Help Diagnose Overheating.
Thread Starter
Senior Member
Joined: Aug 2001
Posts: 266
Help Diagnose Overheating.
Pleas help me diagnose my overheating engine.
Symptons so far:
- Engine temp occasionally goes past the middle in about 20 minutes of stop/go traffic with some 40mph stretches.
- It went up to 3/4 of the temp guage during about a 20 minute highway drive
- Car warms up faster that usual
- I get plenty of heat
- Turning the heat on helps cool the car down a little while driving.
- Just flushed the coolant
- Past two winters had a stuck open thermostat (no heat on highways)
- Bled the coolant system
- Sometimes I hear gurgling from the from passenger side after shutting the car off after the temp goes past middle.
- Both of the fans do turn on when engine gets too warm.
- After getting the temp past the middle, I shut the car off and notice reservoir is past the max level. The coolant is warm and steaming in the reservoir. I hear bubble/boiling noises from the upper radiator hose. A few minutes later, the upper hose starts sucking the coolant out of the reservoir like a straw. I even see it collapse a little when it is sucking. it completely empties the reservoir.
- The upper radiator hose is hot, while the lower hose is cool to slightly warm.
- I thought it would be a clogged radiator, but I squeeze the lower hose with the radiator cap open and coolant comes out of the radiator filler neck. Basically, I can pump coolant out of the radiator by squeezing the lower hose.
- There are no visible coolant leaks.
Anybody have any ideas? I was just about to buy a radiator, but went out to squeeze the lower hose and it seems to be forcing coolant out of the radiator meaning that the radiator is not clogged..?.? My next guess may be a stuck closed thermostat? Please help!
Thanks in advance!
Johnny
Symptons so far:
- Engine temp occasionally goes past the middle in about 20 minutes of stop/go traffic with some 40mph stretches.
- It went up to 3/4 of the temp guage during about a 20 minute highway drive
- Car warms up faster that usual
- I get plenty of heat
- Turning the heat on helps cool the car down a little while driving.
- Just flushed the coolant
- Past two winters had a stuck open thermostat (no heat on highways)
- Bled the coolant system
- Sometimes I hear gurgling from the from passenger side after shutting the car off after the temp goes past middle.
- Both of the fans do turn on when engine gets too warm.
- After getting the temp past the middle, I shut the car off and notice reservoir is past the max level. The coolant is warm and steaming in the reservoir. I hear bubble/boiling noises from the upper radiator hose. A few minutes later, the upper hose starts sucking the coolant out of the reservoir like a straw. I even see it collapse a little when it is sucking. it completely empties the reservoir.
- The upper radiator hose is hot, while the lower hose is cool to slightly warm.
- I thought it would be a clogged radiator, but I squeeze the lower hose with the radiator cap open and coolant comes out of the radiator filler neck. Basically, I can pump coolant out of the radiator by squeezing the lower hose.
- There are no visible coolant leaks.
Anybody have any ideas? I was just about to buy a radiator, but went out to squeeze the lower hose and it seems to be forcing coolant out of the radiator meaning that the radiator is not clogged..?.? My next guess may be a stuck closed thermostat? Please help!
Thanks in advance!
Johnny
Thread Starter
Senior Member
Joined: Aug 2001
Posts: 266
Originally Posted by MyGreenMax94
How did you bleed the system???You probably didn't get all the air bubbles out of the system....
When I bled the coolant, I parked in the car on a very steep driveway. The front was about 3 feet higher than the rest of the car. I filled the coolant in the reservoir to Max level. Then I then started the engine with the radiator cap off, keeping the engine revving to about 1500 RPM. As the car ran, I saw bubbles coming out of the filler neck. I kept topping it off once the level went down a bit. I did this for about 20 minutes.
I think that the cool lower hose and hot upper hose is a critical symptom that may give an obvious answer to experienced mechanics or Max owners. But I do not know what this tells me.
When squeezing the lower hose, coolant will flow out of the radiator fill neck. Does this tell me that the radiator is not clogged?
If I were to test the radiator to see if it is clogged, is it OK to just take the radiator out and run water from the upper hose and see it it flows out from the lower hose?
Johnny
Originally Posted by johnnyo319
When I bled the coolant, I parked in the car on a very steep driveway. The front was about 3 feet higher than the rest of the car. I filled the coolant in the reservoir to Max level. Then I then started the engine with the radiator cap off, keeping the engine revving to about 1500 RPM. As the car ran, I saw bubbles coming out of the filler neck. I kept topping it off once the level went down a bit. I did this for about 20 minutes.
I think that the cool lower hose and hot upper hose is a critical symptom that may give an obvious answer to experienced mechanics or Max owners. But I do not know what this tells me.
When squeezing the lower hose, coolant will flow out of the radiator fill neck. Does this tell me that the radiator is not clogged?
If I were to test the radiator to see if it is clogged, is it OK to just take the radiator out and run water from the upper hose and see it it flows out from the lower hose?
Johnny
I think that the cool lower hose and hot upper hose is a critical symptom that may give an obvious answer to experienced mechanics or Max owners. But I do not know what this tells me.
When squeezing the lower hose, coolant will flow out of the radiator fill neck. Does this tell me that the radiator is not clogged?
If I were to test the radiator to see if it is clogged, is it OK to just take the radiator out and run water from the upper hose and see it it flows out from the lower hose?
Johnny
Your water pump blades may be corroded bad enough for it to not circulate the coolant properly....
no coolant leaks? then it's not your radiator cap.
possible causes:
1 clogged radiator. the tiny passages through the tubes may be blocked with scale or junk. this is your most likely cause, and the easiest to fix. (swapping a radiator on a VG is easier than swapping a thermostat.)
this constricts water flow and lessens the cooling capacity of the system. I've seen your exact issue happen on customers with clogged radiators.
even though the lower coolant hose is cold (which means the water is hot going in, cool going out- a good sign), that doesn't necessarily tell you if it's flowing as much as it should be, and you can't tell just by squeezing the hose. you need to be able to push a gallon every few seconds, not cups per minute.
2. water pump fins corroded off, as mentioned above. low coolant flow will cause the same things.
3. thermostat stuck closed..
If I were you, I'd take a real good look at the radiator and thermostat. the water pump is going to be a PITA to replace.. the other two are quicker and easier to verify.
the gugling noises you're hearing in the car when you shut it off is the coolant actually boiling in the engine block, then the bubbles run up the hose, cool off, then re-liquify. makes your engine sound like my intestines after a night of cheap mexican food.
possible causes:
1 clogged radiator. the tiny passages through the tubes may be blocked with scale or junk. this is your most likely cause, and the easiest to fix. (swapping a radiator on a VG is easier than swapping a thermostat.)
this constricts water flow and lessens the cooling capacity of the system. I've seen your exact issue happen on customers with clogged radiators.
even though the lower coolant hose is cold (which means the water is hot going in, cool going out- a good sign), that doesn't necessarily tell you if it's flowing as much as it should be, and you can't tell just by squeezing the hose. you need to be able to push a gallon every few seconds, not cups per minute.
2. water pump fins corroded off, as mentioned above. low coolant flow will cause the same things.
3. thermostat stuck closed..
If I were you, I'd take a real good look at the radiator and thermostat. the water pump is going to be a PITA to replace.. the other two are quicker and easier to verify.
the gugling noises you're hearing in the car when you shut it off is the coolant actually boiling in the engine block, then the bubbles run up the hose, cool off, then re-liquify. makes your engine sound like my intestines after a night of cheap mexican food.
Thread Starter
Senior Member
Joined: Aug 2001
Posts: 266
Originally Posted by Matt93SE
no coolant leaks? then it's not your radiator cap.
possible causes:
1 clogged radiator. the tiny passages through the tubes may be blocked with scale or junk. this is your most likely cause, and the easiest to fix. (swapping a radiator on a VG is easier than swapping a thermostat.)
this constricts water flow and lessens the cooling capacity of the system. I've seen your exact issue happen on customers with clogged radiators.
even though the lower coolant hose is cold (which means the water is hot going in, cool going out- a good sign), that doesn't necessarily tell you if it's flowing as much as it should be, and you can't tell just by squeezing the hose. you need to be able to push a gallon every few seconds, not cups per minute.
2. water pump fins corroded off, as mentioned above. low coolant flow will cause the same things.
3. thermostat stuck closed..
If I were you, I'd take a real good look at the radiator and thermostat. the water pump is going to be a PITA to replace.. the other two are quicker and easier to verify.
the gugling noises you're hearing in the car when you shut it off is the coolant actually boiling in the engine block, then the bubbles run up the hose, cool off, then re-liquify. makes your engine sound like my intestines after a night of cheap mexican food.
possible causes:
1 clogged radiator. the tiny passages through the tubes may be blocked with scale or junk. this is your most likely cause, and the easiest to fix. (swapping a radiator on a VG is easier than swapping a thermostat.)
this constricts water flow and lessens the cooling capacity of the system. I've seen your exact issue happen on customers with clogged radiators.
even though the lower coolant hose is cold (which means the water is hot going in, cool going out- a good sign), that doesn't necessarily tell you if it's flowing as much as it should be, and you can't tell just by squeezing the hose. you need to be able to push a gallon every few seconds, not cups per minute.
2. water pump fins corroded off, as mentioned above. low coolant flow will cause the same things.
3. thermostat stuck closed..
If I were you, I'd take a real good look at the radiator and thermostat. the water pump is going to be a PITA to replace.. the other two are quicker and easier to verify.
the gugling noises you're hearing in the car when you shut it off is the coolant actually boiling in the engine block, then the bubbles run up the hose, cool off, then re-liquify. makes your engine sound like my intestines after a night of cheap mexican food.
Thanks Matt.
I was hoping a you or another 3rd Gen expert will chime in! I think I'll try:
1. Changing the thermostat
2. Remove and check the radiator
3. Hopefully there will not be a 3rd step.
Would spraying water inthe radiator with a garden hose and letting the water come out the lower hose be a good enough test to check for a clogged radiator? If water comes out strong, it is ok, and if it trickles out, then it's clogged. Or would I need to do something more substantial?
Johnny
pull the cap, drain the radiator, and look at the inside of the thing. if you see scale or junk clogging the holes, then you've got problems.
sometimes you can use a really strong chemical engine flush and remove the scale, but its better to just replace the thing and move on. the chemicals will damage more stuff than it fixes.
sometimes you can use a really strong chemical engine flush and remove the scale, but its better to just replace the thing and move on. the chemicals will damage more stuff than it fixes.
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