Timing belt tension.

[naasaa]

New blue timing belt. Thightened to 113 Hz at 30 BTDC.

All good! However, looking at how fare the tension adjustment bolt is sticking out from idler pulley body concerns me a bit.

Can anyone confirm if this looks OK?

 

[910Esprit]

My AC idler sticks out a similar amount

[naasaa]

16 minutes ago, 910Esprit said:

My AC idler sticks out a similar amount

Maybe I put it wrong calling it idler. I am refering to the adjustment screw for the timing belt tension pulley. 

[910Esprit]

Yes, that's true, it seems to be sticking out almost as much as the recommended 'slack' setting for belt removal.

[jtmco]

Mine is an S1 (obviously, not a turbo) and my adjustment screw goes in much farther. 
 

Does the spring fit inside the adjustment screw?  
 

Good luck figuring it out. 
 

Jim
 

 

[naasaa]

4 hours ago, jtmco said:

Mine is an S1 (obviously, not a turbo) and my adjustment screw goes in much farther. 
 

Does the spring fit inside the adjustment screw?  
 

Good luck figuring it out. 
 

Jim
 

 

You might be right.

I replaced the springs, but fail to noticing this before I placed the engine back in

 

[Gis]

I think it looks ok Lars. Mine is similar. I replaced the tensioner springs a few years ago. I remember measuring the screw distance and it was around 16-17mm out from the top irrc when I changed my last blue belt. So it looks similar to yours. 

[naasaa]

14 minutes ago, Gis said:

I think it looks ok Lars. Mine is similar. I replaced the tensioner springs a few years ago. I remember measuring the screw distance and it was around 16-17mm out from the top irrc when I changed my last blue belt. So it looks similar to yours. 

Hi Gis.

Kind of glad to hear this, as I am a bit reluctant to disassemble the engine again. Nor taking any risk  

This 84 is equipped with AC.

[910Esprit]

Its possible to remove and service the tensioner assembly leaving the cambelt in position.  (I have done this)   As long as nothing is disturbed, the belt will hold its position until the tensioner is reinstated.   As the tensioner should only be backed-out a max of 12mm, even for belt removal, I would investigate further.

NB - Mine is also an 84 with AC with recent tensioner springs and I run a lower Hz (typically 107) which would require a 'slacker' tensioner screw (My threaded portion sticks out by maybe 4mm beyond the locknut).

 

[jtmco]

To follow-up on Steve’s post, if you zip tie the belt to inlet, exhaust and auxiliary pulleys  (perhaps in two places each), the belt should not slip. 
 

Have you already turned the engine by hand?

[naasaa]

Good point with zip ties. 
yes, I have turned the engine by hand. Several times. 
The belt is tight, but I find the adjusting screw kind of far out. 
which worries me a bit. 

[910Esprit]

I suppose if its somehow the properties of the blue belt that causes it, there may be an argument for shortening the springs slightly, to ensure good engagement on the threaded screw

[Sparky]

Or (dons flak jacket) not using a blue belt?

[naasaa]

Is there any reason to suspect that the blue belt is the culprit?

Belt a bit shorter?

The belt is from SJ Sportscars, and have a similar belt at my 82 TE without any issue. (If its from same supplier?)

During this weekend I will attend it a bit further.

[Sparky]

3 hours ago, naasaa said:

Is there any reason to suspect that the blue belt is the culprit?

Not really.  It's simply something I refuse to fit.  Correct tension and whining are forever cropping up in discussions, and I'd rather check the belt and related items on a regular basis (granted, for me, a belt change is a formality).

Although a blue belt might make a minor difference, that tension adjuster is definitely out more than I'd expect.  Not much use to you now, but I always make a note of the screw position before belt removal, as it gives me a benchmark for reassembly.

[naasaa]

Not really.  It's simply something I refuse to fit. Will you please colaborate?

[Gis]

On 04/01/2023 at 20:20, Gis said:

I think it looks ok Lars. Mine is similar. I replaced the tensioner springs a few years ago. I remember measuring the screw distance and it was around 16-17mm out from the top irrc when I changed my last blue belt. So it looks similar to yours. 

Correction Lars. I found the photo. About 12mm to the top and about 6-7 threads exposed. That’s with 3 year old springs

[obi-nu]

Interesting discussion. I enquired with SJs about the blue belt when I was having mine changed recently and was told it's really for very high performance cars/ track cars and wasn't really necessary. I therefore opted for the normal black one on my S1 - especially as the belt is more visible on a non turbo.

[rgh0]

I would certainly investigate further why the tensioner adjustment screw is out so much. It looks like it is not screwed in far enough for the locking pin to be inserted.  On my S1 with the standard black belt it is in much further and when changing the belt I screw it out to fit the locking pin less than shown in the photo.

For the last 40 years I have always just used the twist method to check the belt tension but this discussion has motivated me to buy the correct tension measuring device.  I looked at second hand Burroughs ones on Ebay but most looked in poor condition and i would not have trusted their calibration. They are now made new by OTC who bought out Burroughs and new ones are not that much more expensive at A$260 than the rough looking used ones and available ex-stock next day from Amazon in Australia at least

https://www.amazon.com.au/dp/B000I198J0?psc=1&ref=ppx_yo2ov_dt_b_product_details

Always a sucker for an excuse to buy a new special tool or measuring device 😀

cheers

Rohan

[naasaa]

Thanks for allthe input.

It turns out that the plastic piston is kind of cocked  in the tension body bore, and not moving freely.

Ordered a new piston and bore from SJs.

[jtmco]

I’m glad you investigated and found the problem. Saved yourself a lot if future pain. 
 

 

[esprit22]

Obi- nu, sj's obviously failed to inform you that the blue belt (Gates) is guaranteed not to fail for a minimum of 100k, albeit time cannot be guaranteed. 

[ekwan]

On 07/01/2023 at 09:22, rgh0 said:

I would certainly investigate further why the tensioner adjustment screw is out so much. It looks like it is not screwed in far enough for the locking pin to be inserted.  On my S1 with the standard black belt it is in much further and when changing the belt I screw it out to fit the locking pin less than shown in the photo.

For the last 40 years I have always just used the twist method to check the belt tension but this discussion has motivated me to buy the correct tension measuring device.  I looked at second hand Burroughs ones on Ebay but most looked in poor condition and i would not have trusted their calibration. They are now made new by OTC who bought out Burroughs and new ones are not that much more expensive at A$260 than the rough looking used ones and available ex-stock next day from Amazon in Australia at least

https://www.amazon.com.au/dp/B000I198J0?psc=1&ref=ppx_yo2ov_dt_b_product_details

Always a sucker for an excuse to buy a new special tool or measuring device 😀

cheers

Rohan

I have been using the Facom belt tensioning tool with no issues. Alternative is the cheaper Optibelt tensioning tool.

Edited January 31, 2023 by ekwan

[obi-nu]

On 17/01/2023 at 22:00, esprit22 said:

Obi- nu, sj's obviously failed to inform you that the blue belt (Gates) is guaranteed not to fail for a minimum of 100k, albeit time cannot be guaranteed. 

Interesting to know, thanks. I think SJs recognise S1 owners are unlikely to get anywhere near 100k in a given period before the time factor is again a potential issue hence the advice given.