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I'm wondering if I do in fact actually NEED a timing belt tensioner spring.
IF I'm interpreting the instructions in the (G100, assumed to be applicable to G11) workshop manual correctly, you slacken the tensioner pulley locking bolt so the tensioner spring sets the belt tension, then you tighten it off again, so the spring does not in fact continuously apply tension to the belt while the engine is in operation, as I had assumed. Its just used to set the tension initially.
IF this is the case, since any re-purposed spring I've come up with so far seems to be heftier than the original item. I might be better off just using finger pressure to set the tension.
Of course I'll be guessing at the finger pressure, but that might be less risky {and much easier) than guessing at a spring pressure and then trying to reproduce it.
Heres a discussion of a different {but, from the photo. broadly similar) car system, which seems to support this view.
geometroforum.com/timing-belt-tensioner-spring-t31...c
Edited by edlithgow on 13/07/2023 at 14:53
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Ed, I know this sounds harsh but I think it's maybe time to say goodbye to this old girl, imho opinion she's reached the end of the road, there's only so much make do and mend you can do.
Let's be honest the chances of it ever running again ( properly and reliably) are slim at best, the plug repair will fail as soon as you attempt a start, the head gasket will almost certainly leak like a sieve, ( I won't comment on the ruined bore!).
I know you post your trials and tribulations in a light hearted way and they do give us all a giggle, I particularly love your uses of sunflower oil for almost everything.
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Noooooo it’s my favourite car on the forum! Keep it going Ed, I greatly admire your make do and mend attitude.
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Ed, I know this sounds harsh but I think it's maybe time to say goodbye to this old girl, imho opinion she's reached the end of the road, there's only so much make do and mend you can do.
Let's be honest the chances of it ever running again ( properly and reliably) are slim at best, the plug repair will fail as soon as you attempt a start, the head gasket will almost certainly leak like a sieve, ( I won't comment on the ruined bore!).
I know you post your trials and tribulations in a light hearted way and they do give us all a giggle, I particularly love your uses of sunflower oil for almost everything.
I appreciate that this is dragging on and may be becoming a bit tedious for y’all, but after all, the titles give fair warning of the content so you can avoid according to taste.
Im tempted also to suggest that perhaps the issues encountered are a bit more “old school fundamental” than your average fault codery, though it isnt any kind of mission.
I will suggest that it MIGHT be time to give up when your plausible dire predictions come true, but not before.
(Im not too bothered about the bores, having seen a lot worse work fine. Plug and HG Im less sanguine about, but theres only one way to find out)
Edited by edlithgow on 14/07/2023 at 06:12
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Re “The head gasket will probably leak like a seive” I suppose this comment may be prompted by my use of constant angle rather than constant torque, with lubricated head bolts, and by thevariation in observed torque between the bolts.
I didnt expect this variation to be quite so great (though some interaction between head bolts is expected ) and it does bother me a bit.
Im not reverting to the “clean and dry” spec, butt still have the option to apply a constant torque (say 30 ft-lbs, the highest attained at constant angle) though it would feel a bit of a copout
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Ed, I know this sounds harsh but I think it's maybe time to say goodbye to this old girl, imho opinion she's reached the end of the road, there's only so much make do and mend you can do.
Let's be honest the chances of it ever running again ( properly and reliably) are slim at best, the plug repair will fail as soon as you attempt a start, the head gasket will almost certainly leak like a sieve, ( I won't comment on the ruined bore!).
I know you post your trials and tribulations in a light hearted way and they do give us all a giggle, I particularly love your uses of sunflower oil for almost everything.
While this conclusion, based on the loss of an unobtanium part that apparently I dont need, doesnt appear to make much sense, it would be reasonable in the case of the loss of an unobtanium part that I DO need, which would be a show stopper.
Like, say, the cam sprocket bolt.
Which I've lost.
I'd guess I probably lost it when I was turning the car upside down looking for the tensioner spring that I apparently didn't need, ironic idiocy stylee.
However, although it appears to be unobtainium as a specific part, its just, like, a bolt, so there might be some hope of sourcing say a grade 8 bolt and thick washer that would do the job.
I'll need to somehow measure the thread pitch of the blind hole in the end of the camshaft, probably by taking an impression in some way.
How much clearance would be typically allowed between the end of the bolt and the bottom of the hole?
Any other gotchas? From a bit of poking around, bolt head clearance seems to be an issue on a lot of cars, but I dont recall this seeming especially shallow
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Ed, as a first guess, if you measure the diameter of the hole in the sprocket that should give you the bolt diameter, stick a pencil in the hole to find the depth and then you have an idea of the size and length, if you can get bolts of that type there can't be many thread options (assumed to be metric rather than UNC or UNF) and careful trial may decide which.
Good luck!
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Ed, as a first guess, if you measure the diameter of the hole in the sprocket that should give you the bolt diameter, stick a pencil in the hole to find the depth and then you have an idea of the size and length, if you can get bolts of that type there can't be many thread options (assumed to be metric rather than UNC or UNF) and careful trial may decide which.
Good luck!
Thanks
I think it may be JIS (Japan Industrial Standard) which is almost-but-unfortunately-not-exactly metric.
(I suspect we are likely to achieve interstellar travel before we manage to standardise stuff like this, but its an old car so there may have been some East meets West progress since it was built, though this wouldn't necessarily be good news for me)
There is a table of bolt sizes, grades and torque ranges in the (probably) relevant manuals, but for 8 mm (which is the hole diameter) the highest grade listed (7T) has a lower torque range than that specified for this bolt, so it may be something special.
I'd guess its likely to be a fine thread, since they are stronger and more vibration resistant according to Wickipedia.
I havn't managed to loose the crank pulley bolt yet, which MAY be a larger version of the cam bolt (visually it looked like one as far as I can remember) with a flange on the head and a similarly super-thick washer.
I could take this around the bolt emporia as a pattern, though that might cause more confusion than its worth.
Edited by edlithgow on 21/07/2023 at 05:40
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Like 1DCGUY says in your link:
toss it away .... and just a very light push down to tension the belt.
I'd add, a good bit tighter than the auxilliary belt (IME).
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You dont HAVE to “toss them away” (and the only reason for doing so AFAICT, would be so you can run a higher tension than the spring would provide/allow, which doesnt seem a good idea to me)
They ESCAPE.
2 solid days of searching and no findee. THINGS ARE EVIL.
Best guess is one of the EVIL hooks in both the EVIL ends of the EVIL b***** thing caught in clothing and carried it FAR, FAR AWAY.
Or its lurking biding its time until its all buttoned up.
Anyway, you seem to agree that its possible to do without it, which is reassuring, thanks, though assuming thats true ill still have to guess at the appropriate belt tension, for which Im ill equipped.
Edited by edlithgow on 14/07/2023 at 06:15
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You dont HAVE to “toss them away” (and the only reason for doing so AFAICT, would be so you can run a higher tension than the spring would provide/allow, which doesnt seem a good idea to me) They ESCAPE. 2 solid days of searching and no findee. THINGS ARE EVIL. Best guess is one of the EVIL hooks in both the EVIL ends of the EVIL b***** thing caught in clothing and carried it FAR, FAR AWAY. Or its lurking biding its time until its all buttoned up. Anyway, you seem to agree that its possible to do without it, which is reassuring, thanks, though assuming thats true ill still have to guess at the appropriate belt tension, for which Im ill equipped.
If you tighten the belt to 1/2 inch deflection at the middle of its longest point, that should be enough, go too tight and may cause it to be noisy, ie it may what I call moan at the tensioner bearing. which used to happen a lot
or anywhere between 1/2" and 1/4 preferably closer to 1/2" deflection should be ok, over that is too loose and may slip-or timing may be out
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Thanks. I think ive seen that rule of thumb mentioned elsewhere on’t internyet, though it isnt much discussed and its good to have it confirmed.
It also seems they are pretty tolerant of looseness, which isnt all that surprising, since, if they don’t tension automatically and continuously, they must loosen off some during the service life of the belt.
I wonder if that might in fact be a determinant of the service life. Overtightening, OTOH, is likely to cause bearing failure, particularly in camshafts.
Im reminded of my Lada which had a manual timing chain tensioner. Lack of this 1 minute job apparently killed a lot of them. Id guess it worked in a similar way, but the bolt was accessible without dismantling.
Edited by edlithgow on 15/07/2023 at 03:51
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I wonder if that might in fact be a determinant of the service life. Overtightening, OTOH, is likely to cause bearing failure, particularly in camshafts.
the cambelt if over tightened, usually cause tensioner bearing failure before camshaft bearing, but you can normally hear the bearing moan when engine started and revved, though how loud they complain depends how overtightened they are
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ill still have to guess at the appropriate belt tension, for which Im ill equipped.
All you have to do is lever the tensioner till the belt is at 1/2" deflection at longest part, or quarter turn iirc, which should be adequate, used to do it all the time where no tensioner gauge was available, never had any problems unless you tighten too much which will soon be apparent, they get noisy
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