From what I've read from others, It is ok to turn back counterclockwise a small amount. I've never tried going back from a 90° spring forward. If you decide to go clockwise, you will have to turn the crankshaft small amounts in order to let valves open and clear the pistons as they bump them. This can be a challenge but doable. Just be mindfull not to force the cam as you turn it and it stops, adjust the crankshaft.
Just to be sure, understanding that the crankshaft turns 2 to 1 to the cams. With the rear cam lined up on the mark, piston on #1 cylinder should be TDC (at the top of the cylinder). This can be gauged by putting a long extension or a screwdriver in through the sparkplug hole.

 

Thanks. I did more searching in the meantime and it sounded like as long as the belt was off, going back counterclockwise on the cam sprocket would not cause a problem. I actually found that using my serpentine belt tool on the sprocket bolt gave me great leverage and the ability to easily finesse small movements of the sprocket. I was able to move the cam sprocket in small increments counter-clockwise until the marks lined up perfectly. Got the belt back on, reset the grenade and will reinstall and then turn the crank bolt two revolutions and re-examine my marks. I will take your wise advice and remove plug # 1 to make certain the piston is at the top. About how many inches in should my extension go if the piston is at TDC?

 

I will take your wise advice and remove plug # 1 to make certain the piston is at the top. About how many inches in should my extension go if the piston is at TDC?

It will be apparent. If it was off 1 rotation, the extension will fall in like dropping it in a coffee can. You can rotate the crankshaft with the extension in the tube and watch it go down or come up.

 

Thanks so much! I pulled plug #1. (Glad you didn't say #3) Used 1/4" extension and it goes in maybe an inch at most before touching the piston. I used a mirror to verify I wasn't just hitting the bottom ledge of the spark plug well and I could clearly see the extension was in the hole. Will proceed forward and hope to not have to beg for help again! Thanks again!

 

Turn the cam that snapped forward backwards if needed. You really don’t want to be playing the dance with turning the crank and everything else. Another tip - I had to move the back cam forward just a bit (like a tooth) to get the belt on and be in time.

 

Just to add my experience, I had the exact same thing happen with my timing belt change. And I found it very frustrating because I was being so careful. I painted my marks with white paint for all 3 sprockets. The first attempt, checked my marks all good, put the belt on, tensioner, checked my marks, pulled grenade pin and turned the crank shaft 2 revolutions. Front cam good, crankshaft good, but the rear looked like it was a tooth off. And you know it's not the easiest thing to check that rear cam right? It's a tooth behind, the sprocket mark is a tooth closer to the firewall of the car compared to the mark on the head. That's weird, I must have allowed it to turn somehow, just chalked it up to human error. So I took the belt off, moved my rear cam forward slightly so it was back on the mark. Reset my grenade pin in a vice. 2nd attempt, exact same thing happened, only I was positive my rear cam was dead on the marks before my 2 revolutions of the crank shaft. ok wtf is going on. So I did a little reading here, and went back. This time I moved my rear cam slightly forward and boom it wants to go forward like 4 teeth. So it's right on the edge of that compression release. So I moved my rear cam forward a tooth, it wants to go 4 teeth, and I moved it back counter clockwise so it was a tooth off. The paint mark on the cam was a tooth forward towards the front of the car. Put the belt on, tensioner, pulled the grenade and checked my marks. rear cam is still a tooth forward, good. Did my 2 crankshaft revolutions and all 3 sprockets are dead on the marks we are good to go.

Did 2 more sets of 2 revolutions, checking my marks again after each 2, and all marks are dead on. Whew! I watched South Main Auto video and if that guy was painting his marks, lines on cams etc you just know this can be a tricky job because he's done a ton of them and is still very careful like that.

Thank you for your post it pointed me in the right direction.

 

Happy to report everything back together and she purrs like a kitten. (Whew) Thanks for the help guys!

One little thing I'll mention here that may help someone else. I saw a couple other threads where guys were saying the new timing belt seemed too short and it wouldn't slip over the tensioner pulley, and maybe leave the pulley bolt a little loose until you slip the belt over it. I was having the same problem and then I realized the belt wasn't fully seated in the teeth on the rear sprocket. I had put a binder clip to hold the belt in place on the top and it wasn't fully seated in the sprocket teeth on the backside of the sprocket behind the clip. Once I removed the clip I was able to seat the belt fully in all the teeth and it then easily slipped over the pulley and I was able to pull the grenade pin.

I'll bet that was what caused my rear cam to get out of whack in the first place, because the first time I got the belt on but had to force it over the pulley. The belt wasn't fully seated in the rear sprocket when I turned the crank bolt two revolutions on the 1st go around and it probably jumped a tooth or two and that's how my rear cam sprocket got out of place. I was being dumb and figured the belt would pop correctly into the sprocket when I turned the crank bolt. Lesson I learned was if the belt won't easily go over the tensioner, don't force it. If it's tight like that, your belt is probably off-kilter somewhere else in the line.

 

Well I want to thank you for asking about what I really need to know and thanks to the people that help you and without knowing helped me working on a Kia with broken belt and back cam gear timing mark was to far forward and I was uncertain if I could just turn it backwards, now I know

 

Also Honda actually says in the service manual to leave the idler pulley a bit loose while installing the belt - it does help a little.

 

I commend everyone who takes this task on. I have done all the work on my Honda but this is one that I take to a mechanic. Mine is actually getting replaced today.

 

It's just a belt, what could possibly go wrong? 🤣🤣🤣

 

I've been following an interesting SAE study, where the study author postulated that these things like bolts and screws should be labelled "un-fasteners", and replaced with one-time use securing mechanisms. The car manufacturers' duty is to make things the cheapest way possible, and only provide un-fastening options when there's a chance that the manufacture or their agent (dealer) might have a need to un-fasten something during a warranty operation. Since we are getting to a point where we just swap whole components, the only un-fasteners needed are the ones that hold those components to other components. Rivets are cheaper than bolts and screws it seems, and we can teach robots to precisely place and install them for a lot less cost than screws and bolts. Especially if we have to hire humans to do that placement.


My little retirement consulting gig is focused on software for automating combined-cycle power plant operations. I started out as a mechanical engineer in manufacturing, added EE then CS to the tool belt. The chronic question is "How many people will this replace?". And the answer is always "none!". We need smarter people for all this stuff, and it only works if you maintain the rest of the components. Throughput and efficiency will go up, but body costs might stay the same but will probably increase along the way. Of course, the push to lower CO2 emissions is dooming this generation technology. States are establishing hard sunset dates for fossil generation. I certainly don't depend on the work at this point, and will be long gone by the time the last units are cycled off. I love all the technology, and still enjoy a certain amount of un-fastening stuff to maintain it.

 

As a retired millwright/machinist at both fossil and nuclear power plants, I struggled constantly with poorly designed pumps, motors, etc. next to a wall or below a tangle of pipes, Now I know you are one of “the F….g Engineers”. LOL

They decommissioned and demolished two coal plants I worked at in NJ. Sad day…

P.S. I also let others work on my cars. Just can’t get under them anymore

 

Tangent --

The Good News is that I was not one of the design engineers on these projects. I also preached that every one of those “F….g Engineers” needed to come to a site for commissioning and operations, and be a victim of their own work. So many times I'd here "... but that's the way we did it on the last five projects!". "Lessons-learned" programs for designers and design engineers are all but wasted. They bid and perform cut-and-paste "engineering", without the available time and budget to figure out that the last five sucky designs didn't work there either.

A huge port of my software engineering targets process, design, and equipment-spec fails. Manufacturing equipment, power plants, cars, are all designed "already running". The transition from cold to design operating conditions is exactly that, an exercise in off-design operation. A recent project include the guidance that I spend no time on off-design operations because the plant would be running 24/7/365. That was ignored, to their benefit. They cycle on and off daily, thanks to solar and wind capacity. Turns out that the Real World is way different from the Camelot they designed for.

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I still have the tools and the space to do my own work, or farm it out if I don't feel like doing it. It's therapy for me. Cheaper than all the couch time with a team of shrinks.

 

I had the cam sprocket rotate a little on a Honda Accord. No big deal, turned it back to the mark, and carefully installed the belt. I just did the timing belt on my 07 Pilot and I find it easier to install the tensioner AFTER installing the belt, then put in the hydraulic tensioner. The grenade pin on the Aisian sucks, but the tensioners are great.

 

I just went through a hell of a time replacing my belt. I enlisted the help of a mechanic to fix the belt (I did the disassembly and reassembly). I still don't understand why painting the marks helps (because there are already marks on the pulleys and 'back plates' or whatever they are called), but the mechanic that helped me added whiteout to the marks. I'm an educated guy (two engineering degrees and an MBA...i.e. master bullshit artist), but apparently I have no common sense. I commend you guys that can replace the belt yourselves. Despite excellent advice provided by extremely knowledgeable people on this forum, it's still magic to me how you guys line up that rear cam. That rear cam gave me nightmares. I was also a conceited bastard and thought I could remove the crank bolt with strength and cheater bars. Nope. The fatter Lisle (or generic variant) socket + an impact wrench is the ONLY way I will remove a crank bolt going forward. In 10 more years l'll be 56 and I'm not sure I will ever attempt a timing belt again, unless I have a spare car and a week to burn with trial and error. The videos and advice people give make it seem easy. But Larry Bird and Michael Jordan made stuff look easy, too 😊😁.

 

I still don't understand why painting the marks helps (because there are already marks on the pulleys and 'back plates' or whatever they are called), but the mechanic that helped me added whiteout to the marks. 😊😁.

The marks help with my 55 year old eyes! When you put that white paint sharpie on all the marks and even lines on the belt if I remember, it's just easier to see. Especially from a distance and when you are using a mirror. I have no idea what I'm going to do in another 10 years, maybe they'll make neon paint lol

 

The double-top-secret trick (don't tell anybody about this...) is getting the tension on the sections between the crank sprocket and the forward cam, then between the forward cam and the rear cam. I use Binder Clamps, the ones you use to hold paper piles together before you punch and binder-book them. They are a little stiffer than the chip clamps, plus I have a bunch of them for lots of other things. The chip clamps tend to be busy clampng, um, chips bags. Plus since they are technically under the territorial supervision of mrs dr bob, they can serve no useful purpose in the garage.

Loop the belt around the crank sprocket, maybe with a rubber band to keep it in place. Then pull it tight towards the front cam and fit it over that sprocket while verifying that the marks line up. If there's an issue, rotate the cam with a wrench (17mm IIRC) a bit clockwise of the mark, then verify the mark with the belt on after pulling gently counterclockwise on the cam with that wrench. Fit a binder clamp to hold the belt on, or use a plastic cable tie to do the same thing. Go to the rear cam and do the same thing, rotating the cam slightly clockwise to fit the belt, then pull the wrench counterclockwise with the belt fitted. Verify that the timing marks line up while you have tension on the wrench, and add the binder clamp or cable tie. You cam use a mirror or maybe your camera phone to verify the rear cam marks lineup, since there's no easy way to get your head down there by the rear cam to eliminate parallax error with the belt installed.

More: There's really no such thing as "half a tooth off". Unless you've milled the cylinder heads or the block surfaces, half-a-tooth "errors" can be traced to the crank exactly not at TDC #1, or visual errors with alignment marks. That's where a small square and a mark on the belt (or on masking tape on the belt...), combined with the mirror or cell camera, will help you confirm the alignment before you "pull the pin". If there are still questions/doubts, remember to use a wrench on the rear cam to pull it snug counterclockwise to take any slack out of the drive section of the belt, then look at the marks again to confirm alignment before you pull the tensioner pin. All belt slack will be between the rear cam gear and the crankshaft, right where the tensioner and idler will be able to take it up.

At this point, erase your belt marks or lift that masking tape, remove the clamps or cable ties, cut the rubber band if you used one, and rotate the crankshaft clockwise two revolutions to TDC #1 again. The belt is tight via the tensioner at this point, and the marks should still line up. Use new marks on the belt or masking tape again if you need them. (The old marks won't help you at this point.) If OK, rotate the crank two more revolutions and verify lineup one more time just to be sure before you start putting more pieces back on.

Virtually all belt and cam timing errors can be avoided this way. You'll find it a lot easier to fall asleep at night after doing it this way, with no nagging mistimed worries clogging your head.

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For the tech-heads:

There are two pistons at top of stroke at any 120º point from that TDC #1 mark on the crankshaft. With the crank rotated 60º (one sixth of one full rotation) from that mark in either direction, it's safe to spin the cams with no worries about valves contacting pistons. For folks who accidentally take the belt off with the cams 180º out (crankshaft at top of #1 exhaust stroke, 360º crankshaft from compression TDC #1) this may be a relatively safe way to recover without putting the belt back on, tensioning it, and rotating everything together to get everything lined up again. Turn the crankshaft that 60º counterclockwise from the #1 mark, turn the cams the 180º to align their marks, then bring the crankshaft clockwise to line up its mark again.

The very important warning about "only turn the crankshaft clockwise!" is critical while the belt is installed. Rotating the crank counterclockwise with the belt installed puts tension on the tensioner squeezing/collapsing it, and puts the slack belt section between the crank and the forward cam drive where it risks jumping teeth at the crankshaft as you turn it. Once the belt starts around a gear without seating in the cogs, the belt will be too short if you continue much, and either stretch/break the belt, damage the tensioner, or break the nose off a camshaft. None of those options sound appealing, to me anyway.

 

Dr. Bob, I'm going to print what you just wrote and stor it in the manual. Either you or some other knowledgeable gentleman told me this info in another thread. But I must have been doing something wrong, because no matter how tight I thought I had the belt around the crank, idler, front cam, and water pump, I could NOT lift the belt over the rear cam. Maybe it was because I did no move the rear cam slightly clockwise (I was scared to). I also didn't see how rotating the rear cam was going to help me out if I couldn't even lift the belt above it to attempt to get it on. Like I said, I must have been doing something wrong. So I'm going to print what you said so I can try to do this again in 10 years if we still have the vehicle. We drive it slowly (because it drinks gas). Our 2012 has 103k miles on it, and when I changed the belt the other day (actually had to put it on again with the help of a mechanic yesterday...long story) the belt looked in great shape. So I'm not going to attempt to do this again for another 10 years. I think it's recommended to change it every 7 years, but screw that, I'll roll the dice and let it go another 10 years.

 

I could NOT lift the belt over the rear cam. Maybe it was because I did no move the rear cam slightly clockwise (I was scared to). I also didn't see how rotating the rear cam was going to help me out if I couldn't even lift the belt above it to attempt to get it on. Like I said, I must have been doing something wrong.

Your problem was you had the belt over the tensioner already so not enough slack to go over rear cam.

Tensioner is the last pulley to put the belt over.

The correct order is
Crank - idler- front cam - water pump - rear cam(roll slightly forward with wrench, put on belt then roll back to correct timing mark) then over the tensioner pulley.

Check timing marks and that belt is tight between all pulleys except around the tensioner.
Pull pin.
Rotate 2x and check timing marks again.

 

I'm 66 and the last time I removed my crank bolt I used a 1/2" breaker bar with an extension pipe, and of course the socket for the crank pully.
Retorqued to 147# pounds plus 60deg. And I had a bilateral lung transplant 4 years prior...

 

I could have sworn I just had the belt around the crank, idler, front cam, water pump, and then got stuck at the crank. I moved CCW from the crank. I wasn't drunk, either 🤣 As for me not being able to remove the crank bolt manually, I don't know what to say. I guess it was the fact that the harmonic balancer holder tool was never in properly, hence it slipping out me chipping the balancer. But I was able to put all my 195lbs into it before it slipped, and I guarantee you I'm in great shape....and I was using a cheater bar. 😁

 

I just re-read the whole thread, including my own posts with the timing guidance. I noticed that I did make a few assumptions in my descriptions, specifically that folks are in fact leaving the tensioner itself or the other idler roller loose and out of the way as the belt is fitted and cam timing is verified. The rear cam gear (really a 'sprocket') has a lip on the front, plus it seems to have the most chance of valve-spring pressure turning it while you place and time the cam to the belt. So the set-up procedure still has you place the belt over the front sprocket first, then work your way counterclockwise to the rear cam and then tensioner pulley. At that rear cam gear, the belt is in fact already on the gear when you first 'test' your timing by rotating the rear cam counterclockwise with a wrench. If you are off a tooth, still easy to get the belt off of everything, move a tooth on the rear cam, place the front again.

On the first fitment, tensioner loose and rear cam pulled counterclockwise with a wrench to tension the belt some, I add tabs of masking tape with sharpie lines to the belt where it lines up with the marks on the head. Only then check that the marks on the gears line up with the marks on the belt. So long as the belt isn't moved on the crankshaft in any of the on-and-offs, the marks on the belt (tape tabs) will -always- be the target for the cam gear marks, even with the belt a little slack between cams. This way you will always be indexing the cams to the marks on the belt, with no parallax error or poor sightline issues.

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I'll confess that I tend to write for folks who think in 4D, and already understand the terminology. Guidance that's just explaining the reasoning behind some process or actual assembly procedure the audience is already familiar with. It's possible that I'll change the cam belt on our Pilot again, but age (mine) and the really low mileage we add to the car every year make that less likely. If I do, I'll set up a couple video cameras to document my relatively fail-safe cam timing & verification method.