labrat Posted February 25, 2002 Share Posted February 25, 2002 Ok, as everyone here knows by now, i've been having some cooling system problems. This motor has been sitting for a while with plain water in radiator (no antifreeze) and the water jackets are full of rust. I believe this is what is clogging my radiator (I felt cool spots in the rad once i took the A/C condensor off). I want to flush my radiator and the water jacket of my motor. Can i use dilute muriatic acid to do this, if i flush with plenty of plain water afterward? I think it would be great for removing all the scale and rust flakes in the block, but i don't want to shoot myself in the foot. Will this fubar my motor? I just wanna get some opinions before i really goof something up... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 26, 2002 Share Posted February 26, 2002 I can't think of anything you would hurt. I know you wont hurt your block. The only thing I would worry about would be the radiator, but I dont think any thing there would be harmed either. Maybe someone at a radiator shop could give you some definitive answers. George Quote Link to comment Share on other sites More sharing options...
labrat Posted February 26, 2002 Author Share Posted February 26, 2002 Ok, here's what i did, and it worked great! I removed my radiator and left one hose attached to use as a filler spout. Poured in about a quart of muriatic acid, and let it bubble for about 10 minutes, then rinsed and fluse=hed well with fresh water. then, with water pump removed, i poured about 1/2 gal into upper rad hose attached to manifold. let sit, and then flushed for 10 minutes or so through upper heater hose, letting the water drain out through the holes where the water pump sits. i let all the water drain through an old piece of window screen to catch all the debris, and ended up with enough gravel and scale to fill a coffee cup! the water pump wad leaking, so i replaced it. The inside of my copper radiator is now so clean it looks like a new penny! it was definitely a cheap $3.00 fix for a problem that was driving me crazy! If this doesn't solve my cooling problems (I haven't tested it yet, i wanna wait for the sealant to cure), then i definitely need a bigger radiator. Quote Link to comment Share on other sites More sharing options...
denny411 Posted February 26, 2002 Share Posted February 26, 2002 just a thought, Wouldn`t it be possible that some of the sediment is still in the block around the base of the cyls,in the water jacket? This is lower than the holes for the pump,especially the the far left and right hand sides of the block. Did you remove the plugs down by the pan rail on each side of the block? This would allow all of the coolant to completely drain from the block. Thanks for the tip Quote Link to comment Share on other sites More sharing options...
labrat Posted February 26, 2002 Author Share Posted February 26, 2002 I figure it's likely that some sediment did remain in the lower part of the block, but my aim here was to rinse out anything small enough to be carried into the radiator and clog it up. Where i live, i have VERY high water pressure (water hoses don't last very long) and i'm confident that i got enough of the smaller chunks out that can wash into the radiator. Enough to last for the year or so I plan to run this motor (gotta save up for a fast burn 350). Quote Link to comment Share on other sites More sharing options...
labrat Posted February 27, 2002 Author Share Posted February 27, 2002 Just an update, but it worked like a charm! The Z is no longer overheating on the highway! I think the major trick was removing the radiator from the mount and angling the filler cap end up at 45 degrees to get it higher than the motor in order to fill the system completely. When i took the thermostat housing off, i noticed a large air pocket in the intake, and i think this air pocket was moving to the radiator when the engine was on. It was impossible to fill completely because the radiator filler cap was lower than the manifold and upper hose. But the cooling system works great now! I highly recommed the muriatic acid flush for those of you out there doing it on your own. I flushed with plain water for what seemed like days, till nothing else came out. Added the muriatic and let it sit, and sediment then came pouring out when i flushed it. I'm running plain water right now, i plan another flush (both block and radiator) in about a week when everything has a chance to get knocked loose. Better yet, instead of recommending this flush, i recommend starting with a new motor in the first place, not one that's sat forever! Bill Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted February 27, 2002 Share Posted February 27, 2002 Hey Bill, Thanks for the flushing tip. Could you give a little more detail on how you did it. I'm assuming the car wasn't running and the thermostat was removed? Stupid questions but I want to try it too. Thanks John 1977 280Z8 1966 383-Charger Quote Link to comment Share on other sites More sharing options...
labrat Posted February 27, 2002 Author Share Posted February 27, 2002 No, the car wasn't running, and the water pump was removed. I had a thermostat in, but it was gutted out anyway (spring and stuff removed) so it was basically just a 1" restriction in my hose. You would probably want to remove yours. I left the upper radiator hose connected to the water neck, and the lower hose connected to the radiator to use as filler spouts. I removed the radiator, and flushed with a water hose for about 15 minutes or until i couldn't get any more sediment out. Then i poured in about a quart of muriatic acid and using the hose as a handle, swished the acid around as much as possible and let it sit for about 10 minutes. Flush for 10 minutes, spray acid off of the driveway, repeat as necessary till sediment stops coming out of radiator. This is a copper radiator, I have no idea what would happen with aluminum, probably bad things! Acid really eats aluminum! After getting tired of messing with the radiator, i moved to the block. Using the upper radiator hose as a spout, i poured about 1/2 gal of acid into the block, and let it sit for about 15 minutes. I only flushed the block once because of my aluminum intake manifold. After spraying off the drivewa again, i flushed the block through the upper (manifold) heater hose. It fit over my hose nozzle perfectly. Just wedged a bolt in the nozzle handle to keep it spraying, and let the water come out the water pump passages. Waited 15 minutes or so, and considered it flushed! When i reinstalled the radiator and water pump the next day, i noticed a little bit of debris floating around in the water, so i'm going to run it for a few days and then repeat the operation. It worked like a champ, and now i can cruise the highway all day long at 180~190 degrees! Just watch out for the acid. It will remove skin, and it will eat your driveway. It will also kill any plants it gets sprayed onto... I hope this is as much detail as you need! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 28, 2002 Share Posted February 28, 2002 I was advised by an old friend to use the dish washer detergent "Electrasol" on a really corroded over heating radiator in a junk pick up my brother bought for temporary service as a hauler for moving . Poured a couple cups in and a few days later drained and poured in a couple more cups for good measure since it was working but still looked a little rusty. My brother kept driving it without over heating from then on. The second time we flushed with a kit; we filled it back up with anti freeze mix and it never overheated again until I drove it without oil for a few miles almost a year later after the radiator quick fix. It burned about as much oil as gas. Hitchiked back home that day and never looked back. Quote Link to comment Share on other sites More sharing options...
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