over heating and pressure in cooling system

[BTlilred]

Pressure build up and over heating, blows off the reservoir cap, no coolant in the oil, no oil in the coolant, has plenty of coolant in it, new radiator, new thermostat. Head gasket?

 

[Rearanger]

Cracked head at exhaust will put excess pressure and heat in system. I'd remove stat then run engine with rad cap off to look for bubbles. May not occur until temp rises. Wear eye protection and avoid looking directly down rad cap opening.

 

[det107]

I'd remove stat then run engine with rad cap off to look for bubbles.

Perhaps the baby needs burping after the T-stat/ radiator work-

 

[RonD]

Cold engine
Remove rad cap
Top up coolant
Start engine

It may burp a bit of coolant but it shouldn't keep pushing it out, if that happens then yes, you have a cracked head or head gasket issue.

A cold cooling system has no internal pressure.
A water pump is not a "real" pump, it is just a circulator, it adds no pressure.
Pressure in a cooling system comes when the coolant get above 180deg and starts expanding, this creates pressure when the rad cap is on.
So cold engine with cold coolant should not push ANY coolant out the rad cap opening.

Each cylinder in the engine has 150+ psi of pressure when cranking, after startup that jumps to 1,000+ psi when cylinder fires.
If any of this pressure can get into cooling system then that will cause coolant to be displaced in the head and flow out the rad cap opening, if it is off, or into the overflow tank if cap is on.

Coolant in the oil is no longer that common with head gasket issue, it can happen but not that common.
And cracked head would never show coolant in the oil.

Also smell the exhaust, if there is a cylinder leak then pressure will be pushed out and often coolant will be sucked in on intake stroke, coolant has a sweet smell when burned.

If you do have a cylinder leak then you can find out which one with the Glove Test.
Or if you just want to confirm a leak then use the glove test.

Cold engine
Unplug Coil, you want a no start
Place a latex glove over rad cap opening and seal it with rubber band.
Remove over flow hose and block that opening.
Cooling system is now sealed.
Crank engine

Glove will bounce(inflate) each time leaking cylinder is on it's compression stroke

Now remove 1 spark plug at a time and crank engine
Glove will stop bouncing when there is no compression, spark plug removed
Put last removed spark plug back in to confirm.

 

[Rearanger]

A water pump is not a "real" pump, it is just a circulator, it adds no pressure.

There is no "circulation" without a pressure difference. All pumps create flow, resistance to flow creates pressure.

Just to be picky.

 

[kimcrwbr1]

Probably a head gasket you can confirm by doing a leakdown test on all of the cylinders.

 

[AllanD]

An engine water pump is not a "Positive displacement" pump

IT is a FAN that "Blows water", and in the specific design of engine cooling systems
it blows water in a direction it is already inclined to flow.

It is not able to generate any real "pressure" it does generate "Flow"

The most diffinitave test for a cracked head leaking combustion gasses into the
cylinders is a chemical test strip that changes color in the presence of combustion gasses.

I'm not sure where you'd buy these today, I used to get them from my Brother's Snap-On Dealer

 

[Rearanger]

It is not able to generate any real "pressure" it does generate "Flow"

Does't matter what you class as "real pressure", a pressure difference is required to generate flow. An auto water pump (impeller pump) has a high rate of internal leakage but is adequate to "pump" fluid.

 

[JP02XLT]

Those test strips were available at Advanced auto & Orileys, or you could do the latex glove on the radiator and watch for the glove to pulse, which represents a leak either from a cracked head or head gasket

JP02XLT

 

[kimcrwbr1]

The circ pump creates very little static pressure it just gives you flow volume. There is less than 1 psi static pressure in and out total on the pump. The pressure cap is release volume pressure as the coolant expands when it gets hot. When the pressure gets too high flow cfm stops.

 

[BTlilred]

Well problem solved, It shut off at 70 mph on the freeway on the way home from work. Oil was spraying out from somewhere on the driver side and the front of the motor so I think I have a much larger problem now. A few taps and a small pop and that was it. Thanks for the help though everyone.

 

[Rearanger]

Those test strips were available at Advanced auto & OrileysJP02XLT

Given the violent coolant explosion and no other symptoms I can't imagine what else, other than exhaust gas in the coolant.

The last time I diagnosed one of these I used an IR temp gun to compare head temps. The bad head was 100* higher. That's why I prefer to remove the stat as it gives time to observe without getting to super heated coolant.

Too bad the OP continued to drive this, now sounds like he's got bigger trouble.

 

[Rearanger]

There is less than 1 psi static pressure in and out total on the pump.

There is little pressure because there is little flow restriction, although an impeller pump is designed to flow fluid not provide much force. But you can't have flow with equal pressures in and out, there needs to be a pressure differential.

The pressure cap is release volume pressure as the coolant expands when it gets hot. When the pressure gets too high flow cfm stops.

Are you saying when heat pressurizes the system there is no fluid flow?,

 

[kimcrwbr1]

When the water temp is above 220 degrees it turns into steam. All tho steam is considered a fluid it is a gas and the impeller is designed to move liquid.

 

[BTlilred]

Down side is I probably blew the motor. Up side is I have an excuse for a 5.0 swap... decisions decisions......