I need to test the cooling system for leaks, Visual inspection has not worked. If anyone has a home built tester, I would appreciate pics and description so I can make one. It's for a '62 Pontiac.
Run down to Autozone "borrow" their cooling system pressure tester, Pay the 80 something buck deposit. Go test the cooling system, get things figured out and take the tester back and get your deposit back. For rather spendy tools that you may use once a year or once every two or three years that works great. Figuring out a cap that you can put pressure to is a challenge in itself and then coming up with a pump and gauge.
...You'd also need a check valve to allow air into the system but not allow it out while pumping, or you'd never build any pressure...
Not home made, but, I have used the Murray tester with great success. Can not remember where I bought it. O'R shows it at $74.99 https://www.oreillyauto.com/shop/b/...ant-system-pressure-tester-12682/3a8e8dc6b794 EDIT: This might be the one in the Autozone loan a tool program.
Get another rad cap. Take it apart. Drill a hole in the base plate to take and fit a bolt in tyre valve stem. In the top cap make a hole that the valve stem will go through, may be necessary to add a valve extension to get long enough to come though. Assemble back on rad as it would be normally as per normal cap. Then use a foot pump with a gauge to pump up to a suitable pressure.
Not trying to be a smart a**, but from how I understand the OP is that he is looking for a leak? So if the engine was warmed up, wouldn't that put the system under pressure? From the statement made, looking for a leak, it doesn't make any difference how the system is pressurized (my thoughts) you still need to "see" the leak. A pressure tester will only confirm what is already known, that a leak is present. I say that perhaps you should try bypassing the heater core and see if that eliminates the leak. Take a close look at the water pump weap hole. Perhaps the cylinder heads/bolts.
Sometimes a leak only happens when an engine is cold. It is also easier looking for a leak on a cold engine. I have the tool the OP needs. I would loan it to him if he was local.
Replace the top hose with a section of motorcycle tube with the valve in place,(cut either side of the valve to the right length),pressurised to the same pressure as your cap is rated to and start checking. Still won’t “see” an internal leaking head gasket though.
I put the hose connection in a old cap and pump the system up with a few pounds of air and listen.. This works better then running the car...
Ya remember seeing it being done that way but with a bicycle inner tube which would nearer the outlet sizes. Cheap and easy.
The coolant dye that glows under uv light is also helpful and cheap when trying to figure out a difficult leak.
I appreciate the advice but don't want to buy a $80 tester for a 1 time check and Autozone does not have one to rent/loan. I'm hoping a member can post a pic of a home made tester. I know I need to incorporate a schrader valve and a pressure gauge. I just don't know how. It's a slow leak and I'll have to keep the system under pressure for quite a while in order to find the leak.
I used an air fitting and hooked it up to my compressor. Set the regulator to 20 psi and used another pressure gauge on the thermostat housing. Also used a couple expansion plugs to close off the water pump outlets. Worked great, no leaks!
I thought about this, but wouldn't the pressure cap keep the compressed air out? The pressure cap has a spring that pushes the seal down into the opening, once the pressure inside the cooling system exceeds the cap rating, it burps. The overflow tube is "outside" of the seal, so it would not pressurize the system IMO.
Just curious, but can you elaborate on that a little? Why do you think you have a slow leak? You're losing coolant somewhere? Normally you'll see evidence of coolant leaks as it will leave behind traces of antifreeze/water. At least you should be able to narrow it down. If you don't see any evidence, maybe the leak is internal, in the engine.
When you remove the radiator cap and warm the engine up, do you see any air bubbles flowing in the coolant ? If so, do a compression check and look closely at your spark plugs for signs of a blown head gasket. I made some tools for pressure testing a radiator and I hook the air compressor directly to the radiator. I only use about 10 lbs as the radiator cap will release pressure if its too high. Also too much pressure may rupture something. You might be able to get a heater hose loose and then make an adapter to put pressure through there. Another way is to remove the thermostat housing and weld a bung and tap a fitting hole in it. Then screw an air hose fitting in it. when done, remove the fitting and screw a plug in it.
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