'93 90CS Cooling system problems
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'93 90CS Cooling system problems
CS,2.8 with heater core that died. At the time, car lost coolant to interior, and overheated.
Bypassed core with "U" pipe & still have serious overheating issues. Thought that bypass and refill with coolant would return car to normal temp operation. Didn't happen. Hoping that problem is with air in the system or, worst case, a bad thermostat.
Flushed system using both heater hoses at firewall, open draing plug on radiator and overflow tank. Ran water into each of the two hoses alternately with overflow tank until clean water was flowing from all of the other hoses/tank and from the bottom plug on the radiator. Once I had water to the top of both heater hoses and the overflow tank, plug at bottom of radiator was closed and heater hoses re-joined. Started engine, and loosened bleed screw near firewall once engine was warm. Got a bit of air out, then a good flow of water.
Car ran fine, for about twenty minutes, then temperature began to climb though never much past mid range on the temp gauge. Warning lamp began to blink. When we checked under the hood, we were getting steam from the cap, and a constant surge of what appeared to be water and air into the overflow tank through the small hose at the top of the radiator. After engine was turned off, we could hear and feel water thumping through large hose between engine and top of radiator too. Fans appear to be operating normally, running for a while then shutting off.
If the thermostat were stuck open, water would be flowing constantly through the engine, even before it warmed up so this wouldn't be a cause of overheating. Correct?
If thermostat were stuck in a closed position, would we have REALLY hot water everywhere in the system? Seems like that is most likely what's going on here.
Safe to assume that a bad water pump wouldn't be pumping water to and through the heater hoses we have joined, and that we could check (before engine warms too much) by disconnecting these hoses and check to see since it is the highest point in the system? Haven't tried this yet. Any other way to check function of water pump? Had front cover off to look for thermostat, and water pump doesn't appear to be leaking. Can turn shaft slightly against friction of timing belt, and it seems tight and free.
Finally, Bentley says thermostat can be changed without removing timing belt. Looks like it might be possible with radiator and fans out of the way, but access seems pretty tight. Can it really be done?
Timing belt, thermostat and water pump were done just under 50K ago, so unless pump is bad, hoping to get by with only a thermostat - or less if someone has another idea about symptoms described.
Sorry for the length, but wanted to provide enough detail to get best possible responses.
Thanks
DS
PS - We've been advised to try bleeding the system again. Can we do this properly while the engine is cold, or must engine be warm with thermostat open to allow flow to every place that might be harboring air?
Bypassed core with "U" pipe & still have serious overheating issues. Thought that bypass and refill with coolant would return car to normal temp operation. Didn't happen. Hoping that problem is with air in the system or, worst case, a bad thermostat.
Flushed system using both heater hoses at firewall, open draing plug on radiator and overflow tank. Ran water into each of the two hoses alternately with overflow tank until clean water was flowing from all of the other hoses/tank and from the bottom plug on the radiator. Once I had water to the top of both heater hoses and the overflow tank, plug at bottom of radiator was closed and heater hoses re-joined. Started engine, and loosened bleed screw near firewall once engine was warm. Got a bit of air out, then a good flow of water.
Car ran fine, for about twenty minutes, then temperature began to climb though never much past mid range on the temp gauge. Warning lamp began to blink. When we checked under the hood, we were getting steam from the cap, and a constant surge of what appeared to be water and air into the overflow tank through the small hose at the top of the radiator. After engine was turned off, we could hear and feel water thumping through large hose between engine and top of radiator too. Fans appear to be operating normally, running for a while then shutting off.
If the thermostat were stuck open, water would be flowing constantly through the engine, even before it warmed up so this wouldn't be a cause of overheating. Correct?
If thermostat were stuck in a closed position, would we have REALLY hot water everywhere in the system? Seems like that is most likely what's going on here.
Safe to assume that a bad water pump wouldn't be pumping water to and through the heater hoses we have joined, and that we could check (before engine warms too much) by disconnecting these hoses and check to see since it is the highest point in the system? Haven't tried this yet. Any other way to check function of water pump? Had front cover off to look for thermostat, and water pump doesn't appear to be leaking. Can turn shaft slightly against friction of timing belt, and it seems tight and free.
Finally, Bentley says thermostat can be changed without removing timing belt. Looks like it might be possible with radiator and fans out of the way, but access seems pretty tight. Can it really be done?
Timing belt, thermostat and water pump were done just under 50K ago, so unless pump is bad, hoping to get by with only a thermostat - or less if someone has another idea about symptoms described.
Sorry for the length, but wanted to provide enough detail to get best possible responses.
Thanks
DS
PS - We've been advised to try bleeding the system again. Can we do this properly while the engine is cold, or must engine be warm with thermostat open to allow flow to every place that might be harboring air?
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