W124 heater hose blew out! Cause?
 

Searched the archives and didn't find anything related to this.

Just passed inspection and on my way home, stopped off at the day care to drop something off. Left car running.

Came back out and smoke was emanating out out the driver's side near the hood hinge. Popped the hood and saw (and smelled coolant) near the fuse box area! :confused:

Immediately discovered the plastic mating piece on the heater hose ruptured. So I quickly glanced at the gauge cluster and saw the temp gauge pegged to almost the 120 C mark! I was a block from home, so I took a chance and limped it to the garage.

The replacement isn't costly, and I don't believe any serious damage has resulted yet, but my real concern is whether the hose damage was a result of old age or something else? The rest of the hose actually appeared to be okay, but the plastic joint rupturing has me worried. Any clues?

I had a similar experience on a 126 car with the upper radiator hose. It slid off the upper radiator pipe. Not long before this I had checked the snugness of the hose clamps.

The interior of the hose felt slick as I refitted it to the radiator pipe. I suspected age, although the exterior of the hose seemed ok.

Purchased a new OEM hose and have not had a reoccurrence.

Don't try to limp home when an engine is overheated and leaking coolant.
The stakes are just too high.
I have the cracked heads to prove it.

If it's a slow enough leak, let it cool down, top it off with water (very slowly, just to be safe), then try to limp home before it overheats again.
Carry extra water if possible.
Do not push it to the red before stopping again.

G-Benz

Had a very similiar thing happen with the 91 300e in the middle of the city on a Sunday morning.

It was the heater hose that comes from the engine and goes through the firewall by the fues. It was worn where it attaches to the engine, just above the clamp. I used the MBZ tool kit, took it off, cut it back and reattached it.

I know there is a service recommendation to change all the hoses after I think 4 years.

That little plastic connector failing is weird.

Haasman

Not that weird of a failure, they are made of the same material that the radiator tanks and the 90 deg elbow is, plastic. 140 cars has a similar cluster behind the l/h head that'll do the same thing. The coolant goes acidic and eats at the interior of the plastic. Hence the recomendation of the Benz long life coolant, its more resistant to this.



Joe

I believe tap water is the cause of most problems with cooling systems. Sticking with distilled water and MB coolant will ensure a long and trouble free life.

I do my own maintenance so no one uses tap water for anything in my cars.

Good to know that the failure is not a prelude to bigger problems...

...although I had managed to dodge the headgasket issue for years...this last overheat probably sealed its fate! :rolleyes:

Unless things have changed recently, Mercedes tells you not to use distilled water.

Installed new hose and coolant level sensor last Thursday and used MB coolant and tap water.

Test drove on short trips this weekend prior to commute this morning. No overheating, so I guess the head and gasket are still sound (knock on zebrano)...