legend71

I have dug through so many threads here to sort out this issue so I figured it was time to ask before throwing money in all directions again...

My motor is a 95 VRE383 Sportsman LT1 built in 2015. It was installed in 2016 and has run with a few hiccups over the last three years. My build process is here https://www.thirdgen.org/forums/ltx-lsx/725481-383-vre-le2-lt1.html for reference. it has LE head cam and intake combo using Trickflow 21deg heads with 2.055/1.60 valves, Voodoo cam with 239/247 .587/.600 110Lsa, 1.6 RR, high flow oil pump, moroso, 7qt pan, and about 11.5:1 compression.

The motor has recently PASSED leak down and compression checks.

At the initial completion of the build, I utilized the stock PVC and CCV system from a 94. At WOT and high RPM 5000+, oil would shoot out of the dipstick and coat everything. I switched to the 95 style using the port on the front of the intake with no change. I then installed valve cover bungs and lines to a catch can per multiple recommendations. It seemed to work at first, but then the oil mist kept appearing. The pass head failed due to a poor casting and I had the trickflows installed. Shortly after, saw oil on the ol garage floor and found the rear main and front seals were seeping pretty bad.

Do I need a vacuum pump or will T-ing my valve cover lines together, running through the can and back to the throttle body be good enough?

Is there something that could be installed wrong, clogged or missing that would cause this excess pressure? Is my throttle body missing some passage for vacuum that prohibited the normal system from working? PVC works at idle and vacuum goes to 0 at WOT as expected. Also throwing a MAP low code (33) but some have suggested that’s the cam’s fault.

Trying to get to the point I can enjoy this thing rather than baby it around so advice is welcome.

Polyalphaolefin

The main problem is you have too much crankcase pressure. This is caused by blow-by and leakdown and compression tests won't always see the problem since they only see things at low pressure and cranking rpm. The typical leakdown test is done at 80-100 psi where as combustion pressure easily exceeds 1,000 psi. Your rings may be sealing until you go WOT / high rpm and they start to flutter, causing your blow-by. A stock type PCV system can't keep up, and that catch can / breather system can't keep up either. With it blowing out hard enough to carry oil mist out past the breather means you've got a lot of blow-by going on. This is also contaminating your oil heavily and increasing the chance of oil aeration.

How many miles are on the engine and how was it broken in? What oil was used for break-in?

What pistons and rings did you use? What's the ring gap and PTW clearance?

legend71

Probably 3000 miles maybe less. Broken in with Brad Penn 30w break in oil. It was broken in by normal driving with varying rpm

Polyalphaolefin

Good choice of break-in oil, but wrong break-in procedure. You have a limited window after the first start up to seat the rings and it's vital that you don't baby the engine through this window. The rings need high heat and high pressure in order to seat. If that window is passed, the rings can glaze the hone on the wall and never find footing in the ring grooves. The result is excess blow-by.

What were your leakdown numbers?

legend71

forged SRP pistons, I don't have info on the rings

atlantadan

Yeah, the worst thing that can be done on ring break-in is to baby it. 10 minutes or less of low-load to get the oil and coolant to temp, and then 20 minutes of varying intensity between 50 - 100% load, without going below 1500 rpm's. Including a handful of WOT runs. A quick visual check is to pull the plugs and look for ones with oil deposits. If glazing is the issue, some people have had luck with a top-end cleaner. GM used to make some stuff that was magic and worked most of the time, but they no longer make it. GM still makes but I don't know much about it. BG may have something worthwhile...

Other than that, a hone is the only real solution IF glazing is the issue. There are lots of other causes to investigate before you go tearing it down for a hone. Bad PCV system is one - but you seem to have checked that out, bad head gasket, cracked block, and others.

legend71

Yeah... don't have that either... I don't have any reason to doubt the person who did it. The break in though is probably the issue. "Stop and go" was the instruction I received I should have asked for an elaboration. What should I do now? Does it need re honed and new rings?

atlantadan

Try the GM cleaner above or google-fu some other options. It really can't hurt at this point. The correct solution is to pull it, tear it down, and hone - but that's only if glazing is the problem. A bad HG would be something to check, as are the exhaust valve seals. What happens when you pull the breather off the VC while its running?

legend71

Yeah I’ll give it a shot. When I use it should I run it up to high rpm like a break in? I’ll double check the head gaskets but they’re new with new heads and this issue was before the head swap. The oil looks good. Nothing really happens when you pull the breather off, but I’ve only checked it at idle and half throttle

Polyalphaolefin

My break-in process with a roller cam engine is simple. I fire it up, let it idle for a max of 10 seconds, just long enough to ensure I have oil pressure, no major leaks, etc... then I bring the rpm up to 2,000. I hold it there for 5 minutes or whenever I see the oil temperature exceed 180*F. There's two main reason for holding the rpm higher like that. One is to increase friction in the piston/ring area and valvetrain as friction is what facilitates break-in. The second reason is to get the oil up to temperature quicker and boost ZDDP's formation of a tribofilm.

After running it at 2,000 rpm for 5 minutes, I then start hammering on it at WOT and making it pull under load across the entire rpm range all the way to rpm cutoff. It should spend more time under load than without a load and even when not under a load, I don't let it go under 2k rpm. By 15 minutes total run time into the break-in, I'm on the dyno doing WOT pulls and tuning. After the tuning is done, I change the oil filter (not oil) and top off the oil. I then run the break-in oil for around 100-200 miles depending on use. If it's a drag only car, I just make 4-5 1/4-mile passes with the break-in oil. Then I dump the break-in oil and filter, and put in the oil of choice. The break-in is done. My engines routinely have less than 2% leakdown afterward.

Breaking in an engine is a lot like breaking in a new baseball glove. You have to beat the snot out of it to make it fit well and flex easier. Same concept.

atlantadan

Poly, great method - I think most gearheads are on the same page. I just get it up to temp and start beating on it. I also would add that when doing the pulls (if you are on the street ), keep it out of "drive" and run through the gears manually and let the trans pull the rpm's back down - don't coast. The decel and corresponding internal engine physics also help with ring seal.

legend71

I did not do it nearly as aggressively unfortunately

It’s going in a local speed shop soon but no one around here really deals with LT1s anymore so they seem to skip over some of the quirks of the motors. Can’t get it dyno tuned either unless I go multiple states away it seems.

legend71

Yeah the deceling with it loaded up backfires like crazy which is fun. I’m worried about making the rear main and front seals worse or am I past that point?

legend71

And even though there’s probably a couple thousand miles on the motor? I mean I’ll try it if there’s a chance

atlantadan

EDIT: make sure you're not dealing with something else. Pull ALL the plugs out and look at them. That will tell you a lot. You've got more diagnostics to do before you write it off as glazing.

Once your options have been exhausted, I'd try the top-end cleaner. You literally have nothing to lose at this point. Google may have other top-end cleaner suggestions, too

moehorsepower

iTrader: (3)

what poly and atlan said on break in, I fired up mine (forced inducted) let it get to temp, checked oil pressure and then down the drag strip!
Our engine builder who only builds outlaw engines, puts the fresh engine on the dyno and does the same, up to temp then rips into them, he says this is the way to seat the rings.

Shownomercy

iTrader: (1)

Aside from pulling your motor apart, I would look into running a can that pulls vac

Look into the mightymouse setup, you may benefit from that.

NewEnglandFormula

that big cover on the underside of the intake can get gummed up with sludge on the inside. that will increase the crankcase pressure.

legend71

Looking on the interwebs I've found a couple of cleaners so I'll try that route after looking at the plugs this week. I saw many mentions of the mighty mouse setup looking the last couple of days.

atlantadan

Just keep in mind that too much crankcase pressure is not the problem. It is a symptom of the problem. Figuring out a way to lower crankcase pressure without addressing the cause is......unwise.