Honda head Gasket? Stumped.

[446k]

Hi, I have 30 yrs DIY wrenching experience and I'm stumped.

Bought a 2018 Civic EX 2.0 (no turbo) 140,000 kms from my wife's co-worker in mint condition and no past problems. Well, it's definitely loosing coolant. Here are my tests & results to date:
- no visible leaks
- no mixing of engine or trans oil
- compression 175/170/110/175. The 110psi cylinder is leaking out the intake valves (leak down test).
- 15psi rad test loses 1psi after 10 hours on cold engine. Loses 1psi after 1 hour with warm engine.
-Camera inspection of cylinders at bottom: great cross hatching, no blow by, and no coolant drops. Pistons are not damaged. All pistons have the same amount of carbon build up and color.
- spark plugs are original and have the same color. They look normal.
- on cold start-up the exhaust is clear for 5 secs and whitish-grey for 10 secs, then clear. I have an 02 civic and 15 Odyssey and they both have clear exhaust at start up and no whitish-grey.

Did I miss anything before I remove the head? Any recommendations on this particular Honda? It's K20C2 engine.

 

[ecotourist]

My 2007 Accord V6 was losing a bit of coolant. I replaced the tiny hose from the radiator to the overflow tank and that fixed it. There was a trace of coolant residue in that area and that was such a simple thing it was worth a try. If I hadn't been looking for an explanation for the loss of coolant I would never have seen the coolant residue.

 

[rijndael]

Did I miss anything before I remove the head?

Combustion gas test in coolant. A block tester.
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=asc_df_B06VVBSFTF

 

[cptbarkey]

Combustion gas test in coolant. A block tester.
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=asc_df_B06VVBSFTF

This is one of the initial things you could have done to save some time.

The leak down test results are pretty much confirmation. I'd say you are safe to proceed to the HG repair and disposition is good.

 

[trd1zz]

Now you know why they sold it

 

[446k]

Combustion gas test in coolant. A block tester.
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=asc_df_B06VVBSFTF

Thanks, I'll order a test kit.

 

[446k]

My 2007 Accord V6 was losing a bit of coolant. I replaced the tiny hose from the radiator to the overflow tank and that fixed it. There was a trace of coolant residue in that area and that was such a simple thing it was worth a try. If I hadn't been looking for an explanation for the loss of coolant I would never have seen the coolant residue.

Thanks. I'll take a closer look at all the connections.

 

[Spring Break '92]

Quick and dirty way to test for a bad HG is to have someone start the car from dead cold, with your thumb in the radiator filler neck. Once it's started, remove your thumb and if you smell exhaust, it's the HG.

 

[Hirev]

Sounds like it has two problems that need fixing. Head gasket and valve and seat work needs to be done. So yep looks like the head needs to come off to me.

 

[D60]

Block tests can be ok to confirm a suspicion but a negative result means little as they're not all that accurate. IOW I think false positives are rare but false negatives abound.

And make darn sure you know the color to start because the change can be gradual and subtle. I reco pics with the same camera, same angle and same lighting before/after for a sanity check -- although it's entirely possible the need for frequent sanity checks is unique to myself

 

[The Critic]

- 15psi rad test loses 1psi after 10 hours on cold engine. Loses 1psi after 1 hour with warm engine.

Pressurize cooling system with your tester and allow it to sit pressurized for a while. Using your camera boroscope, preferably an articulating one, you may find drops of coolant entering each cylinder.

 

[parshisa]

Pressurize cooling system with your tester and allow it to sit pressurized for a while. Using your camera boroscope, preferably an articulating one, you may find drops of coolant entering each cylinder.

View attachment 295468

I've seen videos of this being done for diagnosing 1.5T honda engines blown head gaskets. Looks really cool...on someone else's 1.5T

 

[Trav]

I would also put some UV dye in the system, run the engine long enough to circulate. Use a black light at night to see any traces of dye, it will make it easier to see if there is leaking in the cylinder. In this case the head has to come off anyway for the intake valve issue so you are just confirming no external leaks.

https://www.amazon.com/Genuine-GM-12378563-Fluorescent-Coolant/dp/B000QIJH2I

 

[Cujet]

I can't remember how many times I've had engines lose coolant, only to find some simple, but well hidden leak. Only once was it a real engine problem.

 

[mk378]

Yes in particular there is a coolant system through the intake and throttle body which can leak into the intake and cause white smoke just like a bad head gasket.

Valves should be adjustable from outside. You could loosen the valves on the bad cylinder to make sure they are all slack then leakdown test again to see if there is an internal problem.