I have read a lot of threads, and tried most of the suggestions but nothing seems to fix my issue. Granted my issue is somewhat my fault to begin with, but thats life. The full history will take a while so I will make it short. Had a blown head gasket (4.7), had it fixed, it lasted a year, started leaking in cylinder 3. So, I tried a leak stop chemical. I know!!! Now the truck is overheating. I drained the coolant, flushed the radiator, changed the thermostat, and the radiator cap. Didn't help.

One issue I know I still have is a cracked resovour tank. Could this alone cause it to overheat?? Also, IF I plugged the heater core, will that cause it to overheat?? If so can I bypass it to test?

Lastly, how can I test the radiator to see if it is clogged. When I had the coolant drained I ran water through it, but it only trickled out the bottom unless I pressurized it by blocking off the upper radiator hose and spraying water in the overflow line.

Thanks in advance

 

Trade it in

 

after it's warmed up. turn off truck and feel the radiator if there is cool spots replace it or have it re cored..Also turn on the heater.see if both sides of the heater hoses are warm..Don't be surprised that your heater core will be pluged or will be pluged in the future.But it sounds to me the radiator is the problem..Heater core I know on the late models it does not matter because i have put in valves in the lines to keep the heat out in the summer time.
Please use commonsense when doing this.I don't know if you have electric fans or what you have modified under the hood.
Hope all helps

 

Thanks for the info. Yesterday I bypassed the heater core, but it didn't fix the problem. So you may be right. This afternoon I plan to pull the thermostat back out and test it just to be sure it wasn't defective out of the box.

One thing I was thinking about trying is leaving the thermostat out. Is it safe to run the engine without a thermostat? If so, shoule you see a constant stream of water into the overflow resevoir, or should it all be going through the radiator? It would seem to me that when the thermostat opens all the water should go through the radiator not the resevoir.

Thanks,

 

you will see the fluid flow threw but the core is what cools down the fluid..if the core has cool spots that means no water is in the core..Kinda like putting tape across the radiator.no air passes threw the water gets hot..if no water is going threw the core of the radiator (the center where all the fins are) then theres no cooling.(its like by passing the radiator)..So check to see if theres cool spots.

 

The radiator is partially clogged would be my guess.

 

Drained the system, and rigged up a back flush kit using several pipe fittings. See attached photo. Using this I back flushed the radiator giving it short bursts of air to help break everything loose.

Checked the thermostat and it was fine. Also, ran a good amount of clean water through the water pump and heater lines. Now it seems to be running fine. Drove it around for a little bit, and let it idle for about 40 minutes without any issues. Hopefully that is behind me. Thanks for the feed back.

I haven't flushed the heater core yet, but I know it needs it since the heat wasn't working. After that it will be back to the original problem of fixing the head gasket leak!

 

Blown head gaskets arent far from cracked heads. Have them pressure checked and magna-fluxed for cracks

 

Not sure its worth it. The truck has 140K on it and I have already had the heads machined once. That is why I opted for the so called quick fix this time.

I know the gasket is leaking, the only real thing I could learn from these tests would be if the head is cracked. Not sure I gain anything from that.

With the 4.7 being a problem child for head gaskets, what are the best methods for prevention. Maybe an aftermarket engine cooler, or lower temp thermostat, special coolant, etc...?

 

Im not sure there really is a good prevention. It seems some guys with 4.7s have issues while others do not. i think the radiators are sufficient but I do run a 180* stat in mine and stay around 185* per me Trinity gauges. Royal Purple makes a coolant additive that is supposed to be good.