1985 22R loosing coolant

Thermostat:

Leaking out the weep hole at the bottom of the pump shaft. Could also be a worn timing chain that has eaten into the back of the water pump housing and caused coolant to leak into the oil.

Yes, have it pressure tested. You can also see if the pressure rises while the engine is running, too much might indicate that engine compression is pressurizing the cooling system and causing it to blow out the radiator cap and overflow the tank.

a worn timing chain that has eaten into the back of the water pump housing and caused coolant to leak into the oil.

while the engine is running, too much might indicate that engine compression is pressurizing the cooling system and causing it to blow out the radiator cap and overflow the tank.

I finally got a chance to start looking yesterday evening. Topped of radiator. Checked Cooling fan for excess free play, seemed fine. I started it up in the day light and let it warm while watched and observed closely. It did not overheat, BUT it had about 50 times too much exhaust, which gradually tapered down to 10 times too much exhaust. No external leaks or steam other than exhaust. Removed oil filler cap while warm & running. I don't usually do this, but I noticed a vapor / mist and the underside of cap had milky looking sludge. Pulled plugs - looked white & crusty / scaly thick deposits on electrodes and insulators. Tested compression, 1-4 checked: 180 , 189, 190, 185 PSI.. Book says is should be 171, and max difference should be less than 14 psi. Went to AutoZone, and borrowed a cooling system pressure tester. Cap pops off at ~13 PSI. but the adapters in the set did not fit the radiator neck. bummer. I would really like to pressure check the cooling system prior to digging in.

timing chain chewing a hole still seems likely .

Can the timing cover, ....chain tensioners.... be accessed from below by dropping the oil pan??? The guy at AutoZ suggested it was common to do the job without removing the head.. In my case the front grill is already off . seams like if radiator I would have easy access from the front also.

Thanks, Scott

a worn timing chain that has eaten into the back of the water pump housing and caused coolant to leak into the oil.

while the engine is running, too much might indicate that engine compression is pressurizing the cooling system and causing it to blow out the radiator cap and overflow the tank.