Rebuilt 3B Advice after 2K Miles (lots of Blow by)

[82BJ40]

Hello,
I had my 3B enigne rebuilt at a machine shop. They disasembled the block and reassembled it with new sleeves and pistions. I put the rest of the engine back together.

After puting on some miles it was noticable that there was a lot of blow by. Without much expereince and reading some threads that it takes a long time to break these engins in. I just keep running and adding oil when needed. After about 3000 miles it realy became to much and I assumed something must be wrong.

I just took the head off and it looks like the pistons are realy poorly aligned with the cylinders. Maybe this is realy obvious but I just want to get some confirmation that there isn't something normal about a gap between the piston and cylinder when it is at the bottom of the stroke. When they come to tdc the gap is much better but I can still see it in not a uniform gap around the piston.

If the photos don't show it well I can make out the top ring the gap is large enough.

Thank you
Dan

BJ42 1982 3B with Turbo

 

[AirheadNut]

Did the machine shop use an oversize bore sleeve with stock size pistons? You're right, it definitely doesn't look right, you shouldn't be able to see the piston rings from above.

 

[82BJ40]

I provided the rebuild kit and it came with sleeves and pistons. I would assume they were the correct size. With the gap being worse at the bottom of the stroke it seems like the cylinder was cut at a taper.

Is it standard to cut the sleeves to size once they are pressed into the block?

I am going to pull the engine and take it a different shop and get a better assessment of what went wrong.

Thanks

 

[lacalvette]

Finish liner don't but semi-finish liners need to be bore after they are installed.
On a different note, looking at your picture, seem that you used after-market piston. Not sure which one you use but I have ones from Engine Australia with mention: "do not turbo charge...", I can say they don't have steel top rings groove like the Toyota.

 

[82BJ40]

Since I am in the USA and the rebuild was done about 4 year ago, I worked with a Canadian parts shop in BC. I believe they sourced the rebuild kit out of Austria. The shipment was direct from Austria. I was just the middle man between the machine shop and the parts and didn't pay that much attention to the parts that came in so I don't know if they were Finish liner or semi-finished linear. Also don't know about the pistons.

I could see a parts shop sticking a don't turbo warning on any part that wasn't original design as a turbo component.

I didn't know there was a difference in available pistons for the 3B between Toyota and Aftermarket. The pistons had 3 compression rings and an oil ring. Does the Toyota piston have 4 compression rings or does it have 3 but are in a different position. I am not sure I can get toyota pistons, but would like to if the aftermarket one are not as robust. Do you happen to know the Toyota part number?

Thank you

 

[lacalvette]

Engine Australia are full alu. Toyota have a steel groove on the top ring. Both have two fire ring and one oil ring.

 

[lacalvette]

Builds - 1985 JDM 3B Engine Rebuild and Other Stories

Looking Good bud!

forum.ih8mud.com

Post 142
The entire thread is very interesting.

 

[82BJ40]

I was able to pull the pistons and found the number one piston had half its skit broken off. Any ideas on what may have happened to cause this catastrophic of damage? The other pistons didn't have the same damage, but were also very loose in the cylinder.

I took a picture of the piston up close and it appears to be closer to genuine Toyota piston then an aftermarket one, when references the phot that "Lacalvette" posted. Mine has the steel ring on the top ring, but the hole pattern is more like an aftermarket piston. Any thought if this piston could be an original Toyota piston?

Another thing I noticed when I was breaking down the enigne, is the physical timming was two teeth off, see the picture. My thought was because both the cam and injector pump was the same number of teeth off, this wouldn't be an issue.

 

[roscoFJ73]

Looks like the bores are out of vertical alignment. A really shoddy machining job

 

[OGBeno]

Wow. Looks like you might have used the same asshat clown machinist i did.

 

[roma042987]

The whole "breaking in" thing is b.s. A properly built engine doesn't need to be broken in. Definitely looks like some shoddy work there.

 

[TonyP]

I was able to pull the pistons and found the number one piston had half its skit broken off. Any ideas on what may have happened to cause this catastrophic of damage? The other pistons didn't have the same damage, but were also very loose in the cylinder.

I took a picture of the piston up close and it appears to be closer to genuine Toyota piston then an aftermarket one, when references the phot that "Lacalvette" posted. Mine has the steel ring on the top ring, but the hole pattern is more like an aftermarket piston. Any thought if this piston could be an original Toyota piston?

Another thing I noticed when I was breaking down the enigne, is the physical timming was two teeth off, see the picture. My thought was because both the cam and injector pump was the same number of teeth off, this wouldn't be an issue.

View attachment 2867416

View attachment 2867417

View attachment 2867418

I'd guess the horrendously fitting piston was slapping around at the bottom of the stroke against the cyl wall and busted the skirt. Why they fit so poorly, who knows? They certainly didn't use the FSM for simple timing procedures so who knows what they did with the sleeves and pistons.

The whole "breaking in" thing is b.s. A properly built engine doesn't need to be broken in. Definitely looks like some shoddy work there.

Can you sort your references? Rings and bearings do needed to be worn in and oil changed.
That said, engine break-in has been debated for decades.

 

[OGBeno]

Remember, these are sleeved engines. So the sleeve to cylinder bore might have been done incorrectly (as in my case) and then the piston to sleeve bore could have been done incorrectly as well.

 

[roma042987]

I'd guess the horrendously fitting piston was slapping around at the bottom of the stroke against the cyl wall and busted the skirt. Why they fit so poorly, who knows? They certainly didn't use the FSM for simple timing procedures so who knows what they did with the sleeves and pistons.



Can you sort your references? Rings and bearings do needed to be worn in and oil changed.
That said, engine break-in has been debated for decades.

I'm not sure what you mean by "sort your references" perhaps your referring to where I might have read that? In which case I didn't, that comes from experience and a thorough understanding of the intricacies of how an engine works. For instance if the bearings are properly sized and installed you won't have any "set in" or particles that "wear in" and need to be flushed out with early initial oil changes. Same goes for passages being thoroughly cleaned after a rebuild and not introducing contaminants into the oil. Perhaps the most pertaining to the discussion here would be ring "seating" again not really a thing unless perhaps something was done incorrectly and tolerances are too tight. Have you ever seen the cylinder walls on a good running high mileage engine that still has cross hatch at 300k+ miles? These "break in" theories are basically done with the intentions and hopes of rectifying mistakes done during a rebuild. I firmly believe the rings are "set" the first time an engine is started and at operating.

 

[82BJ40]

It makes me more worried if there is a potential that the previous machine shop has damaged the block. Is this likely

I looked through my 3B manual an could find any specifications about the engine block and OD of the linear.

Is there a min wall for the linear? Can you correct a bad engine bore by boring the linear if the linear wall doesn't get to thin?

Thank you

 

[TonyP]

I'm not sure what you mean by "sort your references" perhaps your referring to where I might have read that? In which case I didn't, that comes from experience and a thorough understanding of the intricacies of how an engine works. For instance if the bearings are properly sized and installed you won't have any "set in" or particles that "wear in" and need to be flushed out with early initial oil changes. Same goes for passages being thoroughly cleaned after a rebuild and not introducing contaminants into the oil. Perhaps the most pertaining to the discussion here would be ring "seating" again not really a thing unless perhaps something was done incorrectly and tolerances are too tight. Have you ever seen the cylinder walls on a good running high mileage engine that still has cross hatch at 300k+ miles? These "break in" theories are basically done with the intentions and hopes of rectifying mistakes done during a rebuild. I firmly believe the rings are "set" the first time an engine is started and at operating.

Basic engine building and metallurgy would disagree. New rings need to wear to cylinder walls and new bearings wear to their races.
This is not conjecture, this is a mechanical fact.

The rings seating have nothing to do with this discussion. It was poorly machined and assembled. End of story.

"I firmly believe the rings are "set" the first time an engine is started and at operating."
They aren't. This is a fact.

 

[FJBen]

I agree with the above. Shoddy machine shop work.

The 3B has press fit dry sleeves and unless the liners are the wrong size, or the block has damage, you shouldn't have to bore the actual block. Depending on the liners you got, the shop could have bored them when they didn't need to or done it incorrectly.


In any case, a lot of blowbly means rings, pistons, clearance. OCCAMS razor says that bore isn't right, blowby till she gave up.

 

[FJBen]

It makes me more worried if there is a potential that the previous machine shop has damaged the block. Is this likely
I looked through my 3B manual an could find any specifications about the engine block and OD of the linear.
Is there a min wall for the linear? Can you correct a bad engine bore by boring the linear if the linear wall doesn't get to thin?
Thank you

Have you measured the liner like it shows in the manual? That will tell you a lot of information on each cylinder.

 

[roma042987]

Basic engine building and metallurgy would disagree. New rings need to wear to cylinder walls and new bearings wear to their races.
This is not conjecture, this is a mechanical fact.

The rings seating have nothing to do with this discussion. It was poorly machined and assembled. End of story.

"I firmly believe the rings are "set" the first time an engine is started and at operating."
They aren't. This is a fact.

Ok buddy whatever you say. There is theory and there is reality.

 

[TonyP]

Ok buddy whatever you say. There is theory and there is reality.

Solid, helpful, fact-filled, reply.

@82BJ40 Hope you get it sorted.