Engine failure questions (pics)

[IH8TEC]

Issues came around after about a week or driving it on the new tune with a 7000rpm limited and running 10psi

Was installed in his car with different plenum, fuel system, ignition system and ECU. Ran fine like that too for a couple of months until it was again tuned and thats when the issues seem to have started.

enough said, tell him to take a hike, and take it to court if he wants.

[IH8TEC]

and to add to that, the only head problem i've had personal experience with is in bazda's car pulling about 7500-8000 coming onto the motorway, and got valve float. where the springs can't keep up and the collets lift. something like that.

due to weak valve springs in a FI setup, i dont know how different the silvertop ones are from blacktop head, but he was runnign 16v pistons also, and i think a valve just knicked a piston and bent it. so hardly any damage was done.

[TRD Man]

HRT, my advice to you is simple.
Stay away from the mechanic and the motor. Do not engage in any discussions about the cause of the failure.

Simply make a statement (written or verbal is OK) to whoever is making a claim against you that -
The engine was sold as a running and functioning motor at the time of sale and that no warranty was expressed or implied and none was requested. Further, that you have no control over the purchaser's use or treatment of the motor since delivery, bear no responsibility for it's subsequent failure and are not prepared to enter into any further debate on the matter.

Then walk away.

[Mr Revhead]

and still! i walk away!

[AE25]

to me.. the valves hitting other pistons would've/could've happened after a valve was dropped or something foreign entering #4. with a valve head floating around in a chamber.. surely the broken head would jam between another valve.. and the subsequent shock on the cam is enough to make the cam pulley jump a belt tooth or 3.. causing damage to other cylinders after the event?
also with that sort of damage.. the guy was either doing huge revs or kept driving after losing a cylinder and lots of crunching

[fivebob]

to me.. the valves hitting other pistons would've/could've happened after a valve was dropped or something foreign entering #4. with a valve head floating around in a chamber.. surely the broken head would jam between another valve.. and the subsequent shock on the cam is enough to make the cam pulley jump a belt tooth or 3.. causing damage to other cylinders after the event?

Have another look, there appears to be carbon build up on the valve indentations in the other cylinders, indicating they occured before the engine failed. If it happened as you surmise, then you would expect to see bright metal, not black carbon.

[ollieboy]

In reality none of this is your problem if you are worried about rectifying the problem. You are covered by the Sale of Goods Act. It states:

Risk prima facie passes with property

(1)Unless otherwise agreed, the goods remain at the seller's risk until the property therein is transferred to the buyer; but when the property therein is transferred to the buyer the goods are at the buyer's risk, whether delivery has been made or not

If you aren't worried about it then just ignore me

[try_hard]

you should tell the person to take the engine into "Geoff Crystie" or even the pics. he has alot of knowledge of 4ages and has build afew him self for his rally car. he may be able to shed some light on the situation.. but in full honestly i wouldnt of used the pistons with the 20v head for this very exact reason with the valves.

[sergei]

to me.. the valves hitting other pistons would've/could've happened after a valve was dropped or something foreign entering #4. with a valve head floating around in a chamber.. surely the broken head would jam between another valve.. and the subsequent shock on the cam is enough to make the cam pulley jump a belt tooth or 3.. causing damage to other cylinders after the event?

Have another look, there appears to be carbon build up on the valve indentations in the other cylinders, indicating they occured before the engine failed. If it happened as you surmise, then you would expect to see bright metal, not black carbon.

He is right, the engine did a few hundred turns or even thousands before it stopped. It is easy to tell by the state of the piston which got hole in it, just look how many indents from damaged valves/ valve pieces are there.

[NZ_AE86]

but in full honestly i wouldnt of used the pistons with the 20v head for this very exact reason with the valves.

[mr30%jr]

thats what you get when you dont use pistons with the right releifs

even just turning the engine over to get the right spot with the cam timing can do that

can i ask why the builder didnt use 20v pistons?

[Mr Revhead]

its a turbo engine.
wanted the lower compression forged pistons
there are plenty of cars out there that are interference. the blacktop 20v for example.
you only an issue when something fails

[IH8TEC]

this thread is getting funnier with people who obviously don't know about 4agte's

[try_hard]

you can buy low compression pistons for 20v not from toyota though to my knowledge but arias, BRC and i bet more make them.. i was going to use a 20v head on my project but since i managed to get the 16v ones cheap went for them and are not using the 20v head for this reason. because you are building a 20v 4agte dont mean you HAVE to use the GZE pistons its just the cheap conveniant way

Edit, but for a $50 doller block well maby you will take this risk

[sergei]

you can buy low compression pistons for 20v not from toyota though to my knowledge but arias, BRC and i bet more make them.. i was going to use a 20v head on my project but since i managed to get the 16v ones cheap went for them and are not using the 20v head for this reason. because you are building a 20v 4agte dopnt mean you HAVE to use the GZE pistons its just the cheap conveniant way

...but if you have bought GZE block off a mate for $50...

[NZ_AE86]

This is just funny, do you people have any idea how many engines are interference from the factory?
2e corolla engines are a great example - or do you guys wonder what Mr Toyota was thinking!

It's getting a bit off topic!

This engine expiry has nothing to do with the pistons being incorrect.

This conversion has been done by plenty with no problems.

[ollieboy]

^^ Blacktop 4age is interference as well.

[mr30%jr]

i dont see there being a problem with me and other people learning about usinng different heads with different pistons. its not that i dont know anything, i just dont see the point in spending that money building up a 4agte

if your gunna build something that temprimental you prolly want it non interferance anyways? or just buy some proper aftermarket pistons seems people shy out on the most important part of there powerhouse

[Alex B]

Those pistons have been used in set ups up to 22psi, in most cases they are not temperamental.

[CAMB01]

As long as the motor is tuned right there shouldnt be a problem. Same with the valve to piston clearance, as long as its timed right there shouldnt be a problem.