aggravation

I'm in the process of replacing cam sprockets, I turned the crank clockwise manually to TDC and checked that the cam sprocket "V" marks lined up with the marks on the back of the rear covers....turned the crank 2 more revolutions and checked the V marks again...again they were on the money...

So I continued turning the crank clockwise until the 45 degree mark on the balancer lined up with the pointer attached to the water pump face.
I then installed the flywheel lock. Then I made a mark on each cam sprocket aligned with the groove in the back of the rear covers to show where the sprockets are when the crank is at 45 degrees.

Upon removal of the timing belt the cam sprocket rotated. I was told to continue with the sprocket replacement and then turn the cam back to where it was before removing the belt made it turn.

After installing one of the sprockets I marked it in the same place I had marked the old one and then snugged up the cam bolt and proceeded to turn the cam clockwise by way of the cam bolt....my thought was I would be able to turn the sprocket/cam back around to where it should be. What happens is it starts to turn with a bit of mechanical resistance, travels about 7 teeth then it meets more resistance as if there is contact between two moving parts inside the engine.

Maybe I'm just being a chicken but I sure don't want to be the first one to join the bent valve club and have the distinction of being the first one to do it manually with a 1/2 drive ratchet!!! Needless to say I stopped without really applying any force to it.

By the way, in case it helps the diagnosis, the same resistance can be felt turning it counter clockwise as well, pretty much the same distance turned either way from where I started it seems to 'hit something'.
Maybe I'm just feeling the cam chains starting to move the internals but I would have expected that chain to be free of slack, turning the internals right away and not able to turn relatively free before getting harder.

Please check my steps I outlined and see if I have failed to follow the proper instructions.

UKKid35

Check Wally's Pic on page 2

http://928oc.org/journal/T-belt1.pdf

This shows exactly how the cam sprocket should look at 45BTDC

If the Crank is definitely at 45BTDC you can spin the cams clockwise to your hearts content, but the valve springs are quite strong.

aggravation

Ahhh, that must be what I'm feeling, valve or valves starting to compress the spring/s
Guess I'll go give it a little bit more muscle.
I only snugged up the cam bolt, could the resistance be enough to cause the bolt to tighten? Maybe I should torque the bolt first. I hadn't done that yet because I wanted to get it in position first, now that I think about it I don't know why other than I figured I'll just have to loosen it again to set the timing with the 32V'r tool.

Also, on a related note, the hex washer under the cam bolt appeared to have a small spot of red locktite under it helping hold it to the face of the sprocket....is this factory procedure? Should I do the same?

Charley B

I'm sure you have, but I have to ask, did you remove the flywheel lock?

PorKen

You can check that you have the cam gear lined up correctly to put the belt on with the 32V'r. It has a notch for 45°, either at #1, or #6. For the most accurate results, you should check/set the timing at TDC #1, however.

Whenever you rotate the engine, you should always torque the cam bolt to spec, first.

The red paint you see is the factory mark that the bolt torque has been verified. All critical bolts had red (or yellow?) paint dabs, originally.

Kevin Michael

If it is set to 45 why would you need the flywheel lock? Also turning your cam it will meet alot of resistance as it the lobes contact the lifters. In other words, turn it and it will overcome the resistance at the point you marked it. Funny, 1st time I did it I was in the same predicament but to embarrassed to ask!
Kevin

Hilton

Don't remove the flywheel lock until you've got the belt back on and the cams secured at the right timing. Whilst some say "as long as its at 45 degrees", its nice to have the assurance that it *is* still at 45 degrees, until you're ready to start turning the crank (i.e. have belt on).

If you're changing sprockets, then you're going to have to reset the timing on them to be accurate, using something like ken's 32v'r tool. The sprockets have some leeway on them - the key is large enough around the woodruff key on the end of the camshaft that the sprocket can be 7 or 8 degrees either side of factory spec.

The mark you made on the sprocket won't be accurate until the sprocket is accurate relative to the cam (16V cars don't have this issue - their sprockets are fixed and can't be adjusted relative to the cams).

Your best bet is to:

1. Use ken's 32v'r to set the cam timing based on the sprocket (its based on a fixed position relative to the camshaft).
2. Tighten the cam bolt so the sprocket can't move relative to the cam
3. Make sure the marks you made on the sprocket line up with the notch behind (i.e. rotate the cam until the marks line up)
4. Put the belt on

*then* you can undo the flywheel lock, turn it all around by hand and do belt tension, correct any timing inaccuracies etc.

Garth S

If your 'paint mark' applied on the cam gears for the 45 BTDC crank position is 3 teeth away from the factory notch ... ignore the following However, it reads above as if the factory notch is 21 or 27 teeth away from that paint mark, depending on which way one counts. If so, here's why ....

The target 45 degree crank mark is BTDC - so to arrive at that point, it requires 1 7/8 turns from true TDC ( 45 deg before TDC). If you did it this way, the cam gear index points would be exactly 3 teeth before the backing plate reference points [ 45 BTDC = 22.5 cam degrees, and at 48 teeth/gear, each tooth =7.5 deg, so 3 teeth displacement.]

It is perfectly OK to lock the crank down the way you have described as the 45 deg mark will always leave the pistons in the same 'sweet spot' that avoids valve contact; however, doing so at one crank rotation short leaves the cam gears notch a half rotation + 3 teeth away from the point where it is much easier to visualize what is going on.

aggravation

OK, I feel stupid now!
I think the sudden increased resistance I was feeling was the woodruff key finding the limits of the play in the sprockets keyway.... since I hadn't torqued the cam bolt and since I never put in some short 5mm bolts to lock the hub and sprocket together... as I tried to advance the sprocket and cam together all I was really doing was advancing the sprocket until I felt the key stop the movement when it met the side of the sprockets keyway.

I put the 32V'r ring on there and torqued the cam bolt and was able to advance the sprocket and cam around to where my mark was.
funny thing is the valve springs are making it kind of like a mouse trap, slow and steady increase in resistance then SPROING! kind of scared me. To get it lined up to my old mark it's cocked and ready to go off if it advances much more.

EDITED to add: Wow Garth beat me to it, he answered my following question before I managed to post it! Damn the rennlist is efficient!

Also I think I'm seeing the result of not making the full 1 7/8 turns to get to 45 BTDC... after establishing TDC and checking the cam "V" marks I merely turned it until I hit the 45 mark so I guess I'm at 45 BTDC #6 instead of #1?
Ken, or anyone familiar with the 32V'r tools can you tell me if I have the rings attached correctly and if I'm right, that I should have advanced the crank another 360 degrees to put the #1 cylinder at 45 TDC?

So much to learn...so expensive to get it wrong...
I just remembered I never torqued the 3 bolts that hold the rear cover to the block so the sprocket needs to come back off!! Crap! I need a beer!

Here it is after advancing it so my mark is where it was when the belt was removed:


Here's the right side still to be replaced, it moved a bit too. You can't see it in the pic but the 'key' of the 32V'r tool is pointing toward the sprockets TDC mark just like it is on the left side.

the flyin' scotsman

What Garth said...........the 45 BTDC gives the ability to rotate the cams.

One only has to image where the pistons are at in the order of timing.

PorKen

You are at #6 -45°. That's OK for installing the gears.

The rings are on correctly. Here is what I wrote in the manual. I have to remind myself from time to time!

Garth S

Remember that crank position is always what the harmonic balancer tells you .... ( unless it was installed bassackwards ) - so if it says O/T, #1 piston is always at maximum lift: the confusion generally arises, in that to qualify as TRUE TDC, the valves on #1 must be closed on the compression/power stroke: that is where the engine timing is established, and the point at which the cam gear notch sits at the backing plate reference mark(s).
As long as you are comfortable with that, then the cams can be rotated one turn with the crank locked at 45 deg .... and that will retime the cams to the compression stroke on #1 vs. the exhaust stroke, which appears to be the case when the TB was removed. The crank doesn't care in the slightest, and that rotation of the cams gets you back to effective 45 BTDC on the compression stroke ....

aggravation

Does it matter that when I went to rotate the cam to get it back to where I was when the belt was removed I rotated it 2 times because the first time around it went past the mark? With the crank locked at 45 deg does one revolution of the cam sprocket complete the cycle of possible positions of the cam timing? It seems like the answer has to be yes but I just want to be sure.

PorKen

It's possible you could have locked the crank at #1 -45°, and now the cams are set at #6...

Where was the cam notch pointing when you took off the covers? Hindsight is 20/20, but it's good to take pics as you (I) go along, and/or use the 32V'r to verify at the start.

aggravation

Unfortunately I didn't receive the 32V'r until after I had started removing stuff. I had the covers off before I locked the crank. I turned the crank around until I had TDC on the balancer and the cam notches were also at the reference mark in the rear covers, then advanced the crank 2 more revolutions to see that the cam notches were still at the reference marks, probably even 2 more revolutions cams still lining up to their marks on the rear covers before I then turned the crank (always clockwise) only as far as necessary to get to the 45 degree mark on the balancer. Then I locked the flywheel and it hasn't been unlocked since. I then marked the cam sprockets at the mark on the rear cover so I'd know where they need to be.

Then the belt came off and the cams turned. then last night I installed a new sprocket, marked it in the same place as the old one, turned it clockwise until my mark was back at the mark on the rear cover, then turned it 360 degrees around again because it had gone just past the mark.

That was the passenger side, the driver side still sits in its just-moved-a-few-teeth position from when the belt came off. I believe it's notch was approximately at five o'clock before the belt came off which is where the other one would have been too.

So where would that put me?