JHowell37

In anticipation of frenzy11 I decided last night to check the tension on my timing belt for the first time. So I took of the timing cover and put the tool on the belt and it comes out perfect. I turn the crank a 1/4 turn and check again, and its perfect. I repeat this motion several times, and every time it comes out perfect. I don't drive it too hard, but I'm not driving Miss Daisy either. Let me say this now before anyone asks. I DID NOT touch the tensioner bolt at all. If something looks good, I don't mess with a good thing. So I button it back up, and take it for a drive and a half mile out, the tension light comes on. First time I've seen it since I bought the car. I stopped and had a brief look and nothing seemed out of place. So I got back in, started it up and the light went out. It came back about two miles later. Shut of the engine and immediately restarted it. No tension light for another 2-3 miles. And then it's back. WTF is going on here? It's an '85 32-valve car BTW.

Here are my guesses.
1. When I took the cover off and then reinstalled it, something got jarred in the connection to the tensioner warning wire, and it's acting weird now.
2. Perhaps it's always had enough play to trip the warning but after shifting things around last night, it's making contact to activate it.
3. Maybe I should bite the bullet and get rid of the **** factory tensioner which really doesn't work anyway and stop playing the guessing games.

The belt looked to be in excellent condition. I'm still coming out though.

Tampa 928s

Check you electrical connection on the TBT if it dials in Ok you worked something loose. Move it around after you start it see if the light goes on.

Bill Ball

Check the wire from the cover to the spade on the tensioner arm. It can come off it you look at it the wrong way. I'll bet that's it or the other wire connection on the outside of the cover plug. Also, I have seen the wire break off the other side of the plug on the inside of the cover. That can be repaired with some solder.

Garth S

The quick check is to pull off the alarm wire connector on the center cover ... and check for continuity between the male connector and chassis ground: if there is a break ( no continuity), there is a 95%+ chance something is disconnected on the inside, for you had just confirmed the TB tension to be OK.

BTW, TB tension is best set at TDC .... and another two revolutions to recheck at the same spot. Anywhere in between ( like 1/4 turn) may leave one with differing valve spring pressure fighting against the TB.

Imo000

The factory tensioner is not really all that bad. Also, there is a coupe minutes delay in the system. So every time you start the car, the delay to check the tension warning circuit is re set. That’s why you didn’t see the warning light right away after a re start. Either (probably) the wire under the cover is damaged or disconnected. Since obviously it’s a false warning and you checked the T-belt tension and know it’s good, just drive it until you have time to find the problem.

dr bob

Just a reminder-- The belt tension is checked at TDC on #1 cylinder ONLY. No other position on the crank and cams should be used. If it comes out perfect every time at random crank positions 90 degrees apart, your technique with the tool is also suspect.

If nothing was changed as far as adjustment, and it didn't alarm before but does now, look at the tensioer arm wire, the connection to the arm (screw with a spade lug), the connection on the back of the pass through on the center cover, the pass-through itself in the TB cover, and the connection where the harness wire plugs into the cover pass-through. FWIW, the original wire between the arm and the pass-through was pretty crispy on mine after only 75k and 17 years. So it was replaced with a new part just to make sure. If your wire was as tired as mine was, it's quite possible that it's either broken inside the insulation or broken with the insulation. You can check the circuit easily with an ohm meter while the pass side TB cover is off.

layton108

is this by any chance the red light with an exclamation point on it???

perrys4

on my car it is a dashed belt line that moves around circles. No doubt about what it is.

layton108

hmmmm cuz that light i mentioned goes on everytime i turn my car on however there is a same red light on the center console which is a button also.... i hit the button and both lights go off...its weird i wonder what that is?

Lizard928

I would like for anyone who says this to explain as to WHY they say this.

The belt system in this car isnt rocket science, and the gears are all made to the same size, having the car at 0 deg with the cyl at TDC is just going to insure that the cam lobes are not pushing on the belt, but other lobes will be. I have checked alot of belts and it doesnt matter if they are at TDC or not, the readings are always the same.

unless someone has a real good answer, lets stop all of the old wives tales.

heinrich

LOL Lizard. Here's why it is said: The crank always holds the lower part of the belt the same. But the cams both push the belt forward at certain points of rotation and always don't - at other points of rotation. Along with this spring pressure, compression will push the cams forward. Believe me I have had a cam jump and it scary.


While it may not make much difference, it also may. Yes?
Heinrich

perrys4

Knowing Dr. Bob and the fact that he only speaks what he is 100% sure of, he gets my vote.

dr bob

It is exactly as Heinrich describes. The 'total tension' on the belt is the same no matter what the position of the crankshaft is. But we measure tension on the section essentailly between the crank and the passenger side cam. In normal rotation this is the slack area. At TDC on number one, the cams are in one particular position with some springs pushing the cams forward and others pushing it back. The tension measurement depends on having the right springs in the correct cams pushing to establish a particular tension on the slack side. While it's quite possible that tension on the slack section is similar at several different positions, doing the test at TDC on cylinder one guarantees that the result is consistent, accurate, and repeatable.

I'll speculate that the factory made the 'tension only at TDC' requirement on purpose. For one, it allows tension to be set after the belt is replaced but before the engine is rotated following initial timing setup. Nice if you want to avoid the cam jumping under changes in where the load is applied to the various sections of the belt.

Lizard928

I dont see that there is enough of a change from the valve springs on the cam at different locations to cause a massive change in belt pressure.

If someone has the factory P9201 or the kempt tool, take pics and try it every 3rd tooth, or even every 10th tooth, I would put money on the fact that there will be ZERO noticable change in belt tension.
I just do not see that the valve springs have the force to change the tension at how tight these belts normally run.
And yes I have done a few timing belts and have moved the cams with a wrench to set them, so I know how much force the valve springs produce.

dr bob

Doesn't need to be a 'massive' change to be different. "Massive" is a somewhat subjective amount of change I think, and that drives the point. Do it in the same place on the belt, with the crank at the same location every time, and the results should be identical. Screw with where it is in the rotation, and it may very likely be "close". Is "close" good enough? How "close" is "close", really? And of course the next question would ask why you would settle for "close" when all you need to do is put the engine at #1 TDC, and at lerast have the chance to get identical results --every time--.

When somebody posts that they are having problems with inconsistent results from inconsistent methods, early on the list should be something like 'remove as many method inconsistencies as you can and see if the results become more consistent'. There's a scientific method buried in there someplace.