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I got all the engine together and it's running fine. My problem is that the coolant temps keep increasing and overheats. I usually shut it off before it hits 230F. This is just sitting in my garage.
My cooling system is as follows:
New Aluminum Radiator
New Aluminum Water Pump
New 180F Thermostat
Electric Fans - Just set to 190/175F right now.
Heater Core Deleted
I think it is a coolant flow problem because the upper rad hose is hot, but the lower is cold. I tried get all the air out - heat cycled a few times and topped up the rad a couple times. I changed the thermostat with another new one and no change. The lower rad hose has a coil in it and does not look like it collapses.
Sometimes if I squeeze on the upper rad hose a bunch, or play with the rad cap vent lever it might start to flow and will cool right down to 175F where the fans shut off and it will stay stable like this with fans cycling on/off. I noticed that if I rev the engine (~2000 rpm+) the temps will temporarily stop climbing, but then rapidly increase after I return to idle.
How did you fill it? I've always filled mine up to the thermostat, then put the water neck back on and top off the radiator.
EIther there is still an air bubble, or your water pump is stalling out (I don't think it can, except from air). Squeezing the radiator hose primes the pump.
Are you sure your new aluminum pump is turning in the correct direction for your car?
What do you mean by thermostat housing? The waterneck? The waterneck is aftermarket. I used an aluminum one that is similar to stock but without the emissions junk on it. This is a 1978 btw.
The system pressurizes, so eventually the coolant just pours out of the rad with the cap off. Seems like there is movement.
I filled it through the radiator. I'm not sure what more I can do to get air out if there is any left. I ran it with the cap off. Cycled it several times. The coolant in the rad doesn't drop anymore. Last time I ran it while the front passenger side was jacked up a bit.
I think the pump is correct. It's a Chevrolet performance products pump specific for C3s.
Definitely sounds like its got an air pocket in it.
Normally, I jack the front of the car up, remove the water neck, and fill the entire system up through the intake manifold. This seems to push the air out pretty well, except for the upper radiator hose. After reinstalling the water neck, I top off the radiator while squeezing both the upper and lower hoses quite a bit to "pump" the system. Start the car, let it warm up, remove the radiator cap (before it gets too hot/pressured up) then watch for the water circulation through the radiator. Add more water to fill it to within about 1" from the top.... Heat cycle it a few times, pop the cap when its cold and the radiator should be full. Then put a level in your reservoir and let the system pull in the coolant as it needs it.
I filled it through the radiator. I'm not sure what more I can do to get air out if there is any left. I ran it with the cap off. Cycled it several times.
Originally Posted by ajrothm
Definitely sounds like its got an air pocket in it.
Normally, I jack the front of the car up, remove the water neck, and fill the entire system up through the intake manifold. This seems to push the air out pretty well, except for the upper radiator hose. After reinstalling the water neck, I top off the radiator while squeezing both the upper and lower hoses quite a bit to "pump" the system. Start the car, let it warm up, remove the radiator cap (before it gets too hot/pressured up) then watch for the water circulation through the radiator. Add more water to fill it to within about 1" from the top.... Heat cycle it a few times, pop the cap when its cold and the radiator should be full. Then put a level in your reservoir and let the system pull in the coolant as it needs it.
What he said^^^^^^^^ Nose Up, waterneck off & fill there
It's not necessary unless it is. If you have Vortec heads or an intake manifold that blocks the passage, for example, I believe it is absolutely necessary. . A small hole in your thermostat should do the same thing.
But right now you just need to top off the system. As many have already suggested, filling up to the level of the thermostat through the waterneck opening should get you going, and clear the air bubble at the top of the engine. Then top off at the radiator.
High & Low, high & low. Keep front end high, keep coolant level low.
Several people make burping the system more difficult than necessary.
Playing with the Rad Cap lever does nothing. Leave the cap off.
Continually adding coolant to the brim does nothing. Leave room for the air to escape.
Having the car on the level does not help. Get the front end up. If you don't have ramps, drive up on a piece of 4 X 4 post. Anything to raise it.
We tend to panic when the big burp takes place and immediately pour more coolant in. Leave the coolant level low. Let it continue to burp. All this takes time. Give it time.
I would pull the thermostat just to check if that's it. Put it back together and run it to see if it maintains. If that happens to be it then get a new thermostat.
While out I would drill a couple of little holes in the thermostat to allow easy filling.
Also, check that waterpump part number (on the actual pump, not a box or whatnot). If you somehow got a mis-boxed reverse rotation unit it won't be moving water approriately.
SBC wtr pumps ... reverse rotation ... impeller itself is what truly determines that ... reverse impeller is a stereo image of standard impeller ... If you really think the waterpump might be wrong rotation etc or have wrong impeller installed at factory ... pull back off pump and take a good photo of impeller [ with a quarter coin in field (that way I'll KNOW the photo is/isn't reversed) ]... post pic and I'll tell you what you have.
Self-ID Tip ... in Proper orientation ..typical sbc Stamped impeller Vanes do NOT "cup" the liquid but instead do "sling" it. It'll work pretty well backwards but just isn't as efficient.
It would be EXTREMELY rare OE factory /rebuilder installed wrong impeller ... but stuff happens.
Thanks guys. So you are suggesting I drain it and fill it again through the waterneck while jacked up?
When I put the second thermostat in I did drill a 1/8" hole in it. The rad pulled coolant from the reservoir so I didn't need to add anything to the rad after I drained some coolant to replace the T-stat. I just topped up the reservoir.
I'll check part number on pump. I don't really want to pull it haha.
Thanks guys. So you are suggesting I drain it and fill it again through the waterneck while jacked up?
When I put the second thermostat in I did drill a 1/8" hole in it. The rad pulled coolant from the reservoir so I didn't need to add anything to the rad after I drained some coolant to replace the T-stat. I just topped up the reservoir.
I'll check part number on pump. I don't really want to pull it haha.
don't drain it. What is in there is in there. Pull gooseneck. Fill to top there. Make sure t-stat is not wrong way up. Take t-stat into kitchen and put in a pan of water on the stove. Watch it open and see if it opens before water boils. Meat or cappuccino thermometer works.
They are ebay knockoffs of the spal 11" dual fans. https://www.summitracing.com/int/par...2052/overview/ Looks like they use the same molds as spal as the shroud and fan blades are the same. Probably just with cheaper motors. I had $15 off coupons so I thought I'd give them a shot for $75. Been working fine for a year on my '74 firebird and move a ton of air. We'll see how long they last.
I jacked up the front of the car and put it on jackstands. Bumper was about 10 inches higher off the ground.
I drained some coolant so I could remove the thermostat without spilling any. I refilled coolant at the water neck and put the waterneck back on without a thermostat. Coolant was about 2" below the rad cap.
I ran the engine while jacked up with rad cap off. Coolant was flowing through the rad and almost immediately I could feel the lower rad hose warming up.
I let it cycle a couple times - coolant temp hit 190F where the fans come on and then temps would drop to 177F where fans shut off - stays stable cycling like this.
I topped off the rad while it was running.
I think I'll leave the t-stat off because it's actually working now and it seemed like it didn't take much longer to warm up. The electric fans wont come on until it's up to temp anyway. I wonder if it was 2 bad t-stats? Seems excessive to get air out!
The T-Stat does more than just help warm the engine, it also restricts the flow of coolant to allow the heat to be removed as the coolant passes through the radiator. You may end up with another cooling issue running without a thermostat. Even some race engines use flow restrictors to slow the coolant down. The purpose of the by-pass is to keep air out of the system. There is no need to jack the car up to remove air from the cooling system, just another urban legend. By removing the thermostat you bypassed 100% of the coolant and that is how the air was removed not jacking the car up.
Overheating Problem - No Flow??
