Jump to content
SAU Community

Recommended Posts

Please take the time to read as it is long but very important

As the mechanic proceded to bolt down the 2nd cam he heard a cracking sound. He took it off and checked to see if the cam had snaped but turned out it didnt. He placed it back down and continued bolting everything back 2getha. He then cranked the engine over to check if everything was ok but could hear snaping sounds. Thinking that he bent a valve he proceed to do a compression test. Thats when he heard a crunch sound. We took the head off and i nearly fainted. A valve snaped and with the cranking of the engine, must of dislodged itself and fell into the cylinder bore. As a result smashed head, damage piston and burred cylinder bore.

He can not explain what he did wrong but suggested that the head had a crack valve seat prior to the cams getting bolted on. And this has not allowed the valve to close properly thus not only hitting the pistion, but on a angle which contributed to the valve snapping. But if it was cracked in the 1st place, then i would have suffered from miss fire in that cylinder. Not to mention under heavy engine load and with the constant high rpm, that valve would of crack long ago. My car has only 50k kms of which ive only put 5k kms and was runnig perfect when i gave it to him. He suggested that the cause of a crack valve seat was because i was runing too lean. But its only ever been boosted (AVCR) the last 2k kms and been below factory boost cut.

My theory is that before placing down the cam, he either set the timing wrong or placed in dwn the wrng way. When he bolted it down the, the force would of pushed the valve onto the piston and snaped it. Could any tech people please give insight and feedback to what has actually happened to my engine? He is trying to shift the blame on me and wiggle himself out of any responsability. This has caused a great deal of stress upon myself.

Link to comment
https://www.sau.com.au/forums/topic/136302-major-neo-rb25det-engine-damage/
Share on other sites

i bent 2 valves on cyl 6 when i bolted mine in ..

i was later advised that the crank needs to be moved OFF TDC so that none of the pistons are at full extension, that way if the cams are not in the correct location the valves will not meet with the piston.

cant see how it would be able to be that off that the valve would snap though

Which piston did the valve break in? 1 or 4?

As mentioned before bolting the cam down at top dead centre (#1) can cause the valves to contact a high piston and bend or break as the cam may not be perfectly aligned for that timing.

A valve seat would not do this at all unless dislodged. Was there part of a valve seat sitting loose in the cylinder?

He is clearly not a good mechanic. Viewers may have already worked that out. He should have cranked the engine off TDC and put the cams in then retimed and fitted the timing belt. Then he should have cranked it over a couple of times using a ratchet off the harmonic balancer bolt to ensure there was no confliction of the moving parts. He should have stopped immediately there was noise as well, not continued on with a compression test.

If he refuses to repair the damage he has caused take the head and valve piece to a place that does engineering materials analysis for a report on the cause of the failure. They will know if the seat or fatigue or sheer ham-fistedness caused the breakage. You can use the report in a small claims case for compensation.

maybe the cam was bolted down with no reference to tdc at all, and some of the valves opened and had piston contact which would be enough to bend/ crack a valve.. either way its not going to be nice, not exactly a common engine at the best of times.

Not to mention there could be hairline cracks or fractures in the pistons, valve guides are probably cactus and so on.

Not sure what work was done but maybe the cheaper option is to buy a another motor for $1500 and dump it straight in.

24V head work will add up real quick.

what an idiot.

1) put engine on TDC number 1

2) put exhaust cam in with cam gear dot lined up approximately towards where it will be when you put the rear timing cover on. torque it down.

3) do the same with inlet cam

4) fit timing belt and tension it up.

how goddam hard is it?

when your crank is at number 1 TDC, number 4 is there as well (i think it's number 4 anyway) so all you have to worry about is number 1 and number 4 valves hitting the pistons. visually check the lobes to see that they aren't at full extension when you install the cam. it is not a difficult concept.

make him fix it.

owch vcat any 1 take him to vcat to get the cash then get some 1 else to fix it.

ive seen plenty of this stuff recantly (im a tech/mechanic at a nissan/kia dealer) and ppl dont seam to think its worth changing timing belts, had about 7 instances in about 3 months all with major valve snapage and alot of busted cams,pistons heads ect, and usulay they break at highway speeds.

ive also seen various aprentaces stuff up valve timing with predictable results.

the best 1 was his own car (xf with ef motor, twin gt3070 ect) the work shop manual didnt have a crutial step in it for installing the timing gear (so he says anyway) resulting in the cam been about 40 degrees out.

it wouldnt turn over so he put a big snap on bar on it. it would turn but not verry good. so he put it in his car cranked it over and not much happened.

i gave his wolf 3d some tweaking thinking he hadnt set it corectly (it sounded suss at this stage. and when it cranked over and fired (well splutered) there where flames about 4 foot high out of the intake and the exhaust.

it smashed every inlet valve and bent/broke every second exhaust valve. broke every piston and masacred the head. prity funny after the event not at the time

http://i54.photobucket.com/albums/g81/slimvlt/Picture303.jpg

http://i54.photobucket.com/albums/g81/slimvlt/Picture305.jpg

http://i54.photobucket.com/albums/g81/slimvlt/Picture310.jpg

http://i54.photobucket.com/albums/g81/slimvlt/Picture315.jpg

http://i54.photobucket.com/albums/g81/slimvlt/Picture294.jpg

http://i54.photobucket.com/albums/g81/slimvlt/Picture317.jpg

pics of the mess

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

    • But first....while I was there, I also swapped across the centre console box for the other style where the AV inputs don't intrude into the (very limited !) space.  Part# was 96926-4GA0A, 284H3-4GA0B, 284H3-4GA0A. (I've already swapped the top 12v socket for a USB bulkhead in this pic, it fit the hole without modification:) Basically to do the console you need to remove the DS and PS side console trim (they slide up and back, held in by clips only) Then remove the back half of the console top trim with the cupholders, pops up, all clips again but be careful at the front as it is pretty flimsy. Then slide the shifter boot down, remove the spring clip, loose it forever somewhere in the car the pull the shift knob off. Remove the tiny plastic piece on DS near "P" and use something thin and long (most screwdrivers won't fit) to push down the interlock and put the shifter down in D for space. There is one screw at the front, then the shifter surround and ashtray lift up. There are 3 or 4 plugs underneath and it is off. Next is the rear cover of the centre console; you need to open the console lid, pop off the trim covering the lid hinge and undo the 2rd screw from the driver's side (the rest all need to come out later so you can do them all now and remove the lid) Then the rear cover unclips (6 clips), start at the top with a trim tool pulling backwards. Once it is off there are 2 screws facing rearwards to remove (need a short phillips for these) and you are done with the rear of the console. There are 4 plugs at the A/V box to unclip Then there are 2 screws at the front of the console, and 2 clips (pull up and back) and the console will come out.
    • So, a bit of a side trip, but one that might be interesting for people with JDM cars and japanese head units. I know @Pac previously posted about a carplay/android auto adapter he installed which used the AUX input, and @V35_Paul put in one of the Tesla style units that replace both screens. The option I went with was a Lsait LLT-YF-VER5.87_2 (https://www.alibaba.com/product-detail/Lsailt-8GB-Android-Multimedia-Interface-for_1601187633672.html). Price was $1,150 for a single unit although they are much cheaper if you are willing to buy 2....$857ea. Make you you get the version 2 not version 1, it is faster and has a better UI - this is the manufacturer listing: http://www.lsailt.com/product/348.html. BTW if you've never bought from Alibaba before, don't be concerned....these guys can't stay in business unless they are responsive, ship fast etc, they were excellent (probably faster shipping than most local places) So, this was my task for a lazy Sat afternoon....looks complex but was all done in a few hours (it probably helps that I had some of it apart before so it was a bit familiar). I also decided to add a HD USB drive recorded at the same time and the unit also supports an aftermarket reverse cam (if you don't want to retain factory) and also AV in and HDMI out It looks much worse than it is, in fact in was genuinely all plug and play (no custom wiring at all). This video was pretty good (skipped a few steps), unfortunately they are an Aussie seller but no longer sell this unit (I guess Carplay/AA adapters are easier to install and much cheaper) https://www.youtube.com/watch?v=T5hJfYOB8Dg
    • That still isn't a lot to go on. I don't have a Y50 Fuga Head Unit wiring diagram. I can say that a lot of nissans of that age shared head unit plugs, so if you are in Australia something like this would probably help: https://aerpro.com/app091# You plug that into the car loom, then either plug the head unit ISO into that (if it has ISO), or you buy and ISO adapter harness that you wire in. Bit of stuffing around, but once you have ISO its easy to change things in future.
    • It is a kunfine Android screen . Does anyone know the wirering diagram of the fuga ??
    • just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
×
×
  • Create New...