Is it leak down test time?

[fairlaniac]

So, after a few months of home projects, I finally have time to get to fixing my well documented rear main oil leak. So last night I pull the battery, pull the Sniper, drain the radiator and a bunch of miscellaneous things in preparation to pull the engine. I pull the distributor and what do I see? Green! Green antifreeze droplets seen through the distributor hole. Less than 250 miles ago and last May I changed my intake gaskets as I had a small oil leak in the back. So, I’m hoping the antifreeze may be from a mis-installed intake gasket? However, I want to make sure I do some testing before I tear anything else apart. I don't want to assume anything. I don’t want to pull the heads if I don’t have to. Those Cometic head gaskets are about the price of a dozen eggs these days. What is recommended at this point to determine the leak?

Edit: After thinking about this all night I remembered, back in the summer a fellow Fairlane Club member was following me through a tour in Gettysburg. He mentioned something about water coming out of the tail pipe(s).

Would the leak down test be t he best forensic tool at this time? It has not been out of it’s case in 20+ years so I’m a bit forgetful on it’s use. However, I think I still know the steps.

I did drain the oil and there is a very thin film of antifreeze hovering on top of the oil. Not much but it's there.

First time I've ever had the issue of coolant in the oil. Any help or tips are appreciated.

Thanks,

[My427stang]

What are you pulling it to do?  Neither a cylinder leak down or a coolant pressure tester will tell you a lot in this case.  It'd be nice if you could pressurize and see running water through the hole for peace of mind though

However, going inside you should be able to see if a cylinder is getting water from an unusually clean piston, could check the plugs now too,  and if you did have intake issues it could do it as could the start of a head gasket.  Just need to watch close during disassembly

[fairlaniac]

What are you pulling it to do?  Neither a cylinder leak down or a coolant pressure tester will tell you a lot in this case.  It'd be nice if you could pressurize and see running water through the hole for peace of mind though

However, going inside you should be able to see if a cylinder is getting water from an unusually clean piston, could check the plugs now too,  and if you did have intake issues it could do it as could the start of a head gasket.  Just need to watch close during disassembly

Ross, Thanks for the reply. I am pulling the engine to replace the rear seals. I guess at this point it might be wise to just pull the heads and see if there are any head gasket issues. I only pulled the passenger side plugs last night. Nothing odd there. Maybe there will be some sign on the other plugs when I pull them later tonight?

Thanks,

[GerryP]

If you start to tear it down as your diagnostic method, you might not find anything.  It is easier to pressurize the cooling system with the engine assembled.  A plate to block the thermostat, a plate to block one of the water pump holes, a plate with an air fitting in the other water pump hole.  Take out the spark plugs and put air pressure in the engine and see if that exposes anything.  It would be best to include a ball valve cut off with a pressure gauge so you can pressurize the system, contain the pressure, and see if it holds pressure.

A teardown inspection relies on a tattletale somewhere.  It might be a very small crack somewhere that has no clues behind it.  You have the end evidence of a leak so use all the processes to run it down.

[My427stang]

Very good point, pressurizing it with more than cap pressure would be beneficial assuming you could find the leak. Under the intake or a plug out might give some air noise. If you can hear through distributor hole, likely intake, if pulling plugs reveals pressure (I would remove all rockers) then head gasket. If nothing, apparent you’d likely be chasing trails of antifreeze during assembly

[fairlaniac]

If you start to tear it down as your diagnostic method, you might not find anything.  It is easier to pressurize the cooling system with the engine assembled.  A plate to block the thermostat, a plate to block one of the water pump holes, a plate with an air fitting in the other water pump hole.  Take out the spark plugs and put air pressure in the engine and see if that exposes anything.  It would be best to include a ball valve cut off with a pressure gauge so you can pressurize the system, contain the pressure, and see if it holds pressure.

A teardown inspection relies on a tattletale somewhere.  It might be a very small crack somewhere that has no clues behind it.  You have the end evidence of a leak so use all the processes to run it down.

Great idea Gerry. I have almost everything to make the fitting, gauge, ball valve right in front of me on my desk. Just need to make the plates. I guess I'll pull the heater fitting from the intake an put a plug in it?

Thanks!

[Falcon67]

This is same how I handle it - before I drop a motor off the stand, I either pressure it with about 15~20 psi air or adapt my Stant tester to hand pressurize the system and check for leaks. Saved me much grief on wet intake SBFs.