Why Did My Engine Break...why?

[ahh 33 s2]

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

thanks for reading, and hopefully providing some answers,

ill upload more pics as i get them

[zebra]

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

[zebra]

Just in the photo of the cam lobe and lifter...is the lifter sitting a few mm below the cam or is the lobe lifting it but just out of shot?

[blue_vl_t]

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

[snozzle]

valve guide slipped? improperly fitted?

[blue_vl_t]

if the lifters are not touching the cam you have bent valves, or one at least anyway

[ahh 33 s2]

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

[zebra]

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

[Guilt-Toy]

condolences

[snozzle]

Is the engine in correct timing right now?

[zebra]

Can you post a pic of both cam gears?

[ahh 33 s2]

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

[snozzle]

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 October 25, 2011 by snozzle

[zebra]

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.

[ahh 33 s2]

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

[zebra]

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

[Dobz]

Was the timing belt in good nick and properly tightened when you pulled the cover off?

[blue_vl_t]

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.

[ahh 33 s2]

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,

[zebra]

Its a good think that the bottom end turns freely.

Might just need new guides and inlet valves and you're off again