Bore scope is really easy to use,,,,,very inexpensive too . Really , really easy with a Hemi ! You can see a lot from inside the cylinders . Tommy
Ran 100 psi leak test on all cylinders #1 - 90psi #2 - 82psi #3 - 92psi #4 - 90psi #5 - 88psi #6 - 90psi #7 - 92psi #8 - 75psi - not good pressure testing radiator, it’s holding steady at 12psi from the cap. Can’t hear or see any bubbling anywhere. the motor seems fine until it gets to that 140 temp and all hell breaks loose with tons of pressure coming out the cap. when I initially did the fluid test on the radiator gases it was dead cold motor and no change in the blue fluid. I then let it go to 130-140 and instantly it change the fluid to yellow. Then right after the test with the motor still idling, radiator starts getting a rush of pressure, overflowing out of the top. That was at about 150 temp.... got to be head gasket as this thing warms up?
If you don't have access to a leak-down tester you can make your own tool by hammering the porcelain center out of a used spark plug, then welding an air-hose nipple to the shell of the spark plug. Listening for leaking air can be tricky, my recommendation is to cap off the radiator hoses with PVC plumbing caps to prevent damage to the radiator, then take the bypass hose off, cap one end with a pipe cap then thread a short piece of pipe in the other opening. Slip a balloon over the short piece of pipe and tie tight with rubber bands as needed. As you pressurize each cylinder if there is any air escaping in to the cooling system the balloon will let you know .
Strange series of events going on here. It's a fresh motor so 1 low cl could just be rings not seated as well in that one. To find out load that cyl again with same air pressure. Remove the Oil Fill Cap and listen to the crankcase for air leak. Have you re torqued the Head Bolts? Worth a double check. I forget, have you removed the thermostat and run the motor? What did that do? Your symptoms reflect a bad head gasket, but the leak down numbers and Rad pressure test don't.
Retourque the heads, get some Moroso ceramic seal. It's pretty good stuff for a small combustion leak. https://www.amazon.com/Moroso-35500...ocphy=9019580&hvtargid=pla-493078724108&psc=1
Have not re-torqued heads. Ran without t-stat, still a ton of bubbles and once it gets to about 150 temp, it’s a geyser of pressure coming out of the radiator cap. I can’t hear any air leak during the leak down.
Nothing heard in oil cap, also no coolant in the oil. No smoke out the pipes either. Possible it’s a small leak that’s right next to a water jacket... the chemical tests is a definite that there is crank case gas getting in there.
I would do more to identify exactly where the air is going in #8. Do you know how to use a rubber hose as a stethoscope? If so use one and load #8 again. Listen in the Carburetor and the #8 exhaust port. Even if it is a Valve leaking I don't think it's going to be your major issue. I have never used the Ceramic seal as mentioned but have heard good thing about it.
You are Positive you have good water movement, right? I found a plastic plug in a water pump lower hose nipple once. It was a lot easier to find though.
Just did another leak down, all cylinders are at 90psi. I must have not had #8 at tdc the first test when it was 75. I also did one on intake stroke with a gauge hooked to radiator cap to see if there was a change in pressure. All were good. has to be head gasket expanding with heat? Like I was saying before it seems fine before it gets to about 150 temp. what else would cause combustion gas in cooling system? Cause that’s a for sure that’s im getting gas in there...
Plugs look great. Lake headers with baffles. Pertronix dizzy set to 8 initial and limited to 20 mechanical.
When I did the combustion gas test on radiator the first time, I did it with cold motor right off start up. There was no issue. Then I warmed up motor real good, purged some coolant off the top so it wouldn’t interfere with the test fluid, then it was positive for gas. Like it had to get to that warm temp before gas got into the system. Kinda like when there isn’t much air/pressure when cold, but when it get to that 140-150 I get tons of pressure/bubbling and heat jumps quick.
I would think if it was a head gasket, it would be getting coolant in a cyl also. When it gets to 150 or whatever, I would think it would suck coolant in a cyl as well as blow it out into the water jacket. Lippy
Is 28 total enough? But the real problem is gases n the coolant, my money is on a head gasket, but ya never know unless the heads are pulled..My experience is the engine can run good and the spark plugs look normal..
It’s about 29 advanced with a dial back light. But ya you’re right, the real issue is gasses in the coolant. Pull the heads and look around I guess... I’m pretty sure I’ve tried everything else haha
First off, it isn't crank case gasses in your radiator, it's combustion gasses from a cylinder. Second, the purpose of a leak-down tester is to determine cylinder health, the purpose of the tool I suggested that you build is to find out what's leaking air, as in burnt valve, piston ring problems, or head gasket issues. Now on to the main event; if you pressurize each cylinder through the spark plug holes you can find which cylinder has a problem but you won't be able to determine exactly what the problem is, if you do what I recommended, which is pull both radiator hoses off of the radiator and cap with PVC plumbing caps, you can now pressurizing the cooling system in an effort to force air into the problem cylinder. While the cooling system is being pressurized you can (hopefully) with a boroscope see exactly where the air is leaking into the cylinder, as in blown head gasket, cracked head, or cracked cylinder.
Ok got it. Now how much pressure do you think I would need to put to the block in order to replicate the leak? I pressurized the system up to about 14psi through the radiator. Now I know that’s not a ton, but I didn’t want to over pressurize the radiator...
On first run in 9 years ago you had no heat issues at all, is that correct? Or is that when the factory soft plug blew out?
Bought it 9 years ago, it’s was fresh on a crate. Was told it had only run on an engine stand and that’s it. I have never run it, this is the first time. Very first start up last week I blew a freeze plug. Got my HH plugs 3 days ago and now this is where I’m at. pulled valve covers and oil pan, it was definitely a fresh build. Pan was drained, but evidence of a break in run. I primed motor with a drill and got good oil pressure before firing. Still at 50 on oil pressure
I understand now. I'll get back to ya tomorrow. I'll think on this overnight. Good oil pressure and good leak test so it isn't past salvage probably. I've learned there are very few reasons to sell a fresh build. Most of them aren't good ones. Let's hope for the best.
Basically what you are trying to do is isolate the engine block and heads from everything else in the cooling system. This is to prevent higher than normal pressures from damaging those other things, like radiators and heater cores. How much pressure will it take to find your leak? Unfortunately, you mention the problem doesn't show up until engine temperature reaches 140 degrees so you might not be able to pressurize the engine high enough (safely) using PVC caps in order to find the leak while the engine is cold. The next alternative is to pull the water pump and make steel block-off plates, one with a tire valve to pressurize the engine. If you do that you can safely apply much higher pressures. Unfortunately, from the information you have given us so far, I believe you have a cracked cylinder bore, which would also explain the blown out freeze plug.
That would be unfortunate, but these can be sleeved. I have a few on the road that we sleeved back to functional.
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