300SD slow warmup - PeachParts Mercedes-Benz Forum

dave_zook@hyper · #1 03-13-2006, 11:03 AM

It got cold here in Colorado this past weekend and I noticed that the temperature on the guage was registering just over 40 for quite some time. It didn't go up much even after about 20 minutes. The heat wasn't all that good either inside the car. I read here somewhere that the car should warm to about 80-85 within 5 minutes. Is that right and if so, what do I do to fix the problem?

I didn't seem to find a forum addressing the problem but what do we newbies know anyway?

Thanks,

vwbuge · #2 03-13-2006, 12:16 PM

Kind of going through the same thing with mine now. At idle and leisure driving the thing will never get up to operating temp. An open highway romp or steady 20-30 minute or so driving around town should bring you up to temp. My heat seems weak also. I am waiting for my new thermostat and I will then do an acid flush and new coolant to see if that cures it.

79300sdtd · #3 03-13-2006, 12:28 PM

I am over in aroura co and my warm up takes about 8-10 mins on the way to the highway. even in our recent cold weather. I have read on here that the Tstat being stuck open will create a situation that the car will warm up really fast. so maybe yours is stuck closed.

Al Magaloff · #4 03-13-2006, 12:34 PM

When a T-stat sticks open, the motor takes more time to heat up,not less,but once it's hot, runs hotter than it would with a good T-stat.

boneheaddoctor · #5 03-13-2006, 02:02 PM

Read this thread.. Watch your Temprature guages

84300DT · #6 03-13-2006, 02:10 PM

i want to say replace the t-stat as well....

dieseldiehard · #7 03-13-2006, 03:10 PM

Replace the T-stat! And if you have to drive in REALLY cold weather stick a piece of cardboard across most of space across the front of the radiator to block most of the airflow.

Hatterasguy · #8 03-13-2006, 04:16 PM

Replace the T stat. But even with a working one if its real cold these cars take forever to warm up. Mine takes about 15 minutes on a 15 degree morning. If I hit the highway right away it will come up a bit faster.

dave_zook@hyper · #9 03-13-2006, 04:45 PM

Thanks everyone. I will replace the Tstat and let you know how that works. Is a Thermostat from one of the auto parts stores just as good as one from a Mercedes dealer?

dieseldiehard · #10 03-13-2006, 04:48 PM

Quote:

Originally Posted by dave_zook@hyper

Thanks everyone. I will replace the Tstat and let you know how that works. Is a Thermostat from one of the auto parts stores just as good as one from a Mercedes dealer?

Depends I suppose, on who made it. You could also have Phil ship you a Behr. Even the factory T-stats have been known to be faulty. Its only a little effort to put one in a pot of boiling water and watch it open, I used a digital thermometer and it started to open right near 80 Celsius (176 F).

dave_zook@hyper · #11 03-13-2006, 04:52 PM

Good Idea to order from Phil. I will do that. I have to say that the other day I ordered a new oil pan from him and it came to me in Colorado in about 3 days. That was real good service in my book.

Thanks.

Hatterasguy · #12 03-13-2006, 05:01 PM

Well you really want a Behr T stat, Behr makes most of the cooling system parts OE for MB.

dave_zook@hyper · #13 03-13-2006, 07:50 PM

Thanks for the advice about the Behr Tstat. I have ordered one from Phil.

westkill · #14 03-13-2006, 07:51 PM

Just went through the same thing on the wifes SD. Car would heat up to 60 C then drop back down a little and the heat was SO-So. Replaced the thermostat and now it runs perfectly at 80-85C.
I tested the old thermostat in a pot of boiling water using a probe attached to my multimeter. The old stat opened perfectly at 180 degrees BUT as the pot of water cooled the stat remained open all the way down to 135 degrees!. There was the problem. The darn thing always stayed open. I have added a new stat to the list of things I automatically change when I bring home another Benz to the stable. Its so much easier to change all the belts fluids etc right in the beginning because now you know there DONE! HTH Mike

dave_zook@hyper · #15 03-13-2006, 07:58 PM

I've had my benz for only a few months. I have been learning a lot. I did replace all the fluids when I got it and have since changed the oil again. Didn't think of the thermostat. So now I know.

I also put on one of those aftermarket air intake things that are like a KN. It made the thing noisey and I could swear that it made the car more sluggish. I put the old stuff back on and it runs like the really nice cruiser that it is.

Thanks to all of you for your advice. It is great to have this forum as I learn more and more about diesels and benzes.