Timing Chain Tail of Woe: What Now?

December 23, 2020

TL;DR: I have repeatedly had timing issues crop up in my 4Runner, even after replacing the timing chain and timing set, replacing the engine, and replacing the engine again. Am I just that unlucky, or could something else be causing the timing issue? Anyone ever deal with repeated timing issues? Anyone ever successfully fix a timing issue?

Commence my tail of woe: My beloved 2007 Toyota 4Runner started showing a check engine light from time to time about a year ago. My partner and I pulled over, we got it checked out, but then...it went away. We didn't see it for a while, but then it came back. We got it checked out a few times, and most mechanics suspected the timing chain was getting old, or maybe the oil pump was failing. Either would be an expensive fix. The light went off again, so we put it off.

Well, we were on another long road trip this fall, 300 miles from home, when the check engine light came back, and the oil light started flashing. Well, having long suspected timing chain + oil pump, we were very worried! We brought it to a mechanic, and he gave us the bad news: Timing chain. The computer codes said "over retarded timing," I believe.

The car ran fine, as far as we could tell. No weird smells, no weird noises...but we'd known about this possible timing chain for a while, and the car had ~250,000 miles. Not wanting the engine to destroy itself, we got a hotel room and had the mechanic replace the timing chain and other parts, a whole "timing set" and the oil pump just in case. A few days later we drove away...and got the check engine light in 40 miles. Bummer. And this time we heard a weird clicking and then a bad knocking. There hadn't been a knock before! What had happened?

Back to the hotel, and back to the mechanic. We left it with him and took a bus home to wait for the repair this time. Maybe they'd made a mistake because they rushed it last time? They assured us they could fix it. This time the codes said "over retarded timing" and "over advanced timing."

Well...they couldn't. They said the engine was all sludged up and had thrown a rod. They told us we needed a new engine. Mod edit !!!!! Rats. This is what we wanted to avoid by getting the timing chain replaced right away! After weeks of talking with the mechanic and working our butts off to scrape some funds together, we decided to get the engine replaced. We got a junkyard engine because that's all we could afford. Still cheaper than a new car, so what choice did we have? Also we love that 4Runner. We wanted it back. The mechanic would replace our engine, but he'd transfer over our brand new timing set.

A month and a half later (most of that was just us trying to figure out what on earth to do), the car was ready. We borrowed a friend's car to go retrieve ours, started driving, and...well, we made it 150 miles this time, but right after filling up, the check engine light was back again And the code was...over retarded and over advanced timing!!! WHYYYYYYYYY.

Well, we weren't going back to that mechanic again. Apparently timing chains are hard to do correctly. Please correct me if I'm wrong, I'd like to know for sure. We got the car towed home, only to find out, well, we could still drive it, but yeah, there was something wrong with the timing, the new chain was stretched (how??), and the engine wasn't so great.

So we got the engine replaced again again, by someone here at home, without anyone touching the timing chains on the "new" used engines (junkyard engine was warrantied, so we got another junkyard engine in its place). This time we drove away...no code! And the car was so quiet! Phew! We drove around casually with no issues. No big trip yet.

That lasted until I washed the car. Check engine light was back again. This time the code was a bit different, and I know the number this time: P0016, cam shaft position sensor, bank A. But you know what can cause P0016? Timing. Issues. ARRGGHGHG!!!! Please, no!

This code comes on, sticks around for a while, and then tends to go away on its own. Could it just be a sensor? Or has my timing chain jumped again? Could it be something else that's caused three different timing chains to jump? I think the timing set included guides and a tensioner pulley, but then I guess I got another used engine, whose timing area didn't get messed with. Am I just super unlucky? Do I have to redo the timing on my new used engine too? This is getting ridiculous. I want to save my 4Runner, guys! I'm about ready to fix the timing chain myself, if that's what's wrong again. I certainly don't have the money to pay another guy to do it wrong. 😧

Has anyone ever had a timing issue successfully fixed by a mechanic? Has anyone done it themselves? Any troubleshooting tips? I need help.