micwells07

Well, it started off as a missfire that I could not figure out. The spark plugs were new, so I replaced the ignition coils. This fixed the problem for about a month or so. It reappeared shortly thereafter, but went away again after I reset the ECU. For about a month it would only start missing after taking the engine into VTEC (which I am conservative with). It then escalated to where there was a constant missing at idle only, accompanied by a valve train "ticking", which made me think of the retainers.

Upon removing the valve cover I found that most of the intake retainers showed signs of being cracked, and a retainer on cylinder one was cracked so badly that it had been contacting the rocker. This contact had resulted in etching of both the cam lobe and rocker surfaces.

After spending quite a while sitting in the garage, due to me being broke, she is up and running again. I ended up replacing the retainers with AP2 retainers and keepers for the intake side, and new AP1 retainers for the exhaust. I also replaced the damaged rocker, and installed a new set of Brian Crower Stage 2 NA cams.

This (Lisle Keeper Tool) is what I used to remove and install the keepers. It was about 300 times easier than the overhead spring compressor with the knob.

Quick history on the car - I bought it used back in 2010 with 93k miles on it. Within the first year and 10k miles I had to replace the clutch/flywheel/pressure plate, clutch master cylinder shortly followed by the slave, both engine mounts (completely sheared in half, obviously for a long time), and both front brake calipers (siezed while it was sitting around when I was replacing the clutch). The exterior and interior were well taken care of, but it was definitely abused... Ironically, it does not burn oil, and the owners manual reflects oil changes with synthetic oil every 3 to 4k for the first 60k miles on the car.

Below are some pictures of the retainers / cams. There are also pictures showing what the cracked retainers look like with everything still in place in comparison with good retainers.

Cracked Retainers:


Good Retainers (exhaust side), Notice the keepers are completely flush with the top of the retainer:


Etched Cam Lobe (rocker exhibited the same etching):


The Car:

meccjoo

Amazed at the number of over revved ap1s out there. If people would learn how to shift this wouldn't be problem. Glad you caught yours in time before anything serious happened.

tozerman

Holy shit, those pictures are frightening, you had a lucky escape there mate, well done

SpoiledAP1

wow, must have been close to a dropped valve, scarey stuff.

micwells07

Yeah, I think I was incredibly lucky. In hindsight I wish I would have checked them immediately after buying the car. I just didn't know about the issue at the time.

The car has been a pretty steep learning curve, as I've done all the work myself.

SpoiledAP1

It sure does, I learned more in 1 week of owning it than I did the entire lifespan of my first car!

Billman250

Great catch...Very lucky.

The next step is the rocker pivots the broken retainer sideways until it snaps the tip of the valve off. The retainer, keepers, and valve tip come off as one jammed up piece. Valve drops and destroys the cylinder, and likely the head also.

I'm at 125k still on original retainers with lots of 9k operation. I will leave them stock forever to keep proof to the point that this is caused by mechanical over-rev (meaning wrong-gear...not hitting the limiter).

In almost every case, the car was over-reved by the previous owner, and the new owner would never know.

It is important for ALL AP1 s2ks to have the retainers inspected. Once they are deemed healthy, they can be left alone.

By installing AP2 retainers on the intake side, you raise the over-rev RPM limit (9700, retainer crack) to a safer level.

cdelena

Not always a shifting problem... I have been very close (or have) over-rev when racing down mountains... you stay in VTEC between curves but revs build easy on a good grade and sometimes I get extended periods with my rev warning (set at 8500) screaming.

Billman250

Been wondering about this...totally possible.

micwells07

Thanks. I had to take a moment to appreciate that luck after finishing the job and looking at the cracked retainers sitting next to each other on the work bench.

What you describe makes perfect sense thought, and I do not think I was far from reaching that point. The retainer that was cracked the worst was on cyl 1, intake valve 2. There was wear on the retainer around its entire circumference, and I could put a thumb on opposing sides and rock it back and forth a little.

My younger brother has been looking at S2000's and I have told him that a retainer inspection will be the first thing to happen if he gets an AP1.