How to Test a Honda Civic Blown Head Gasket

How to Test a Honda Civic Blown Head Gasket


It’s more than an inconvenience when your Honda Civic blown head gasket is causing your car to overheat. Today we’ll be showing you how to diagnose your 2001+ 1.7 liter Civic for the tell tale signs of being overheated. This guide to diagnose your Honda is an easy way to see if your head gasket has blown or your cooling fans may not be working correctly.

If your Honda Civic still starts and runs, this is a good sign and it’s a positive sign that things haven’t gotten too bad. If your Honda Civic is overheating, there’s a few things that you should check first. Here’s the short list of things to check in your overheating Honda Civic

  • Thermostat is working properly
  • Radiator fan is working
  • Coolant level is sufficient
  • Water pump is not leaking


The next thing to check is of course your exhaust, and if it smells sweet or you have white smoke coming from it. This is a sign of coolant burning in your combustion chamber, and a clear sign of coolant leaking through your head gasket.

If you have white smoke coming out of your exhaust the next thing to check is coolant mixing with your oil. You can check this through your oil dipstick or checking the oil cap to see if there’s a milky substance underneath it.


When you see the milky mixture under your oil cap, this is a result of a Honda Civic blown head gasket leaking coolant into the engine crankcase and mixing in with engine oil. To test this open your Honda Civic engine hood and extract your dipstick or open the oil cap and inspect it.

If you see a milky mixture on your Civic dipstick or under the oil cap, there’s a few things that have happened.

  • Your Honda Civic has overheated and blown through the seal in your head gasket. This leads to oil and coolant mixing in your crank case.
  • Your aluminum cylinder head has overheated to the point where it’s no longer flat. When your head has heated to the point of overheating, it “warps” which means that it will never properly seal again without service

If you don’t yet see the milky signs of cylinder head warpage, good news because you still have a chance to fix your overheating Honda Civic. If your Civic is overheating there’s a few things that can you can check to see how much damage has been done to your 1.7 liter engine.

  1. Compression check your engine

If your head gasket has been compromised between cylinders, a compression check is a good way to determine how much damage has been done.


Compression checking your Honda Civic is easy by using a tool that screws into the spark plug threads of the cylinder in question.

You can rent a compression checking tool at your local auto parts store and use it to check your Honda Civic. For specific instructions on how to test your engine compression, check our How To Guide here.

If your test comes up with one or more of your cylinders reading low, or having no compression at all your cylinder head must be serviced.



For more information on how to service your SOHC Civic engine and repair your blown head gasket, check our How To here. Have any questions about our How to Test a Honda Civic Blown Head Gasket Guide? Leave them for us below!