Symptoms would be helpful??
Head gasket issue or cracked head will first show up as extra pressure in the cooling system, which causes full over flow tank and slight over heating, or up and down movement of temp gauge.
Leaking cylinder might misfire on cold start and then start working again.
As it gets worse so will over heating.
To test for this remove rad cap on cold engine, make sure coolant is topped off.
Put rad cap back on
Squeeze upper rad hose, feel the pressure of it, or lack of pressure is what you should feel.
Feel upper rad hose, it should feel exactly the same
Idle engine for a minute or two
Feel upper rad hose again, it should still feel soft, no internal pressure
If pressure is building you have a breach from cylinder to cooling system.
The reason a head leak goes to the cooling system is because each cylinder is literally surrounded by the cooling system, no where else for it to go.
The reason it causes over heating is because a cold cooling system has 0 pressure, and a cylinder has 160+ psi pressure cranking and 1,000+ psi when it fires, so some of that "air" is pushed into the cooling system thru the leak, this displaces the coolant in the head, when pressure in cooling system builds up to 14-16psi, rad cap pressure rating, that coolant is pushed into the overflow tank, of course with limited coolant engine starts to over heat, once thermostat opens some of that "air" can escape to radiator and it will stay at the top and it will be pushed out into the overflow tank, and the coolant in the rad will start to flow into the slightly above normal temp engine which will cool it back down, so temp needle goes down.
Exhaust can also show more white smoke than normal, and it will smell sweet, the smell of coolant burning.
If a cylinder leak gets bad enough it will spread to oil drain in head or valley or even an oil passage, and you will get coolant in the oil, the milkshake.
Not sure how a fuel injector could do that??
A coolant leak in the intake manifold could cause the white smoke and misfire on startup, also oil milk shake.
But you wouldn't get over heating until overflow tank ran dry
Last edited by RonD; 12-07-2014 at 10:46 PM.