Jump to content
SAU Community

Major Neo Rb25det Engine Damage

drgnball34

By drgnball34,
in Engines & Forced Induction

 Share

Recommended Posts

drgnball34 Rising Star

drgnball34

Posted
Posted

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
Craved Grand Master

Craved

Posted
Posted

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

GTRgeoff Grand Master

GTRgeoff

Posted
Posted

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.

blur Proficient

blur

Posted
Posted

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.

RB30-POWER Mentor

RB30-POWER

Posted
Posted

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.

StockyMcStock Proficient

StockyMcStock

Posted
Posted

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.

SLIMVLT Enthusiast

SLIMVLT

Posted
Posted

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...