Best way to perform home made coolant flush - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat
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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 08-23-2007, 04:36 PM   #1
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Default Best way to perform home made coolant flush

I was working on fixing a vacuum leak and couldn't help but constantly stare at the coolant reservoir with rusty looking chunks floating around in it. It'* bugging the crap out of me and something needs done. I called a garage in the area all my family takes their vehicles to. As for me, I've never taken my vehicle to the garage in my two and a half year driving career, except for transmission work. I don't believe in it. The garage said it'd probably be around $60-$100 to do with chemical flush and everything, depending on how long it took to get all of the sediment out.

I'd like to give this a shot myself... and here was my idea. Let me know if you think it would work at all.

Drain the crap already in the rad into a bucket, take the reserve and hose off and throw the garden hose in there to get all that crap out. Once the whole system is empty, take out the tstat (replace later with 180), and then I'd basically take off the upper rad hose going into the rad, figure out a way to get it pointing into a bucket so it won't spill all over the ground. With the reserve hooked back up with the cap on, take the rad cap off and shove a hose in there and turn it on. From there, basically I'd wait until the water coming out of the upper rad hose was clear-ish. Once it is, put it back on the rad, fill it up with water, run the car for a few minutes, not long enough to get warmed up but enough to get the stuff moving out (without the thermostat in... safe???). Do the process a few times until everything comes out clear.

Does this sounds stupid, retarded, or do you think it would actually work? I'm well aware that I'll have to keep everything cool since after all I am flushing cool water through the system.

By the way, if that doesn't make any sense, that'* because I was designing the idea as I typed it lol.

EDIT: I've also considered the fact that I should refer to the techinfo article on refilling the L36 as well. I'm not sure, but the tag on the top of the intake manifold is a click with 97 through it, and the arm is pointing to a 3. 03-1997 I'm assuming was the manufacture date. If so, I would imagine any parts that like to fail on that intake are close and don't want to have to deal with it just yet so I'd better just follow procedure on that one lol.
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Old 08-23-2007, 10:08 PM   #2
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Since you have the time and the inclination, I would suggest you flush the engine, radiator and heater core separately. Here is one way to reverse flush all three.


Engine: Remove the thermostat, then install the top radiator hose and thermostat hose fitting back on the engine with the radiator end of the top hose disconnected. Remove the lower radiator hose from the radiator. Wrap a rag around the hose nozzle and flush the engine through the top radiator hose until the water from the lower radiator hose runs clear.

Heater core: Remove the hoses from the tensioner assembly and flush through the bottom hose until the water from the top hose runs clear.

Radiator: Remove the top and bottom radiator hoses from the thermostat and the water pump. Wrap a rag around the hose nozzle and flush through the bottom radiator hose until the water from the top hose runs clear.

Run engine briefly and repeatedly to stir up sediment: Install a flushing tee in the top heater hose by disconnecting the hose from the top fitting and using a spare piece of hose to connect to the tensioner assembly. Reconnect all but the top radiator hose at the thermostat. Fill the system with water at the thermostat opening and the radiator using the method described in Techinfo. Install a drilled thermostat. With the radiator cap removed, flush through the flushing tee, periodically starting the engine and allowing it to run for only 7-8 seconds at a time. Flushing must be done on a cold engine and the engine must not be allowed to get warm. Cold flushing water will crack hot engine castings. Depending on how cruddy the engine is, it may take 5 or 10 engine "mixes" until the water runs clear after the engine is run.

Remove the lower radiator hose from the radiator to drain the water from the radiator and partially from the engine. Remove the flushing tee and both heater hoses from the tensioner assembly and blow the water out of the heater core and hoses by mouth or by gentle air pressure. Reconnect the lower radiator hose. Hold the ends of the heater hoses at the same level and pour straight "mixes with any color" coolant in one hose until it begins to run out the other. Reconnect the heater hoses. Fill the engine at the thermostat opening, and radiator as described in Techinfo but use straight coolant. Considering the water remaining in the engine, that should give you at least a 50/50 mix. After cleaning it, fill the expansion tank with 50/50 mix.

1995 SLE
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