smyth1

in the midst of changing dist caps and rotors.i can see the tb through the vent tubes.can the condition or proper tension be determined visually through there?doesnt look cracked or dryrotted.i do plan on replacing it but had an unexpected tras replacement to do so won't get to it for a bit.thanks.

Landseer

Typically you can't see much that way.

Better to pull the inspection cover on the passenger side and that will give a better visual of the belt tracking, its forward facing edge, and its tightness.

Now is the time to look, with the distrib cap off.

SteveG

You can't check tension by looking at the top of the belt. And you can't get a visual on the condition of the cam gears either. You can see if the cams are timed properly; "close enough for jazz" as they say.

PorKen

'86-up have the large notch on the front of the gear with matching nub in the TB breather tube (tubes are also moved closer towards the radiator).

Early '85 have 16V style breathers where the front of the gear is unseen. Late '85 is updated on the 5-8 side, only.


Late '85:

Landseer

^^^^, I looked at the early 85 for the marks until I went cross-eyed. Never found them! And that's why.

namasgt

If you don’t know the status of your timing belt change it with a new Gates or Porsche one. Its not fun when a timing belt breaks on a 32 valve 928, lots of work to fix once the belt breaks and valves get bend from hitting the pistons.

M. Requin

there will be a ton of replies on this one, and almost all will be to the effect that you need to do the drill, well documented here, on properly servicing the belt. Fuel lines and if you have an auto flex plate service are also critical. By critical I mean critical, and you've been around here long enough I hope to know just what I mean.

Tails

Smithy1,

As indicated in the previous posts you cannot determine the actual condition of the belt visually via the vent holes in the camshaft drive belt covers.

In post #4 by PorKen you can actually check the timing mark on the camshaft drive gears visually on MY86 and upwards.

Chris has indicated what should be done in his post #2.

It is a good idea when you post to nominate what model 928 you have, as the more information you give the better the replies and assistance that can be given.

It is suggested/recommended that the timing belt be inspected fully at each yearly service by the removal of the left hand side timing belt cover, rotate the engine clockwise via the camshaft forward bolt heard (easy to do if the spark plugs are removed first), check the tension of the belt with a tension tool, check the tensioner for oil leakage or a cracked rubber boot, check all the tensioner and guide rollers, check the tracking of the belt and also the condition of the camshaft drive gear teeth for wear of the case hardening and sharp edges etc, and check the tension of the camshaft drive gear securing nut as they are known to come loose.

There is also a Porsch Technical Faullt Finding Bulletin that has a flow chart to check the camshaft shart drive belt "slack" alarm.

Tails 1990 928S4 Auto

You can also get a good indication of the tracking of the belt on MY86 upwards whilst viewing the belt when the engine is idling and you can also a very general idear of the condition of the belt from view the area of the belt you can see as it passes under the vent holes.

jon928se

Thats not strictly true. You can certainly tell that the reason the 928 won't run at all is because only black dust or no belt at all is visible.

riviera455

those are not inspection holes,,they are vent holes.