Pfc. Parts

Some may have noticed I've been working on getting the timing belt tension sensor working on my '85 for the past couple of months. I've slowly worked my way through each part of the system from the top down, I finally made it all the way to the tensioner itself yesterday.

I don't know what I ultimately did to fix the problem, possibly removing the tensioner and cleaning all the contacts did the trick, but I'm now getting a solid ground on the lug with the tensioner re-installed and the belt at the correct tension, so that part is good.

The bad part is that when I took the tensioner out, the belt slipped off the passenger side cam. Not a major problem (so I thought) since I had set the crank at 0 TDC and I had placed 0 TDC marks on both cams years ago. I just re-installed the tensioner after moving the passenger side cam to the 0 mark, then tensioned the belt.

The problem arose when I spun the belt through two cycles and brought the crank to 45 TDC. The driver's side cam was perfect, the passenger side cam is so far off I can't even find the mark, I think it may be off by 180 degrees and how that could've happened baffles me.

Normally my choice would be to lock the crank at 45, remove the belt, rotate the driver's side clockwise until the 45 marks were lined up, then re-install the belt. I think that would be the correct "by the book" procedure.

What I'm wondering is if I might just release tension on the belt, slip it off the passenger side cam, rotate the cam to alignment and slip the belt back on, avoiding the time consuming process of removing the harmonic balancer and re-aligning both cams. Anyone done this? Have an opinion?

Bilal928S4

Try rotating the engine one more turn.

soontobered84

I would move the crank to 45 and then reset both cam gears to the alignment marks, then move the crank back to TDC.

Pfc. Parts

I'm sure I'll do that, however I can't see how it could possibly synchronize the cams?

I'm a bit reluctant to move the crank at all for fear of crashing a valve.

Pfc. Parts

I have the crank at 45 now with one cam synced, I just need to sync the other. I expect that's what I'll do then.

I suppose what I was worried about was spinning the cam and crashing a valve, but as long as the crank is at 45, I should be safe to turn the cams. I'm a little worried I may have already crashed a valve by turning the passenger side cam while it was out of sync with the crank.

soontobered84

You probably would have felt it if you bent a valve, unless you used the starter to turn the engine over.

soontobered84

The passenger cam is the one that snaps back while you aren't looking while fitting the timing belt. That's probably what happened. Use a wrench or socket on the large hex washer(30 or 32mm, I forget) to turn the cam back into position and hold it there while you refit that side of the timing belt. Do not use the 17mm bolt head to turn the cam gear as this can overtorque the cam bolt.

Pfc. Parts

I actually used the 17mm bolt to position that cam to 0 TDC during the initial procedure, I won't do it again. I only moved the cam maybe an inch to zero it. Would it be best to back that bolt off and re-torque it? Not sure how I would lock the cam without Ken's bump tool?

Pfc. Parts

No, I spun the crank manually.

Pfc. Parts

So I think what I'm getting is I should leave the crank at 45 where it is, re-sync the passenger side, then check timing at 0 and 45 after re-installing and tensioning the belt?

Mrmerlin

well the good news you have the crank at 45BTDC so nothing you do to the cams will result in any damage.
That said the timing mark for each cam should be 4 teeth before the hash marks.
So put the belt on with each cam positioned 4 teeth before each hash mark lines up .

NOTE if necessary zip tie the belt to the driver side cam pulley and the oil pump so the belt stays put. make sure the tensioner bolt is snugged and applying tension to the belt roller before you turn the crank.
IF you feel any resistance stop.
I would also suggest to remove the spark plugs before proceeding, this will make it easy to turn the engine by hand

Pfc. Parts

4 teeth before the mark on the back of the cam? I've never heard or done that before! What effect does it have? I've always religiously lined up the marks on the cam gear with the marks on the cam cover, never done it any other way. ????

mark kibort

why would you want to "lock" the flywheel? and why do you need to remove the harmonic balancer to do that? anyway, you don't need to lock the flywheel. just leave the engine as it is at 45Degrees BTDC and rotate the cam until you find the 45 degree mark you made. the entire reason for putting the engine at 45 degrees BTDC is so that you an move the cams without worry. If you don't have a 30mm wrench, you can use a vice grip... the large one, to clamp on the outer hex .. this makes it easy to have someone hold it in position when you are putting the other side of the belt on as it doesn't slip off like a wrench can. I have just found it convenient.

Pfc. Parts

I can't remove the idler pulley on the tensioner without removing the harmonic balancer on the crank, and I can't remove it unless the crank is locked. There isn't enough play in the belt to get it off without taking the idler out first.

I have a 30mm socket so that shouldn't be a problem.

Pfc. Parts

I should mention the belt is set up to move now, but I still need an answer concerning Stan's "4 teeth" cam timing modification.