Does anyone have experience with flushing the coolent system? Have a new radiator and water pump with dual Spals and the thing still gets hot.

First of all the car sat for 20 years with the water still in the radiator and engine. Thought that by replacing everything when the engine got rebuilt I would not have any cooling problems but when it started to get hot at freeway speeds, where one would thing it to be the easiest on the cooling, decided to take a look at the fluid. It looked like mud. So after flushing and circulating the coolant many times it looks good but still having problems keeping it cool. Now I'm thinking that the brown stuff that came out of the engine has coated the radiator and is not as efficient as it should be.

Would like some advise on what to use if anyone knows.
Thanks

 

I just asked one of our mechanics at work about that myself. My fluid doesn't look like mud, but there is a film of rust on the top of the water. I went to him looking for tips on flushing the coolant system. My service manual gets into it extensively, but I was looking for the quick fix. During our discussion, he pulled out a Prestone super flush. There are instructions on there how to mix and flush the system. Drain the old stuff out. Fill the radiator with water and run the car. Drain again. I'm going to do this until the water comes out fairly clean. Then I'll try this radiator flush and then probably flush with water again to get all of that out of the system. He then recommended going to the extended life coolant (the orange stuff). The only thing he warned me about was to make sure the flush was compatible with the metal my radiator is made of. I just went to the prestone website and it said it's safe for all metals.

For draining the block, have you pulled the plugs on either side of the oil pan to drain the coolant there? I never knew they existed, but will look for them tonight. I guess that's the lowest point in the block, so that's where you'll get the most dirt. If nothing comes out, run a wire or nail up into the hole. It's probably just plugged with dirt. Make sure to use pipe dope or loctite when you reinstall the plugs.

Hope this helps.

 

also was the block tanked when it was rebuilt????
iv'e had good luck wth super flush

 

Just a note on that Prestone flush stuff: It's good stuff. It'll sure as hell clean out your rad and block, but sometimes it works a little too well. Especially on older cars, I've seen that stuff open up leaks in radiators, water pumps, various fittings, hoses even, etc. All that old muddy crud is sometimes the only thing keeping the coolant inside. Secondly, because it works so well you might want to flush without it first. As in, drain, fill with water, run, drain, fill with water + flush additive, drain, fill with water + antifreeze. Reason being that flush additive will free up that much more crud, and I'd be just slightly worried about that much gunk circulating all at once.

 

I agree. But if you need a really good product ... the stuff on most parts stores' shelves today (including prestone superflush) is simply too weak. I recommend Prestone Heavy Duty Cooling System Cleaner P/N AS100 ... it's a strong 2-part dry chemical. It's been around a long time but because it's strong it's seldom seen at DIY parts stores in these times of much litigation. AS100 is so good that GM recommends it in several current service bulletins and AS100 is available at your GM parts department with GM P/N 12346500 for under $10. I've used it for many years and is safe to use on iron and aluminum. Of course, if a rad/heater core is corroded so thinly that you can nearly read through it ... then any good chemical is likely to open her right up!

I recommend to DO NOT use the DexCool or any extended-use coolant because they are rather reactive with air and the product is a rusty slimey sludge ... you cannot get ALL the air out. Simply use the relatively inert green stuff and change out every other year.

 

When the engine was rebuilt, any reputable shop would have hot tanked the block, so there should be no crud in there. If you replaced the radiator and water pump, the only thing left in the system is the hoses and heater core.

How hot are you running? Is the temperature gauge correct? With a clean block, new radiator and water pump you shold not have a problem unless the radiator seals are bad or the chin spoiler is missing. Did they use a chin spoiler in '73?

 

Could this be a head gasket issue? Remember reading something similar in a recent post...

D. Ocean
Miami, FLA

 

Whoa, wait a minute ... I missed the part about the new radiator. Yeah, I think he's blown a head gasket. Your coolant looks like mud because oil has been mixed into it.

 

I believe the shop did hot tank the block but maybe not enough to remove 20 years worth of corrosion. Have replaced all hoses and heater core also. Hope it did not make the block unusable. Have gone to alot of work to make things last for a few years. Just remembered the spoiler on the bottom of the bumper was taken off to do the body work up front and have not put it back on. Maybe this helps alot more than it looks.

Have purchased the dual 11" Spal's and use their 190° thermostat to control them. My guage in the car says they come on around 200° F. so am guessing its off a bit but still can not put my hand on anything under the hood after a drive because of the heat and even after sitting with the engine idling for a while after a drive the engine does not cool down enough to turn off the fans.

It just ocured to me, should I have installed the shroud once again with the electric fans? This might direct the flow of air across the engine and not down to the ground like it is now doing.

Thanks for the help and advice.

 

I agree with wcsinx. Mud in the coolant is a huge clue to a blown head gasket. How this relates to your cooling problem is that in addition to oil in your cooling, hot exhaust gases are leaking into and boiling your coolant.

Why this happened, don't have a clue, but were the heads re-torqued after the rebuild, quality head gaskets play into it, warped heads or a engine deck that wasn't flat as well.

I think you need to do a leak down test and determine which cylinder(s) are the culprit. With the leak down test and radiator cap removed if you see or hear air escaping, more than likely it's a head gasket that failed.

Good Luck!

 

Thats some good information. Thanks
Hope it is not a head gasket. Only have 450 miles on the new engine. Am going to send a sample of the coolant to a lab to determine any oil contamination before doing a leak down test.
Ran it last night with the radiator cap off and it was not as bad as the first time the mud was noticed.
I remember now when taking the old hoses and radiator off, there was alot of brown mud in the bottom of the radiator. Decided to replace everything then. It looked alot like the stuff in there now. Hope it just crud left over in the block and slowly comming out now.
Will post an update when the analysis comes back.