Weird coolant leak

[KJ Ryu]

Anyone ever seen an anti-freeze leak that comes and goes? For the last month or so, my 401 has had an intermittent leak. Appears to come from the seal between timing cover and block. But, it only leaks 2-3 days at a time. Then goes 3-5 days without losing a drop. It's a pretty severe leak when it leaks. Loses a gallon or more overnight. Temp gauge reads the same as it always has, as long as I check the level; refilling as needed; so I know the thermostat and water pump work.

Today, I noticed that the PCV valve was starting to come out of the grommet. Sticking out half an inch or so. Any chance a failing valve could cause my coolant leak? A gallon seems like a lot for a little air pressure to push out. I'll put a new valve in it tomorrow. It's cheap and it couldn't hurt, anyway. Also got all the timing cover/pump seals on the way but, really want to figure out what would cause it to leak, intermittently, like this.

[BCRAWLER]

Wondering if you have a head leaking pressure into the cooling system.

[Cheapthrills]

My guess is possibly head gasket leaking at exuast port+bad radiator cap=blowing out waterpump mounting surface or thermostat housing/hose) there's no water ports effected by timing cover

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[babywag]

visit car wash and power wash it.
then go rent loaner coolant pressure tester
if you have a leak it'll help find it.

the timing cover leaking coolant is pretty common on these.

[Cheapthrills]

I'm thinking like a sbc.... I feel stupid now... lol... he's right...

My bad

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[440sixpack]

The water pump is on it and the passages to the block go through it.

The PCV has nothing to do with the coolant.

Are you putting any water in the oil? keep a close eye on it if you are it won't take long for antifreeze to wipe out a crank.

[candymancan]

visit car wash and power wash it.
then go rent loaner coolant pressure tester
if you have a leak it'll help find it.

the timing cover leaking coolant is pretty common on these.

Ive been wanting to pressure wash mine clean it uo of all that oil.. besides bagging the distributor and alternator and maybe the carb what do you suggest to stay awake from ? Or should you go all out lol

[KJ Ryu]

Not getting any cross-contamination, just a leak below the left side water port. When it leaks, it's a steady drip until the fluid gets about a gallon low. Doesn't matter if it's cold, warm, running or not; just a steady, fast drip. Then, will miraculously stop after a few days, until it returns.

[letank]

visit car wash and power wash it.
then go rent loaner coolant pressure tester
if you have a leak it'll help find it.

the timing cover leaking coolant is pretty common on these.

x2, papergasket failing after a while... mine was dripping when cold, then stopped after a few minutes.

the pressure tester free loaner at the zone solved my issue...

In fact I bought a pressure tester, too many friends with coolant leaks and exotic cars... that are not compatible with the loaners.

[ferrum]

I had similar issue couple of months ago after radiator replacement. Had little bit of coolant on timing cover. I wipe it down and check later and no leak. But then it comes back. I recheck bolts and they are tight. I got to find out what caused it few days later. It was bypass hose had a pin hole on the back side (hard to see) where it connects to water pump. When it became obvious, I was on my way to work and coolant was lubricating power steering pulley. My hose was over 15 years since I changed it.

[prospector]

Many water pumps have a weep hole, when the pump gets old and worn coolant will leak through this hole to tell you that it's time for a new water pump, this would be my best guess. Replace the pump, temp. sensor, and thermostat, that should be the end of it. But definately check that water pump first, if it dies you'll be on foot, if it seizes you might be replacing the radiator too.