I just purchased a 2004 G4 last week. The truck has 153k but the previous owner put in a newer motor with 65k miles and did head gaskets on them. Before I bought it he said that he was recently having overheating issues with it. He had just replaced the radiator and heater core at the dealership and was still having the problem. It doesn't leak any coolant except out of the expansion tank overflow line after driving it for a while (not overheating yet) Heater blows cold when at a stop and takes a long time to blow hot after you start driving. Today it overheated slightly but the heater was blowing cold air still. So far what I have searched is that there is air in the cooling system, heater core is clogged (but it's new), head gaskets/ block is cracked, or a bad expansion tank/cap. Any ideas to help pinpoint the problem?
2004 G4 overheating issue with new radiator/heater core
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Sounds like a bad water pump. You don't say it's been changed....
No pumping = no cooling and no heat inside.
But it could be several things.
No pumping = no cooling and no heat inside.
But it could be several things.
How long, from a cold start, before coolant is pushed out of the expansion tank?
Does the upper coolant hose get very firm several minutes after started?
Does the upper coolant hose get very firm several minutes after started?
I thought water pump also but I thought those start leaking once they go bad. I haven't felt the hose yet but i will. I notice the coolant comes out of the expansion tank after I park it and a few moments later it comes out of the hose.
Find someone with a vacuum bleeder to bleed the system properly. If you have the same problems, after the cooling system was vacuum bled, check the coolant for CO gas.
If you have air or exhaust gas getting in the cooling system the air bubble usually blocks coolant flow thru the heater core but you'll still be at operating temperature... Once you raise rpm the water pump will move enough coolant to get you some warm air but back at idle it will get cool again. Something is forcing coolant out of the lower portion of the expansion tank cap. If you are getting air in the system remember that cooling systems get hotter once you shut the engine off, therefore the air bubbles get bigger due to the coolant no longer being pushed thru the radiator to be cooled. If you look at the expansion tank cap you'll see two o rings. Between the two o rings is where the steam should be able to evacuate. If the lower portion is broken, cracked, etc replace the cap. This is where some people are confused about cooling systems. They are a sealed system but when water boils it becomes gas and is bled out, which is why you need to top off the Collin system from time to time. Low coolant doesn't always mean a bad thing.
Id do a vacuum bleed and check for CO gas first, going by the previous owner having over heating issues and having coolant work done.
Water pumps don't always leak when they fail.
If you have air or exhaust gas getting in the cooling system the air bubble usually blocks coolant flow thru the heater core but you'll still be at operating temperature... Once you raise rpm the water pump will move enough coolant to get you some warm air but back at idle it will get cool again. Something is forcing coolant out of the lower portion of the expansion tank cap. If you are getting air in the system remember that cooling systems get hotter once you shut the engine off, therefore the air bubbles get bigger due to the coolant no longer being pushed thru the radiator to be cooled. If you look at the expansion tank cap you'll see two o rings. Between the two o rings is where the steam should be able to evacuate. If the lower portion is broken, cracked, etc replace the cap. This is where some people are confused about cooling systems. They are a sealed system but when water boils it becomes gas and is bled out, which is why you need to top off the Collin system from time to time. Low coolant doesn't always mean a bad thing.
Id do a vacuum bleed and check for CO gas first, going by the previous owner having over heating issues and having coolant work done.
Water pumps don't always leak when they fail.
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It could also be the water pump not moving enough volume of coolant but you'd have to remove it to inspect it. If you vacuum bleed it and there is no CO gas in the coolant the water pump would be the next thing I would check.
The first thing to do is to follow the proper coolant bleed procedure. Rule out the obvious first.
The proper one is where you lift the overflow tank as high as the hoses will allow and open the bleed screw at the T in the top Rad hose while the engine is stone cold. Keep adding coolant until a steady stream comes out bleed screw, then tighten bleed screw before lowering tank back into position. Top to line.
Then drive with AC and heat on, if you still have waterfall noises repeat procedure the next time the engine is stone cold.
The proper one is where you lift the overflow tank as high as the hoses will allow and open the bleed screw at the T in the top Rad hose while the engine is stone cold. Keep adding coolant until a steady stream comes out bleed screw, then tighten bleed screw before lowering tank back into position. Top to line.
Then drive with AC and heat on, if you still have waterfall noises repeat procedure the next time the engine is stone cold.
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pull the spark plugs and inspect....look for signs of head gasket failure if you find a plug that has been 'steam cleaned'...get a compression test also.
Rover engines cannot tolerate 'overheating issues'...once they overheat...they warp and cook head gaskets/slip liners very quickly.
yes they are a pig to bleed out...but they aren't THAT difficult....water pump could have a damaged/busted impeller....but unlikely frankly...and yes...they often do leak when the bearing goes bad but they still circulate coolant.
good luck
Rover engines cannot tolerate 'overheating issues'...once they overheat...they warp and cook head gaskets/slip liners very quickly.
yes they are a pig to bleed out...but they aren't THAT difficult....water pump could have a damaged/busted impeller....but unlikely frankly...and yes...they often do leak when the bearing goes bad but they still circulate coolant.
good luck
No heat at idle ? With the overflow leaking ! , it's probably be due to pressurizing the coolant system. As mentioned above in prevoius posts , check for a hard upper radiator hose,which may be do to faulty cap on the overflow, thermostat, worse case being a engine block issue.
I'd have it checked for combustion gases in the coolant.
I'd have it checked for combustion gases in the coolant.