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Car is a 99 pontiac trans am ws6 with 91k miles.
motor=LS1
Car runs great but i think im burning oil. When im floored at high rpms or close to it blue smoke comes out the tailpipes. I had to add a quart of oil after 1000 miles. checked a couple of plugs yesterday and found some oil on the threads of the spark plug.
Im pretty sure it isnt leaking anywhere on the ground. and the oil only disappears when i race or get on it.
Ive had some people suggest valve seals or it could be a pcv problem, and some suggest getting a catch can.
Eric could you help me out? i love your videos man, i love learning about all this stuff and if you could help me out that would be great!
Thanks.
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It sounds like you race the engine pretty hard, so you may have some piston ring issues. I wouldn’t think valve seals would cause this issue at WOT unless they are just trashed. College Man has the right idea, because you are leaking somewhere, and I would guess rings since you seem to trounce the motor.
It’s not valve seals, that would smoke during start up or high intake vacuum and WOT is just the opposite of those. In short, it’s probably a worn out bottom end. During periods of high acceleration you create a LOT of cylinder pressure, if you have weak ring sealing or worn bores and pistons you will experience compression loss and oil burning during these times. In summary, live with it, replace the engine, or rebuild it with larger bores and pistons. The rebuild option will cost you more in the long run in my experience. Make sure you have a good machine shop working with you on the rebuild for best results if you decide to go that rout.
Good luck
I did a compression test today…
1-155
2-180
3-180
4-180
5-185
6-175
7-175
8-185I rechecked cylinder number 1 a couple of times and still got 155.
I then took out the schrader valve in the compression tester hose and put her at TDC and i had air coming up through the oil filler cap.
I’ll try a wet test today to see if its the rings.
What do you think? should i be worried with only 1 cylinder a little lower than the others?Unfortunately you can’t just say rings if you find it leaking into the bottom end which I’m pretty sure it is at this point. To correct the problem you would have to bore the cylinders out and install new larger pistons, you can’t just put piston rings in it because it’s the piston and cylinder walls that are most likely worn. You might consider a replacement engine as that can actually be less expensive and hassle than trying to rebuild the one you have.
Keep us posted.
Can i do a wet test with the other plugs in the block? Its time consuming to take these plugs out do to limited space between the wheel wells.
Also, should i be worried about it losing all its compression anytime soon? I dont think it would for a while at least. But anything can happen. Just wondering if youve seen something like this before and how long it lasted.
you can check it with rest of plugs in if you want, just dont over do it, disable the fuel and spark.
But i would still check valve seal’s, i have see it in some LS1’s working for a Gm dealership, do your wet test if rings are showning some wear well thats to be expected.
but i woudl reccommend using a scope and going down the intake and up the exaust and looking at the valve and see if it’s wet. remove the upper intake and the ypip. just MAKE SURE you look at EVERYTHING before you replace the engine or rebuild it.
Also dont forget about the 5.3 that eric took apart with a dead cylinder where the ring’s and line up and ended up with compression loss;), seen that 2 times at my and the Gm dealership accross the road in 2 year’s, its not somethign you see very often but it does happen. they might not be lined up but are close weird shit happens sometimes:DAnd also working for GM i have access to this information this is taken RIGHT FROM the service manuel for this car.
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1. Charge the battery if the battery is not fully charged.
2. Disable the ignition system.
3. Disable the fuel injection system.
4. Remove all the spark plugs.
5. Block the throttle plate wide open.
6. Start with the compression gauge at zero, and crank the engine through 4 compression strokes, 4 puffs.
7. Make the compression check for each cylinder. Record the reading.
8. If a cylinder has low compression, inject approximately 15 ml (1 tablespoon) of engine oil into the combustion chamber through the spark plug hole.
Recheck the compression and record the reading.
9. The minimum compression in any one cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105).
• Normal — Compression builds up quickly and evenly to the specified compression for each cylinder.
• Piston Rings Leaking — Compression is low on the first stroke. Compression then builds up with the following strokes but does not reach normal. Compression improves considerably when you add oil.
• Valves Leaking — Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.
• If two adjacent cylinders have lower than normal compression and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders.
***********************Wow thanks man! Thats a big help.
So according to #9 my compression is ok. Considering my highest is 185 (185 x 70%=129.5) And, my lowest was 155.When i did my compression test i had all plugs out and had it floored while i cranked it 5 strokes(Now i know its supposed to be 4). So when i do my wet test with the plugs in the other cylinders, how should i disable the ignition and fuel systems? pull fuses?
Also my boss has a bore scope i could borrow i think. Its defiently not long enough to go through my longtubes but maybe the intake. Would it be beneficial to look inside the spark plug hole?
If you hold the gas pedal to the floor as you crank the engine you’re shutting off the fuel pump and holding the throttle open at the same time. This is what I show in the video that was posted.
That said to me I think your compression numbers and your description say your problem is in the bottom end. Keep in mind when you accelerate hard you’re putting a lot more pressure on those rings than just shop air pressure. I know I keep going back to this but your symptoms say a worn out bottom end to me.
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