lgbrown13

Good afternoon Everyone. I made sure to do my homework prior to this post. I will try to summarize my attempt to resolve a cooling issue with my 1991 Honda Accord. Last month I made the decision to keep my 1991 Honda Accord with 250k miles. It has been a great car. I did the following.

Standard Tune Up (Spark plugs, Valve Adjust, Belts, Distributor Cap/Rotor, Oil Change, Tranaxle Fluid change)
Timing Belt
Water Pump
Fuel Pump
Fuel Filter
Alternator
Condenser Fan
Radiator
Radiator Hoses (to include all other hoses cycling antifreeze)
Thermostat
Thermo Switch
Temperature Sensor
Temperature Gauge Sending Unit
Cleaned the IACV
Cleaned and tighten down the diaphragm in the FITV
Battery

My car is still reading that it overheats. I made sure to bleed and allow air bubbles to work out of the radiator. I have pretty much replaced everything that has been posted on the forums to resolve the overheating and the rough cold idle. The car and great compression is all cylinders. Has no leaks. I am frustrated. Any insight you can provide would be greatly appreciated.

Grandhustleman86

Where did you get thermo/temp sensor/fan switch from? Have you checked them with a voltmeter? Checked fuses for the fans? Have you checked the oil for "milky" color...coolant mixing into the engine oil via blown head gasket. Is the coolant level changing? Oil level changing?

lgbrown13

I purchased the majority of my parts from ebay, all parts were new. I did not check the parts with voltmeter. Oil is fine. I just changed it again. Coolant level and oil change level are consistent.

Thank you for taking the time to assist!

tl1r1027

Is the car actually overheating or is the gauge malfunctioning? Do you have good heat out of the heater? Ive had air pockets that were really difficult to purge on other vehicles when I've had that much of the cooling system empty at once.

holmesnmanny

The cooling system has two major components to help keep the car both heated up and cool.

The thermostat helps to keep the car warmed up. The fans help to keep it cool.

When the car overheats, normally either the thermostat is sticking closed or the fans are not working.

With the car warmed up, check the lower radiator hose. It should get hot before the car overheats. If it doesn't get hot then the thermostat is stuck closed.

If the lower hose is hot then before the car overheats BOTH fans should be running TOGETHER to help cool the car down. If not, then you turn the car off, but turn the ignition to the on position without turning the car on and use a paperclip to jumper the connector that goes to the fan switch at the back passenger side of the engine where the lower radiator hose attaches to. Just take the connector off and stick the paperclip in there. If the fans now run then the switch that you just took that connector off of is bad. If the fans still don't work then you have a more advanced issue and more testing is required. Just report back here.

It's best to only buy Honda OEM cooling system parts as aftermarket can be a crap shoot at times.

Grandhustleman86

God bless this is true...to many times do people replace parts with ones from these "online wholesale distibutors" "local auto parts stores" and said part end up being defective at the time of installation. While the part might be more expensive from the manufacturer its piece of mind your buying as well. Good advice sir.

lgbrown13

Thank you everyone for taking the time. I am guilty of using the online parts warehouses for my cooling parts. I am in the process of replacing everything with OEM. Lesson learned. I have a new thermostat, new temp sensor, new temp gauge sending unit and new fan switch.

Update: I ran the car today and put a food thermometer inside the coolant. To my surprise the fan did not turn on when the coolant temp exceeded 200 degrees and the upper hose was really hot and the lower hose was cool.....WTF!!!!!

When I replaced the cooling parts, not only do I refer to the manual (Chiltons) for the appropriate procedure I also use the correct torque. All the sensors, thermostat and switches are less than a month old. I tested the thermostat before I installed it in boiling water. It opened when the water hit 180 degrees. The thermostat is and NTCL 78 degrees Celsius. Is it possible that the sensors/thermostat/switches could malfunction in that short period of time? If so, why? My fear is my water pump that is also a month old is also bad. THAT WOULD SUCK!!!!!!!!!!

Assumption: Replace all senors, switches, and thermostat with OEM parts.

Moral of the Story for all DIYers:Never use aftermarket parts. The savings will never compensate for the hours of rework!

lgbrown13

Update: I removed the thermostat and refilled the coolant. The fans did not turn on unit the coolant was well over 200 degrees. The car on the hot side (60 percent mark on the gauge usually runs at slightly lower the 50 percent mark) when the fans turned on. When the fans turned off I turned the car off and turned it back on and the fan did not come on. It seems like the water pump is fine since both radiator hoses where identical temp to the touch. This was not the case with the, less than a month old thermostat was in place. Another interesting discovery is when I remove the thermostat and ran the engine the heater stayed cool.

holmesnmanny

some aftermarket thermostats have higher opening temps ... same with some fan swtches ... again its best to go oem

lgbrown13

Update: To say this was a learning experience would be an understatement. I discovered my heating problem was partly due to not turning on the heater when filling the cooling system. However this was not the primary issue. I noticed white smoke and milky sludge on the oil cap. DAMN!! Head gasket. So rather than sit there looking at my 1991 Honda Accord, that my neighbors questioned why I did not trash, I started the process. Keep in mind I verified the symptoms of white exhaust smoke, milky sludge, and loss of coolant. Approximately six hours later I had successfully removed the cylinder head. To my surprise, the head gasket was in tact. I am taking the cylinder head to the machine shop to see if the head is warped.

holmesnmanny

When they say the head gasket blows it doesn't blow out like that. It just means the head warps and the head gasket integrity is blown. The head will be warped and the block could be warped as well so you need to check it with a set of precision straight edges.