So need some opinions here. The light is coming on for the TBelt on my 86.5 with about 65k miles. The TBelt is almost 2 years old and maybe 8k miles on it, all the rollers and everything were replaced and the tensioner rebuilt at the time. The light came on a couple of weeks ago and I brought it in to have it tensioned, they set it to 5 bar and and looked into the TBelt warning circuit and couldn't find any issues. It was never re-tensioned after the new belt was put on, I bought it a couple months ago. All was good since then till yesterday when the light came back on, I could swear it comes on after hard acceleration. It goes off after I shut it down and then will eventually come back on.

So should I not worry about it and just disable the circuit, or should I worry about it. Is there a fix for this?

 

I wouldn't ignor it. How long after it was re-tensioned did this business start? A new belt needs to be retensioned around 1500, but you were way past that. You think it comes on after hard accel. I would make it my business to know exactly. Does it come on 2.5 to 3 minutes after starting? That would indicate a continuity problem. I would get a Kempf tool and check it myself; most of us do our own work as we don't want to have the negotiation w/a shop over a re-built engine. Good luck.

 

Bleed and refill the tensioner with oil. I had the same experience, reset the tension twice and only after servicing the tensioner stopped the repeat of the light coming on.

Goog luck

 

It was just rentensioned two weeks ago by a trustworthy mechanic. A guy that worked on the preperation of the Holbert car for the record run.

Sometimes it comes on after 3 minutes or so, sometimes it takes while.

The tensioner was rebuilt when the belt was changed.

 

tensioner may not be flush against the block and fluid has leaked out, under heavy load the tensioner may be giving a hair and setting the light off....

 

https://rennlist.com/forums/showthre...ht=timing+belt

Your description sounds familiar. Maybe the above will help.

 

Bill Ball and I chased this for quite a few hours on my car, which is an 85 with about 10k on the T Belt.

Remove the left timing belt cover and loosen the lowest bolt on the center cover. Remove the sensor plug and check for continuity to ground on the plug connector in the cover while moving the center cover in and out. What happened to me is that the center cover rubs against the spade connector and causes an intermittent connection, even though the spade appears to be well seated and tests well when the engine is not running. If you find evidence of this just remove the connector and recrimp the spade and re-attach. The male end of the connector can be re-oriented via an allen bolt just below the connector in order to minimize the chances of this re-occuring.

 

I believe that the timing belt warning will not come on for three minutes even if it is so loose you could tie knots in it. There is a delay built into the system. DO NOT IGNORE OR DIABLE THIS WARNING! Something is amiss.

 

What zekgb said. I think* the 86.5 has the copper strip that goes from the idler carrier arm to the tensioner pin. I just did this on the 85 I am working on. I took the stupid thing off and replaced with a copper copper wire. I didn't have to remove anything other than the copper strip which looked broken. As stated, the warning system works off of a ground. You can check the path with a multi meter. Its a simple set up and usually gives the issue you are speaking of.

 

There is a 3-minute delay after starting the car, after that it is instant.

The initial delay is there because the stock (de)tensioner cannot compensate for a very cold engine, so the belt is loose for a short time until the engine heats up to at least the temperature when the belt tension was set!

 

I'll have to dig into the wire then. Haven't pulled that cover before, it does't look like the 3 minute task it is for pulling the cover on my 968.

Thanks

 

I just had this on my car as well 2 yr old belt and about 12 K miles the belt was retightened at 1500 miles then again at SATl 07 . Was good for a year or so, the belt light came on again so i replaced the belt and the tensioner bushings,. I removed the dark grey ones and installed the tan colored bushing (The tensioner pivot arm had just the slightest amount of side to side play) so we will see how this works.
My suggestion for you is to check the continuity as Bill B suggests and then have the tensioner filled with some STP oil treatment,
This will take some time, get the biggest bottle of visense that you can find , about a 2 oz I think, remove the tip of the bottle and drill it so the hole is slightly bigger fill the bottle with STP, remove both of the bleeder screws, and place a few rags under the tensioner, begin filling the bleeder from the outer most hole away from the crank the old oil will start dripping from the tensioner as you put in the new.
it seems to be heavier that the old oil so it flows out the other hole , plane on spending about 40 mins to flush out the old oil as you have to let the new stuff sit for a while a few mins so the old stuff rises. The STP being thicker seems to not leak out like the lighter viscous oils do and since it a liquid it still transfers the engine heat to the Bi Metallic washers

 

Only 2 bolts hold the right side cover on, but there is some other crap in the way. You can maneuver the cover around the other crap (coolant hoses, etc.) after you remove the distributor cap. Best to remove the rotor too (note position) for more clearance and sometimes you will have to loosen the coil and slide it forward as well. There may be a plug wire spacer mounted on a bracket on the side cover as well that will need to be removed.

To get a better look at the sensor wire behind the right edge of the center cover, loosen several of the center cover bolts, particularly the one that is hidden from view on the far right edge at the top of the tensioner. You'll be able to feel the bolt head (13mm). Loosen that and a few more of the center cover bolts and remove the small bolt that holds the upper dipstick bracket so you can swing the dipstick out of the way too. Pull the right edge of the center cover forward and you will see the wire Kevin mentioned and a good portion of the copper strip Keith mentioned that runs down the right face of the tensioner arm. The copper strip can fracture, so there is an updated flexible wire, as Keith mentioned, but you'll need to pull things further apart if that needs replacing.

Anyway, you can test continuity of the plug on the center cover through that wire to the arm and ground. In Kevin's car the trick he found to expose the problem was to check the Ohm value while wiggling the wire or moving the cover. Although the wire clip was affixed to the spade, we did not initially appreciate that it was loose and would lose continuity briefly when wiggled. Just testing continuity statically did not show the problem and led to a lot of head scratching and wasted time doing other things that did not resolve the intermittent warning he was seeing despite verified good belt tension.