I need some suggestions guys. What could be my problem? I have a 1986 ford ranger with the 2.9L V6 and M5OD-R1 transmission. I noticed yesterday my truck was running a little on the warm side, about 3/4 up the normal range. So I checked the overflow and it was bone dry, checked the rad and it was a little low. Bought a jug or 50/50 Dex-Tron premix and topped it up. Now my engine is over heating at a very rapid rate and boiling over. Anyone have any ideas that could help me solve this problem.

 

I would check for a blown head gasket. Has the engine been overheated lately. A blown head gasket would appear as bubbles in the radiator soon after starting the engine. Take the cap off the radiator while it's cool and check for bubbles soon after starting the engine. There's testing equipment that can detect combustion products in the fluid for a definitive conclusion.

 

2.9s are notorious for head gasket/cracks/ leaks, if no other leaks are apparent try pressure testing the system........................Make sure there is no coolant in oil. Good news is, 2.9s are simple motors.....Headgaskets are a easy job, re-man heads are readily available if this is the case.

 

Will check for the head gasket leak but there is no coolant in the oil though and no white smoke, the two major signs as far as I know of a blown head gasket/cracked head.

 

Checked that out. No bubbles that I can see. It sucked the level down quite a bit after I turned on the heater. Filled it up again and noticed the level dips and rises with engine speed. Let it idle for about 5 minutes with the heater on and no change in level or temp, see stayed dead cold. Not sure if that was long enough to heat the block up at all though.

 

Most likely the heater core was empty and it refilled it. Keep an eye on the temp and the level.

Running the heat is like having another radiator to cool the engine. The heater core is exchanging engine heat also then.

Also you may want to run it longer than 5 minutes. Try about 30 minutes and leave the cap off. That will allow any air bubbles to find there way out.

Then top it off and drive it to see if the temp changes.

Allen

 

I've got a 1978 LTD II 351W sitting in the driveway with a blown head gasket. Now I can start and run this engine for 20 minutes or so with no problem. As soon as it gets heated up the head gasket starts leaking and pumping compression gases into the cooling system.

 

I had the same thing with a mazda I just sold. It was fine until it heated up then you could see the smoke. Check under the oil cap for signs of water. It condenses on the cooler plastic cap.

Allen

 

Okay. I let her run with the cap off and heater on full for about a half hour. No bubbles, white exhaust, condensation on the oil filler cap or foam on the dipstick. the coolant did however start to flow out of the rad like there is no tomorrow right about when the temp gauge hit the bottom of "R" top of "M" in normal. Is this still a head issue? And if so is it possible it's the gasket or is it the very expensive head itself?

 

It's a head issue, gasket blowing compression gasses into cooling jacket due to heat expansion. It's possible a new head gasket would solve the problem. I'm certain that if it is a blown head gasket, that a new head gasket would be the cheapest repair. The head wouldn't necessarily have to be rebuilt, or milled flat.

There's a test for compression gases in the coolant. It involves using a liquid that changes color in the presence of combustion products. That test would be the definitive test that a mechanic would use. Given these symptoms though, I would say that a new head gasket is needed. Might need only one head gasket, after the engine is warmed up and the radiator fluid is flowing like there's no tomorrow, conduct a compression test on the cylinders. The low one indicates the leaking cylinder.

 

Coolant gushing out without a radiator cap is perfectly normal. It is when the thermostat opens up, and coolant starts rushing to the rad. There is a reason for a radiator cap, it increases the pressure of the cooling system, a higher pressure causes the anti-freeze to have a higher boiler point. Normal engine operating temperature is above the atmospheric boiling point of anti-freeze. So when the thermostat opens, the once pressurized coolant (the thermostat when its closed, creates a small circuit of water that is completely closed off from the rest, allowing it to pressure rise), it starts to boil instantly once it goes into the radiator because there is no cap, and it can't pressurize.

This is why they say never to take the radiator cap off a warmed up, or over heating engine, because the coolant will flash boil..

What you'll want to do is rent/borrow a cooling system pressure tester, pump it up to about 13 PSI on a cold engine. Look for pressure slowly decreasing over a period of hours. If it holds, then start the engine up, and look for a slowly increasing pressure.

 

Lead Head overlooks the fact that the thermostat is going to open as soon as the engine reaches the opening temperature of the thermostat, which is usually below the boiling point of water at sea level, 100C or 212F. Thermostat=195F

Then when cold water from the radiator comes into the engine and hits the thermostat the thermostat closes hence allowing the water to heat up and the engine to cool off while maintaining a temp below boiling at sea level 100C or 212F.

When the engine heats up, the metal of the engine expands, i.e., gets larger, this shifting causes the head gasket to allow combustion gases to enter the cooling jacket. Now normally the head gasket is "glued" to the head or the block, depending on the surface of the gasket. When the "glue" breaks the head gasket is not doing it's job correctly, hence the need to install a new head gasket.

The 351W is the fourth time I've seen this phenomenom. So it's a known symptom.

 

is it possible it's not the head at all?? I got some water into my gas would that cause the overheating??

 

Do you live on the river up there in Canada?

The Nile?

or as we call it down here, De Nial

 

Water still we begin to vaporize well before the boiling temperature, still allowing it to build pressure. The boiling point of coolant in the cooling system is much higher then the boiling point atmospheric pressure - which is why most cars actually run around 210-220*F without problem.

Either way that is not the point, coolant will still gush out once the thermostat opens with no cap. Dracosix, when the coolant does start coming out, does it constantly poor out, or will gush for a little bit, stop, then do it again a little while later? If its constantly, then perhaps you do have a cracked head (2.9s are more known for cracked heads then head gaskets). If it does it in cycles, then that is just normal thermostat operation.