Timing belt tensioner bolt broke while driving

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Originally Posted By: Bottom_Feeder
I would bet there are more belt-driven interference engines out there than not. No reason to single out Subaru for it.

All of Honda's lineup and any timing belt-driven Toyota engine with VVT-i is interference as well.

And I just installed the Gates kit on a friend's 2003 Forester - but I just used the basic kit sans water pump. The tensioner was an NTN-made piece.
 
I'm glad you heard from Gates and hope they pay your claim.

I had a six month old MSD ignition box die on me when I was driving on a fast boulevard and was almost rear ended by a bus. I contacted MSD about the ignition box and they never responded to me about repairing the box or refunding me on the box. I then contacted Summit Racing, where I purchased the ignition box, and they promptly sent me a new ignition box with a prepaid return label. The rep on the phone with Summit Racing told me that he has seen a lot of MSD ignition boxes go bad. He also told me that they have a lot of problems with Optima batteries.

A few months later I sold the vehicle.
 
Summit Racing is a stand up operation. It's worth buying through them just because they care about customer service and they do respond, quickly. They have a great reputation among people around here. Over the years we've all purchased stuff from them. It's interesting looking through all the stuff they sell.
 
I'm with Vikas. There is no reason for the bolt to break, unless it worked loose and saw movement. Properly torqued, it should have lasted forever. It's not the manufacturer's fault, but the installer's fault.
 
Originally Posted By: Kestas
I'm with Vikas. There is no reason for the bolt to break, unless it worked loose and saw movement. Properly torqued, it should have lasted forever. It's not the manufacturer's fault, but the installer's fault.


Have you never heard of defective bolts? I purchase steel, fasteners, and sub-contracting for a Tier 1 and 2 automotive supplier. My best-in-class automotive fastener supplier will only assure me 25ppm for their products. The average for fastener suppliers is 40ppm. Having said that, most visual defects are missing threads, damaged threads, damaged (double hit) heads that would be caught before we install. But, we do see breakage in the installation process - not often but it does happen.

Perhaps the heat treat step was incorrect, perhaps when they batch process the raw parts from one stage to another a stray bolt gets stuck in the bin and misses the heat treat...this does occur and I have 8D reports to prove it.

Then you have the whole issue of Chinese made stuff that is pure fake. Do not accuse Taiwan of this - they are the best in the world for high volume fastener manufacturing.
 
Originally Posted By: KGMtech
Originally Posted By: Kestas
I'm with Vikas. There is no reason for the bolt to break, unless it worked loose and saw movement. Properly torqued, it should have lasted forever. It's not the manufacturer's fault, but the installer's fault.


Have you never heard of defective bolts? I purchase steel, fasteners, and sub-contracting for a Tier 1 and 2 automotive supplier. My best-in-class automotive fastener supplier will only assure me 25ppm for their products. The average for fastener suppliers is 40ppm. Having said that, most visual defects are missing threads, damaged threads, damaged (double hit) heads that would be caught before we install. But, we do see breakage in the installation process - not often but it does happen.

Perhaps the heat treat step was incorrect, perhaps when they batch process the raw parts from one stage to another a stray bolt gets stuck in the bin and misses the heat treat...this does occur and I have 8D reports to prove it.

Then you have the whole issue of Chinese made stuff that is pure fake. Do not accuse Taiwan of this - they are the best in the world for high volume fastener manufacturing.


Exactly. Defective manufacturing is rare, but it happens. There are issues all over the forums of tensioner bolts breaking.

Either way, somebody should be on the hook for it.

I have not even been able to enjoy this car having it such a short amount of time.
 
Originally Posted By: coachditka
But the dang parts cost 10x as much for the same thing!

Live and learn.


So, do you recall what you paid total (you purchased Gates kit and had Indy shop install)? Did you ever get a quote from a Subie dealer?

Just wondering what the difference would have been....
 
Originally Posted By: KGMtech
Originally Posted By: Kestas
I'm with Vikas. There is no reason for the bolt to break, unless it worked loose and saw movement. Properly torqued, it should have lasted forever. It's not the manufacturer's fault, but the installer's fault.

Have you never heard of defective bolts? I purchase steel, fasteners, and sub-contracting for a Tier 1 and 2 automotive supplier. My best-in-class automotive fastener supplier will only assure me 25ppm for their products. The average for fastener suppliers is 40ppm. Having said that, most visual defects are missing threads, damaged threads, damaged (double hit) heads that would be caught before we install. But, we do see breakage in the installation process - not often but it does happen.

Perhaps the heat treat step was incorrect, perhaps when they batch process the raw parts from one stage to another a stray bolt gets stuck in the bin and misses the heat treat...this does occur and I have 8D reports to prove it.

Then you have the whole issue of Chinese made stuff that is pure fake. Do not accuse Taiwan of this - they are the best in the world for high volume fastener manufacturing.

I've seen my share of defective bolts. I routinely perform failure analysis on fasteners for my colleagues who buy bolts. It's not fair to condemn the bolt without a proper failure analysis of the assembly.

Defective bolts will generally fail upon installation, not in service when it's in a static condition. Failure in service indicates movement of the assembly. Movement of the assembly indicates improper installation.

I'm not sure what you mean by ppm... Aluminum?
 
Someone should check the published torque spec for that bolt and make sure it is correct. I once found a gross error in a MB Unimog FSM after twisting off a couple flywheel bolts.
 
Originally Posted By: Phishin
Originally Posted By: coachditka
But the dang parts cost 10x as much for the same thing!

Live and learn.


So, do you recall what you paid total (you purchased Gates kit and had Indy shop install)? Did you ever get a quote from a Subie dealer?

Just wondering what the difference would have been....


Gates kit with lifetime warranty (we shall see) with water pump was $150ish plus I got the crank and cam seal at NAPA for $15.00 Also ordered a Gates thermostat at the same time to go with the WP.

http://www.amazon.com/Gates-TCKWP307A-Engine-Timing-Water/dp/B003TU4VBC


Subaru dealer parts for the same thing were close to $600.00 with a 12/12 warranty if the dealer installed them.

I never buy "cheap" aftermarket stuff, Gates has been a great brand for belts and hoses my whole life and I never had any issues.
 
Originally Posted By: coachditka
I never buy "cheap" aftermarket stuff, Gates has been a great brand for belts and hoses my whole life and I never had any issues.


Belts and hoses maybe, but the rest I wouldn't be so sure (especially water pumps). I put a Gates kit on my Accord and about 15,000 miles later the Chinese water pump started to leak and I had to replace it. I know someone in this thread mentioned that the OEM tensioner bolts are failing too, but for me the only aftermarket stuff I'll buy is from Aisin. Although they weren't OEM for my Honda, the parts were all either USA or Japan made and the difference in appearance between the Aisin water pump and the Gates one was like night and day.
 
Originally Posted By: kschachn
Originally Posted By: coachditka
I never buy "cheap" aftermarket stuff, Gates has been a great brand for belts and hoses my whole life and I never had any issues.


Belts and hoses maybe, but the rest I wouldn't be so sure (especially water pumps). I put a Gates kit on my Accord and about 15,000 miles later the Chinese water pump started to leak and I had to replace it. I know someone in this thread mentioned that the OEM tensioner bolts are failing too, but for me the only aftermarket stuff I'll buy is from Aisin. Although they weren't OEM for my Honda, the parts were all either USA or Japan made and the difference in appearance between the Aisin water pump and the Gates one was like night and day.


I almost bought the OEM WP for 150, but my shop said no worries on the Gates WP so I trusted them. Everything else in the kit was USA belt and Japan tensioner and pulleys.
 
Originally Posted By: Nate1979
It's recommended to not get the Gates WP for Subies.



I've heard. If I was going to do it again, I'd get the OEM or Asin.
 
Preface: I've never replaced the timing belt on a subaru, though I plan to try myself the next time my subaru needs it done.

I didn't mention this over at legacygt.com, but I'm not convinced that the bolt broke. In the video I posted there (link), briansmobile1 talks about removing the pulleys and tensioner in a certain order, so that there is no stress on the tensioner bolt when you remove it. If there's a lot of tension on that tensioner bolt when you're trying to remove it from the aluminum threads, I would worry about stripping those aluminum threads. For those asking, the factory service manual calls for the tensioner bolt to be tightened down to 28.8 ft/lbs.
 
I've done the TB a couple of times on the older 2.2L single cam subarus and they are really well-thought out for that job. lift the radiator fans and overflow tank out and there's tons of room to work in. Very comfortable with that job. I've never done the dual cam motors but hopefully if you pull out a few layers of plastic there would be a lot of room there, too.

I'm not sure about yours, but the oil pump and front main seal used to be a quick add-on -- pull the pump, tighten all the screws/bolts on it's inside surface, tap in a new front seal, and slip it back on over the crank. That, with the water pump, only added 30 minutes. good luck!
 
Oh, I will mention I had a problem with the aftermarket TB. This was a long time ago, but I think it was a gates belt and it stretched after 35,000 miles. lifepsan was 60k. the stretch resulted in a stumble at idle and misfire codes on cyl 4. Nobody could figure it out. I eventually did the 2nd TB when the water pump started to leak at 106k, and the stretch was obvious. I used an oem replacement belt and pump and all the problems went away.
 
Quote:
Defective bolts will generally fail upon installation, not in service when it's in a static condition. Failure in service indicates movement of the assembly. Movement of the assembly indicates improper installation.
Even assuming improper installation, I just do not see how that particular bolt could be subjected to lateral shear forces. What kind of force that tensioner is exerting on the belt? Ten pounds? Twenty pounds? Heck two finger deflection test hardly applies few pounds. That bolt is not holding the cylinder head! If the bolt was tightened way too much, it would have caused the threads inside the aluminum to give up first.

Since you are the failure analyst, please provide your conjecture as to how the bolt could have been subjected to massive shear force for it to snap.
 
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