4A-GE Excessive Blowby 3000km after Rebuild

[allencr]

Now the engine is running limp.. ...new plugs and still limping. So could it mean that the limp is from compression leak, hence blow-by?

What's the compression?
Then figure out what is causing your 'limp' & blow-by. Probably broken ring/s IMO, but could include electrical and/or fuel.
Read & re-read any site at all about engine break-in, as what you've done by babying & 3000km oil change is the opposite of 99.9% of what you'll find on the WWW.
Good luck.

[old_mr2]

Yep as above, re hone. Then take it out on the street and flog it! I used a running in oil on mine. Changed it at about 600km and 1500km. Currently at about 5000km and making good power. Now using semi synthetic oil.

[ballpencil]

okay lol. i have just enough responses to say i'm not being trolled. definitely not gonna baby the engine this time. so in short:

1. open the engine
2. pray to Ares i don't have to rebore
3. measure slug-bore clearance
4. if safe, rehone and fit new rings to GZE slugs, swap them in
5. finish rebuild
6. mineral oil for the 1st 500km
7. run the engine like crazy keeping RPM to 3/4 from redline
8. replace oil and enjoy?

[thechuckster]

You forgot:

9. do epic skids

[TERRA Operative]

When you read to drive it hard, it's not just revving it out.

You have to load the engine up, so put it in third and make the engine work, then let it coast in gear back down the rev range. Do that a stack of times and you'll get the engine sealed up good.
Best bet would be to head to the hills and give it a good hard drive.

[andrew_mx83]

quick and easy way to check the bore is to put a brand new ring down it and check the gap. if its got a big gap (high end of factory tolerance) it probably needs a bore. hopefully you will be ok with just a hone or "dunny brush" (pic above)

why the gze pistons? wouldnt they be lower in compression?


can you get oil like this where you are?
RUNNING IN OIL - Penrite Oil

its pure mineral oil, with no additives and detergents etc which glaze up the bores. run something like this for the first 500km or so, then normal mineral oil for a couple of thousand, then synthetic or whatever you like.

on first fire up, have someone play with the thottle a bit to keep it from idling while you quickly check for leaks, then get straight in the seat and go! dont muck around for 15 mins, usually they havent even got to temperature before im driving em.
running in is best done at night when the roads are empty, so you can get into it without worrying about traffic. hills are best, otherwise empty industrial areas are good too. remember hard acceleration in highest gear possible, then bring it back down through the gears not using the brakes if possible. this will push the rings out in the bore and scrape the oil off.

[ballpencil]

engine opened up today and here's the problem (or should i say, the aftermath)



Broken ringlands found on all FOUR pistons. Pistons were installed on the right orientation (the notches for the oil squirter were on the right position). You'd have to be a very crappy mechanic to install the pistons incorrectly anyway. However, the conrods were said to be installed the wrong orientation. There's an oil breather hole on the rods and said it should face the same side as the oil filter. Is this correct?

Is this a case of oil starvation? Or too much timing advance? Am using megasquirt so spark map isn't really stock.

[ballpencil]

btw, i can say goodbye to not needing rebore. they were scratched and i have to get new liners to swap the same sized GZE slugs. byebye money.

why the gze pistons? wouldnt they be lower in compression?

because i'm putting turbo and might as well do it now.

since i have to flog the engine good this time, would i be safe with flogging using the same fuel and spark map on my Megasquirt? compression's definitely lower so i should be safe, no?

[ballpencil]

When you read to drive it hard, it's not just revving it out.

You have to load the engine up, so put it in third and make the engine work, then let it coast in gear back down the rev range. Do that a stack of times and you'll get the engine sealed up good.
Best bet would be to head to the hills and give it a good hard drive.

okay.. basically try to get it as close as possible to 100 kPa MAP reading, while keeping RPM not so high, correct? start with 2nd or 3rd gear and hill climbs, and lots of engine brake. try to avoid idle.

[andrew_mx83]

wow couldnt you hear that?

what max ignition advance on the map? did it ping at all?

[ballpencil]

wow couldnt you hear that?

what max ignition advance on the map? did it ping at all?

nah, i didn't hear any pinging.. here's my spark map. i think it's slightly aggressive? the engine ran great with this though.

perhaps it could use more advance on high RPMs?

[thechuckster]

stay away from 100kpa MAP areas during running-in - you want to significantly load the motor up but not so much that you're washing the bores with fuel.

You could probably loose some of the advance in the idle area and during running in, pull any >38 degree areas down to 38. Once run in, retune.

Also, the low rpm (500-1500), high MAP areas could loose some advance otherwise you may get some detonation.

Go finds some undulating hills and accelerate up them (not WoT, but MAP climbing up to 60-80kpa) with revs around the 2.5-5k prm range then decel (foot right off, MAP down as low as possible) on the downhill bits.

[RT40Corona4AGTE]

unlucky there mate, I also agree that you should pull a bit of timing out of your low rpm regions. I also agree that everything above >38 as a miniumum be pulled down to 38. But I would be conservative and pull down to 34 or something atleast if it was me.

was there any combustion chamber damage? photo of chambers please?

[ballpencil]

so are you guys suggesting that this was due to predetonation?
i put the idle advance value the way they are from having read that actually the stock ecu idles at 16 deg as well! i'm using ford edis system but that shouldn't matter, no?
okay i'll be more conservative this time and get max 34 deg and lower idle region before dyno this time.

[SHEPPO3930]

when i see damage like that i immediately assume the ring lands got smashed with detonation. and considering how strong those GZE pistons are, there must have been some serious detonation going on!