Скачать или смотреть I made a costly mistake on this Subaru EJ25

Following up on the Subaru EJ25 from my last video.

The head gaskets on this car were done about 600 miles ago…

The vehicle had overheated before we ever touched it, which is a key part of this story.

When we originally did the head gaskets, the cooling system was filled and bled using a no-spill funnel. Everything bled normally, the system held pressure, and there were no visible leaks from the radiator, filler neck, or cap at the time. We drove it afterward with no immediate issues.

This car originally came from a customer who planned on fixing it but ultimately decided they wanted to be done with it and sold it to us. When we got it, the engine was already partially torn apart… the heads were off, the block was still in the car, and the original heads were cracked around the spark plugs.

We checked the block deck to make sure it wasn’t warped and installed remanufactured single-overhead-cam EJ25 heads that had been machined and shaved. The car also came with an aftermarket head gasket kit, which we decided to use. That’s another lesson learned here… I don’t know if that contributed to the failure, but it’s worth mentioning.

What actually went wrong ended up being the radiator filler neck.

On these Subarus, the radiator is aluminum with plastic end tanks. When a car has overheated in the past, the area where the radiator cap seal sits can become heat-damaged. It may still seal at first and show no signs of leaking during the initial bleed and test drive. But after more heat cycles, that plastic can deform, deteriorate, crack, or even melt.

I’ve seen this happen a handful of times over the years — maybe five times out of hundreds of head gasket jobs (on Subarus). Most of the time, I catch it early when the radiator cap starts leaking shortly after a head gasket job. In this case, I didn’t catch it before the car left. The filler neck deteriorated, started leaking at the cap, air got into the system, and the engine overheated again.

Lessons learned:

• From here on out, every head gasket job gets a brand-new radiator and radiator cap, no exceptions.
• We’re also sticking to OEM turbo EJ25 or Six Star head gaskets only.
• New head bolts every time — no reusing old bolts.

Small details like this matter. I’m sharing this not just to document the wins, but the mistakes too — so others can learn from them.

Follow along for more Subaru content and the next video where we tear this engine down to see exactly what failed.