My timing belt cautionary tale

Hey guys I wanted to share with everyone my experience with doing my own timing belt job. Hopefully this isn't a novel and maybe someone can learn from my mistakes. TLDR at bottom.

This past August I did the timing belt job on my 4.7. It had about 150k miles on the belt, so a bit overdue. Here's a look at the belt condition


I also found this crusty water pump while I was in there. Good thing I got the whole Aisin kit with new water pump!


And finally down at the bottom, a crank seal that had been leaking for a while. I also did the crank and cam seals while I was there.


Some notes from my experience, mostly it went pretty well:
-Self-tapping screw trick worked great to pull the crank and cam seals. No puller needed for me.
-I was never able to break my fan clutch loose, so it just stayed on the bracket. That makes it annoying to get to a few bolts but it is possible to do the whole thing with fan still attached to the bracket.
-A/C compressor has a bitch of a back bolt. 3/8 wobble head on a long extension worked wonders back there.
-Breaking the cam bolts loose is also a bitch. My hercules impact couldn't do it. So I had to wedge a big pin wrench against some deadwood in the engine bay, and then use a 4' breaker bar on my wrench. Sounded like a 22 going off when they finally gave.

Now onto my cautionary bit, the harmonic balancer/crank pulley.
This bolt did break loose with my impact no problem. But that damn pulley was stuck good. I got the correct puller from HF and bottomed out the screw, only to have the thing still stuck at the last little bit. I pulled and pulled and couldn't get it off, so out came the pry bars. It took some working around the pulley to find good spots, and pull here then pull there, finally it popped off but in the process the outer ring shifted a bit from the rubber. I didn't think too much of it. I'm pissed at this point, I've been at it all day and should have taken a break. So I carried on with the job, got all my new parts in place, the truck back together and it's running great. Everything is happy. Just a new slight wobble at the harmonic balancer, belt runs true. No problem.

Fast forward to December 23. It's almost the holidays. Driving to work and coming off a red light I have a sudden loss of acceleration. Engine is running at idle speed with no weird sounds but I've lost all accessory power. I coast into the parking lot and kill the engine, look under the hood to find that harmonic balancer had fully separated. I think no big deal, got a ride to the auto part store for a new harmonic balancer and belt, collected up some tools and I'm about to fix this thing in the parking lot and still make it to work. So I replace the parts, had to pull the radiator to do it so made another run to the store for coolant, get her filled up and try to start it. Crank Crank Crank but no fire. Damn. I figured maybe the crank position sensor was damaged in the process, so I'm back to the store to grab one and I pull the old one. This is where the horror show really starts.

Stuck to my crank position sensor is little bits of melted plastic. I get into a position where I can see inside the hole for the sensor when I find that the broken pulley had cut a huge gash through the lower timing cover. Big problem.


So I get the truck towed home, fearing for the worst. I pulled enough off the front of the engine so I could see the belt at the crank and both cams. Bunch of plastic debris behind the lower timing cover. I begin to spin the engine a bit and see that the belt is lose on one side and overly tight on the other. My belt had skipped timing. Worst case scenario. It's now christmas eve and I have to let the truck sit for two days.

Thursday comes around and I head to the part store to borrow a compression tester. My wife is already shopping for new trucks. I tested all cylinders and we're still happy, good even compression on all 8! All in the 155-170 range. So I carry on with repair. I put my cams back on their T marks, pulled out the tensioner and eased the belt off. Since the belt was so new I was able to just make out the timing marks still. I set it back in place on the cams and the crank was off by 7 teeth! So I rotated everything back where it was supposed to be, got the belt on, compressed the tensioner with a C-clamp and put everything back together.
I wasn't able to find a new lower timing cover in town, so I got creative with some sheet steel and JB weld:

Nervous as hell, I get in the truck with everything back together and some fresh coolant (again). Turn the key and she fired right up! Hell yeah! I'll be damned if I'm buying a new truck yet! A bit of white smoke out of the pipe for about 5 minutes while I was burping the coolant system, but it cleared up and it running clean now. The engine sounds fine, idles normally, and everything is happy again. I've driven it 20 miles now. Hopefully it stays that way.

TLDR: I got careless while removing the harmonic balancer and shifted the outer ring. Four months later, it breaks and cuts trough the timing cover, sending debris into the timing belt and causing the engine to jump timing. Thankfully it still runs after getting lined back up, but could have been a bricked engine! If you damage your harmonic balancer during removal just go ahead and get a new one.

 

Damn! What a story! Thx for sharing. Glad it worked out.

Lube/penetrant is your friend on pulling the crank pulley, but you know that now.

 

Great story! What a hardship, but at least you prevailed and helped prove the non-VVTI V8 engine has a very low chance of valve damage if it’s really an interference engine.

 

Dang, hell of a story...

Speaking of lube... I read something funny a while back and saved it, i think now is an appropriate time to share it.