3S 'blowby' mystery

[jonchai]

I add to this, that a 3sgte (also Gen 1) professionally raced by another person has had the same problem and resulted in 3 destroyed main bearings. He had a few solutions including the one i use, but also some custom work to the head (hard to explain, essentially, lowering the height of the oil drain holes) and some other really wierd option.

all i'm saying is that, there are always problems associated with certain engines. some are easier to fix than others. Like the gaskets of 7mgte's and the rocker arms of sr20 engines. the one particular to the gen1 3sge is the oil pressure, and associated blow-by. and the fix is this!

[GBC_069]

john - how can i know if i have this potentially damaging thing to my 3s ??

[crown crazy]

Did you replace all rings or only oil ones? replacing rings if there is wear in the bore leaves an ongoing problem, compression can get past rings into sump without oil going past into firing chamber to create smoke. I have made it a rule of thumb that if you replace rings etc then the head should be serviced to replace valve stem seals and at least clean valve seats. unfortunately when rings are gone and there is knocking it's a fair bet bearings are on way out too. Sorry not good news.
crown crazy

[3sgte]

john - how can i know if i have this potentially damaging thing to my 3s ??

If you are not burning oil, the engine is installed on the same angle as intended (ie, not stood up for an RWD conversion), you are not "professionally racing" it, and you are keeping the revs at a reasonable level (below redline), then don't worry about it.

The main consideration for the OP I would say is the noise.


There are tens of thousands of 3SGE out there, including a used Gen II one I drove the piss out of for 48,000 kms, and 2 different ST 165 before that.

The oil return holes are huge. I agree that the PCV system on the first gen was somewhat lacking, but I don't see a need to cut a hole in the block. (excluding, possibly, the RWD conversion stood up racing scenario...)

Sorry, this doesn't help the OP's situation.
I hope you can get your noise resolved!
Is the timing belt tension set properly?

As for the pulsation/breathing thing, urantia is pretty much on target.

[1jzracing]

DO A COMPRESSION CHECK!!!

simple ... if the compression is within 10 psi then its all good it should be in the range of 170 to 190 or there abouts. its more important to note how even they are if there is a problem then it will usually only show up in 1 or 2 cylinders

eg. if a piston gets overheated through detonation or lean out it can pinch the top ring and that cylinder will drop to 120 psi or something.... and obviously there will be a lot of blow-by

all engines have a certain amount of blow-by its quite normal

[thechuckster]

make that compression check a dry one followed by a wet test (some oil down in the cylinder). Significant improvement in pressure suggests stuffed rings.

note: motors with long rods or wide pistons will generate a significant pulsation of air in the crankcase (and up to the rocker cover if you havn't blocked the heads' oil drains).

Another easy test to see if things are OK is to hold a small sheet of cardboard over the oil filler hole (covering it) - it should alternate from being blown up and then sucked back onto the hole as pistons rise and fall. You can also use this text to see if the PCV valve is working (behaviour should change if valve is removed or disabled).

cheers,
Charles.