V8 Overheating - Benzworld.org

c140v8 · 12-13-2005, 04:02 AM

Well here are some pics of my temp guage while I was sitting in the McDonalds Drive Thru earlier tonight. It was about 6:30pm, quite a humid day and A/C was on cold. It seems to get this hot when idling for a minute after driving in stop/go traffic. I had the dealer look at the cooling system when It was in for the ABS?ASR fault and they assured me it wasn;t overheating. I insisted they replace the trhemostat which they did but nothing has changed. Tomorrow I will check the viscous fan clutch bu doing the test of switching off the engine and seeing if the fan keeps spinning when it's hot. I've done a bit of a search and come to the conclusion that it could be that or the water pump. What do you guys think?

Corsica · 12-13-2005, 04:57 AM

We have an almost identical problem with our S600 in similar ambient conditions. The dealership also reported that everything was in order, although we occasionally suspect that they were probably mistaken. Because our car is driven almost exclusively on the highway, we haven't yet pursued this issue to a complete resolution. I will tell you that the water pump on our car was replaced not long ago as a preventative measure, and that does not appear to have resolved this problem. Of course, that is purely anecdotal.

I know that this question may seem out of left field, but your transmission doesn't shift hard from 1-2 or 2-3 in warm weather, does it?

(Pete, where are you? If you're reading this, I'd love to hear your input. [8D])

pcmaher · 12-13-2005, 06:27 AM

Looks a lot like my temp gage before I changed my viscous fan clutch (VFC). Replacing the VFC solved my "not overheating" problem. I know that MB says 120 C is not bad, but when I opened the hood, I felt you could cook a ham under there. The new clutch has lowered my running temps significantly. I used to see 110 C when it was 40 F outside. You can imagine what it was like in the summer with AC on. The auxilliary fans were on almost all the time. It runs right around 90 now.

kutz · 12-13-2005, 06:50 AM

Quote:

pcmaher - 12/13/2005 8:27 AM

Looks a lot like my temp gage before I changed my viscous fan clutch (VFC). Replacing the VFC solved my "not overheating" problem. I know that MB says 120 C is not bad, but when I opened the hood, I felt you could cook a ham under there. The new clutch has lowered my running temps significantly. I used to see 110 C when it was 40 F outside. You can imagine what it was like in the summer with AC on. The auxilliary fans were on almost all the time. It runs right around 90 now.

Also, check the fuses for the two fans up front and make sure nothing is blocking the the air flow. But ususally this is the fan clutch. I used to get around that temperature untill the two fans in front kicked in at around 120 Celsius. I replaced the fuses in the front, but it only started to kick in at about 115 Celsius. Had to change the fan clutch.
While your there might want to change the rubber belt (serpetine belt??) if you haven't done that yet.
You can ride with that temperature but as pchamer said, "I felt you could cook a ham under there" which is not a good sign no matter how large the engine is.

**Nimrodthewombat** · 12-13-2005, 08:06 AM

The official party line is that if it's not in the red it's okay. You might want to do a search for "cool harness" on here, or it might be on www.Mercedesshop.com. Mine used to go up into the high range until I got a cool harness. It kicks on the aux. fans at a lower temp to keep the coolant cooler. It's around $50US and it's a plug and play setup.

c140v8 · 12-13-2005, 01:53 PM

Guys, thanks for the replies. Im going to check the VFC today and go from there... I might research a cool harness, also. Do you think he'd ship it to new zealand? I'd just feel a lot more at ease if it ran a little cooler, as ya do!

Corsica, its funny you mention the transmission thing. Im sure this car should be shifting smoother than it does and its been on my mind lately. Do you think this mighthave something to do with the heating problem? Its a smooth gear change on hard accelleration but a little rough and clunky on moderate accelleration. When I nanna it off the line very slowly, its pretty smooth.

2-3 and 3-4. (remember it starts off in second)
Mine is a 4 SPeed BOx.

Corsica · 12-13-2005, 06:30 PM

Quote:

c140v8 - 12/13/2005 3:53 PM

Its a smooth gear change on hard accelleration but a little rough and clunky on moderate accelleration. When I nanna it off the line very slowly, its pretty smooth.

2-3 and 3-4. (remember it starts off in second)
Mine is a 4 SPeed BOx.

[xx(] Yes, our car has the same problem, especially from 2-3. The transmission was rebuilt not long ago.

c140v8 · 12-13-2005, 09:11 PM

well i got it nice and hot today and then when i turned the engine off, the fan didn't jolt to a stop, it kept going for a second and would spin freely when i tried to spin it after shutting the engine off. I guess it needs a new VFC. bugger.

so were you saying yours was shifting rough after having the transmsssion rebuilt or before?

do you think mine needs rebuilding (god help me!)
The tecnician said "oh they're not the smoothest changing gerabox anyway)

kutz · 12-13-2005, 09:42 PM

Quote:

c140v8 - 12/13/2005 11:11 PM

well i got it nice and hot today and then when i turned the engine off, the fan didn't jolt to a stop, it kept going for a second and would spin freely when i tried to spin it after shutting the engine off. I guess it needs a new VFC. bugger.

so were you saying yours was shifting rough after having the transmsssion rebuilt or before?

do you think mine needs rebuilding (god help me!)
The tecnician said "oh they're not the smoothest changing gerabox anyway)

The only problem with the transmission on early W140 is it takes a long time to shift from park to reverse or to drive. It would take about 3 seconds before it kicks in. That's when you know you need a rebuilt.

c140v8 · 12-13-2005, 11:20 PM

mine shifts into gear straight away, it just shifts rough sometimes when shifting between gears. Sometimes, if i lift the accellerator just before it changes gear it will be smooth.