Burp a hose at the highest point in the system that you can. On many older vehicles, this is often a heater hose. Depending on your set-up, you may want to permanently install a bleeder valve somewhere.
Is the rad cap the highest point on the cooling system? then what I usually do is fill rad up, and start squeezing the upper rad hose, the level should drop, refill and repete, usually can't do lower hose cuz of the spring in it. then I will run it with the cap off, if you rev it up alittle the level might drop then add more water, put cap on run till wamed up then stop and let it cool till you can open the cap and re check level. Some are more putzy than others...
When you install the thermostat, drill an 1/8" bleed hole or two on the outer ring, then follow the upper hose burp method above. Then wait 5-10 minutes and repeat. If you were dry before, it'll still burp pretty heavy due to air in the heater core and hoses, which you'll never get out without the engine running, cause they're usually higher than the engine & radiator. Safe plan is to only fill em 75%, let the thermostat open, and top off. Still may get antifreeze on your shoes when it belches.
Shop I go to uses a big funnel which attaches to the top of the radiator. Run the engine till the fluid gets hot. Excess fluid fills funnel. Thermostats opens, fluid level drops and replenish fluids. Bear on newer cars though, thermostats don't open until real hot. Couldn't burp a new corvette because it never got hot enough to open thermostat. 265 degrees.........
one of these kits, they're about $25 and worth every penny. if it has no heater valve (if it does have a valve the open the heater controls), just fill up system with the funnel (it will burp as you go), when you have a 1/4 of the funnel full go have a soda for about 15 min, then refill. you can run the car until the thermostat opens up with the funnel on. also drill a small hole in the thermostat like described above to aid with air exiting.
Sure it wasn't cause new cars have remote reservoirs? GM puts a couple bleed valves in em nowadays, just gotta know where to look. You'll endure hell trying to get em bled the conventional way.
1Oldtimer is totally right. That kit he's got pictured is some of the best 25$ I ever spent. I worked as a mechanic for 10 years before a new co-worker showed me one of these. I LOVE it! I can't recommend it enough. ANother trick a co-worker used to do was to rev the engine to about 2000 rpm and them take a hose to the radiator to cool it down. Coolant level would then drop and he'd add coolant. OR run it for a few minutes then let it sit and completely cool. The level should drop onits own- then fill. One last tip would be to lift the front end of the car up higher. Maybe get it a foot in the air- this will help make the radiator spout the highest point in the system. Jay
yes,1old timer is right the funnel discribed works verry well.i have worked in a new car dealer for 20 years and some vehicles are quite difficult to bleed out.another way i have found to work well is to use a stant or simular radiator pressure tester and pressureise to 5 to 10 psi and loosen the highest hose availble ie heater or byp*** hose.this will force out any air in the system ,most times i will not have to wait for the thermostat to open to push out any remaining air .dont forget to press.check your cap also a cap not able to hold press or bleeds off press will cause a mul***ude of problems most i find are commonly overlooked.
Since they started using 195degree thermostats, I've found some sbc's can't get up to operating temp with out boiling over with the cap off, seems they rely on the pressure to raise the boiling point of the coolant. I noticed this on a 305 pick-up, which had the light weight heads, so I think they probably have hot spots.Drilling the thermostat is something I do normally, there is no reason not to!
One thing I didn't see mentioned. Turn the heater control to heat/hot to make sure the coolant runs thru the heater core.
My grandfather gave me the raise the front of the car idea.. about a block from the house was a pretty good hill, we'd drive the car over there and bring a jug with us and that would always make the radiator cap the highest point.
If you are talking about the 56 Chevy in the picture...open the radiator cap and wait for the upper hose to warm up. If you are talking about something made in the 80s or 90s then you might need one of those new plastic kits that were never needed or available in the 60s and 70s. Oh yeah I never had to drill a hole in a thermostat either. Remember thermostats don't snap open like a mouse trap at their stated temp. That temp marking indicates the temperature at which the Therm. is COMPLETELY open. It will probably start to open and therefore release any trapped air, about 125 degrees. If you are talking 56 Chevies, what makes you think that it needs "burping". If you are talking 90's stuff...I have no clue and I'm not too interested in learning.
Thermos don't "snap" open but they start opening alot later then 125o.Put one in a pot on the stove & watch it. I saw on "how its made" TV show, pretty interesting, its made with a expandable type waxy ****.Seems like it would take alot to have one go bad
100% on the money here, if your worried about losing a shot gl*** full of coolant, leave the cap on at first notch, start, warm, nature will take care of the rest, trapped air didn't become a problem till they started making the block higher than the radiater. As far as drilling T-stats, good on a flathead Ford, uneeded on an SBC, because they have a byp***.
The above are good suggestions. I work on School buses and they have a very flat/long cooling system.... One method that always works is "power filling". 1. Warm up vehicle. Make sure thermo is open. 2. bring throttle up slowly to 2000-2500 rpms and hold there. 3. top off water at radiator-not overflow tank. 4. Immediately replace cap. 5. Drop rpms to idle. 6. top off overflow tank. 7. DONE In my 56 years, this has never failed to work, even on the most difficult systems. PS: those bleeder ports in the hoses most times just let air back in if not used correctly.
You are correct. I underestimated the "start opening" temp. A modern thermo will probably open much later because it doesn't open fully until a much higher temp is reached but I never tested one. The only one I had in the shop is for 37-48 Fords. NORS still in the box. The bellows hangs down into the head. As it heats up it pushes the flat disc on top up letting the coolant flow. You can easily see the factory hole that the flathead guys always recommend. It came this way. I believe this hole is peculiar to flathead applications. This one is rated at 175* and started to open about 150. You'll have to take my word for it. I was too clumsy to get a picture of the stat starting to open with a clear picture of the thermometer reading 150ish but my original point was that the stat starts to open at a temperature below the stat rating temp. I believe this old type was filled with a volatile liquid that expanded when heated pushing the belows up opening the stat. Thanks for the challenge. I bought these years ago and never looked at them since. I was surprised to see the hole from the factory. Sorry to get so far off track but I think it's interesting.
Relating to the thermostat being partially open when you're filling. Ever hold a thermostat in your hand at ambient temperature, is it closed? Yes. Guess what position it'll be in when you fill up a motor that's sitting at ambient temperature????? My money's on closed. Small block chevys only have a byp*** in platforms like 70s trucks that run one of the heater hoses to the radiator tank, which would make drilling the thermostat bleed hole futile. Standard p***enger cars that hook the heater core to the water pump and intake manifold don't have byp***es because the heater system is closed loop underneath the thermostat. If you look at the newest design small block, the LT1, guess what the factory put in the special LT1 thermostat? A bleed hole
Here's another old-timer's trick that'll work on problem vehicles. If you have the stat out, block it partially open with an aspirin or two before reinstalling it. This will allow you to get a good fill. By the time it's need has p***ed, the aspirin will have dissolved.
Try using a "Fail Safe" brand of thermostat if you can. They come with clips that lock the thermostat in the open position. You can press them open if you prefer - before installation. I've had great results with this apparatus.
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