I started the process of a coolant flush on my 03 ls today, pretty sure the coolant is original from factory. There is rust colored gritty sludge in the coolant and the overflow reservoir is caked in the stuff, as well at the fill neck of the radiator. I'm currently doing a super flush, just repeatedly draining and filling with distilled water, then running the car to extract more gunk. I will be replacing the overflow tank to help solve this issue. Any ideas as to what may have caused the problem? Oil looks good doesn't appear to be coolant in it.
Thanks in advance y'all.

 

I would recommend putting a flush T on the heater hose line and properly flush the system if there is sludge in the system. Would also be beneficial if you back flushed the heater core ( remove both hoses off the engine and flush both directions with water ) Good luck.

 

Any coolant (Dex or good ole green) can get gunky. Dex tends to do it more often than green from what I have seen. Also, I believe Dex is supposedly good for 10 year/100K miles (which I honestly don't buy into that). Flush it good and re-fill with coolant of choice. And I agree with Jeff, adding a flushing T will help a lot.

 

So grab a flush kit from autozone? As long as it has a hand pump I'll be able to clean it out properly? But this isn't oil contamination right, the coolant just went bad?

 

Yes a flush kit from AutoZone is perfect. As for coolant it possible it that's way from lack of maintenance , never being flushed or bad water ( hard . iron, acids) can cause gunk, foam ,sludge etc. Odds are it's throughout the system not just radiator. Might take a couple flushes to get if I out. Good luck

 

I agree, add a " T ", and flush,flush.flush !! mine was gunked up with gunk, I blamed it on the " Death Cool" !! LOL, I replaced with good ole green antifreeze and havent had an issue since?