Willy Wonka: 87 4runner, 5VZ, SAS w/ FJ62,

[helipilot77]

   

[kneedownnate]

You may be ok and never seen an issue, but if that's regular teflon tape you may develop leaks wherever it is used.  There is a similar tape made for oil/gas based use that seals the same but is resistant to petroleum products, or you can get it in paste form.  At my last job I've seen many oil and fuel fittings leak with teflon tape, but seal with the proper tape or paste.

[zippo]

So I got home to night was excited about getting my Megasquirt in the mail. Took the runner out for a pre squirt drive and something blew up. Its no longer running. Drained the oil didn't see any metal, possibly head gasket. Blow by test didn't turn up good results. Not sure where or what went.... f- me......

[John Doe]

 

[Nation]

NOOOOO!!!!   

[1985CRAWLER]

 
u said u had no compression in cylinders 1 and 3?

[helipilot77]

  NOOOOOOO!!!

[zippo]

Noooooooo is right. I hope its nothing to xrazy. Guess im pulling a 22re apart in the next few weeks.

[Nation]

I'm gonna say simple stuff!! Time consuming but simple.. keep our fingers crossed for a head gasket

[twistedtoy92]

Oh no that's a real downer!!! Hopefully it was just the HG... Time for a MLS gasket!

[zippo]

AAAAAAAHAHAHAHAHAHHHHHHHHHH!!!!!!!!!  Got the head off and found the problem! Way to much piston to to side wall clearance. Spec calls for .045mm (.0017") I have am to push a .6858mm (.027"). This explains a lot! The sumbitches machinest has some questions to answer. Now to call and see about getting it fixed!!!! !

[emsvitil]

So it blew out the rings ?

[Cheesemaker]

You didn't check that when you built the motor?   

[zippo]

I dont have the proper tools to check this accuratly bore gauge and large enough calipers.  It also seems to have more clearance front to back then side to side. I checked side to side. Which is where you get the wear. I will take the hit for not checking all the way around. But I dont remember it being an issue. Live and learn I guess.

The best part is it still has its cross hatch!

[Nation]

    

[zippo]

[twistedtoy92]

I take it you didn't measure the ring gap? Almost sounds like its .030'' over rather than .020''

[zippo]

Of course I measured ring gap and they were all in spec. I even have a pic on here. Of me checking the ring gap. Lol. My dad asked the same thing and I did the math the difference in ring gap over the difference im looking at would have still been in spec.

[twistedtoy92]

Good, I thought you did.

[helipilot77]

This makes me sad. 

[zippo]

SOOOOOO. I got it all apart and all I can say is wow. I will say my post above is inaccurate and they are not overbored as much as stated. But  when measureing the side skirt, with a fela gauge (which is very inaccurate for this task) I am getting .152mm (.005"). The spec is .04mm(.0015") so still crazy over bored and it shows below. I left the pics a little large so you can see all the detail. Everything else looked great. And this will be an easy rebuild after a quick trip to a different machine shop. All 4 pistons had the same issues, some worse then others.

[emsvitil]

Maybe you can get something out of these:

http://speedtalk.com/forum/viewtopic.php?f=1&t=19031&sid=7942a8177d4d0b1ab7360225b2faa41f&start=15

http://www.moparchat.com/forums/archive/index.php?t-69454.html

[zippo]

Good links. The rings show no sign of butting, which I would agree could cause it. (and the ring gaps were in spec) Also detenation was a big topic, cause by to much fuel in between the rings or timing (I ran FSM timing) issues/fuel issues. I never noticed long periods of overly rich or lean AFRs, but this could be a cause (though several posts stated, a sign of this would be a dark top ring, which I did not notice?) However it doesn't explain all the blow the motor had, which seemed to get worse and worse over time. (multiple/different problems?) The cause of this is beyond me as I'm not a prof engine builder, though I can't ignore the glaring problem of the way out of spec clearance. I might email the pics a few places I deal with and see what they say. Still crazy though.

[jimbo74]

shouldn't the machine shop have realized the overbore? are they at fault here? sounds like a warranty issue unless you messed up on the specs you gave them or something

[zippo]

I took them the pistons and spec sheet. The pistons (other then the ring lands) have no damage and almost no wear. I am going to have another machine shop measure the clearence with the proper tool and they will be able to give me a 100% answer. One day I might buy a dial bore gauge and large enough micrometer calipers. But anyhting in the 92mm range is $$$$

[toyodaaddict]

  How frustrating. Good luck getting things straightened out, hope it doesn't cost ya to much.

[twistedtoy92]

I have all those tools in my box, too bad you are on the west side of the state...

[K.Lund]

Detonation Kills. Get some forged pistons for the rebuild, the ring lands are stronger. How are you retarding your timing under boost?

[zippo]

I was told at 5 psi, the FMS and timing curve would be fine. By multiple sources. Yeah I think it was a combination of things.

[K.Lund]

Next time, I would start out with a few degrees of static timing retard, and make sure your air fuel does not go leaner than 12.5:1.  Also, think about sanding the sharp edges on the piston tops, anything that can cause a hot spot will lead to detonation.