-2009, 01:44 PM

I'm glad it worked out for you, and that it was a simple fix. Those are the best kind.