My 260E is hitting 110C within about 15minutes out here in Arizona. Ambient temp today is 105F and I cannot drive with it like this. With the heater full blast I can keep it at ~100C...but that is absolutely unacceptable.

What could be the problem?

I have replaced the belt and the tensioner tightened up, so safe to say it is OK?

Radiator could be original, water pump is almost certainly original.

I am using Zerex G-05 coolant and the level looks ok. Cap releases pressure when I take it off, so I don't think it is a cap issue.

Any ideas? I cannot run like this or I will certainly blow the head gasket real fast.

 

Fan clutch? Press the gas with it warm and in nuetral. It should sound like a 747.

If not, try the good ol' newspaper trick.

 

I replaced the fan clutch with one on ebay that works. I can hear it spin during first 10-15 seconds during cold start up so should be OK.

But either way, it is something more than a fan clutch. It's gotta be a flow issue.

 

My 525i displayed the same symptoms when the clutch went. Second in line for me would be the thermostat. If it were that simple though, knowing you, you would have fixed it on your own by now.

If you aren't sure, check the hoses a few minutes after startup. They should begin to warm up as the car does. If your car gets hot, and they don't feel as warm as you would expect for 100C water to be flowing in them, I would suspect the T-stat.

 

Yeh the thermostat is 3months old...I did get the 87C version though without thinking, but now since I am moving to AZ I bought a new 79C one along with a new Nissens radiator. I figure my cooling needs to be tip top shape anyhow so I just went ahead and ordered it. And I have already flushed my and cleaned current radiator before so only thing left is to simply replace it.

I have a feeling its gotta be a flow problem rather than fans...but then again I don't have much experience under my belt.

The hose before the TStat is red hot, so its gotta be working to some extent...For $15 though its a no brainer.

I hope it is not the tensioner or water pump though...

 

All the hoses should be firm but not hard...check that there are no bubbles in the system as well...

I'd have it at least diagnosed by a good mechanic first..

 

aww come on you should know me by now

I found the correct procedure to filling the coolant, so I will do that when I replace the radiator this time around.

By time I have paid a mechanic to diagnose it, I could replace half the system myself and be that step closer to a long lasting engine.

 

What is your coolant to water mixture ratio...50/50?
Are your auxiliary fans turning on around 100C ?

 

Before you put that new radiator in run some MB citric acid through to try to peel the calcium scale off the alum, will help heat transfer. Check for hot spots in your current radiator, maybe clogged. Unplug your temp switch and see if your aux fans are working properly.

Thats about all I can think of.

 

Robert, you may want to invest in a infrared temperature gun. They're pretty cheap, and can tell you worlds about your cooling system. You can figure out if there are hot spots on your radiator, where a blockage might be occurring, hose temps, and even help deduce if there is buildup preventing heat transfer somewhere in the block.

Hope I'm not jynxing anything, but you may have another headgasket failure. You may have had a crack in the head previously that went unnoticed.

 

Looks like most things to check are posted but here are a few more:

Is there any loss of water pressure at all? Small leak can lose water volume and pressure for flow.
What is your temp when it's not 105 ambient? Is this the first time your car was in this high of temp?
Is the temp same when on highway and in traffic?
Is high temp with or without A/C on?
Is the temp accurate? Use another instrument to confirm.
Is the fan guard and lower engine panel installed?
Are the AMG front bumper lower front vents open?

Agree with checking for air bubbles that can prevent flow.

 

On the freeway with 105 ambient it stays in the high 90's (C). Lower engine panel is not installed, fan guard is. High temp was with and without. I had the A/C on, then the compressor kicked off (I believe there is a shutoff temp...this is how I know it is not a misreading sensor) and also the car slowed down considerably. It was an absolute slug.

No drips or coolant loss.

I have no issues at all here in socal, even in 95F days. I guess the lack of moisture in the air in Arizona?

I left the car in AZ and flew home...so when I move out there next week I will tackle the issue...Thanks for the ideas guys.