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Old 11-11-2010, 07:51 PM   #1
mvette76
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Default problem with gm zz427

we are having a problem with the motor in my dads 66 vette. about two years ago we did a body off and my dad purchased azz427 & tremmec 5 speed . well from the strart it always puffed white smoke on start up and between shifts. well towards the end of the this summer it has gotten way worse big clouds at start up and between shifts .my dad has been in touch with gm and the dont want to deal with him at all tell him the have had no other complaints . he spent $10,000 for a motor that burns almost a quart of oil in 100 miles and he is not happy! looking for some advice he keeps hearing about some snake oils that will fix his problem but nobody can remember the exact name. is there a snake oil that will work? oh forgot to say we put new valve seals in and no change in the oil burning! or are we going to need to rering it? only has 2000 miles on the car since the frame off
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Old 11-11-2010, 08:17 PM   #2
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First of all, are you sure it's white smoke? Oil burning is usually blue smoke. White smoke is coolant getting into the combustion chambers, usually from a cracked block or head, or a bad head gasket.
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Old 11-11-2010, 08:20 PM   #3
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My guess is head gasket incorrectly Tq'd.
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Old 11-11-2010, 08:21 PM   #4
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Unfortunately, this is a fairly common problem with GM crate motors, particularly the big blocks.... ZZ502s are well known to be oil burners. From what I have read is, the general consensus to this issue is that GM did not use a torque plate when honing the blocks, therefore when the heads are installed and torqued down, the cylinders slightly distort(this is normal) but now the hone job is screwed and the rings basically eat themselves up and the pistons are sloppy in the bores....

Really crappy that this happens, especially for such a stupid short cut in the build process but.... it is what it is...

The only real resolution is to pull the motor, tear it down, bore it, hone it (WITH A TORQUE PLATE) and install the correct sized pistons/rings..... sux but.....thats the reality..
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Old 11-11-2010, 08:37 PM   #5
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What's your compression? If it's good then check your PCV valve. (if you have one) Could be sucking oil. Pop it out and see if oil residue is on the tip. Common problem with aftermarket valve covers. You may not have baffles in your valve covers at all and that will surely enable your PCV valve to suck oil. Cheap valve covers have cheap baffles and allow oil into the baffle area for the PCV valve to suck up.
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Old 11-11-2010, 08:54 PM   #6
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ya it is a blue oil smoke! we tried disconnecting the pcv no change! dad talk to some vender a sema and blamed it on the rings said he has rings with a higher tension and would fix the proble after a hone?
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Old 11-11-2010, 09:02 PM   #7
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mvette76,
So are you planning to pop the top and bottom off of the motor and hone it in the car? Damn that's a lot of work. If you end up pulling it to hone it, just take it to a machine shop and bite the bullet and get it done right and honed with the torque plates. Yeah it sucks, but that solution you mentioned doesn't sound very good to me. I'm no expert though so good luck with whatever you decide.
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Old 11-11-2010, 09:06 PM   #8
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Quote:
Originally Posted by mvette76 View Post
ya it is a blue oil smoke! we tried disconnecting the pcv no change! dad talk to some vender a sema and blamed it on the rings said he has rings with a higher tension and would fix the proble after a hone?
Did you guys change the intake by any chance? if so, MAYBE it could be sucking oil up through the intake gaskets into the intake ports but......not likely....

If it wasn't a GM crate, I would be looking at all other options but.....I'm putting my money on a ****ty hone and out of shape bores....ZZ502s have a lot of problems with this...
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Old 11-11-2010, 09:21 PM   #9
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Block that was honed without a torque plate....had 3200 miles on it and it was drinking oil.....

This pic was after it was thrown on the honing rig and ran the piston through it for 6 strokes..... Notice the blue area....cylinders are now out of round just from a crappy hone job with no torque plate..

Click the image to open in full size.

This is not a ZZ block right here but the same scenario...
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Old 11-11-2010, 10:17 PM   #10
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no the motor never had the valve covers off until we did the valve hasseals! we will pull it if it comes to that (yuck)and have done whatever it needs to be right and maybe a cam change! i think the cam in it is 211@.050 on the intake dad never like how it sounded through the side pipes
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Old 11-12-2010, 12:42 AM   #11
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Quote:
Originally Posted by ajrothm View Post
Did you guys change the intake by any chance? if so, MAYBE it could be sucking oil up through the intake gaskets into the intake ports but......not likely....

If it wasn't a GM crate, I would be looking at all other options but.....I'm putting my money on a ****ty hone and out of shape bores....ZZ502s have a lot of problems with this...
Actually, the biggest reason the 502's consume some oil is GM uses low tension oil rings instead of standard tension ones. I don't know what rings are being used in the zz427's.

I doubt this is due to not being honed with a torque plate. It sounds like the rings have never properly sealed. How was the engine broken in? What oil was used? If you're using synthetic, dump it and put straight 30 wt petroleum oil in it and then run the crap out of it for a few days. With 2k miles, you may have to re-ring it if the above doesn't work.

Last edited by Ben Lurkin; 11-12-2010 at 01:01 AM.
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Old 11-12-2010, 12:56 AM   #12
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all of those engines are expensive, and to put out crap like that?
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Old 11-12-2010, 02:56 AM   #13
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Ajrothm ,
thanks for the input about oil issue with GMPP BBs.
i was just thinking one day to swap my L88 engine for something more streetable ( both for easier use and possible easier resell of the whole car: possible buyers in Europe doesn't want just " a crate engine " but a GMPP because it's Chevy). But surfing the net i'vee never heard of such issues and the fact that it's not torque plate honed , it's simply crazy.
I've spent a bunch of $$$ on my L88 clone... i think i should be happy then because i know it's made in best way.
ah... on youtube there's a video of a brand new zz454 throwing out a rod on the dyno: bolt-nut not properly torqued !

http://www.youtube.com/watch?v=bGNNvl9WNL0

Last edited by elle88; 11-12-2010 at 02:59 AM.
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Old 11-12-2010, 07:54 AM   #14
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Maybe BLOCKMAN will chime in on this...I know he has repaired tons of these GM Crate oil fogger motors... There is way more wrong here then just low tension rings... Low tension rings and low mileage(<2000) is not gonna cause a motor to drink a quart of oil in 100 miles...

Not all of these zz motors have this issue but many do. Some are worse then others, some are livable but....

I know two different zz502s here locally that smoke like a chimney everytime they start them up at the cruise in...I seem em every week and just shake my head knowing thats an $8k engine right there....
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Old 11-12-2010, 08:03 AM   #15
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I see someone else has run into some of the friendly people at GMs warranty center.
Half the reason you buy a GM crate is for the warranty and then they just blow you off.
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Old 11-12-2010, 08:05 AM   #16
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I have nothing against crate motors but the guy who machines my motors does not like them. He has repaired like Blockman many a crate motor. He once told me and this makes perfect sense, GM builds many of these motors an hour. It takes him many hours to do one motor. He takes his time and measures everything and makes sure it is correct. Which engine would you rather have between your fenders when the tach is approaching 7000 rpm? I ran a replacement LT1 shortblock for a couple of years and it ran pretty well. I wanted to freshen it up and took it over to him to check out the block. It had maybe 4000 miles on it. We measured the bores and I was amazed at how out of round they were. He showed me a freshly machined block he had just done. The bores were perfect. Which one is going to seal better. Some crate engines are good some not. It is a chance you take. My advice is to remove this motor and have the block machined correctly and use good parts going back together. You will be rewarded with a good performing motor that should not use oil.
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Old 11-12-2010, 09:46 AM   #17
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Im not fond of crate motors for the same reason, youhave no idea what kind of quality control is in place at the factory and the warrantee is rarely worth the paper its printed on.

I've installed 2 crate motors in my life, and to be fair only one was a gm crate (and the generic 350 at that) the other was a kragen rebuilt motor It came in a crate so I assume it counts ) both motors we cracked the crankcase and checked torque on rods and mains and both motors were loose.

If i were to ever buy a gm zz motor i would likely either get it in kit form like some of the big block crates seem to be available in, or i would dissassemble the thing before i even began. - way too big an investment to mess with.
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Old 11-12-2010, 12:33 PM   #18
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Damn, I must have lucked out with RamJet I know it was initially a marine engine before being offered as a crate motor. Haven't heard the horror stories from the boat guys.

Click the image to open in full size.

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Old 11-12-2010, 01:40 PM   #19
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Quote:
Originally Posted by mvette76 View Post
no the motor never had the valve covers off until we did the valve hasseals! we will pull it if it comes to that (yuck)and have done whatever it needs to be right and maybe a cam change! i think the cam in it is 211@.050 on the intake dad never like how it sounded through the side pipes
Have you talked to the folks at GMPP? The engine does/did have a warranty. The guy at SEMA is likely correct given what I've seen with a few 502's - low tension rings. A rehone & rering job, however, is not a trivial repair. If it is still under warranty, don't mess with it until you get it looked at.
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Old 11-12-2010, 06:43 PM   #20
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Quote:
Originally Posted by Ben Lurkin View Post
Have you talked to the folks at GMPP? The engine does/did have a warranty. The guy at SEMA is likely correct given what I've seen with a few 502's - low tension rings. A rehone & rering job, however, is not a trivial repair. If it is still under warranty, don't mess with it until you get it looked at.
Good luck with that!!!
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Old 11-12-2010, 06:43 PM
 
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