The car is a 1992 400E

I have had no problems with this car after buying it about a month ago.
Today, after a modest run at freeway speeds when I parked at work, there were no indicator lights.
When I started it up, the yellow "radiator" light came on, and when I checked under the hood, it was obvious that the top rad hose had blown. There was a ragged split in the top of the hose just outside of the clamp.

Why would this happen when the engine was not running? I can see a hose collapsing as the engine cooled down -- perhaps there is a vent plugged somewhere. A coolant recovery hose plugged maybe? But how does a hose BLOW?

Is there any downside at all to replacing the hose with one from a parts shop?

Also, I was told that it could be cause by my thermostat sticking closed -- but this makes little sense to me since if that were the case, I think that the car would have overheated, and I never noticed this -- and I check gauges often.

Would it be wise to change out the thermostat anyway? Much bigger job. The hose I can handle myself, but I would not want to do the 'stat w/o the manual.

Regards,
Vorpal

 

Hi Vorpal,
Hoses have a limited life dependent upon original specification.
Don't know whether yours are original or replacement and whether they are "ordinary" grade or special heavy duty high temperature "rubber". You can't tell by looking.
Top hose is the one which has the most demanding work. Hottest coolant temp, highest pressure plus high under bonnet environment.
Hoses can split if the fabric webbing within the rubber was not laid perfectly. Another vulnerable area is adjacent to hose clips especially if they have been overtightened.
I suggest you replace with an original equipment hose from MB. OE hoses usually have MB and part no. written on them.
Maybe the engine overheated but this shouldn't cause a burst but if temp gauge was OK I would replace hose and see how things go. Keep a very careful eye on the temp gauge until your confidence returns. Make sure you use correct grade coolant. Aluminium engines are VERY fussy about what you put in them.
I'm not sure how the MB header tank cap is supposed to work on your vehicle. i.e. whether it is intended to control overall system pressure.
Stuart

 

Thanks, good points.

Could not find a hose anywhere locally, so I've got one coming in. Should be here by Thursday.

How do I tell what type of antifreeze is in the car now?

I was checking out various products today, and some were marked "propylene glycol", some "ethylene glycol" and some said not to mix the two.
Some of the ethylene ones said "safe for aluminum engines" and the propylene ones said "specially formulated for aluminum engines".

Where can I find out what SHOULD be in this car, and how do I tell if that is what is really in there?

Regards,
Vorpal

 

I always thought that when thermostats went bad, they stayed open, not closed. Maybe I'm wrong (I have been before)