Focus Fanatics Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
279 Posts
Discussion Starter #1
With 108K miles, I decided to Thermocool my coolant system.
While running the engine with clear water to rinse out the solution, water came out the cylinder coolant plug between 1 and 2 and filled that spark plug cavity with clean water and sizzled. This isn't the first time, it happened around 70K miles when I flushed the coolant system with distilled water only, and water combined with rust left and left a rust residue around the spark plugs.

At first I was bummed, thought I blew a head gasket, then did some research and it's not the case. Now I'm wondering why these things are there in the first place, and what the function of them are for. Perhaps this leak with pure water is a good thing, letting excess pressure out. Or maybe it's a bad thing, like the plug is bad and needs repair. I don't know where to get the correct plug from.

It doesn't leak with 50/50 coolant.

Just wanted to see what others think.
 

·
Registered
Joined
·
279 Posts
Discussion Starter #3
It was when I filled the system with clear water, took a long test drive and pulled the car in the garage. I heard a sizzling noise, pulled the #1 plug wire and saw water boiling in the spark plug socket.

I'm not going to worry about it, could of been water that slip through the plug wire when I was washing the engine down. And the rust came from the spark plug.
 

·
Registered
Joined
·
16,057 Posts
Not leaking, if it was then antifreeze makes it WORSE as antifreeze always does with a leak. Antifreeze 'slicks up' water to make it leak much easier. Why you can leak check to OK with straight water at first, add coolant later, and suddenly you have 2-3 leaks.

A plug has nothing to do with freezing and cracking, they are there to replace holes that were used to remove casting sand that filled head to create cooling passages for the head. They then machine the holes to accept a plug to close it off. Most holes get freeze plugs instead, the plug hole could be used in the interim to locate head for machining operations.

If it ever leaked once it would keep on leaking, they do not fix themselves. You shot water in there some other way.
 

·
Registered
Joined
·
279 Posts
Discussion Starter #5
I agree that water slipped by the plug wires.
Thanks for explaining why they are there. Appreciate!
 
1 - 5 of 5 Posts
Top