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In late January of 2023 around 220,000 was when I noticed the water noise in the heater core on startup and I started experiencing rough startups sometimes in April 2023 while on a road trip. I'm guessing at cylinder 3 and maybe a little of 2 as well based on the stored misfire codes. Spark plugs were finally changed around 190,000 miles even though it was called for in the Maintenance Minder around 95,000 to 100,000. I checked them back then and they still looked good and I had no misfire history. No misfire codes until April 2023 to my knowledge.
And post #10 I corrected some of that info:
Oh, no, I didn't explain very well. I didn't mean that the misfires occurred at 190K because of the age of the original plugs. I just changed them because I was reminded again to do it and I skipped it the first time around. I just checked and I actually changed them July 30, 2022 at 208,139 miles. I didn't notice any misfires until April 2023 around 232,800 or so and that was a couple of months after I noticed the lower coolant level and started topping it off some mornings. It doesn't need topping off every time so I suspect that it's a minor leak currently and sometimes it leaks more than others.
I'm firmly of the opinion that the head gasket issue is fouling a plug or two for some startups. Sometimes it's fine, other times it misses for 15-20 seconds on startup. Might be related to where the piston stops the night before. After they warm up I don't experience any further misfires at all until the next morning.
Now I have pictures to add to this discussion. Here are the details: (Engine has 244,482 miles for these pics)
It had been a couple of days since I drove the car so the cooling system should have been under some pressure as I parked. Radiator was a little low and I was able to pour all the coolant from the overflow tank back in the radiator and still had to add a tiny bit of new coolant to the radiator and more to get the coolant tank back up to the COLD line. I probably drove 110 miles or more since filling it last.
I'm considering cylinder numbers as #1 at the belt end, #4 at the transmission end.
I removed the Ignition coils and the spark plugs and used my new borescope to get these pics. This one has a side camera which came in handy. I did not turn the engine at all for these pics.
Spark plugs 2 and 3 smelled a little sweet and were darker than the others. Almost a little wet looking, but not quite.
Piston and Cylinder #1 looked clean. Piston and Cylinder #4 looked mostly clean as well. I've attached pics of those two pistons only. No Cylinder pics for 1 and 4.
Piston #2 has a puddle of coolant sitting on it. Cylinder #2 was found with a few drips rolling down from the head gasket.
Piston #3 might have had a small puddle forming but I'm not sure. Cylinder #3 was also found with some drips. One I watched rolling down the cylinder wall in real time.
Interestingly, it looks as though the head gasket is leaking on the intake / fuel injector side. That might just be how the engine is sitting though.
After these pics I put everything back together and started the engine which idled rough for about 30 seconds. I drove another 20 miles (including short stops) without issue after the idle smoothed out the first time.
Time for a head gasket kit! I'll have to find a good machine shop too possibly. Luckily, I've never had the engine overheat or even get warmer than usual so I don't expect any warping or damage to the head or the block.
Re: 2018 2.0/10AT, Head Gasket Leak around 220,000 miles
Yep, nice diagnosis.
I would not recommend driving it in that condition. If it worsens as you drive and a cylinder fills with coolant you will hydrolock it when you go to restart it, which can/will either crack the piston or bend the rod. Additionally the coolant contamination in the oil can result in bearing failure.... then you're really fucked.
On the plus side, the bottom end looks to be in perfect health. The cylinder walls look mint, and the piston tops look squeaky clean. Machine the head, slap a gasket on it, maybe a set of ARP's, and let it ride.
Last edited by RollingRoadEFI; Nov 28, 2023 at 11:12 PM.
2018 2.0/10AT, Head Gasket Leak around 220,000 miles
Here are the details: (Engine has 244,482 miles for these pics)
