K20 Timing Chain & Tensioner Replacement

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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.

Bad mistake!

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:

K20 Timing Chain Cam Gears

As you can see in the photo, there's a difference of about one link.

Stretched Chains

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:

K20 Stretched Timing 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:

Lined-up camshaft marks K20 timing chain

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! 🙂

K-Series Chain Tensioner

K20 Oil Pump Chain

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2 Comments on “K20 Timing Chain & Tensioner Replacement”

  1. i have already done two timing chain and phaser kits on a couple k24 in the both with less than 100k miles, i see this being an Honda issue. fairly simple job just didn’t understand why with such low mileage on a chain set up.

  2. I’ve done about 30 timing chain and tensioner replacements and some cars have hit 200k miles without needing it, and one with 120k miles. Average is about 150k miles, which is where I recommend doing it at. The reason they need it sooner, is the oil consumption and how well the owner kept on top of it. If they check it and top it off on a monthly basis, it should last 200k miles. If they wait for every 3mo, and instead just change the oil, then they may be down up to 3quarts and have decreased the life of the chain, the motor, or worse.

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