LS4 coolant flushing.

Mr312712 said:

About 3 months ago I took It to the dealer for a coolant flush. Didn't notice a thing they supposed to have done. Reservoir was still gross looking like It hadn't been touched and no sign of hose removal. So I tried cleaning the reservoir but was still gross so I ordered a new one. Now a month later the reservoir Is starting to look gross again. So today I took the lower hose off at the thermostat housing and let that coolant drain (that caused the reservoir to drain also) and took the thermostat out as It was stuck open anyway. Filled It back up with water at the radiator cap and let It run and went on my way. But I wanna know how to get all the sludged up dexcool completely out. I know the heater core and radiator are both holding dex cool crap. Obviously the whole system didn't drain but enough came out to plug my drain pan up. To flush the radiator I fill through the top and let It drain out the bottom? And for the engine I fill through the top and let It come out the thermostat housing? Correct? Heater core I plan on flushing by Itself. Thanks.

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You can get flushes at auto parts stores. Maybe Walmart, too. You pour them into the system, fill it up with water, and run the engine a while, then drain and flush, then refill with coolant/water. Follow the directions on the label.

The only concern I have is that you might remove that one bit of crud that's plugging a leak somewhere in the system.

If you want to forego using a flush additive, then I would simply fill the system with water and drive it for a while, then drain and fill with coolant, etc.

HTH.

Doug

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Just did our 08 durango this past Thursday, the second coolant service on it. Used prestone flush and radiator cleaner they sell at walmart. Drained out as much of the old as possible, opening up the both the radiator drain and the bottom radiator hose. Pulling off the hose always helps get out more of the old coolant. Put distilled water and the cleaner in and ran it for about 30 minutes with the heat both rear heat and front wide open on the highest heat setting. Re drained the system and put in equal parts of new coolant and distilled water.

There is a product that is sold by prestone that allows you to plumb in a fitting that accepts a water hose which allows you to keep the drain open and flush all the old out while running fresh clean water in. Downside to that is the source of water will obviously not be distilled water. I used one of those on an older truck I had, cleaned the system with fresh water from a hose and never had any known issues.

I would question what the dealer did in your case. If you paid for a flush, there should be NO sludge, it should be clean everywhere and they should have put back in fresh dexcool. I would be taking the car back to that dealer if it were mine.

Well today I wasn't doing anything so I gave the SS some attention. I pulled the lower hose off the thermostat housing and let that drain. Pulled the upper hose off the radiator and flushed through the top of the rad and let It drain out the lower hose until It was clear. Ran water through the top rad hose that goes to the engine and let that run out the thermostat housing until that was clear. Flushed and back flushed the heater core from the rubber hoses and flushed the hard heater lines that run from the water pump back to the core. Wasn't as bad this time. So tomorrow when I go to work I'm gonna swap the thermostat and buy the one that comes with the housing as my housing Is corroded. But I'm pretty sure I got 95% of coolant out the system, even took the reservoir out and flushed that. Put everything back together and filled the system through the top heater core hose, to make sure I had heat even though I don't need It. But for now all I have to do Is replace the thermo housing and Install the thermostat and put some fresh dexcool In as It's just pure water In It.

For anyone wanting to know how to get at the thermostat on the V8's, It's not hard at all. Alot of people say to take the exhaust manifold off but It's much easier to just take off the manifold heat shield and run some 1/4 extensions behind the manifold to get at the rear housing bolt (10mm). Seriously took me 5 minutes to get the old thermostat out.