Bad Rebuild? Again

[Rick]

My buddy has a GN that he recently had a local shop rebuild. Not very long after the rebuild, it started smoking and getting worse. He took it back to the guy and he said it was running way too rich and it washed down the cylinder walls and destroyed the rings. I told Terry to get the oil filter and have the oil tested. It came back negative for having fuel in it. Anyhow, the guy worked out a deal to rebuild it again. Now after about 500 miles on it he said it is smoking at idle. He pulled a plug last night and it had oil on it. I'm going to the garage he has it at tomorrow with my Turbolink. I'm almost afraid to run it, any advice on what to check first? He thinks it is running rich at idle not burning oil but with oil on the plug I'd have to wonder.

[jmidolo]

You said rebuild, but didn't give specifics... Was it just a stock bore w/stock pistons re-ringed, new bearings etc, or did he have block machinine done w/.30 over pistons, cut crank and all... What components were used if new pistons, how's the machine shop that was used for the work if any? What about the mechanic..does he do turbo Buicks much or not at all?

[Bruce]

My buddy has a GN that he recently had a local shop rebuild. Not very long after the rebuild, it started smoking and getting worse. He took it back to the guy and he said it was running way too rich and it washed down the cylinder walls and destroyed the rings. I told Terry to get the oil filter and have the oil tested. It came back negative for having fuel in it. Anyhow, the guy worked out a deal to rebuild it again. Now after about 500 miles on it he said it is smoking at idle. He pulled a plug last night and it had oil on it. I'm going to the garage he has it at tomorrow with my Turbolink. I'm almost afraid to run it, any advice on what to check first? He thinks it is running rich at idle not burning oil but with oil on the plug I'd have to wonder.

What was the tune like?.
BLs, any KR?.
How much boost?.

Compression, or leak down testing done.

Oil possibly from a compressor seal in the turbo?.

Oil vs Fuel fouling can be easily confused.

[Rick]

Keep it coming, I'll have him get me all of this info. Thanks! Tuning I won't know until tomorrow night.

[tweaked]

Are all of the plugs oiled or only a few? Or all of them?

Did you check the vacumn block at the top of the TB for oil?
Did you check the TB throat for oil residue?
Did you clean out the intercooler after the rebuild[s]?

A bad PCV can cause what you are seeing.

Also bad valve seals or worn guides can cause individual cylinders to oil.

What kind of ring set and hone job was used?

Sounds like 50 questions huh??

Inspect the vac block. If it has oil clean everything and then pinch off the PCV hose for awhile.

Good luck and have a nice day.

LC

[turbodave]

Are all of the plugs oiled or only a few? Or all of them?

Did you check the vacumn block at the top of the TB for oil?
Did you check the TB throat for oil residue?
Did you clean out the intercooler after the rebuild[s]?

A bad PCV can cause what you are seeing.

Also bad valve seals or worn guides can cause individual cylinders to oil.

What kind of ring set and hone job was used?

Sounds like 50 questions huh??

Inspect the vac block. If it has oil clean everything and then pinch off the PCV hose for awhile.

Good luck and have a nice day.

LC
I was thinking along the same lines. If the intake gasket they used didn't have the stock type valley pan, then the PCV could very well be sucking huge amounts of oil.

[John Larkin]

PCVs suck huge amounts of oil regardless. It ran out of the darn vacuum pod once on me when I removed it.

[turbodave]

PCVs suck huge amounts of oil regardless. It ran out of the darn vacuum pod once on me when I removed it.Well, maybe. They're not supposed to, and if you have the correct PCV, they really shouldn't be pulling much at all. At least neither of mine do (except for the times I put the wrong PCV in :mad: )

And before you ask, no, I don't run check valves.

[gnsrule]

Hows the blow by ?? Do a leakdown test, that'll verify if its the rings.

[Rick]

Thanks for the replies, I'll call him as soon as I am done here. He called me with some info. The first rebuild they went .020 over. When he had to do it over he went .040 over. Bear with me on this info, as I am no expert but here is some more info. Left bank leak down test 47%, 70% and 60% with rockers off. Cylinder walls at 4.5 - 5 ?? and .025 top and bottom. Hypeuretic pistons. I don't know if this makes sense but maybe you guys can figure it out.

[Rick]

And also, he said the crank was turned and bearings replaced. The first rebuild the rings were toast after a few hundred miles. It seems this is happening again. What is done or not done during a rebuild to cause the rings to fry? I don't know what a line bore is but if it wasn't done, could it cause the rings to not last? The rebuilder as far as I know is a respectable builder but I don't think he has a lot of 3.8 turbo experience.

[HairDrier]

What kind of rings are they using?

What kind of break in procedure? How is your buddy driving the car for 500 miles? You need to vary the rpms, and load the engine periodically to seat the rings. No excessive idling. No extreme boost.

Did anyone verify that the turbo is not bad? And a compression test is a must. This engine block may already be ruined with all the machining being done

[gnsrule]

If im reading it right, the piston to wall clearance is set at .0045-.005 and the rings are at .025.
Acording to KB, the pistons should be at .002-.0025. The rings look right acording to KB, altho imo, 25 is too loose. Are the walls preped right and clean prior to install ? I wipe down everything w/ laquer thinner prior to assembly. You'd be suprised the shit thats left in the crosshatch even after a final clean from the hot tank or parts washer.

[EightSecV6]

What kind of break in procedure? How is your buddy driving the car for 500 miles? You need to vary the rpms, and load the engine periodically to seat the rings. No excessive idling. No extreme boost.



I have to disagree here!!!!!!!!! :add_wegbr

[Rick]

Molly rings is what he says. Break in was extremely easy. He was very careful about it since what happened on the first rebuild. He wanted to do everything right. I don't know about the methods used for cleaning the cylinders. Also, found out there is no oil in the up pipe or plenum.

[HairDrier]

I have to disagree here!!!!!!!!! :add_wegbr

Well Bill its safe to say your car is in a class by itself :star: :jean:

[Rick]

Well, looks like the rings are shot again. The leakdown was 70% on the one he showed me yesterday. That's it for the block too as he already went to .040. He's trying to settle it out of court for $1900. If he has to go to court then he'll go for all of his expense. I just wish he'd get this car done as he has had terrible luck with it since he bought it. Thanks for the help guys!

Rick Joest
Indy

[HairDrier]

$1900? Must have been a cheap rebuild. Be sure to include a few hundred for the next block he will need since this bum ruined his!

[jmidolo]

That's a major bummer, what's the details on the builder? Does he know how to do a TR motor or is he a 350 guy or what? Whats the builders take on the whole ordeal? Must be trying to pass the buck I would guess.

[Rick]

I don't know much about the rebuilder except he is here in town and has a good rep in building "other" engines. I doubt he has much experience with the T-6. The first time he started having problems he took it back to the rebuilder. He tore it down and told Terry it was running so rich that it caused the rings to fail. I told Terry to get the oil filter to test the oil.
This time, he said Terry must have let it idle too long. We still are not sure if the guy actually punched it out further the second time or just threw rings on it. We'll know soon as he has a guy that is going to take the heads off and measure. The money Terry has in it is probably around $4000.

[HairDrier]

That really sux because for 4 Large he could have had Frank or Bruce or someone that knows what they are doing build it. I dont know how fast he wants to go but I wouldnt push a .040 block past mid 11's

[jmidolo]

A lot of people don't understand that just cause you can build a chevy or a pontiac motor, doesn't mean you can do a Buick 6.....head similar stories over and over.