Coolant Sludge!

[gabkwong]

The coolant expansion tank on my 99 has this thick sludge deposit that I can hardly see how full/empty it is. I took it out and scarp the inside of the coolant expansion tank with a screw driver. I am amazed how much deposit there is! This give me the idea/worry how much worse is in the coolant passages inside the engine! In theory, this can not be good for cooling of the engine. In the real world, does it matter? Is there anything out there works like Pac Man that I can put into the cooling system to eat up this deposit and restore the cooling effectiveness like the day it got the boat from Japan?

[sammm]

If the car isn't getting hot I wouldn't worry about it. The radiator is getting long in the tooth though...might want to start saving pennies for a new one.

[JDSM]

a lil' of topic, but I have "gritty" stuff in my expansion tank... distilled water and Peak.

[POS Racing]

Oil in Coolant will make Sludge..... When was the last time you flushed the system??

[black roadster]

Water wetter has been known to sludge up too.

[gabkwong]

Oil in Coolant will make Sludge..... When was the last time you flushed the system??

When I drained the coolant there was no oil sheen or oily smell etc. The drained coolant looked very clean with that clear and fluorescence greenish color. I’ve never “flushed” the system. I just drain it once and fill it every other year. This time I drained and filled the system with distilled water 3 times before putting in new coolant to get all the old coolant out.

I have never used Water Wetter.

Where is the temp sensor located in the engine? Does it measure the temp of the core of the block or just coolant. If it only measures the coolant, the block can be hotter than suggested, especially since now I may have a coat of sludge in the coolant passages inside the engine.