How-To/DIY: Replace A Thermostat On A Honda Integra B-Series Engine

Hey folks! I hope everybody around the world had a great Halloween weekend! Thanks for visiting again for another installment of a How-To/DIY article. Today I will be discussing a crucial service maintenance for long motor longevity: regulated cooling.


Now for a motor to perform optimally, it needs proper cooling. An engine will usually have a water pump, thermostat, radiator, radiator cap, fan switch, cooling fan, coolant and several different size rubber hoses that circulate coolant throughout the whole cooling system.

If there is not proper cooling, the engine block will heat up very quickly which will cause severe damages to the cylinder short-block & cylinder head. When a temperature needle raises past the middle mark and towards the hot mark, it is usually an early warning sign to pull over, check the system for leaking or burning of coolant because any further damage will cause severe failure of engine performance. The head-gasket blowing will probably be the first sign of failure, causing a mixture of oil and coolant inside the engine block. If a head-gasket is indeed blown, you can check by removing the oil cap and checking for a milky-like texture & color.

So to avoid all the mishaps & disasters, I HIGHLY advise to have a properly maintained cooling system for your engine. If you have an older car, then I recommend replacing the thermostat first because it controls the regulation of coolant going in and out of the engine block. Other smaller and easier replaceable items would be the radiator cap, coolant & main radiator hoses. For this How-To/DIY article, I will be showing you how to replace the thermostat and the steps to bleeding/removing air bubbles in the engine.

WARNING: System is under high pressure when the
engine is hot. To avoid danger of releasing scalding
engine coolant, remove the cap only when engine is cool.

Warning: Use this guide at your own risk. I am not a professional and am not responsible for injury to you, your vehicle, or anyone/thing else if you choose to follow this guide.

NOTE: If any engine coolant spills on the car’s paint, rinse it off immediately. Check all hoses for damages, leaks or deterioration and replace if necessary. Check all hose clamps & re-tighten  if necessary.

NOTE: Cooling System Capacity including the heater core & reservoir:

B18B1 w/ Manual Transmission – 6.4 liters / 6.8 US quarts

B18B1 w/ Automatic Transmission – 6.7 liters / 7.1 US quarts

B18C1/B18C5 w/ Manual Transmission – 6.7 liters / 7.1 US quarts

 Okay let’s begin the How-To/DIY: Replace A Thermostat On A Honda Integra B-Series Engine

Step 1: Locate the thermostat housing & unplug the ECT/fan switch plug. It is usually located beneath the intake arm and distributor. Unbolt the 10mm bolt holding the ground terminal.

DIY Thermostat (1) copy

Step 2: Remove the 2 x 10mm bolts and remove the thermostat cover. I would recommend either placing a towel underneath as a small amount of coolant will spill out.

DIY Thermostat (3) copy DIY Thermostat (2) copy

Step 3: Remove the old thermostat. Prepare the new thermostat with it’s proper rubber gasket. Here you can see the OEM thermostat on the left and a Autozone generic brand on the right. REMEMBER: Install the thermostat with pin up.

DIY Thermostat (4) copy DIY Thermostat (5) copy





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Step 4: Clean the surface area & scuff off the leftover liquid gasket.

DIY Thermostat (6) copy

Step 5: Place the new thermostat inside the thermostat housing.

DIY Thermostat (7) copy

Step 6: As a precaution, I recommend applying liquid gasket maker on the outer thermostat housing for a better seal to avoid leaking. Reinstall the 2 x 10mm bolts with 12nm/8.7lb. Plug the ECT/fan switch back & ground terminal.

DIY Thermostat (8) copy

Now that everything is back together with a new OEM thermostat, it’s time to bleed the system of air bubbles and add coolant.




Steps to Bleeding the Engine Coolant

NOTE: Do not mix different brands of anti-freeze/coolants.

Step 1: Slide the heater temperature control lever to maximum heat.

Step 2: With a cooled down engine & radiator, remove the radiator cap.

Step 3: Start the engine and let it run until it warms up in which the radiator fan comes on at least twice. As a precaution, check the temperature needle to make sure it does not get too hot.

Step 4: Turn off the engine and add coolant if needed to the top of the filler neck of the radiator.

Step 5: Put the radiator cap on tightly, run the engine & check for leaks.

From past experience, if you remove the radiator cap, turn on the engine and it sprays coolant upward, there is a strong likelihood the head-gasket is already blown & damaged. If this is the case, then you’re out of luck unless you go the route of rebuilding the engine.

Well that is it for today, I hope you learned something new and enjoyed this How-To/DIY article to Replace A Thermostat On A Honda Integra B-Series Engine. I hope you have a great day! 🙂

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