Jump to content
SAU Community

Strange Piston/gudgeon Pin Failure

bren

By bren,
in Engines & Forced Induction

 Share

Recommended Posts

bren Contributor

bren

Posted
Posted

Anyone got any idea what might have cause these failures? The gudeon pins have snapped in two. The same thing happened in two different engines. Both CA18DETs (similar to RB but 4 pot rather than 6), both using Wiseco pistons, both failed in only 100kms.

Its a strange one as I know of lots of people using Wisecos in CAs with no problems and yet this one guy has two identical failures. Any idea what he is doing wrong?

1.6.06%20joo%20020%20(Small)(1).jpg

IMG_2311%20(Medium).JPG

IMG_2314%20(Medium).JPG

Link to comment
https://www.sau.com.au/forums/topic/126195-strange-pistongudgeon-pin-failure/
Share on other sites
BezerkR32 Veteran

BezerkR32

Posted
Posted

piston is not fauling on crankshaft counterweight is it, or crankshaft have excessive endfloat? unless pin is grabbing little end and piston, lubrication problem. never seen anything like it, thats big.

Anyone got any idea what might have cause these failures? The gudeon pins have snapped in two. The same thing happened in two different engines. Both CA18DETs (similar to RB but 4 pot rather than 6), both using Wiseco pistons, both failed in only 100kms.

Its a strange one as I know of lots of people using Wisecos in CAs with no problems and yet this one guy has two identical failures. Any idea what he is doing wrong?

1.6.06%20joo%20020%20(Small)(1).jpg

IMG_2311%20(Medium).JPG

IMG_2314%20(Medium).JPG

bren Contributor

bren

Posted
  • Author
Posted (edited)

Those are the only pics I have Im afraid. Its a guy in another country thats having probs, I havent been involved with the build myself. The pistons are nothing out of the ordinary, as I say, they have been used with great sucess in a large number of engines to date so I cant see why they would suddenly foul on the crank. I can see maybe one set of pistons being mispacked by Wiseco but two, and both sets going to the same guy? Nah, too much of a coincidence.

Maybe the piston to bore clearance isnt correct and the pistons nipped up when the engines got hot but to snap the gudgeon pics? Ive seen the effects of hydraulic locking and even then it was the rods that bent, not the gudgeon pins snapping.

Very wierd.

Edited by bren
EfiOz Rookie

EfiOz

Posted
Posted

I've seen it before in a V10 Viper and it was a detonation issue. It broke 2 gudegeons and had 4 more cracked ones.

That was a brand new engine with Wiseco's. It was rebuilt and retuned (the right way!) and it's never had anothe problem since, even with the same pistons.

discopotato03 Grand Master

discopotato03

Posted
Posted (edited)

I tend to think that the gudgeon pin tried to sieze in the small end bush . You can see how the bush has tried to screw itself out of the rod and no doubt up against the inside of the pistons gudgeon pin boss . Since both pins are sheared in the middle it seems logical that half the pin was trying to stop the piston articulating with the rod and was the weakest link . Luckily the other half must have kept the small end located in the piston otherwise the rods and pistons would now be schrapnell on the road . I would be measuring up the broken and surviving pins to see if the tolerances were adequate .

I would also check to see if the propper lubrication was available to all four rods/pins/pistons .

Cheers .

Edited by discopotato03
T04GTR Grand Master

T04GTR

Posted
Posted

ok. the only thing that causes a gudion pin failer is either a clerance issue or fauly materials. (dodgy gudion pin)

the fact that it shered could be due to the fact that its been hammering away at its self. elongating the piston pin bore and/or hammering the bush in the conrod.

to a point where it has hammerd it so hard that its fractured the gudion pin.

or.. partaly siezing in the pin boss or little end. ie.. one side getting galled andthe othere side being ok.

so basicly the cause is to little or two much clearance inbetween the piston and the gudion pin or two much clearance between the gudion pin and smallend bushing :D

ie.. poor engine assembly.

ps... if anyone for a minute thinks that detonation has caused this please slap yoursefl ;)

rob82 Mentor

rob82

Posted
Posted
ok. the only thing that causes a gudion pin failer is either a clerance issue or fauly materials. (dodgy gudion pin)

the fact that it shered could be due to the fact that its been hammering away at its self. elongating the piston pin bore and/or hammering the bush in the conrod.

to a point where it has hammerd it so hard that its fractured the gudion pin.

or.. partaly siezing in the pin boss or little end. ie.. one side getting galled andthe othere side being ok.

so basicly the cause is to little or two much clearance inbetween the piston and the gudion pin or two much clearance between the gudion pin and smallend bushing :D

ie.. poor engine assembly.

ps... if anyone for a minute thinks that detonation has caused this please slap yoursefl ;)

I'm with you on this one, detonation isn't going to do this. I would still like to see the big ends as they will probably show more of the story. If the little end is hammer the big end certainly is going to be showing signs of abuse as well.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • The Bogan
      NC MX5

      By The Bogan · Posted

      After using a protractor for an actually accurate assessment of what is required,  and by NOT using my uncalibrated eyeball I worked out I need a 25° silicone bend from the TB ro the MAF, but, my choice was either a 30° or a 23° (23° is a weird spec), so I grabbed the 23° one from Raceworks I also grabbed 1mtr of 3" straight from Just Jap, I needed 350mm, but they only had 300mm, or 1mtr lengths....meh Also ordered a 1/2" hose bulkhead fitting from fleabay, this has a smoothish mushroom looking head (they are designed for below the water line of boats) that will fit inside the bend, the hose bit and threaded bit looks to long, but nothing that a hacksaw cannot fix if required, the hose will then just get jamed on the threaded bit up to the retaining nut Fingers crossed and the unsightly amount of hose clamps will be reduced down to 4 once all the parts arrive 
    • joshuaho96
      R34 25GT Engine Light 21

      By joshuaho96 · Posted

      Oil change does not trigger code 21. Code 21 is for coilpacks primary side connection. You can try to clear the code with a battery disconnect, hold down the brake pedal to drain capacitors through the brake lights with the ignition on for 10-15 seconds before you reconnect the battery. I have seen R35 coil conversion permanently cause this code with no ill effects so it might be the resistance it wants to see isn't quite right on one or more coilpacks. Could be inside the ECU, could be the harness, could be a coil. You can test it all if you want or just ignore until the car actually starts misfiring.
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I forgot you have a Nistune ECU. Use Nistune to do all the tests I mentioned instead of faffing with 30+ year old electrical connectors. You can read MAF volts off that too, there are reference values in the service manual to tell you roughly what it should be in different conditions.
    • GTSBoy
      R32 GTS (RB20DE) Injectors Replacement

      By GTSBoy · Posted

      No. I think it might be the AFM. Hence the use of the terms "swaptronics", which implies the use of swapping out electronics for the purpose of diagnosis. It's about the only way to prove that a small/niggling/whatever problem with an AFM or a CAS or similar is actually caused by that AFM/CAS/whatever. A known good item swapped in that still gives the same problem is likely to be caused somewhere else. They're all the same. Spraying AFMs with cleaner is an each way bet between cleaning it and f**king it.
    • codygrimm27
      Can you mount the ATTESA pump in other locations?

      By codygrimm27 · Posted

      Oh wow! This might actually work amazingly. Do you know the ratio of the diff? I was told the only thing you need to make sure of is if the front & rear diff ratios are the same. Ours is a 4.083 Thanks!
×
×
  • Create New...