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C L R cooling system flush ?


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As the proud new owner of a 1940 BUICK LIMITED there is soooo much to do. So I had a discussion with my local radiator shop about the old girl running hot, and I asked if he would do a "flush" to the cooling system. He said he would do it and charge me a lot of $$$ but why not do it yourself with 4 bottles of CLR and plain H2O. Drain the coolant out first, refill w/ 2 bottles of CLR and water and run the engine for about 15 minutes, Drain and repeat W/2 bottles of CLR a second time, flush with plain water, and reinstall the 50/50 antifreeze solution. Allowing for cool down time this should fill up an afternoon, and save lots of $$$.

Has anyone tried this ? If so could you comment on the success of it ?

Best Regards,

Mike in Colorado:o

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1. Flush with some radiator flush from your autoparts store it is easy to do. Test

2. Check to see if distributor is advanced correctly. Test

3. Check the radiator fins. Test

4. Check Fan

5. Check to see if you have all splash pans and air deflectors. Test

6. Open thermostat housing and make sure all parts are there. Test

7. Check water pump impeller.

8. Pull Block Freeze plugs and check for corrosion build up especially around rear cylinders. Use the Radiator as a filter and run some more radiator flush.

9. Pull Radiator and have it rodded out then you should have a cool running engine.

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Mike, I don't think that your flush program using CLR will hurt anything as long as you do that final flush with clean water and don't leave the final two bottles in there very long or maybe just use one bottle for the second round. CLR is pretty mild phosphoric acid and it may have some acetic acid in it also. I hope that this flush is all you need but I'm skeptical when it comes to quick fixes on overheating problems.

I'd bet that over 90% of the overheating cases end up being a plugged radiator and one that is plugged will not flush and may not even be roddable. I guess that is a worst case and it is why we spend a lot of time and energy looking for the other possible causes - hoping for something less intensive or expensive. I wish there were some better ways to either indict or rule out the radiator. I've heard of the IR temp guns being used and I've seen one post that suggested that a radiator should be able to dump its contents out the bottom in about 2 seconds. Perhaps such experiments may be worth a try?

Your Buick has a bypass valve that may be circumventing flow in the radiator. If I recall correctly, it needs to be closed so that it does not simply redirect block discharge flow back into the pump suction. You might be able to tell if it's closed by just looking into the radiator and verifying that you're getting good flow there. Of course you can run through all the things that Eric has pointed out and try your best to not end up at his No. 9.

Do make sure the outside of the fins are clean. Good Luck!

Edited by JoelsBuicks
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I suggest removing the drain near the starter. If little or no coolant comes out, then you have rust debris in the back of the block.

Grandpa

I agree. We had the same situation. Car still runs hot. It's a 47 engine and has a bigger pulley that a 39. We have a 39 fan belt, so we're going to put a smaller 39 pulley on to speed the water pump up.

Cheers

Grant

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I suggest removing the drain near the starter. If little or no coolant comes out, then you have rust debris in the back of the block.

Grandpa

Ditto thanks "grandpa" from Mike. I'm waiting for my reprint shop manual to arrive, and your picture saved the day. I will definately check that plug. She is running hot and I found the temp sending unit at the top end clear in the back of the engine, so I will definately pull that plug.

Mike Simpson

Buena Vista Colorado

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Well, just to report back, I did the CLR flush Saturday, after checking w/ my radiator guy, he said 2 bottles the first time and one bottle the second time, then a clear flush TWO TIMES then fill w/ 50/50 prestone. So that is what I did, running her for 15 minutes @ each fill.

Results are, lots of crap the first time consisting of rust flakes and really nasty stuff. Not so much the second time, but a good stream out the drain Grampa showed me in his picture. Thanks so much to him. The clear h2o flush ran full stream and clear, and on the 50/50 fill, the temp, after a 20 minute idle, with towels over the grille, never exceeded 190f.

This proceedure DID fill up my afternoon though.

Best Regards,

Mike in Colorado

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