Coolant Flow Passages in E320

[TomLatos]

I believe that I have debris in the coolant system as a result of a head gasget repair done last summer. Poor heat in winter, washer tank fluid only warm, higher than normal temps in the summer. I believe that the source of this contamination was bits of old head-gasket which fell down into the block during the repair.

So here is the question. Among the rad, heater core, oil cooler, block and head passages & washer heat exchanger, where is the smallest coolant passages that are most likely to collect the debris? My plan is to do a through back-flush of the system over the XMAS holiday, and this will help me target the backflush strategy.

I can state that it is not the rad passages, because I have already had the rad out of the car and did a flush on the bench and got zip.

[ILUVMILS]

Hi Tom, I doubt a cooling system restriction is causing your problem. You'd have to drop a lot of stuff in there to block a passage. It sounds like your thermostat is stuck open, not allowing the engine to reach operating temp. A quick way to check is to block the air intake on the grille. Watch the temp closely and see if the heat output increases. As far as higher temps in the summer, if the coolant doesn't spend enough time in the radiator it can't get rid of the heat. Flushing the cooling system is a good idea regardless, but I've never seen a blockage in anything but a radiator that caused a problem. I have however, seen dozens of thermostats stick open and cause exactly the problem you've described. Good luck