Aaaaargh.

Keith Tanner said:

Streetwiseguy said:

I'm just going to state the bleedin obvious here for others, to help avoid this situation.

You should always roll an engine over to get everything in time, and make sure you understand the timing marks before you take  it apart.

I state this  from personal experience, including a Subaru with the fake timing marks once...

I did roll it over about three times. My mistake was not realizing that the cast-in arrow on the crank pulley was not a timing mark and that the factory manual does not provide this information. In fact, the manual (at least the portion I was using) seems more interested in making sure you can properly put Sharpie marks on the belt than anything else. I was using the timing belt R&R instructions, it's possible there's another set in the manual that is written for when you're building up an engine from scratch.

Again, I think the root cause was the fact that I was addressing the engine from below instead of above which is an artifact of the engine swap. From what I remember, the secret mark is much more obvious (ie, actually visible) from above. On the cam gears, the real timing marks are on the front of the gears but on the crank they're not.

I'll see how quickly I can rectify this tonight. 

Bolded the important line.

People who do that on Miatas are people who don't read the manual :) You can disassemble one of those without having to mark anything. Silly me, I thought the same would apply to the Subaru and of course the last time I put this belt on I was starting from a bare block. So it was perfectly reasonable to expect I could do it again. I guess the secret marks weren't memorable enough.

The factory R&R procedure talks about marking the belt if the factory marks are gone. On my 250 mile belt, they were not.  I'm going to double check but I'm almost positive the secret marks are not referenced, so using the cast arrow on the crank seems a reasonable assumption. 
 

I wonder how many times you'd have to rotate the engine to get the belt marks lined up again. Lowest common denominator of the number of teeth on the belt and the number on the crank pulley. 

K

The new motor feels great. The van will cruise at 80 mph and has acceleration to spare...

Wait, this part doesn't sound right.  Normally Aspirated?  Are you sure it's a Subaru engine?

Hey, you've gotta remember where it started :) It's not exactly doing wheelstands but I can accelerate at 80 mph. I didn't get it over a ton but it did hit 90 at least once when I wasn't paying attention. Takes surprisingly little throttle to maintain 80. I think it's because it's right in the fat part of the torque curve there.

So I was wrong. The secret mark is visible in the manual if you realize that's what it is. I interpreted this as the mark that should be on the belt, which was still there. Note the clear arrow on the cam gear which does not align with the timing mark (seriously, why?) but no arrow on the crank.

Here's the only other reference to it. They didn't even draw the trigger wheel that the mark is on.

So I thought I did understand the timing marks. I checked the manual many times, I was in there with a mirror and a flashlight, I rotated it a number of times to see if it would come back to the starting position but realized that would take quite a few turns if I was lucky and a very large number if I wasn't.

From a manufacturing standpoint a cast mark would be imprecise on a gear with machined teeth and a keyway.  Now it it were a stamped or cut arrow that's a different story.  Timing marks will be machined in relation to a key. 

Except for the stupid timing gears that don't have a key.  

I have to admit to spending a few minutes on Utube before my first Subaru timing adventure.  That arrow threw me for a loop too.

A timing mark only has to be accurate to one tooth.  Well within the range of accuracy for casting and that's how Mazda does it. The one in the trigger wheel might be cast but stamped makes more sense.

When given the choice, I prefer factory manual to randos on YouTube. Serves me right.

The arrow on the sprocket is what any sane human would assume. Key word being assume.

I hate it when manufacturers play silly-buggers like this.

Ford Y-blocks have a mark on both timing gears but you don't line the marks up. You count the number of links between the marks, 12 if memory serves.

Bloody stupid.

I think some of the 'timing marks' on newer engines are simply 'left overs' from days gone by. A case in point would be the 'timing marks' on mid-late '90s GM 4.3 V6 engines. Said T marks have no use what-so-ever when comes to setting the ign timing.

Happens to us all. Glad the consequences were minor.

So like, what's that arrow even for?

It's apparently a TDC indicator for, umm, when you need to know where TDC is. Although maybe something like Right Dead Center would be more appropriate for a boxer.

I think the arrow is for doing certain services where you want the pistons to be down.  Maybe.

Not all engines are timed at TDC.  You can get in trouble if you set the crank to TDC and assume that the cams have to line up.  One example I can think of is Volvo,  because in the past twelve months I think I set up the cam belt about a dozen times (no exaggeration, may be low actually) on mine.  The mark on the crank is something like 15 degrees off of TDC #1, so if the cams move you don't bend a valve when trying to sort it out.

I know there are some engines that are timed at 90 degrees from DC.  Can't remember which.  Might even be Subaru.  You don't line up marks on the pulleys to the back, you line up marks on the pulleys to lines on the belt.

The Mazda B6/BP engine has a little bit of spring tension on the intake cam at TDC. Enough that people have been accidentally timing them one tooth off for at least 30 years because the cam will move if you don't pay attention :) It is the source of many YouTube videos and workarounds. Had Mazda timed it a few degrees off, there would be a lot fewer people counting teeth on their timing belts.

If that arrow is TDC, then the Subaru engine is indeed timed at 90 degrees off.

Pete. (l33t FS) said:

I think the arrow is for doing certain services where you want the pistons to be down.  Maybe.

 

Not all engines are timed at TDC.  You can get in trouble if you set the crank to TDC and assume that the cams have to line up.  One example I can think of is Volvo,  because in the past twelve months I think I set up the cam belt about a dozen times (no exaggeration, may be low actually) on mine.  The mark on the crank is something like 15 degrees off of TDC #1, so if the cams move you don't bend a valve when trying to sort it out.

I know there are some engines that are timed at 90 degrees from DC.  Can't remember which.  Might even be Subaru.  You don't line up marks on the pulleys to the back, you line up marks on the pulleys to lines on the belt.

On the five cylinders, the cams will just sit there quite nicely, too.  The four's don't, and they are kind of a pain in the ass.

In reply to Streetwiseguy :

My main experience with the fives is with dual variable cam timing, so you make marks from the belt to the cam sprockets and transfer the marks to the new belt, unless you need to change the seals, in which case you spend three hours accessing the back of the engine so you can put the cam alignment tool on.  On the fours, it's real EASY to put the lock tool on, of course, because you don't really need it due to the fixed pulleys.  (IIRC the four was only sold here in the NEDCAR S40, which did not have an engine mount bolted to the back of the head, so you only need to remove the turbo's charge pipe.  Not the chassis crossbrace and motor mount and airbox and turbo inlet pipe and the FU bracket that is on press fit dowel pins...)

For the anti-DIY marks crowd.  Volvo cam sprockets, with variable cam timing, do not HAVE factory marks.  The sprockets/VVT hubs have no keyway on the cam, and they have no "home" position - with no oil in them, they will freely flop around about 40-50 degrees.  The factory procedure is somewhat involved with preloading them thisaway, tightening the center bolt, then double checking how they line up by loosening three perimeter bolts and shifting the pulley on the outer hub, like an aftermarket adjustable cam gear.

Then, per the service manual, after it is set correctly, you're supposed to make your own marks with a marker, so the next time you have to do a timing belt, you just make marks on the belt and line them up... 

Pete. (l33t FS) said:

In reply to Streetwiseguy :

My main experience with the fives is with dual variable cam timing, so you make marks from the belt to the cam sprockets and transfer the marks to the new belt, unless you need to change the seals, in which case you spend three hours accessing the back of the engine so you can put the cam alignment tool on

I have a phaser pulley coming today for a 5.

Have you ever read the instructions for timing the pulleys on a six cylinder?  My brain starts to lock up, and I have better than average reading skills. I just lock the engine down with the belt still on, then take the belt off and figure out where I am in the travel of the phaser.

Also, if you look closely enough, there is a tiny mark on the original phaser pulley that lines up with the slots on the top cover.  New ones don't have one, and you don't have to use the marks, but they are there...

Best idea I've ever seen is to leave the belt on the engine but split it down the middle with a knife.

Take the outer half of the belt off and start the new belt on.

Cut the last half of the old belt, remove it and push the new one onto the sprockets all the way.

No locking or figuring needed.

Problem with that is the lifetime of cam/crank seals and the lifetime of the belt. On the Miata, the front crank seal lasts approximately 50% longer than a belt change interval. Which means you'll think you got away with something for about 30,000 miles. 

That's a great idea ShawnG. Thanks for mentioning it.

In reply to FMB42 :

I can't take credit, I watched Fuzz Townsend do it on a TV show and it was one of those "why didn't I think of that?" moments. Seems so obvious now.