This may sound like an odd and/or obvious question here but I wanted to shoot it out there... here is the scenario: 1991 5.7 TBI 9C1 police engine with 100,000 miles on it. Burns oil. Smell is prevalent. About 1 quart every 100 miles or so - pretty bad. What could this be? Bad piston/piston ring? Valve seals? Etc etc. What do you people think? Thanks!

F-Messenger.

 

Could be your rings or your valves.....or you could have an oil leak somewhere! Check for visible oil leak, if you have none then do a compression check!! After that take out a spark plug and squirt some oil through the hole.....then do another compression check on that cylinder!! If the compression goes up from what it was before then your rings are bad!!

 

Yeah, I agree, if you have an oil leak somewhere it could cause some oil loss problems. If its the rear main seal, that could be pretty darn hard to fix, so check your valve covers, timing cover, oil pan, intake, ect. Also, it could be that your valve seals are totally shot, that was the case on my car. I bought a new set of seals from TPIS for $16 and had them installed when I put on my new springs for the LT4 HOT Cam.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

Update:

Engine has light blue smoke that comes out from engine during operation and there is no noticable leaks at at. Also, no noticable lack of power from engine. Thanks guys for your responses so far!!

F-Messenger

 

When does it smoke the worst? If it is worse when you are heavy on the gas at higher RPM- rings. If, when you let off the gas for a moment and then back on you see a larger puff - valve seals.

Good luck!

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91 RS/3.1 - Stock except stereo system, daily driver.

86 IROC - Pep Boys 350 longblock, Performer 750 carb, Performer RPM intake, Comp Cams 280 magnum, Hooker 1 5/8" shorties, Flowmaster Y pipe, 3" pipe to Flowmaster 2 chamber Dual outlet, TH 350 performance rebuild w/shift kit, Daco 2600 Stall, 3.42 Gear Moser 12 bolt w/Eaton posi.

[This message has been edited by Racerwannabe (edited March 23, 2001).]

 

If it smokes really bad on startup, but then runs clean after a couple minutes, it's the valve seals.

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Michael Bangert
mbanger@iupui.edu
'88 5.7 IROC
'99 CBR1100XX
'00 Silverado LT

 

Update: It is confirmed that smoke stays same color but increases (gets worse) at higher rpms. Beginning to strongly look like piston ring(s), amoung other things possibly. Is it common for just one ring to go or multiple rings from high mileage? Hmm. All of your answers have def. helped thanks alot!

F-Messenger

 

Sounds like a ring/rings all right! Could be one ring...could be several!! What's gettin' me is that it's only got 100,000 miles on it! Oh well, I've seen stranger things happen!! My car has over 200,000 miles on it and was runnin' peachy clean until my last oil change!! I changed the oil and when I started it up again it smoked like crazy and still does!! Probably that engine flush I used.....it's good for mid mileage cars but not high mileage ones like mine! Just a warning! I think it ate my rings AND seals....LOL!! Hope you get your problem figured out!