RngTrtl

Dear all, (1985, 5.0, 32V, Auto, 928S)

I have been looking at removing my TB sensor/adjuster and checking it for proper operation. Currently my TB light is on and I need to verify that the sensor/adjuster assembly is working properly. Can I remove it with out taking off the center timing belt cover? Or do I have to remove all the belts and such to get the center cover off and then remove the sensor assembly?
Thanks to all for the help.

Jim bailey - 928 International

First the tensioner has no self adjustment(other than slightly looser when hot). Second the "sensor" is a simple contact it either has a ground or does not. Often the wire which passes through the timing cover gets broken and that eliminates the ground triggering the warning. The warning has a time delay and after a few minutes it looks for a ground signal if none is there it flashes a warning. About all you can check or fix without removing the timing belt is going to be the wire. This warning system is very basic and can give false warnings HOWEVER the consequences of ignoring it can easily be a t-belt failure with the resultant valve damage. Typical shop repair costs of say $4,000-$7,000. So do you feel lucky ?

RngTrtl

I have every intension of getting to the bottom of the reason why my TB light is on before I drive this beast for sure! I was thinking that perhaps the tensioner (I know it is a manual tensioner and all the other stuff about how it works) may just need to be removed, cleaned, rebuilt, or something of the equivalent. My biggest concern was whether I had to remove all the other stuff to get to it. I was hoping that I could just remove all necessary mounting bolts for it and get it out and ascertain its condition. I did remove the pass. side cover and distributer so that I can check the tension when the tool arrives and saw that the wire looks intact for the sensor. I just really dont feel like removing all those damn belts and was looking for a way not to do more than I needed to do. These beasts are difficult enough to work on .
Thanks for the help!

ErnestSw

If you can use a multimeter you can remove the wire from the front of the timing belt center cover and check for continuity to ground. In my case the tab broke off the wire INSIDE the timing belt cover. If your tension is good and the belt looks good and you confirm a broken connection you're pretty safe assuming it's the warning system.

RngTrtl

ErnestSw,

Its amazing that you are in Dallas. Thats where I got my 928 from off of Ebay (for 2K), next time im out there ill give you a holler. Thanks for the help, Ill try to see if it an electrical problem when the tensioner tool arrives on Friday.

Jim bailey - 928 International

You can also ground the tensioner arm with a jumper wire and see if you get a warning, if the tensioner is dry no oil you might be getting flutter at high RPM which allows the contact to be open momentarily and throw the warning but that usually does not happen if the belt tension is correct.

Garth S

Take the top right dist. cap and cam cover off and verify that the TB tension is correct: IF it is, then there is a continuity issue in the wire path Jim described. If you drain a little coolant and remove the top right hose (5-10 min), it is easier to access the center cover bolts. Usually, it will not come off - but will back away enough to see the carrier arm, the center cover pig-tail to the carrier, and the ground strap ( likely a flat copper strip on your car) from the arm pivot to the tensioner piston rod. If there is not adequate room, the whole fan assembly lifts out easily by separating the bracket to the block
With this exposed, chassis ground a multimeter and probe back from the piston rod checking for the 'beep' of continuity ..... up to the harness outside the cover.
A fractured copper strap or center cover wire is not unusual .... and saves the hassle of removing the tensioner.

RngTrtl

From the advice thus far it is looking like I am going to be removing the fan, belt, and bracket to get to the center cover to remove so that I can inspect and/or remove the tensioner. Damn, I was hoping for a easier solution...What was I thinking???

ErnestSw

The "simplest" answer is a broken wire. You'll still have to remove the center cover. Try Garth's method.

Garth S

Well .. if you have reeeealllly skinney hands, .....

Bill Ball

You need to remove the right-hand (passenger US) side TB cover. If you do not replace the belt and/or water pump, the center cover can stay on.

Find the bolt that holds the oil dipstick to this cover and remove it. Behind the dipstick, right below where the bolt was, you will see the wire lead for the low-tension warning. It plugs into the cover and has a spade on the inside of the cover. A wire from that spade goes to the tensioner arm to another wire or copper strip which make contact with the end of the tensioner plunger/shaft. If you are lucky there is a break somewhere in this part of the path. The warning is tripped by a loss of ground. So, you can check at the plug in the TB cover and if there is no ground, look for a break (wire off spade, other break).

BUT, you must check the belt tension regardless, as finding a break doesn't rule out the belt being loose too. You will need a tension check tool. Read more here:
http://members.rennlist.com/v1uhoh/checking.htm

SteveG

Didn't see any mention of when the belt was done. So if it makes you feel any better, you are doing the right thing and need to get inside the center cover (assuming it is continuity prob) to see which wire is broken or disconnected as well as to confirm everything else that the belt touches is good. If the "connector" running from the tension piston to the top of the arm is broken and is of the flat strap design, that is, not a flexible wire, specify the wire-type replacement not the flat strap when you are ordering. My belt was also of unknown age. Everything looked good, EXCEPT the pinch roller at bottom of crank had grit and did not turn as freely as it should. It was a pain opening it up, and yes, I stripped a bolt on the new water pump. But I would never have caught that roller and I just know it was going to disintegrate. If the PO was running it w/broken wires, it is not a good sign. Good Luck. Welcome to the shark tank.

Checking/changing the belt is the equivalent of the secret hand shake; it is it's own reward.