Over-tensioning Of Bolts

[rob83ke70]

Just wondering if anybody has ever had any problems with idler pulley or tensioner bolts breaking on the timing belt of a toyota s series engine? I replaced a timing belt on either a 3s-fe or a 5s-fe, and the idler/tensioners were noisy so I replaced those as well. less than 10,000km/6months later the bolt for one of them has broken, apparently from over-tensioning. I'm sure I didn't over-tension the bolts and I'm sure they felt quite ok when I did them up. Somebody else has done the repairs, apparently there was considerable damage to the valves when the whole lot came unstuck :)

 

Just wondering if anybody has seem this before, I know there are a lot of people on here with toyota experience.

 

I *think* it may have been the second time the belt had been replaced, I can't quite even remember the exact car!! I've done plenty of camry timing belts with that engine and this is a first for me!! It is bothering me a LOT because obviously I don't want engines to blow up!!

 

Robert.

[towe001]

Tell me if i'm wrong but i thought the 3s/5s was a non-interference head - the valves don't touch the pistons

[altezzaclub]

So... they have photos of a bolt with turning shear marks where it was overtightened?

 

If the shear marks are straight it could be fatigue, not overtightening.

 

...or did they just toss it in the rubbish and tell the customer that?

 

These days I photograph everything and send them off to manufacturers or customers or whoever needs them, and I don't take anyone on their word any more.

[rob83ke70]

there were no photos involved, we didn't do the job just copped the bill.... and apparently the valves were damaged :) I'm not sure if they are free-running or not. It was definitely an "s" series engine.

 

I'm sure the boss has the shits with me over that, as it cost him a lot of money, and it's playing on my mind to the point where I'm not sleeping properly (along with other things too I suppose) because I don't remember it feeling funny when I did the bolt up, and I'm sure I would have used a 14mm spanner or a 3/8" ratchet to do it up, and I can't see how I would have over-tensioned it.

 

I'm not quite sure what is going on.

 

Robert.

 

 

So... they have photos of a bolt with turning shear marks where it was overtightened?

 

If the shear marks are straight it could be fatigue, not overtightening.

 

...or did they just toss it in the rubbish and tell the customer that?

 

These days I photograph everything and send them off to manufacturers or customers or whoever needs them, and I don't take anyone on their word any more.

[rob83ke70]

lesson: Robert doesn't do anything up without torque wrench in hand anymore!!!

 

Robert.

[corolla_nut]

http://www.gates.com/part_locator/index.cfm?location_id=3002

 

gates say that both the 5s-fe and the 3s-fe are NOT interferance engines....

 

maybe time to check this with toyota, and then maybe I should ask the boss what on earth is going on???

 

Robert.

[beerhead]

Damn. What a nightmare...

 

I've pulled apart most of the S engines around, they have such huge recesses cut for the valves that it should be nearly impossible to clip the valves on the pistons, maybe revving on the limiter they could interfere if a timing belt snapped, but it shouldn't happen unless aftermarket high lift cams are fitted.

 

On my Camry if you look to the right hand side of the head near the rear water outlets you can see a 15 x 10mm chunk of head gasket hanging out. If that doesn't look shiny and new I doubt the heads been off. If it looks crusty ask to see the receipt from the machine shop for the head repairs when they refuse, tell them they're being reported to the MTAA for illegal activities and it is within your right to hold them liable for the value of the repairs not carried out and stress and mental anguish over the ordeal that only happened due to there fraudulent activities.

[rob83ke70]

then there begs the question as to why the bolt broke, if I used a 14mm spanner or 3/8" ratchet and socket, and it didn't feel funny when I did it up (I would have remembered!!! I don't let dodgy stuff go!) then how is it over tightening that caused the bolt to break? shouldn't it be more like fatigue? and how is that to do with me??

 

I'm at a loss as to whats going on, the whole time this repair was carried out (in a workshop in sydney) I wasn't told or informed very much at all other than "you've stuffed up, you must have overtensioned the idler bolt and now the engine has busted valves" and there were a few phone calls going back and forth between that workshop and the boss, but I was never in on the loop...

 

This is really really bothering me because the boss is really unhappy about me "costing him thousands of dollars" recently. There were two other mistakes that come to mind, one of which didn't *cost* anything, rather very ebarrassing and I've worked out what I did wrong and there was actually no harm done (could have been very serious though) and the other one was a small mistake on a very large job that I was rushing to get through.

 

I'm starting to think that small businesses, especially those run by families are just as bad as dealerships but in a different kind of a way!! I got my ass reamed for the serious mistake, it hasn't and won't happen again, and as far as I'm concerned that is finished!! the other mistake I'm happy to take the blame for as well, I didn't clip the crank sensor wiring in the right spot on a 2uz-fe in a 100 series landcruiser and the wires rubbed on the belt and wore through.

 

Whilst I'm in the mood for venting:

 

If I have a late model toyota which specifies dot 3 fluid only, and it has toyota genuine brake fluid in it (yellow) and I have to replace the brake fluid as part of the service, and want to put dot 3 valvoline brake fluid in it (blue), should I:

 

A) replace the fluid in the resavoir, drain a little bit of fluid from each caliper, the fluid coming out of each caliper is still yellow when I'm finished, and I've only used 500ml or less of brake fluid (some resavoirs hold more than that, and cars with abs have huge systems)

 

or

 

B) replace fluid in resavoir, flush through each caliper until blue fluid comes out, using probably 1000ml (two bottles).

 

I was taught as an apprentice that only one type of brake fluid should be used in a car at once, ie not to mix two different types. Now I know these are both dot 3 fluids, but they are from different manufacturers and are different colours, and god knows if there is anything else different in them. Is this correct? or am I doing it wrong?? I can't see the problem with charging a customer for 1000ml of brake fluid if you use 1000ml of brake fluid to do the job either?

 

 

Robert.

[rob83ke70]

I was told they did a compression test before removing the head, now I'm quite sure that they would have had to pop a lot of engine back together first to do that! the engine was probably low on compression due to wear and tear, not bent valves!

 

I am kind of worked up...

 

Robert.

[Jono]

if you are in the right, then stand up for yourself. Its fair that your boss is pissed off but it shouldn't be at you if you did nothing wrong, its just part of running a business that he will suffer losses from time to time. Also, it all sounds a bit fishy and maybe your boss is being scammed by the customer. He should in theory listen to you, then back you up and possibly refuse to pay whoever did the repairs. On the other hand for good PR he could just pay and know he has a happy customer who will hopefully use him again and over time he will recover the costs.

[altezzaclub]

Lesson number one in business- never pay for someone else to fix your mistakes!!

 

He should offer to fix the engine if its his fault, and refuse to pay anyone else to do it. Its just asking to get screwed. The customer can have the car freighted back to your workshop if he wants it done.

 

We get it with washing machines and appliances all the time. It might be under Electrolux guarantee, but the customer has to get it into our workshop or pay for travel time outside of Orange itself to get it fixed. So accepting some risk with any machine is part of buying it.

 

Without photos I'd say you're being screwed! It's a difficult one to prove, although I'm sure some University Engineering School would know how to check how it happened.

 

If you overtightened it it would have suddenly gone loose as it started to shear, and that puts rotational shear lines on the end. If it has no rotational shear marks it would be metal fatigue. After all, the stress in use on that bolt is at right-angles to its head, so the cambelt tensioner is not trying to rip the head off the bolt.

 

Anyway- get onto Toyota and find out if they are interference engines. If they're not then its nothing to do with you...

[philbey]

Mate, It's easy for them to pull the bolt out and say it's from overtensioning but in all seriousness, it's most likely just bad luck.

 

Overtensioning will stretch the bolt so it would be obvious that's the failure mode. More than likely though, it's a fatigue failure as mentioned by altezzaclub, or perhaps a defective part.

 

Get them to explain how they diagnosed it as overtensioned; what particular thing did they identify as a symptom of overtightening.

 

Also, these the belt tensioners I've seen are usually in shear under load, not in tension?

 

Sounds like crap to me, and your boss is getting stitched up.

[rob83ke70]

the repair has been and gone, the other workshop did it, I thought it was over until it got brought up again on friday when I got an arse chewing...

 

I told the boss today that it was a free-running engine, he said that he's pretty sure thats the case too, apparently this other workshop did the water pump and heaps of other goodies too while it was apart at our expense... and apparently they wouldn't just put a belt on and see if it was all ok, they insisted the head had to come off and all that stuff....

 

I'm failing to see how all that money was my fault? and I'm failing to see how or why it should be brought up again?

 

Robert.

[beerhead]

The workshop did the shifty mate, and your boss is just venting the f#$k up at you. Sounds like just bad luck that the tensioner bolt* snapped, nothing that happened could you have anticipated or avoided.

 

It's standard procedure to dummy fit the belt before the head comes off and check with a compression testor or run the motor to make sure the valves are OK. They have admitted that they weren't sure if the head needed work, and decided to sting your boss for the "Worst case scenario repair" without checking the damage so they've comitted fraud saying that it "must to be done". It would have taken 20 minutes for them to fit up the new belt to guarantee that the head was damaged, and they didn't do there job.

 

Report them to the MTAA, workshops like this deserve to be shut down and the owners put in jail. If you don't report them they'll rip off your mum your nanna and every other person you know who's not mechanically minded.

Edited November 16, 2009 by beerhead

[altezzaclub]

Yeah, Toyota confirmed the same with me today. Both 3S & 5S are non-interference, and that dodgy workshop will be ripping people off all over the place.