No good deed goes unpunished…. Timing belt saga

1998 Taco extended cab, auto, 4wd, 3.4, 220 Kim’s

May long weekend I ordered in a timing belt kit with water pump from Rock auto as my timing belt was looking iffy.

ripped her all down, went to put on new belt and all seemed right til I went to start it. No work. Bang, sputter, flutter,…. After dozens of attempts to ensure that the timing marks all lined up, I got fed up and bought another belt locally. I should say the first belt had 2 alignment marks across the face of the belt. The new one had 3, so I know for a fact that everything is in perfect time.

it now started poorly but ran, sort of, puttering away at about 250 rpm. Had a mechanic buddy with a high tech scanner, who said it is misfiring badly, replace your coils and wires. The only code showing was for an o2 sensor. Bank 1,upstream.

bought new coils and wires. Installed.. exact same effect. I am baffled.

my first question is could I have done internal damage IF I started the truck with the first belt possibly being 1 tooth longer. I know they are non interference so if the belt breaks no damage, BUT how much damage can be done if it’s running close to being timed but just not enough…


I took out the supposed bad O2 sensor and cleaned it really well with CRC for sensors. Sprayed, soaked in a dish of it for an hour, sprayed again, let dry, installed, cleared code, started…. Same same.. 250 rpm and sputtering…

My plan is to do a compression test on each cylinder to see what that tells me.

I have already replaced the crank sensor, just as a guess. No change.

 

I am questioning if and how that O2 would just go.
I am wondering about MAF sensor.
I am wondering about Throttle position sensor.
I am wondering about my pcm?


I also did the erase of the ECM (disconnect pos side, turn on headlights, leave for 15, turn off lights, reconnect). Then recalibrated the tps (key on, 3 slow full throttle, key off.)

none of this worked. Googled up old Scotty Kilmer.. start it, rev to 2000 for 5 mins (in park), put it in low gear,foot on brake, 5 more minutes at 2000. Shut it off. Restarted.. not a change…

I am desperate. My truck has been out of action for almost 3 months with no closer to moving…

this is not the first time I have ever done a timing belt on a 3.4 Tacoma/4Runner. I have done 3 previous with zero issue, but it seems to me all of the other belts had 3 full lines across the belt

 

****Your engine was running before you started this project??

Non interference Engine nothing should be damaged .

I have never used any marks on the belt.

I just line up the crank and the cam marks .I am sure your rotating things enough to make sure the cams are in the correct position to line things up.

I have always used Aircabinman`s Kits off ebay.

The ECM ground can be Finicky . Something not plugged in correct bent pins or corroded connections

Best of Luck!!

 

Did you plug in yhe cam sensor, or damage the wire?

 

As already stated, did the engine run fine before you worked on it? If so then it's simply a timing belt issue. There's some tricks to get it just right but the number one question is did it run fine before you put in the new timing belt?

 

Line up the timing belt cam marks and hold in place with some clamps. Keep everything tight while lining up the crank mark but counter rotate your crankshaft 1 to 2 teeth so that when you spin the crank it will take up the remaining slack. All the slack should be on the left side of the crank which the tensioner will take up when you release the pin. It might take a couple tries until you figure out how many teeth you need to counter rotate the crankshaft to take up the appropriate slack. When all is said and done rotate the crank by hand a few times and check your timing marks to make sure it's still aligned. The marks on the belt might be off after you rotate it but that's okay as long as the cam and crank sprocket marks are correct.

 

The timing marks are on perfect. The engine ran fine before I replaced it.

I suspect that there may have been damage when I tried to start it previously with the timing marks not in alignment.. be it electrical or mechanical..

I have nit had time to work on it, or even to reply to posts. Wildland firefighter, just got home after a 14 day shift.. probably gonna reset and redeploy, so I am hoping to have some time to try to diagnose.

 

Be safe out there man! Following along…

 

Yeah stay safe bro - family and I visited the Granite Mountain hotshots memorial just a couple of months ago up in Yarnell, AZ.
Regarding your timing belt - might also want to check that all the teeth are on the reluctor wheel (or whatever it's called) part of the timing pulley, not the teeth for the timing belt but the teeth on the back that the crank sensor reads. If one of those are broken off you would get timing issues even though everything else is lined up correctly.

 

this right here is so true. This happened to me on my gs300 on a 2jz motor. Car was running fine before a replaced timing belt/water pump. Got everything back on with timing marks and what not and car would not turn on. Took it to a shop after not being able to trouble shoot and even the shop couldnt find the issue. Almost sold the car lol but took a day off of breaking my head trying to figure it out.
Next day went over everything on the car and i noticed i had broke 1 tooth off the sprocket when i initially removed it not noticing it. Ordered a new one got everything back on and bam started right up.

 

Thanks all.. Have had no time when i was off..

I will look at the suggested missing tooth gear..

 

You have to take apart a lot of pieces to get into that job and leaving something disconnected like a vacuum hose or a sensor harness wire can cause it run poorly. If you already double-checked the timing it's time to go back in and look for something else you may have missed.

Did you pull the pin on the tensioner? Could be some step was overlooked.

 

Good advice here. Its very easy to leave something off when reassembling.

Go back through everything. Especially those vacuum lines. Even ones you didn't even disconnect.

 

Well, I found the answer...

Because the belt was the wrong one, when I started the truck it bent a valve...

Swapping in a used 3.4 from a different truck.

 

Shit....so much for non-interference in this case


Was the initial belt sold as a 3.4l one but ended up being too long? I'd have a word or two with the seller...though fighting them for damages might be more trouble than it's worth

That really sucks but hopefully the new (used) engine gives you many more trouble free miles

 

It was from Amazon, so probably no chance..

 

At the very least I'd leave a review of what happened on the seller's page so others are warned, that's a worst case scenario thing to have happen with your timing belt change.

 

Damn, that really sucks

 

Any clue how the belt would've bent the valve? I'm having a hard time picturing how...

 

I am as well. Non interference means just that. No matter how far out the timing is there should always be clearance.