Overheated 230E - results just in!
 

This could be messy...

Our 230E was being driven around when the AC stopped blowing cold air. Thinking this was simply due to a loss of freon, the car was driven for another 20km and was close to being parked when the power steering went and all the lights came on. There may also have been a "slight tapping noise" at this time.

I've had the car towed to a garage and preliminary examination showed that the main pulley has broken in half - not sure in which direction yet as I've been conducting the investigation by telephone in a foreign language :) - so this explains the initial loss of AC and subsequent failure of the power steering and alternator output.

After the fanbelt and main pulley were removed, the engine was briefly started to check on what damage might have been caused and reportedly there is still some noise coming from the engine. Quite how much noise I'm not sure yet as I haven't heard it myself.

I'm having the head pulled later tonight so the mechanic can have a look inside but I'm putting this out for discussion in order to get some idea of what I might be dealing with in terms of replacements required. Pulley and fan belt, obviously, but although there was hardly any water left in the system, the temp gauge didn't go off the scale while the car was being driven and there's no obvious water or oil seepage.

If the engine overheated, what is likely to have been damaged internally? If there's no obvious damage to the top end, the next step would be to remove the motor and take a look at the rest of it.

Before I go that far, can anyone tell me if there are likely to be any obvious things to check first: pulley bearing? pistons? cylinder walls?

Hoping its not going to be too much of a nightmare but I'd like to know what I should be looking at before I schlep over to see for myself.

Car's done 88,000km and previously has been prone to using water and running at higher than normal temperatures - 90+ - which had been largely solved by replacing the coolant pressure cap and a leaky hose. Auto transmission. Fan belt was showing signs of wear and was marked for replacement at next service.

I don't think the engine over heated. You'd have known it if it did. Sounds like you parked just in time. The 230E is a noisy bugger of an engine to begin with. My guess is the belt tensioner was what started making the noise when you parked like a diesel.

the results
 

well, after an engine rebuild, here's what caused the overheating and pictures of the results.

First off, the damage was caused by the failure of the crankshaft damper, which i presumed used to be two metal discs joined by a rubber damper. Attached is a photo of the old one...

worst hit component was the camshaft. three out of four pairs or lobes had serious damage

then of course, there's the bearings...

end result, one shagged engine which required a rebuild. new pistons, first oversize rebore, new mains, big ends, camshaft, crankshaft damper, fanbelt (which was overdue for replacement) and the discovery that the electromagnetic clutch on the main fan had been disconnected and the fan bolted directly to the pulley. don't you love those POs...

cost was around US$1,500 and the job took a week. Have left the fan clutch as is for the moment while I wait to find out how much a new unit will cost.