weird popping sound from my 3TC exhaust

[CHB]

i noticed that there is a weird sound coming out from my side pipe.. during idling, the motor idling very well. just that there is a popping sound in between the exhuast pulses. its like "pop.. pop...pop" consistently through the rythem.... i removed the spark plug cable one by one... i found that if i removed spark cable number #2, the sound disappeared(of course the motor running rough"... any one can help me on this?
it is EFI controlled by MS II ECU

[hi-ace]

A couple of things it could be. sticky/burnt exhaust valve and it's firing out throught it when it should be sealed shut.
If it's only on no2 plug then I can't see it being timing.
Do or have a compression test done.

[CHB]

i didn't do compression test yet. what would cause the burn exhaust valve?

[hi-ace]

Instead of writting down all the things that can cause your valve failure have a read here.

http://www.engineproblem.com.au/valve_burnt.htm

hope this helps out.

[Hurricane]

i didn't do compression test yet. what would cause the burn exhaust valve?

running straight out side pipes i think?

[CHB]

ok, the myths of the popping sound has be reveiled. i've turned the ignition timing down but yet still can't solved the problem. so i end up open up the valve cover to check the valve/retainer clearance. guess what happened after i open it up?
6 out of 8 of my double valve springs were broken into pieces!!! all the springs that holding my valves currently are the smaller diameter size springs, 6 of of the big one all broken into half... i stared at the head assembly still can't figure out what would have cause this! luckily i installed a double valve spring and save my low comp pistons..
any one experienced this before?

[Vios-GT_07]

this is very familiar to something Progkamol experienced.. breaking all the valve springs..

and from memory this was our conclusion

1. Asian stuff are dodgy
2. Part numbers are dodgy (in his case, he threw out the packaging so there was no proof of what or where the parts came from)
3. Tools that think the know everything install this
4. Issues with valve clearances and cam-shaft duration and lift not matching up to the springs
5. Spring coiling / binding..

but yea as we all questioned how metal springs can break, OC was pretty close to the answer... but like most of Progkamol's threads, there's no actual conclusion

good luck with it mate.. hope this helps

[CHB]

when the time i got this set of valve springs, it was dry and with a little bit of hard surface on it.. what do u guys comment as if u r in my current situation?

[thechuckster]

doubt it ... the spring failure would have come from within the springs - not the surface.

Ether the springs were too big, or the cam to big or a mix of over-sized everything.

fwiw: my turbo 18R uses stock springs, they were coping with >14psi boost, theres no need to change the springs unless you're building a race motor.

[Rodger]

Well there you go. Never would have picked that one. You can ignore anything I came up with on the 3Tc forum.

I broke an OEM outer valve spring in my 2T. They just get tired from age. I replaced all with new genuine ones and have done plenty of competition on them now.

If spring bind was a problem then it would have shown up the first time you tried to turn the motor over. It would not have turned.

Regards

Rodger

[CHB]

i broke most of my outer valve springs. my cam and rocker arms all still oem toyota. should i buy a new set of racing springs or stay with my previous stock 3T valve springs?

[Rodger]

CHB,

Go with OEM parts. Probably cost the same. Now do you have a "nearest" Toyota dealer?

Regards

Rodger

[CHB]

i went to few spare part shops. but when i ask for valve spings, they all said :" the valve springs never fail or break, so we don't spare it".
Rodger, how much does it cost for a new OEM valve springs cost you for a 3T?

[Rodger]

From memory, $50 AUD each. I will price a set up for you if interested.

That was about three years ago.

Did you know that 2T/3T valve springs can be taken in and out without removing the head?

I do it regularly. Not that it happens often. Last year I added inner springs into one of my 2Ts, gained 4kW.

Gotta love these push rod motors.

Regards

Rodger

[thechuckster]

i'd just find another 3T engine and strip the valve springs out of it.