Question about 1991 Honda Accord
When the car is completely cool,check the electric fan(s) for smooth rotation.
Clean/check/change the thermo sensor,contact and wire.
Excavate air pocket in coolant system / check for head gasket leak
This test will kill two birds with one stone.
MAKE SURE THE COOLANT SYSTEM and ENGINE IS COLD!
RAN THIS TEST IN A WELL VENTILATED AREA ONLY!
You will spill some coolant during this air pocket purge test.......BE KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!
Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .
Top of the coolant reserve tank
Let it ran for 10-15 minutes.
Monitor for air pockets escaping from coolant reserve tank.
Small amount of bubbles is OK at 1-5 minute mark
After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.
If you do not see any in rush of bubbles then your thermostat may be partially stuck or rusted badly inside the thermostat hosing.
Give the thermostat host few gentle taps.
If you see larger bubbles surfacing after 15 minutes then should do a hydrocarbon (HC) dye test to test for potential head gasket leak.
Let engine cold down and top off coolant reserve tank.
Start monitor for coolant lost
A coolant flush is require every 2 years or 24,000 miles.
I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.
Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.
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Posted on Dec 05, 2009
J, the upper radiator hose should be hot, it directs coolant from the hot engine to the radiator, where it flows downward, being cooled by the air rushing through the radiator from driving, and from the fan, until it reaches the bottom hose, where it is sent back through the engine to absorb heat from passageways throughout the engine block and head, and back to the radiator again.
A couple of things to check: 1st, is the fan kicking on when the engine temp rises? If not, check the cooling fan switch, if it is bad, it won't signal the fan to go on. 2nd The cooling fan may have a bad motor, again, if it's not drawing air through the radiator, the car will overheat. 3rd Make sure there is no air in the cooling system. Your accord should have a bleeder screw on top of the engine. After draining and then refilling the system to replace the radiator, or some other cooling system component, the bleeder screw should be opened to allow air to exit the system, or it will overheat. Your thermostat probably isn't the problem. You are correct that If it was stuck closed, it would cause the engine to overheat, but the top radiator hose wouldn't be hot because no coolant would be flowing through that hose with the t-stat closed. If you squeeze the upper hose at operating temp. you should be able to tell if coolant is flowing through. Although I don't think it's the t-stat, it you want to check it, remove it and place in pot of boiling water, it should open immediately, if not it's no good. , Hope this helps, good luck,
Posted on Oct 17, 2009
NO sounds like the water pump isent working but carnt think of why not as you only changed Rad and heater hoses.. but did you turn on the heater to HOT when you fitted the new heater hoses as to let the coolant run through and to get rid of air locks ..
IF the thernostat was sticking open then it would only get warm.. If stuck shut it would cause the engine to boil but from the bottom (bottom hot top cold).
So it still points to water pump BUT what you can do before anything else take out the thermostat and lets see if the whole water system gets warm if yes then
its the pump.
Also check to see if the water get hot in tank and any bubbles . Let me know what you find Ron
Posted on Oct 17, 2009
Given the fact that you have worked on the cooling system, very likely the overheating is related to air locks. With a cool engine uncap the radiator and top off if needed and while you do that open the bleeding valve that sits right next to the engine and fill the radiator until you get flow of coolant from the valve. Close the valve, keep the radiator uncapped, open your heater valve fully and turn engine on. Once the engine warms up, you should see coolant flow in the radiator and that would indicate your water pump is doing what it should do. If it does not then you may have a bad pump. Once the engine is warm, both upper and lower hoses should be warm of hot to touch.
Posted on Jul 26, 2014
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