Hello guys

 

I was in a road trip with friends when suddenly  the battery light came up, it is a new alternator with less than 20k km on it so what could be? when i open the hod, i see the belt out of its place and a belt tensioner misplaced, i pick it up and saw this:

 

It was a Sunday, and i had to go back to home... i did 140 or something on battery alone,

Once in home i did remove the broken screw and replace it with a better grade steel (the one broken was the factory one.

 

I did 3 road trips more, and yesterday i was 270km away from home and when returning, the battery light came up again....

 

i said, no!, again?

 

when i lift up the hood, the same situation, and yes, a broken screw...

i drive 240kms back to home with battery..., yes, incredible.

 

What is going on with that screw?

 

the belt is a 6pk1100, it is the right one, i was thinking about using a bigger one maybe 6pk1110, may be to loose some tension, but i dont think that is the reason,

 

someone told me that if the screw is not tight enough could get broken and if it too much tight, could be broken too...

 

i need help with that

Sounds like something could be suddenly jamming up causing the belt to put a shock load onto the tensioner. Or there could be excessive vibration of the tensioner which is causing the bolt to weaken and snap. Maybe the new alternator is causing it as I think they have some kind of clutched pulley on them? Could even be A/C compressor related if it has A/C.

 

Someone else had a similar thing here....

 

https://www.briskoda.net/forums/topic/490289-auxiliary-belt-tensioner-repeated-breakages/

 

 

Edited 15 February, 20224 yr by TMB

Replace the entire tensioner assembly.

1 hour ago, sepulchrave said:

Replace the entire tensioner assembly.

But i got that one new from the house 9 months ago.

How much (if at all) does the crank pulley bolt oscillate while the engine is running? 

1 minute ago, Pete_Ex-Wino said:

How much (if at all) does the crank pulley bolt oscillate while the engine is running? 

I have measured that. 

The pulley oscilate +- 5mm

Just now, Kharl said:

I have measured that. 

The pulley oscilate +- 5mm

 

Blimey!

 

There's your problem.

Replace the whole tensioner and not just the bolt and above all replace the alternator pulley sprag clutch, it is this that is causing the problem.

 

Well that is not actually true, the problem is the acceleration/decellerations at idling speed and the inertia of the heavy alternator, without the one way clutch the belt will be snapping backwards and on the tensioner.

 

It sounds like either the bearing was not checked/replaced with the alternator or my money is that an alternator has been fitted which does not have the sprag clutch.

 

I'm surprised you have not complained of a chirping noise.

4 minutes ago, Kharl said:

I have measured that. 

The pulley oscilate +- 5mm

 

Hmm, that's possibly related.

10mm of end float! 😲

 

Surely not!

Radial wobble, not end float, I think?

Sounds like the pulley got bent when the engine was being fitted.

17 minutes ago, Pete_Ex-Wino said:

 

Hmm, that's possibly related.

i don think so, visually seems very normal that small oscillation, i have seen others which oscillate like crazy, the same car, when it used to have an adapted ac compressor, and bent pulley it used to oscillate way ore than this and never broke the screw

13 minutes ago, sepulchrave said:

Sounds like the pulley got bent when the engine was being fitted.

nop, many crazy things happening while fitting the new engine but no a single touch to the pulley

 

In fact, after the broken screw pulley of the first time (in the road trip of January) i did align with a ruler and a laser level all the pulleys in two axis each one, and they al are very well aligned, i even added a extra 1mm washer to the compressor to correct its alignment.

what about what someone said to me, thtat if it is over tight could broke or if it is the opposite, not enough tight can broke too..

 

i could check the right torque setting but there is no space to fit a torque wrench there. 

I have a store that sells titanium bolts and screws, but i fear if i fit a titanium screw than then could broken something else and not the screw, at lest the screw is the cheapest part

Too tight it would probably break while being tightened, too loose could cause fatigue fracture of the bolt if there's movement possible in the joint.

32 minutes ago, Kharl said:

if it is over tight could broke

I've heard an over-torqued bolt breaking; a whine followed by a snap. There was no load on the bolt other than torque from the socket it was being tightened with.

So, what do i do?

 

would a bigger (longer) belt help

 

i think i found the cause, i found in the manual that screw must be tighten to just 25 nm, that is about 18foot pound.

i know how mechanics in my country are, I AM 100% sure they tighten that to at least 40nm, and the second time i put the screw, i recognize i put lot of effort to tighten it, and 18foot pound is not that much.

 

 

i have a question, the dealer does not have the screw in existence, but they gave two parts number and two measures:

N10610001   m8x90

N10514501   m10x135x45

 

which one is?

 

 

 

I get the impression that you are not recieving (information), you don't seem to want to consider the very good advice given based on experience of exactly the problem that you have and have convinced ourself that two bolts have sheared in service because they were overtightened.

10 minutes ago, J.R. said:

I get the impression that you are not recieving (information), you don't seem to want to consider the very good advice given based on experience of exactly the problem that you have and have convinced ourself that two bolts have sheared in service because they were overtightened.

Hi

i am sorry, it looks i missed that advice, can you show me what was the advice?

(i am posting from a phone and probably misread or red to quickly someone else´s response)

 

Edited 15 February, 20224 yr by Kharl

It's not the original engine is it. What year is the engine and what code? I've been looking at ASY parts but they don't match yours,

2 minutes ago, TMB said:

It's not the original engine is it. What year is the engine and what code? I've been looking at ASY parts but they don't match yours,

I replaced the engine for a similar one, the donor car was a 2002 SDI Fabia, it is a ASY engine

Edited 15 February, 20224 yr by Kharl