What differentiates K-Series engines from Honda's engine series of the 90's?
Of course, the chain-driven valve train.
After decades of building belt-driven engines, Honda's engineers decided to shift to a maintenance-free system to keep crank- and camshafts synchronized.
Maintenance-free? At least, they claim that.
According to this, you can drive your car 300.000+ miles without worrying about the timing chain. Nice benefit compared to belt-driven cars, which need a new belt after every 60,000 - 105,000 miles.
Is the K20 Timing Chain Maintenance-free?
For my swap, I got a K20A2 engine with 80,000 miles on the clock.
With that mileage in mind, I didn't worry much about inspecting or even replacing the chain and auto tensioner.
I enjoyed driving my Civic after the K-Swap was done, but on the other side, I was a bit disappointed about the low power output in the VTEC range.
I noticed a rattling noise in the higher revs and the hyped VTEC-Kick was missing.
I read many posts of people, who complained about stretched timing chains. Could this be the problem?
After a few failed troubleshooting attempts such as cleaning the VTEC solenoid, we pulled out the engine again and inspected the timing chain, guides, and the auto-tensioner.
After we had removed the chaincase cover, we were able to check if the timing was still synchronized.
The engine needs to be rotated clockwise to TDC (Until cylinder one is at the top dead center).
Two marks on the camshaft gears that are supposed to be in-line indicate if the timing is in sync.
Here's the result of our 80,000 miles engine:
As you can see in the photo, there's a difference of about one link.
Looking at the low power output in high revs, the chance was high that the chain in our engine was already stretched.
If the marks on the camshaft gears don't line up anymore, it's a clear indicator.
But I wanted to dive deeper into the topic.
A couple of days later, I received a tiny box from the United Kingdom with a brand new OEM chain and auto tensioner in it.
In the following photo, you can see a direct comparison between the new and old chain:
The old chain (right side) was two millimeters longer.
You're might thinking "... so, who cares about those two millimeters?".
I had the same thoughts in mind. I was even a bit disappointed with the result. I expected a significant difference.
One hour later the new chain and tensioner were installed.
While I was rotating the engine by hand a couple of times, my buddy crossed his fingers that the timing is synchronized now.
This was the final result:
The marks on the crankshaft gears lined up perfectly!
The timing is perfect now. I wouldn't have expected that two additional millimeters have so much impact on the entire timing.
But it's clearly noticeable.
Now I can't wait to drive the car again! 🙂