4AGZE/3SGTE weakneses

[Shifty]

Hi guys

I figure if pulling down any turbo engine it should go back together with:

ARP rod bolts
ARP head studs
Decent head gasket
Forged pistons

Is there anything in particular that needs attention on the 3SGTE or 4AGZE? I've heard that 3S's do head gaskets... anything else that needs attention?

[Shakotan_Aaron]

decked block and head wouldnt be a bad idea, to make sure 100% sure that both surfaces are strait.

depending on $/hp rods as well.

[Shifty]

Thanks, I'd consider that a standard rebuild item so no worries there.

Valve springs, oil pumps, anything else go on these semi-regularly?

[Shakotan_Aaron]

oil pumps seem to be fairly good (on 4ag's anyway).

but obviously you would replace it. best to use a new standard GENUINE pump. no need for higher flowing for the 4ag at least as they already have oil drain problems as it is. i believe that wet sump N2 cup cars use a standard oil pump. there is a TRD gear for it but its been long since discontinued. it was the same as a standard one only a bit stronger.

high boost or high revs you may want to consider valve springs but i haven't heard much in the way of failures happening.

[mattysshop]

maybe some better bearings..

depending on how much you want to rev it, possibly a shim under bucket setup.. but if you planning on doing the revs that would make that worthwhile.. you would need to seriously consider rods and complete balance.. so thats prolly fine.. with my 4AG's i've constantly seen 8000rpm, just with a freshen up, gapless top ring, port job, ecu and quads.. 3 years after i assembled it it, it's still turning to 8k daily (gone through a few hand changes by now)

and 4AGZE pistons have been covered many many many times before, depending on who you talk to.. there forged.. or not quite forged but almost (depending who your talking to).. but they sure as hell ain't cast! (like a 4AGE piston)

[Talasas]

Yep, I'd say good favour to do them is just a nice balance, good bearings, good rings, give the bores a hone and tidy up the head, get the clearances right.

[Cuts]

new oil pump and water pump should be replaced no questions for 3s.

gen3 3sgte have metal hg stock so no worries there. Rods are plenty strong enough. some good bearings (ACL etc)

[trdee]

err... how do you "almost forge" a piston? or anything for that matter? the GZE pistons are definately forged, just read a thread last night from the old forums where oldcorollas had inspected a GZE piston under the microscope and it was definately forged.

I have also been told that GE pistons are forged, but haven't yet seen any literature to back up this claim, but GZE pistons are definately forged.
edit; here
http://forums.toymods.org.au/index.p...t=0#msg_184686

[jonathan yee]

some good info here. weaknesses of 3s eng's etc.

http://www.roadandtrack.net.au/index...&id=1&Itemid=4

[assassin10000]

oil pumps seem to be fairly good (on 4ag's anyway).

best to use a new standard GENUINE pump.

there is a TRD gear for it but its been long since discontinued. it was the same as a standard one only a bit stronger.

On the 4ag's use the 'smallport high comp/late model GZE/silvertop' oil pump; 15100-19036 . It has a round style gear which DOESN'T break like the original square cut version & the reason for the trd gearset (different material). Provides more volume/pressure with less chance of failure.

I did a fair bit of research into 4a oil pumps not too long ago (january). See: http://www.hachiroku.net/forums/showthread.php?t=15957

Andrew

[mattysshop]

err... how do you "almost forge" a piston? or anything for that matter? the GZE pistons are definately forged, just read a thread last night from the old forums where oldcorollas had inspected a GZE piston under the microscope and it was definately forged.

I have also been told that GE pistons are forged, but haven't yet seen any literature to back up this claim, but GZE pistons are definately forged.
edit; here
http://forums.toymods.org.au/index.p...t=0#msg_184686

i know they are forged.. but some ppl depending on who you talk to still have the impression they are not.. obviously unless they have read that write up from oldcorollas.. they belive it's hearsay..

GE pistons definitly arn't forged.. they are just a regular cast piston..

i agree with the 7 rib block version of the 4a oil pump.. as with pretty much that whole bottom end to start with.. they have bigger gudgeon's (20mm) and big ends (42mm) and most come with oil squirters.. some of the early 7 rib block/big port head combo's didn't have the squirters, but the casting is there..

[Hen]

My opinion and experience is that a 4AGZE doesn't have weaknesses. If you make sure it has oil in it then you'll be fine.

Yes, I know it is a simplistic view, and there are general maintainence things to keep an eye on (the Road and Track article is a good start), but I am blown away by how reliable and forgiving they are direct from the factory (or really, direct from a 15 year old Japanese car).

Hen

[TERRA Operative]

Late model oil pump as stated above
Small port head with the extra oil drain,
Enlarge the holes in the head for the water galleries (at the combustion chambers, you'll see what I mean).
1SZ shimless buckets for high revving or big lift, along with aftermarket springs (TRD or HKS I guess)
Smooth off any rough or sharp edges in the oil and water pump for good measure too.

Also, the 4A engine generally blows no. 4 cylinder. maybe check oil flow is going to be sufficient to there. (up oil pressure with a washer in the oil bypass then restrict oil to the head).

Oh, and either get a set of bearings with a groove in both pieces, or get two kits and put them together to ensure maximum oil delivery to all parts of the crank slidey bits.