Today, after driving my car on the freeway for about 40 miles, as I'm pulling into my garage, I noticed that the temp gauge is 110+. The fan is blowing hard. I shut the engine off, but leave the ignition on for about another minute so that the fan can continue to blow.

I popped the hood to help the engine cool and look inside my coolant reservoir. The fluid is boiling like it's angry and trying to escape. Eventually, some fluid overflows and ends up on my garage floor and the fluid continues to boil for several minutes.

Several hours later, I added almost a gallon of distilled water to the reservoir without getting the fluid level up to the recommended level (I'm doing this so that the car will stay cool enough for me to drive it to my mechanic in the morning).

I didn't notice any leaks as I added the water.

Any ideas on what might be wrong? NOTE - just about 10 days ago, I had the timing chain and rails replaced, so many things were taken apart. Also, I got a "check engine" light a few days after getting the car back that I haven't had diagnosed yet.

Thanks in advance.

Frank
'92 500e, 147k

Yikes! sorry to hear about this event- - no doubt your tech will get it sorted out.

Let us know what caused the overheating. First thing I would have done is check the dip stick to see if H20 is mixing w/ oil (brown muck vs. oil), ...then review for pressure leaks (rad/hoses=no holding sufficient pressure) followed by reviewing myself for (stuck closed) thermostat issues...

Best regards and happy new year.

-fad

I've heard that the radiators in these cars need to be changed every 80K due to internal oxidation. I'm not sure how true it is but when I was looking to purchase a 500E I remember seeing that half of them had replaced radiators. The dealers told me this was typical for these cars. Maybe yours is due for a change?

Definitely keep us posted as to the cause and good luck.

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Afshin

Current:
02 C32 AMG

Previous:
92 500E
84 190E 2.3 5 Spd

My mechanic found lots of wetness along the firewall, but no evidence of broken hoses or obvious leaks. Their hypothesis is a faulty heater core. I don't know whether this is plausible. I do know they are saying this is a big job. I'm suspicious.

I've been searching through the archives. I'm now wondering if this is something as simple as air trapped in the cooling system.

First off, for sure it's not trapped air - these systems are self-purging (I just went through 2 fluid changes, so know this to be true). And I doubt it's your radiator - symptoms aren't consistent with a blown radiator, and for the record these radiators last as long as the coolant is regularly changed (mine's

Second, if you've got a wet firewall, check the 2 hoses that pass from the back of the engine through the firewall and back to the heater core - they get baked by the engine and are known to fail (I bet against a failed heater core, plus I doubt a blown heater core would make the firewall wet, more likely it'd soak your interior carpeting!)

Third, if there's fluid on your garage floor, you've filled your overflow tank too - I'd empty it since it's supposed to remain empty...why carry around an extra 1/2 gallon of old fluid if you don't need to? To empty it, jack up the pass. side front of your car, remove the right front wheel, undo 5-6 small fastners & pull down the rear part of your fender liner. This will expose your overflow tank. I think it's held in place with 1-2 screws.

I'm inclined to think you have either a stuck thermostat (was it replaced during your recent service?) or a failing radiator cap that's not keeping the proper system pressure. Why all of a sudden has this popped up? Also, check to make sure all hose clamps are tight.

Good luck and keep us posted!

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"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

I just experienced the exact same conditions in my 92 500E, boiling fluid in overflow tank. With car warm but turned off, put your hand over upper, mid, and lower sections of the radiator. Mine had mid section was much cooler than others (i.e. partial obstruction). As I understand it these radiators have turbulence inducing internals which prevent repair. I have replaced mine. We also noticed that the clutch on the fan had quit working. If the fan spins free when motor is warm, its broke. ( It will always spin free when cold). I have replaced the fan/clutch as well. Only to go for a test run and have the thermostat lock up. Should have replaced it anyway having subjected the car to hot temps anyway. Have now replaced thermostat, radiator cap, changed oil and she's running like a charm again. Check these items before launching into the heater core. As the others mentioned, the core is unlikely. I did recently replace a heater hose...Mine split and was obviously ruptured.

Good Luck.

Dwight

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dwight

Don't go overboard too fast.

any leak, however small, will allow coolant to boil (Pv=NrT) or something to that effect (I'm a banker, not a physics professor, dammit).

Radiator caps go bad (frequently), hoses come loose or develop cracks you can't see...the smallest pinprick will allow water vapor to escape, resulting in boiling and fluid loss.

Mechanic should pressurize system and leave standing for several hours to see if pressure falls...if so you have a leak. I've had this addressed several times.

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RJ
'92 500E
'75 Triumph TR 6

heres the scoop. The fan clutch goes south causing poor radiator flow, inturn taking out the T-stat,engine gets real hot t-stat stick partially open or closed. first thing and always least expensive,repl t-stat,bleed cooling system,these engine are notorious for air pockets, once you do this 1st step. Replenish your coolant run it about 2000 rpms for 3-4 minutes with the defrost switch, should start getting nice and warm in the interior right away,after that observe the temp guage see what the fans are doing, the aux fans turn on @ 110 degree f,the viscous fan turns on or around about 95 degree C..


Also hot tip. The V-12 viscous fans acutally are a direct bolt on, and this fan clutch comes on sooner,since the v-12s run hot. instead of 95 i thinks its like 87-90 C. also there have been guys who have modifed the bi metalic spring to kick thev fans on sooner. I forget who did that.

This is just my 2 cents form being on the line and diagnosing these complaints.



G dog.

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500E Sold
2006 Mini Cooper S
Modified,pulley,injectors,suspension
2009 E350 Sport AMG package

G-dog

Can you get me the application (year, model, engine, etc) and the MB part number for this swap as I would prefer to install this if possable when I do this swap.

Moose

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Jeff (moose)

92 500E 90K miles stock less AMG chip

73 Datsun 240Z, 74 260Z, and a 75 280Z 2+2

G-dog

Can you tell me if there are any other mods needed to use the V-12 fan clutch as they look slightly different on the back flange

Moose

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Jeff (moose)

92 500E 90K miles stock less AMG chip

73 Datsun 240Z, 74 260Z, and a 75 280Z 2+2

Hanfrac, I have experienced 2 over heating probs.

1) same symptoms as you with boiling in overflow, ended out that my freon level was low and fans (they operate with 3 speeds when a/c is on starting at 90 degrees (low) and so on) were coming on late at high speed only, around 110 degrees, by then it was too late and system could not recoup. Turn a/c on and check if fans come on low at around 90 degrees.

2) Yesterday, got back from 700 mile trip and coolant was low, started overheating, small hose from firewall driver side going down into block had a pin hole.

Regards, Marc 1992 500e 100k miles

Jeff moose. Hmm I dont have the part no# off hand. But its a direct bolt on. Also enquire on this forum, Jim F. Do a search,look for cool harness. bUy one of these from him. It fools the system,s thinking the engine is actually hotter and turning on your aux fans sooner. That fan clutch isnt cheap. If your not overheating dont worry about it. Its not easy to remove/ radiator has to come out.


g dog

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500E Sold
2006 Mini Cooper S
Modified,pulley,injectors,suspension
2009 E350 Sport AMG package

I was needing to replace the clutch and wanted to upgrade it.

I was needing to know since the cars that came with v-12's all seem to have the same fan clutch and since there is a slight difference in the looks of the 2 if there were any concerns that needed to be addressed.

I guess I will ship both of them from FL and then return the one I don't use

Moose

I will post the results here

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Jeff (moose)

92 500E 90K miles stock less AMG chip

73 Datsun 240Z, 74 260Z, and a 75 280Z 2+2