Jump to content
SAU Community

Recommended Posts

hi all,

so my 500km old RB26 just shagged itseld in what looks like a fairly destructive fashion, a quick run down

a quick run down.

cp pistons, forged rods, ati balancer, nitto pump, balanced, +1mm in and ex valves, bronze guides, tomie buckets, and type b springs, tomie 10.8 x 270 in ane ex cams, tomie cam gears, 6boost and GT35

so built the bottom end myself and had all the head work done at a local shop, assembled the engine and put it in my self and had a loom and tune done at one of the better shops hear in perth,

first build so told them to go over it with a fine tooth to make sure i hadnt missed or mucked anything up, obviuosly couldnt check the bottome end work, but was fairly confident in that work,

so after 7 weeks at the shop i finally get the good new that it running and sounding healthy, at about 400km of driving i started to hear a noise, but only on warm start up idle for about 5 seconds or so, sounded like a knock but i never heard a engine knock before, so got it home and was gonna take it to the shop the next day, but before i did i got the mrs to start it with my head under the hood, no noise, sweet maybe i was paranoid, any way after a little bit of driving i turn it off and come back about 20 mins later, and we could both here this "knock"

so was gonna get it towed to the shop but thought just see if it does it so turned on and no noise again, so drove it there hoping that if it was gonna do it, it would do it at the shop, not the same noise but the boys there couldnt here any internal suspicious noise

so next day all happy that i have a healthy engine i turn her on let it warm up and then head off

150 metre down the road it comes to a screeching hault, would start or even turn over, feeling like shit i push it home and get it towed the next day to the shop,

not even 10 minutes later i get told that its seized and what ever i want to do its not gonna be cheep, so i proceeded to swear a little and get heavily intoxicated,

so get to the weekend time to pull it out, i notice the inlet cam gear has retarded itseld by 2.5 marks on the gear and start to think that hey maybe i didnt stuff up but this was overlooked at the shop, although realising that this is probably more damaging then bearing and what not,

any way i havent got the head off but pulling plug number 5 out something has definatly come incontact with it, which further made my heart sink,

looking at the bottom end there is no discolouration in the rods but again i havent pulled the girdle or the rod caps off,

so after that novel my question is,

do you think retarding the inlet cam by that much would be enough to hit the pistons, and cause the car to stop and not start and seem as tho it is seized,

so as you can see in the pics u can see how much it has moved by, and that it looks like the buckets arent pushed up against the lobe on the inlet side but the exhaust side looks normal,

and also the engine would rotate backwards but not forwards,

im not looking to blame the workshop, but just want some sort of answer

IMG_0892.jpg

IMG_0894.jpg

IMG_0896.jpg

thanks for reading, and hopefully providing some answers,

ill upload more pics as i get them

Link to comment
https://www.sau.com.au/forums/topic/381206-why-did-my-engine-breakwhy/
Share on other sites

  • Replies 70
  • Created
  • Last Reply

Top Posters In This Topic

What were the clearances?

A couple of degrees of cam timing wont cause pistons to whack valves unless the timing was way out to begin with...

May have dropped a valve? or dislodged / broken a ring?

Just guessing until the engine is pulled to bits though

agree, 2 marks are 4 degrees, which is not a stupid amount, assuming the cam timing was alright to start with

Did you you use higher compression pistons that stock.

pull the head off and you may find the answer,

I feel for you :(

on the inlet side the is a gap between the lifter and the cam lobe on all the cylinders except the cylinder that would have the valve open,

on the exhaust side they are all up agianst the lobe

what do you mean snoz,

the shop said they checked my initial cam timing,

pistons was just standard RB26 86.5mm pistons,

head will be off tomorrow arvo, so will update with more pics and info

but would this cause it to stop dead and not turn on at all and seem as tho its seized?

as you can prolly imagine im rather guttered as this had been 3 years of hard saving and close to 25k in the making, and its all gone to shit,

gave no signs of packing up, up intil this faitful day

Then I would say the cam timing was well out to begin with, and the 4 degree slip means 12 bent intake valves

If the engine timing was out to begin with, the garage wouldnt have tuned / fixed it before it got tuned. My car got tuned by the same garage and before tuning started they found that the timing was out by 1 tooth on both cams in the same direction so it obviously skipped a tooth on the crank when i was changing the cam gears somehow. They fixed it for me and continued on with the tuning, luckily they didnt charge me an arm and a leg either haha

4 degrees will not cause the valves to bend like that. My money is on the valve guides stopping the valves from comming back up and in turn pistons hitting them.

Whatever the issue may be, sad to hear mate :(

Edited by snozzle

turn it backwards until one of the cam gears is lined up with the backing plate marks (if you can) If both cam gears line up then it wont be the cam timing (but at this stage its looking like the culprit) Also maybe the cam belt slipped at the first knock when you shut it off, then when you restarted it the others hit the pistons.

zebra, no pictures of both gears,

i was prepared for spun bearings as its my first build, but not this kinda of part mutilation, and it doesntl look like it was oil pressure related as when it stopped i looked in the head and there was def oil up there,

guides where new tomies, valves where new ferrea, springs where new tomie, so nothing should have failed, unless not done properly at the shop

Do the Tomei collets match up to the groove in the Ferrea Valves?

Thats if you used the tomei retainers/collets

After market stuff isnt always the same as factory with things like that

Edit - Im kinda thinking out loud here....As I said we are guessing until the engine is apart

is the engine actually "seized", or can you turn it over with a ratchet and socket until the valves hit the pistons,

so what I'm saying is the "engine" may be fine, but the top end is what is causing it to appear seized.

the bottom end is not siezed, although wouldnt turn forward, could turn it backwards almost the hole way around and the forward again ubntil the same spot,

not really thinking that clearly as its not a task i wanted to be doing, so didnt check the cam timing before i tooke the belt off, and have sinced moved the cam and what not so i could get to the head studs,

belt was tight when i took it off and new when put on and still in good nick

i can only presume the valve and retainers matched up as i didnt hear anything from the shop that did the work

didnt even get the thing on gate as it had a boost cut in the ecu and stiff springs in the gate,

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

    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...