Yesterday I saw the engine temp run up into the 240 range before falling back to 190. Never seen that but maybe I just haven't been paying attention.

Anyway today I opened the hood and saw the coolant reservoir was empty so went to fill the radiator and Yucch there is brown sludge all on the radiator cap. I read here that can happen with DexCool and now I wonder, is the gunk is jamming up the thermostat?

The radiator only took a pint. But I've decided to give it a good flush, anyone used CLR and lived to tell the tale? Should I drive around with it for a couple of days till it dissolves the gunk, if it can? Also I would like to open a heater hose and run garden hose water down that and back up through the radiator. What size is the hose so I can get a "T" adapter for it, if necessary?

So many questions, I know!

 

What I did, is I've pulled off the bottom radiator hose and flush from the top with a garden hose.

And definitely check out the thermostat. 240 is somewhat too high. Plus, the inspection may bring You an additional info.

 

You need to do a complete and thorough flush of the entire engine cooling system to clear out the crud. It was caused not by the Dex-Cool, but by air mixing with it. A compression test is needed to find the source, but you most likely have bad LIM gaskets, bad radiator cap, bad reservoir cap, or other leak.

 

Edited for accuracy. Yeah, could be the leak too, especially if consistency resemble sort of a butter. It may be worth checking if there are any changes into the engine/transmission oil too.

 

If someone previously put some stop-leak in the coolant, that can cause a sludge too.Time for a system flush I'd say.

 

Flush with hose water then refill with coolant and distilled?

 

Make a compression test first. The compression of a cooling system ofc.

 

Actually, though the radiator only took a pint, the reservoir was empty, so in total it was down maybe three quarts. So yes, there must be a leak in there somewhere. I saw a youtube making a pressure tester by installing a T in the heater hose, with a schrader valve in the cap, maybe I will try that and see where the leak might be.

 

There is a pressure contraption that you attach to the radiator fill fitting with a pump and a gauge. You can test for engine compression leaks with that sa,e pressure gauge or a test for combustion content in the coolant. Also you can look for bubbles while the engine is running. Don’t over pressurize the coolant system.

George

 

It's been a couple hundred miles since I filled up my radiator and well, I guess there wasn't a leak - the gauge reads cool and coolant level is holding steady.

Nevertheless I bought four gallons of distilled water to flush and get the sludgy stuff out. I found the petcock, white plastic thing but couldn't turn it. Read here it was better anyway to pull the lower hose off the radiator, but could not get at the clamp so that was the end of that project. Later I read you have buy a clamp tool and then remove the battery and maybe the battery tray(?) to get the tool on the clamp. To fully flush you have to do this removal/replacement 3-4 times, running the car in between each time.

Tell me there is a better way!