Over heating,replaced thermostat still overheated

Coolant level? Is water pump working? Is thermostat stuck? Are cooling fans running? Do radiator hoses and heater hoses feel hot? You can either provide this information or take your vehicle to a qualified professional and have it properly diagnosed and repaired.

Connie, Were the radiator,water pump and thermostat replaced to try and fix the over heat issue or as maintenance. Engine overheating can be caused by a lot of things, Leak in cooling system, air in system, bad rad. cap, slipping belt, faulty thermostat or installed upside down, faulty water pump, plugged radiator (inside/outside), collapsing rad hose, faulty cooling fan, leaking head gasket, sludge plugging engine water passages, poorly tuned engine, etc..
Take into a good shop for diagnoses and estimate for repair. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
How to Troubleshoot an Overheating Engine
Steve Litt Overheating Guide
Diagnose Engine Overheating Auto Repair Help
How to Troubleshoot an Overheating Engine DoItYourself com

Over heating the engine is a serious concern. With the hood raised you should hear the motorized fan turn on just behind the radiator as the engine requires additional cooling.. If you look in from the rear of the radiator you should see the fan blades.

This electric powered motor operates on a thermostat and when the engine temperature rises this fan should come on. I'm assuming from your description that when driving and air is flowing through the radiator as the car travels the engine is nor overheating.

Check fan motor thermostat, check fan motor and check wiring.

Wiring Diagrams related to the Honda Civic
http://www.wiringdiagrams21.com/category/automotive/honda-automotive/civic

Motor engine cooling fan only runs as engine temperature requires additional cooling.

Drive the vehicle until operating temp. Turn vehicle off and CAREFULLY put hand between engine and radiator. If you feel any cool spots on your hand on the radiator side, you have blockage and are only using a fraction of the radiator to cool with. This is most likely the issue. But here is a list of what I would do first. Drain fluid. Remove thermostat. Install thermostat housing without thermostat. Run a flush through engine following instructions for deep cleaning. Drain . remove hoses. Run water through block. Make sure water can pass through. Replace thermostat. Run hose through radiator. Replace all hoses fill it back up and check again. Also replace hoses if they are old or weak. If the problem occurs going up hills but seems OK on flat ground I would blame the radiator.

Could be any or all three or a bad cooling fan. I'd start by replacing the thermostat since they are dirt cheap. After replacing the thermostat warm the vehicle up and feel the upper radiator hose if its hot the rhe thermostat opened and the water pump is circulating coolant next check the radiator it should be hot near the upper radiator hose and significantly cooler near the lower with an even heat distribution if any parts of the radiator dont get warm/hot then you radiator is plugged. Also you need to check the operation of the cooling fan with the engine warm turn on your ac that should immediately turn the electric fan on

the thermostat opens and closes to allow the coolant to flow in when it's supposed to and out to cool the engine and keep the engine temperature steady. The part is there for a reason and purpose. I would replace it before you have an issue.

Hi Kim,

I can feel your frustration. It sounds like you've done all the logical stuff already. The "donut hole" in your process would seem to be not changing the water pump. The water pump as you might imagine, is responsible for circulating (pumping) the relatively cool water in the radiator into the running engine that contains the hot water. Hoses connect the two together. A thermostat is between the radiator and the engine. Once the water in the running engine gets to a certain temperature, the thermostat opens allowing the water pump to send cool water into the engine and hot water out to the radiator to be cooled. The heater core is usually on the passenger side firewall area.

It sounds like the water pump is the only thing left to change - if it isn't working - it can't circulate the water - and will result in overheating. Lastly, a clogged heater core shouldn't cause the engine to overheat - in fact, if the engine begins to overheat, you should turn the heat to HIGH fan and HIGH temperature to help remove some of the heat in the coolant.

Good luck!

looks like your thermostat is sticking, and will need replacing,

this part is used when engine is cold so it heat up only a small part of the water jacket, once is warms up the thermostat opens and allows heat to car to warm you and keep the engine cool.

this is not a difficult job but messy and you will need to top up coolant water afterwards.

the termostat once removed can be tested in boiling water when cold and you should see it open if it does not it needs replacement and new gastkit and sealing.

best to have a qualified engineer do this job. is should not be too expensive.


I hope this was useful.

There is a blockage in the engine coolant path causing insufficient cooling. When the coolant flows, it removes the heat produced from engine combustion to radiator to cool. If there is no flow then the coolant becomes stagnant, therefore the heat is built up without being dissipated to nowhere hence the engine gets overheated. If this is not fixed then the heat will cause the head-gasket blown due the the metal expansion.
Repair at this stage becomes very expensive.
1- Take off the thermostat.
2- Put back the hose connection.
2- Run the engine and feel the upper hose to see if cooling flowing through it.
4- IF Yes. Run engine like this for few days, if no over heat , buy a new thermostat and put it back. Your problem is resolved.
5 IF No. You have a bad radiator. It clogs up so you don't feel the cooling flowing. Buy a new radiator, don't ever use a rebuilt one.
Good luck.

This could be a multitude of things:

Stuck closed thermostat.

Cooling fan not coming on.

Clogged radiator.

Low on coolant.

Water pump failing/leaking.

Head gasket blown, leaking exhaust into antifreeze.

Clogged catalytic converter.

Thermostat: If the Van heats up, then feel the upper radiator hose. If it's cold, then your thermostat is closed. Replace thermostat.

Coolant: If low, simply fill with distilled water and coolant. Low levels will let engine over heat.

Radiator: If there are cold-to-the-touch spots on the radiator after it should be warmed up, then a clogged is probably occuring. Have radiator flushed.

Head Gasket: If you smell exhaust fumes in your coolant reservois tank, then you got a blown head gasket.

Cat Converter: Only can be tested if off the car. Or you could try a non-contact thermometer. These are also good to testing cold spot on radiator or if thermostats are open.

Cooling fan: If mechanical it'll be spinning. If electrical, it should come on automatically with the A/C, or when it gets hot.

Water pump: Will be leaking from the front if it needs replaced. On a van, it's a tough job.

Good luck!