I purchased a 1999 xk8 from a dealer last year in eBay. Car runs
Great but when I arrived to purchase the car, the mechanics were putting prestone antifreeze in it. I didn't question it no t knowing what had previously been in it. Car recently popped off its coolant hose but was stopped prior to Any overheating. I purchased new hoses, clamps , water pump , thermostat and aluminum housing. When I took the hoses off there is a waxy type of sediment at the bottom of the pipes. Pic is below. What is your t and how to properly flush it out. Thanks

 

Prestone is simply a brand name. They make all sorts of coolant types, some of which are correct for your car, and some that are not.

The sludge you've found is typical of two incompatible types being mixed together. It would be essential to back flush the system

 

Well, you have a sample of the material. I would start with the "standard" Prestone radiator cleaner from the parts store, and mix it with it to see if it somehow dissolves. Maybe you need to heat it up. If it doesnot work, maybe you can reach out to a radiator shop and ask them what they use for their professional cleanup.

Also, I believe there is a engine block drain that could be used for a more complete flush.

Reputedly (I have not seen it myself), mixing incompatible coolant types causes a gel. Maybe this is what it looks like.

Also, if there ever was a leak somewhere in your cooling system, sellers have been known to add sealing products to the system for a quick sale. Maybe this residue is what remains. Following that logic, the cleaning might unfortunately bring that leak back.

Last, make sure you thoroughly clean the radiator. You might have overheated because it is plugged by all that stuff.

Best of luck, keep us posted.

 

Thanks for the quick responses. Great idea on the using the flush on some of the removed gel. I'll let you guys what happened . Thanks sgsin

 

Please keep us posted. Coolant gelling is a real thing and has been discussed, but I too have never seen it.

 

Wasn't your car supposed to use DexCool? ( the crappy, orange stuff) My '98 does. Whenever I've seen green and red mixed up (even after a drain and fill - so much of the previous never really gets drained) the result always ends up being gelled coolant. Next complaint you'll have is the heater doesn't work and it'll be from the gelled coolant plugging it or the heater valve, etc.