110 tlb building pressure in cooling system and overheating

[gravedigger2]

I have a 2005 110 tlb it builds pressure in the cooling system and overheats mainly while driving and the higher the engine rpms the faster it builds up heat. Pressure stays within the system for quite a while hours to overnight. have replaced radiator cap and thermostat, was told it could possibly have a blockage in the cooling system by the water pump

 

[beemerphile]

Head gasket?

 

[Coyote machine]

Before starting remove the radiator cap and then start it. See if coolant is flowing past the filler neck and watch what it does as it warms up. If you see a lot of bubbles when it's reached normal op temp and then it eventually overflows at the neck, chances are you have a blown head gasket. Once it cools down look for any signs of leakage at the block/head interface and all around the engine.
Post back results.

 

[bandaidmd]

from a dead cold motor start up and run for 40 seconds then shut it off. remove radiator cap and if theres pressure you have combustion gasses getting into cooling system via a head gasket leak. This was taught to me by a guy who runs a radiator shop. Running the motor for such a short time will not heat up the coolant and cause it to expand so if there pressure it came from the cylinder.

 

[Zebrafive]

Also check the engine oil. Antifreeze may be getting in the oil. Not a good thing.

 

[gravedigger2]

compression is within specs on all cylinders, no antifreeze in oil

 

[gravedigger2]

no antifreeze in oil

 

[jenkinsph]

from a dead cold motor start up and run for 40 seconds then shut it off. remove radiator cap and if theres pressure you have combustion gasses getting into cooling system via a head gasket leak. This was taught to me by a guy who runs a radiator shop. Running the motor for such a short time will not heat up the coolant and cause it to expand so if there pressure it came from the cylinder.

Makes sense to me and what I would try first this morning.

Coyote machine also has a good post to consider next.

 

[Tx Jim]

Makes sense to me and what I would try first this morning.

Coyote machine also has a good post to consider next.

I agree but on these newer machines with a coolant recovery tank won't it be more difficult to see air bubbles if present?

 

[Coyote machine]

I agree but on these newer machines with a coolant recovery tank won't it be more difficult to see air bubbles if present?

No. Sometimes the boiling of the coolant from exhaust gases escaping the combustion chamber IS seen in the overflow tank. Either way, if exhaust is bubbling the coolant, the most likely cause is a blown out head gasket.

And, with the radiator cap off, as I suggested earlier the coolant should not be building pressure, aside from coming up to temperature when the t-stat opens; therefore if the radiator overflows there is pressure present from the combustion chamber(s). A normal operating engine will not overflow the radiator when the t-stat and water pump are functioning correctly. Instead a flow of coolant past the filler neck will be present- just like a river running through it. Pressure is created by the presence of the radiator cap sealing the system. When the fluid expands under this normal set of circumstances, then the expansion of the coolant goes to the expansion tank.