Jump to content
SAU Community

Recommended Posts

Hello all, this is something many of you may or may not know about so I thought I would put it up and see what people think.

Recently an engine was built by me and the bolt for the idler pulley on the timing belt snapped. This happened about 2000km in (I think). All my engines get new bolts there so it came as quite a surprise. The owner and I decided to investigate. I have never had a new bolt break in this way.

He flies aircraft and has contacts for testing bolts etc so we bought 10 8.8 high tensile M10 x 70 bolts and sent them to his guy for MPI (Magnetic Particle Inspection) testing.

7 out of the 10 failed the MPI due to surface irregularities that are at high risk of a crack starting in that area.

So we had three we could use on his engine. I decided to send the other 7 off to be treated to see if we can improve the statistics and then have them re-tested.

I'll let you all know the result once I have them

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/
Share on other sites

Same thing happened to my engine, 500kms in.

New piston, valves, head and a new idler bolt later. Was rebuilt and has been going strong.

If you eventually get a new stronger replacement, i would be buying one off you in a second if i or anyone i knew was building an RB.

As the result of a snapped $15 bolt creates a whole word of heartache :(

And Daniel im sure you have done a few timing belts, but i think the tension has a part to play with these bolt failures also.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4854482
Share on other sites

Out of interest, was any other damage caused when this bolt snapped? Was it a bolt supplied by Nissan or otherwise?

yeah every valve touched. Decoro valves too.

I know what you mean NYTSKY but I can assure you overtension is not a problem.

I would have done 20 belts this year alone. Always set them a certain way and double check deflection after 4 rotations.

It was a genuine Nissan bolt and washer. The other 10 purchased are aftermarket bolts

I'm going to try cryogenic treating them first, then back in for MPI

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4855292
Share on other sites

never heard of it, are those bolts being torqued up or by hand, Ive done many on rb engines and never felt the need to replace the bolt, i tension by hand with loctite using original bolt, Is sounding like the brand new replacement bolt isn't up to the original spec.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4856150
Share on other sites

never heard of it, are those bolts being torqued up or by hand, Ive done many on rb engines and never felt the need to replace the bolt, i tension by hand with loctite using original bolt, Is sounding like the brand new replacement bolt isn't up to the original spec.

Go and get an old idler bolt xrayed. You'll never put one back in, I gaurantee it!

the new bolt that snapped was a genuine nissan bolt made for the idler pulley specifically ??

yes it was.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4857691
Share on other sites

Go and get an old idler bolt xrayed. You'll never put one back in, I gaurantee it!

yes it was.

yes the new bolts are actually a Navara part number which is a little bit of a concern.

Edited by DiRTgarage
Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4857708
Share on other sites

Um couldn't you simply sue Nissan for the damages if you can prove, with xrays and whatnot, that it was their genuine bolt that snapped due to shoddy QC ?

Already considered that but it's not really in my best interest (or budget) to chase a large car dealership for around $2000

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4858446
Share on other sites

small claims tribunal costs nothing .. I'm sure they'd pay up to avoid bad publicity if you had expert opinions (and xrays) that it was their bolt that failed under normal conditions.

1. It's probably like 3 - 4 days of my time which works out to be about $3k

2. It's not working under normal conditions considering its a RB26/30

3. They could just say I have to prove it wasn't my fault, which there is no way that I can other than going off the other gazillionty timing belts I have done without problems.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4858492
Share on other sites

+1 Get a higher grade. The extra safety factor in property class 12.9 or 10.9 bolts will help or you can try removing the surface irregularities by polishing

Property class 12.9 is 1200MPa UTS and 0.9x(1200)=1080MPa yield

Property class 10.9 is 1000MPa UTS and 0.9x(1000)=900MPa yield

as compared to

Property class 8.8 is 800MPa UTS and 0.8x(800)=640MPa yield

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4858695
Share on other sites

  • 3 weeks later...
Anyone had this problem with the tensioner pulley stud? I just snapped mine! :thumbsup:

Luckily no engine damage though! :)

Yeah I had a guy come in with a noise once. Turns out the tensioner stud broke and the belt was pushing the bearing into the side of the lower cover. Lucky save that one was.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4893249
Share on other sites

Yeah I had a guy come in with a noise once. Turns out the tensioner stud broke and the belt was pushing the bearing into the side of the lower cover. Lucky save that one was.

Yeah... pretty much the same problem here. The car started making a horrible noise. Pulled off the timing covers to find heaps of slack on the tensioner side of the belt. So lucky not to skip any teeth!

I wonder if this is in any way related to power levels ? ie. has anyone had either the factory tensioner or idler pulley bolts snap out of the blue on a mildly modified car ie 200-270kw?

Mine would fall in this category.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/#findComment-4893647
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • OK, so again it has been a bit of a break but it was around researching what had been done since I didn't have access to Neil's records and not everything is obvious without pulling stuff apart. Happily the guy who assembled the engine had kept reasonable records, so we now know the final spec is: Bottom end: Standard block and crank Ross 86.5mm forgies, 9:1 compression Spool forged rods Standard main bolts Oil pump Spool billet gears in standard housing Aeroflow extended and baffled sump Head Freshly rebuilt standard head with new 80lb valve springs Mild porting/port match Head oil feed restrictor VCT disabled Tighe 805C reground cams (255 duration, 8.93 lift)  Adjustable cam gears on inlet/exhaust Standard head bolts, gasket not confirmed but assumed MLS External 555cc Nismo injectors Z32 AFM Bosch 023 Intank fuel pump Garret 2871 (factory housings and manifold) Hypertune FFP plenum with standard throttle   Time to book in a trip to Unigroup
    • I forgot about my shiny new plates!
    • Well, apparently they do fit, however this wont be a problem if not because the car will be stationary while i do the suspension work. I was just going to use the 16's to roll the old girl around if I needed to. I just need to get the E90 back on the road first. Yes! I'm a believer! 🙌 So, I contacted them because the site kinda sucks and I was really confused about what I'd need. They put together a package for me and because I was spraying all the seat surfaces and not doing spot fixes I decided not to send them a headrest to colour match, I just used their colour on file (and it was spot on).  I got some heavy duty cleaner, 1L of colour, a small bottle of dye hardener and a small bottle of the dye top coat. I also got a spray gun as I needed a larger nozzle than the gun I had and it was only $40 extra. From memory the total was ~$450 ish. Its not cheap but the result is awesome. They did add repair bits and pieces to the quote originally and the cost came down significantly when I said I didn't need any repair products. I did it over a weekend. The only issues I had were my own; I forgot to mix the hardener into the dye two coats but I had enough dye for 2 more coats with the hardener. I also just used up all the dye because why not and i rushed the last coat which gave me some runs. Thankfully the runs are under the headrests. The gun pattern wasn't great, very round and would have been better if it was a line. It made it a little tricky to get consistent coverage and I think having done the extra coats probably helped conceal any coverage issues. I contacted them again a few months later so I could get our X5 done (who the f**k thought white leather was a good idea for a family car?!) and they said they had some training to do in Sydney and I could get a reduced rate on the leather fix in the X5 if I let them demo their product on our car. So I agreed. When I took Bec in the E39 to pick it up, I showed them the job I'd done in my car and they were all (students included) really impressed. Note that they said the runs I created could be fixed easily at the time with a brush or an air compressor gun. So, now with the two cars done I can absolutely recommend Colourlock.  I'll take pics of both interiors and create a new thread.
    • Power is fed to the ECU when the ignition switch is switched to IGN, at terminal 58. That same wire also connects to the ECCS relay to provide both the coil power and the contact side. When the ECU sees power at 58 it switches 16 to earth, which pulls the ECCS relay on, which feeds main power into the ECU and also to a bunch of other things. None of this is directly involved in the fuel pump - it just has to happen first. The ECU will pull terminal 18 to earth when it wants the fuel pump to run. This allows the fuel pump relay to pull in, which switches power on into the rest of the fuel pump control equipment. The fuel pump control regulator is controlled from terminal 104 on the ECU and is switched high or low depending on whether the ECU thinks the pump needs to run high or low. (I don't know which way around that is, and it really doesn't matter right now). The fuel pump control reg is really just a resistor that controls how the power through the pump goes to earth. Either straight to earth, or via the resistor. This part doesn't matter much to us today. The power to the fuel pump relay comes from one of the switched wires from the IGN switch and fusebox that is not shown off to the left of this page. That power runs the fuel pump relay coil and a number of other engine peripherals. Those peripherals don't really matter. All that matters is that there should be power available at the relay when the key is in the right position. At least - I think it's switched. If it's not switched, then power will be there all the time. Either way, if you don't have power there when you need it (ie, key on) then it won't work. The input-output switching side of the relay gains its power from a line similar (but not the same as) the one that feeds the ECU. SO I presume that is switched. Again, if there is not power there when you need it, then you have to look upstream. And... the upshot of all that? There is no "ground" at the fuel pump relay. Where you say: and say that pin 1 Black/Pink is ground, that is not true. The ECU trigger is AF73, is black/pink, and is the "ground". When the ECU says it is. The Blue/White wire is the "constant" 12V to power the relay's coil. And when I say "constant", I mean it may well only be on when the key is on. As I said above. So, when the ECU says not to be running the pump (which is any time after about 3s of switching on, with no crank signal or engine speed yet), then you should see 12V at both 1 and 2. Because the 12V will be all the way up to the ECU terminal 18, waiting to be switched to ground. When the ECU switches the fuel pump on, then AF73 should go to ~0V, having been switched to ground and the voltage drop now occurring over the relay coil. 3 & 5 are easy. 5 is the other "constant" 12V, that may or may not be constant but will very much want to be there when the key is on. Same as above. 3 goes to the pump. There should never be 12V visible at 3 unless the relay is pulled in. As to where the immobiliser might have been spliced into all this.... It will either have to be on wire AF70 or AF71, whichever is most accessible near the alarm. Given that all those wires run from the engine bay fusebox or the ECU, via the driver's area to the rear of the car, it could really be either. AF70 will be the same colour from the appropriate fuse all the way to the pump. If it has been cut and is dangling, you should be able to see that  in that area somewhere. Same with AF71.   You really should be able to force the pump to run. Just jump 12V onto AF72 and it should go. That will prove that the pump itself is willing to go along with you when you sort out the upstream. You really should be able to force the fuel pump relay on. Just short AF73 to earth when the key is on. If the pump runs, then the relay is fine, and all the power up to both inputs on the relay is fine. If it doesn't run (and given that you checked the relay itself actually works) then one or both of AF70 and AF71 are not bringing power to the game.
    • @PranK can you elaborate further on the Colorlock Dye? The website has a lot of options. I'm sure you've done all the research. I have old genuine leather seats that I have bought various refurbing creams and such, but never a dye. Any info on how long it lasts? Does it wash out? Is it a hassle? What product do I actually need? Am I just buying this kit and following the steps the page advises or something else? https://www.colourlockaustralia.com.au/colourlock-leather-repair-kit-dye.html
×
×
  • Create New...