I worked with an engine shop for the machining and I assembled it in my garage. Its a 97 GTS with 40k on the drivetrain and chassis, mods: 11:1 comp, k&n filters, smooth tubes, edelbrock headers, 3" corsa no cats, sct tune. In its best pull it cranked out 490rwhp and 540rwtq, stomping the previous version that only managed 400rwhp and 425rwtq.
The problem is its burning oil on deceleration, enough of it to make me not want to drive it...in the day time at least. Last time I did, I had to drop it out of gear every time I let off the gas. I've only really driven it hard at night, but I want to keep putting the rings through heavy deceleration while the crosshatch is still fresh (230miles on the build) without having to worry about smoking out the highway.
I removed my intake manifold and found oil in every single port and runner. I figured to start with the PCV system...thinking excessive vacuum is building and pulling oil past the valve seals(brand new). I'm basically running the factory PVC system, the few differences are that each bank has a -10 hose from a vent block on the valve cover going to an individual catch can. The inlet ports to the catch cans are at the same height as the factory PVC port on the air box. The cans aren't "catching" anything, they are just venting like the factory set up without rerouting back into the air box. I used the original valve cover vent ports for a balance hose connecting both banks to equalize the pressure. I'm thinking this PCV system isn't efficient enough for the new ring gap and compression bump, maybe the oil that should be caught by the cans is pooling on the heads, maybe even submerging the valve seals...?
With those test results, the only other culprits I can think of are the valve seals and valve guide clearance. I assembled the heads a few months before the short block was ready, could the assembly lube have dried up, and essentially have dry seals from start up onwards? The engine shop did freshen up the valves and seats. I didn't question their work, so I hope they didn't miss the guide clearance.
What do the plugs look like? You'll get many key-board engine break-in opinions in the coming days. But from my University SAE days, our procedure for engine break-in procedures had several aspects.
1. Cam and engine bearing break-in. high idle (2000 RPM) at initial strartup for 20 min. Look for leaks, temp issues, and so on.
2. Change oil
3. Ring seal process: Series of mild load accelleration to mid RPM followed by high vacuum decell. Increase engine loading and accelleration followed by high vacuum decell. Finally series of WOT loading/accelleration followed by high vacuum decell.
With not knowing your end gaps, etcetera, its hard to know if your issue is with ring sealing, valve guides, or some other blow-by condition. If its just on decell, i'd suspect the rings aren't seated yet. If it smokes at first start-up, I'd suspect valve seals as well. Regardless, you don't have too many miles on it yet, have good compression and leak-down numbers, so I would guess the rings aren't quite there yet...
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"Aspice, officio fungeris sine spe honoris amplioris." (Face it, you're stuck in a dead end job.)
What do the plugs look like? You'll get many key-board engine break-in opinions in the coming days. But from my University SAE days, our procedure for engine break-in procedures had several aspects.
1. Cam and engine bearing break-in. high idle (2000 RPM) at initial strartup for 20 min. Look for leaks, temp issues, and so on.
2. Change oil
3. Ring seal process: Series of mild load accelleration to mid RPM followed by high vacuum decell. Increase engine loading and accelleration followed by high vacuum decell. Finally series of WOT loading/accelleration followed by high vacuum decell.
With not knowing your end gaps, etcetera, its hard to know if your issue is with ring sealing, valve guides, or some other blow-by condition. If its just on decell, i'd suspect the rings aren't seated yet. If it smokes at first start-up, I'd suspect valve seals as well. Regardless, you don't have too many miles on it yet, have good compression and leak-down numbers, so I would guess the rings aren't quite there yet...
This! EllowViper is a genius with this stuff! One day I'll be half as good as Ol'Ellow!
What do the plugs look like? You'll get many key-board engine break-in opinions in the coming days. But from my University SAE days, our procedure for engine break-in procedures had several aspects.
1. Cam and engine bearing break-in. high idle (2000 RPM) at initial strartup for 20 min. Look for leaks, temp issues, and so on.
2. Change oil
3. Ring seal process: Series of mild load accelleration to mid RPM followed by high vacuum decell. Increase engine loading and accelleration followed by high vacuum decell. Finally series of WOT loading/accelleration followed by high vacuum decell.
With not knowing your end gaps, etcetera, its hard to know if your issue is with ring sealing, valve guides, or some other blow-by condition. If its just on decell, i'd suspect the rings aren't seated yet. If it smokes at first start-up, I'd suspect valve seals as well. Regardless, you don't have too many miles on it yet, have good compression and leak-down numbers, so I would guess the rings aren't quite there yet...
The break in procedure I used was
1. Normal idle until operating temp, looked for any issues, then turned over by hand while checking the valve train.
2. Mild to hard accel and deccel through the rev range, after 20miles changed the oil and cut up the filter. Nothing unusual was found.
3. Continued to drive hard snapping the throttle on/off.
My end gaps are .025 and .026 on Pro-Select molly rings.
The smoking is substantially less on decel than when I drove it for the first time. It use to smoke briefly on start up, it stopped after I installed the balance hose in the PCV system. Currently also noticed droplets of water with carbon when it idles at start up, it freaked me out at first...I thought it was oil spitting out the exhaust!
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Factory valve seals or aftermarket?
I used oem valve seals, except on the intake of no.2 cyl. At some point before I owned the car the valve guide was replaced, the oem seal was too big. Had to dig around and source one that sort of fit, even then had to file the guide down to make it work. This was the only hole that was emitting a visible atomized substance while cranking the engine during the compression test. Number 2 cyl also has the highest comp of all 10.
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I would check your valve stem seals.
Just have to wait for my "heads on" valve spring compressor to arrive, I'll probably install new ones to rule them out 100%.
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I would sell it at night-you guys are all pussies.
Just a thought.... I might be off here, but you said "deceleration".... So, could oil be seeping into the air intake from the valve covers? Oil entering into the system via intake and not valves? Maybe need "catch cans"?
Yea I already have catch cans, each bank has its own. The only place where oil could find its way into the intake manifold is through the pcv port in the block. I kept the factory valve and tubing. I'll remove the tb's to see if there is any evidence of oil pulling through there. Going to rethink the pcv system, I don't think its good enough for my set up.
Yea I already have catch cans, each bank has its own. The only place where oil could find its way into the intake manifold is through the pcv port in the block. I kept the factory valve and tubing. I'll remove the tb's to see if there is any evidence of oil pulling through there. Going to rethink the pcv system, I don't think its good enough for my set up.
Couldn't you either block off the CCV office (one in the block) or just run a line to either atmosphere or a catch can? Roe blower guys cap it with no ill effects. I believe the catch can setup AC performance sells also has you cap off the CCV.
hmm...I did have the CCV blocked at first but because of the oil burning I thought there wasn't enough ventilation so I reinstalled the factory ccv system. If the Roe blower guys have no issues with it blocked, my problem must be somewhere else. Thanks for your suggestion! I'll look into adding another catch can.
Is it burning oil from both sides of the engine or just one side? Maybe just the #2 cylinder side? I had the fancy aftermarket seals in my old gen 1 and had the same issue you are having, changed all of the valve stem seals back to oem and problem was solved. Just wondering if the seal you had to mess with is the cause.
Its hard to tell if its only one side or both, I'm leaning towards both because when I removed the intake manifold all of the intake ports had traces of oil. Unless the oil leak is bad enough from #2 that the vacuum is drawing oil into all the ports. I'll have a look inside the manifold and see if there is any evidence..I hope the problem is in the valve seals, and that replacing them will solve the issue like it did for you.
First thing I thought of when reading your post is Valve Seals.. Does it smoke on first startup in the morning or when parked for a bit and then restated? or is it only on decal?
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