M119 is still running hot...What temp does yours run at? - PeachParts Mercedes-Benz Forum

Dcraig · #1 11-13-2006, 11:51 PM

Sprung for the $500 fan clutch today and the car is STILL running hot. New radiator last month because I thought that was the problem. So $1000 in the last 2 months and I still have the problem.

As I understand, the cooling is controlled by the radiator, the fan clutch and the aux. fans. It seems that as the temp. rises, the fan clutch should kick on. If the temp keeps rising, the aux. fans kick on. Since my fans aren't working, I don't know how much cooling the fan clutch is capable of.

Where does everyone elses M119 run at? I'm so confused.

Dcraig

ProV1 · #2 11-13-2006, 11:53 PM

mine is around 80, usually slightly below.

deanyel · #3 11-14-2006, 12:07 AM

Try a new radiator cap if you haven't already. Mine runs about 90 but will run at 100 with the belly pan.

Dcraig · #4 11-14-2006, 12:10 AM

I think I might need a new radiator cap. Can that really cause the temp to keep climbing?

What else is left?

Dcraig

Dcraig · #5 11-14-2006, 12:46 AM

The temp will go up to normal and then will slowly climb to about 105.

I thought the water pump is either an all or nothing?? The rad hose at the bottom has a metal coil in it to keep it from kinking. When I first started up the car after the new fan clutch, there was a lot of air moving, so much tha the aux fan started turning slowly be itself.

The thermostat was the first thing I changed because it was cheap. I figured I'd start with the cheapest fix first.

Other than the expansion tank and the cap, I don't know what's left. I'm pretty sure the cap is holding pressure. I'm not getting any leaking around it.

Dcraig

Dcraig · #6 11-14-2006, 01:44 AM

Just took the car for a spin. Got the temp up to 100 and came home for a look. Seems like the fan clutch isn't coming on. I could spin it by hand pretty easily before I left (under 80) and just as easy at 100.

I don't know if it's a gradual thing or it is either on or off. I would think at 100 it should be on.

Thanks,

Dcraig

wbrian63 · #7 11-14-2006, 08:44 AM

If you can get your hands on an infrared thermometer, I'd try aiming that at the location on the motor where the temperature sender for the gauge is. Maybe you've got an issue with the accuracy of the gauge.

As for water pump and "all or nothing" - not necessarily. Don't remember seeing how many miles are on the car, but with time, there is some (small usually) decline in efficiency of the pump.

I've even seen situations where a large portion of the impeller has degraded over time, but this was usually in cars that weren't well cared for. In the "old days" waterpump housings and impellers were usually cast iron - virtually bullet-proof. Now they're all aluminum, more prone to mineral deposits and erosion.

By moving the filler cap from the radiator to a remote tank, automotive designers removed the ability to run the car with the radiator open to visually gauge water flow - I don't know how you'd do it now.

You might try testing the thermostat. I don't know about the thermostats for MB's, but those manufactured for domestic vehicles are rated to begin opening at the rated temperature. The temp at which they reach full-open status can be several degrees above where they begin to open. A sluggish thermostat isn't beyond possibility. The quality of aftermarket (and even OEM) parts isn't great anymore. I once had to return a brand-new 180 degree thermostat that didn't fully open until 205 degrees.

Suspend the thermostat in a pan of water - don't let it rest on the bottom for more accurate results.

Radiator cap can cause overheating, but they fail less often than other parts of the system. In general, each increase of 1 psi increases the boiling point of water by 3.33 degrees. So a 15psi radiator cap adds 49.5 degrees to the boiling point of water = 261.5 deg F. In a water-contact cooling system, the water must main in contact with the surroundings it's trying to cool. When you boil water in a pan, the bubbles you see in a pan aren't air, they're steam. They form at what is referred to as nucleation sites - the rough surface of the pot has lots of variations to serve as the points where the water can flash from liquid to vapor. (This is why you never heat water in a smooth glass in a microwave - smooth surface, no nucleation sites. No nucleation sites, water heats way beyond 212 - disturb the water by picking up the glass - rapid nucleation and explosive boiling over - ER, here I come) Preventing the water from boiling delays the formation of the vapor bubbles which will rapidly decay the heat-absorption capacity of the coolant.

A weak radiator cap will allow the radiator to boil over sooner. Water doesn't go from non-boiling at 211 to boiling at 212, it's a gradual process. Bubbles begin to form in the solution at temperatures less than 200 degrees. A weak cap will allow the water to begin to boil sooner - small bubbles in the coolant as a result of a weak cap will decrease the overall efficiency of the system - and this will cause the motor to run hotter.

Generally speaking, an engine can probably withstand more heat and not cook itself. IE - a 30psi radiator cap would allow for a boiling point of 311 degrees. However, the external portions of the cooling system - radiator, hoses, expansion tank, etc - won't stand up to that much pressure - and should there be a pressure leak at those temps and resulting rapid nucleation - baaaad things would happen to anyone and anything near by.

The fan should be capable of keeping the motor cool without the A/C on. With the A/C, you probably need the electric fans - the condenser introduces a LOT of heat into the airstream ahead of the radiator.

Short of it - check the accuracy of the gauge, check the accuracy of the thermostat. All else fails, replace the water pump.

Hope this woolly sheep story helps.

Dcraig · #8 11-14-2006, 09:42 AM

It could be the water pump, but because the fan clutch doesn't seem to be engaging, I still think that's the problem.

Different online sellers offer Sachs, Febi or the brand I got, Vemo, made in Germany.

I had bought a low mileage used unit from a local MB dismantler but returned it because I didn't want to have to replace it should it fail, and it only had a 30 day warranty.

I guess I'll check the dealer's price for a new MB unit or see if I can get a Sachs or Febi.

Dcraig

Dcraig · #9 11-15-2006, 11:47 AM

Can someone with a M119 check something for me?

I thought that as the fan clutch gets hot, it engages and turns faster, which means when the engine is turned off, it should be hard to turn by hand.

I changed the fan clutch and the car still got hot, so I returned the clutch and got another one and put it in. The car is staying cooler, but will still get to 100 if I stop at a light. When I got home from the test drive, I looked at the fan and I could still turn it by hand with the engine off.

What's it supposed to feel like? The only think I haven't changed is the expansion tank and cap and the water pump.

BTW, the car has 134,xxx miles.

Thanks,

Dcraig

lkchris · #10 11-15-2006, 12:19 PM

Anybody mention thermostat yet?

IT is what "controls" cooling.

A blown headgasket--beside resulting in mixing water and oil--will sometimes increase running temperature.

Dcraig · #11 11-15-2006, 12:21 PM

Thermostat was the very first thing replaced.

Dcraig

DRICHFL · #12 11-15-2006, 01:24 PM

Consider Jim's website it may solve your problem with fan issue.

http://pages.prodigy.net/jforgione/MB_S500.html

suginami · #13 11-15-2006, 01:36 PM

Quote:

Originally Posted by Dcraig

Since my fans aren't working, I don't know how much cooling the fan clutch is capable of.

I was reading over your first post, and the above statement confuses me.

When you say "since my fans aren't working", do you mean the clutch fan, or the low and high-speed auxiliary fans aren't working?

There should be two fans (in tandem), and they should both be running at the same time, whether at low speed or high speed.

When your a/c is running, these two fans should be on low speed all the time.

When you get to a set temperature, probably around 110 degrees, these fans should be running at high speed. You will easily be able to hear the fans running when you are in the car, even with the windows up. It sounds like a 747.

What JimF.'s cool harness does is change the resistance, tricking the fans into coming on at high speed at a lower temp.

It sounds to me like your auxiliary fans aren't working, either at low speed, or high speed, or both.

Why didn't you take it into Enrique at Mr. MB Motors anyway?

Further, I don't know why you are thinking your water pump is bad. If it is not leaking, and if the bearing isn't shot, it means it's turning, and therefore working.

If the bearing was shot, the car wouldn't be driveable anyway, as the pump would sound like a screaming chicken, and then eventually freeze up, frying the belt.

Dcraig · #14 11-15-2006, 02:06 PM

The story is: The car started running hotter than I remember, climbing to 110 frequently. The aux. fans would kick in and bring it back down to just under 100. Thinking it was the thermostat, I changed it, but the car still ran the same. Next I ordered a new Behr radiator, and changed that. Still no change in the temp. Then the 'check engine' light came on so I went to see Enrique and he pulled the code: bad tranny vacuum modulator. He said I was ok to drive. At that time I asked him about the cooling issue and he said possibly the fan clutch. A couple weeks later, I was on the freeway and saw the temp near 120. I limped home and saw the aux. fans didn't/wouldn't come on. So now I've been changing the fan clutch, but the car still gets up to 100 degrees.

After reading Jim's site, It seems the fan clutch doesn't kick on until after 100 degrees, so I wouldn't know if it's working or not. On my Jeep Grand Wagoneer, when the fan clutch was engaged, the fan was hard to turn when the engine was warm, easy to turn when the engine was cool. The new fan clutch is pretty easy to turn all the time.

I never did think it was the waterpump, someone suggested it. The expansion tank does hold pressure, but I could use a new one.

I was having the car towed to Enrique this morning but AAA didn't send a flatbed and they are really busy today. I'll shoot for tomorrow.

Thx,
Dcraig

suginami · #15 11-15-2006, 02:17 PM

Quote:

Originally Posted by Dcraig

I limped home and saw the aux. fans didn't/wouldn't come on. So now I've been changing the fan clutch, but the car still gets up to 100 degrees.

There you go again. "I limped home and saw the aux. fans didn't / wouldn't come on...."

There's your problem. If the aux fans didn't / wouldn't come one, why did you then suspect the fan clutch? The aux fans weren't on, and they should have been on.

Are we using different word for the same item? The fan clutch is for the viscous coupled fan connected to the front of the motor.

The aux fans are the electric-driven fans at the front of the radiator.