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The valve guides and seals would have to be so destroyed that the engine would hardly be running in order for any significant quantity of gas to escape into the upper area of the head. And you'd be burning so much oil that you'd leave a blue cloud behind you wherever you went.
Add to this that there are several fairly large drain passages to allow oil which has been pumped up into the cam and lifter bearings to drain back down into the crankcase. These passages will, if course, allow air and exhaust gas to pass as well, and will tend to equalize the pressure between the crankcase and the area under the cam cover.
This is why the PCV valve is attached to the cam cover. Its sole purpose is to extract blow-by gasses (gasses which escape past the piston rings, a small amount of which is normal). The design of the engine is such that these gasses flow upwards from the crankcase into the top of the head, and are then extracted via the port on the intake-side of the cam cover.
With the valve cover vented to the intake tract, is it not possible that exhaust exiting from the bad exhaust valve seals would be vented directly to the intake tract?
You mean like this?
Haha! Nope.
Originally Posted by Frenchmanremy
checked my charge piping and intercooler, no trace of oil in them.
If your engine isn't breathing a bunch of oil, chances are there's nothing major wrong. Like someone else said, you will get oil splatter if you take off your oil cap with the engine running. That's normal. I'd focus on doing the compression or leakdown check before worrying about anything else. When something internal really breaks, you'll know it.
Did a leak-down candidate compression wet and dry, all numbers were stellar.
Please describe the "leak-down candidate compression" test in detail.
That's a NEW one for me...
What were your test results?
How "wet" did you get it?
I'm also very interested in pre and post turbo compression numbers.
Please provide testing details. How was it done?
Enquiring minds want to know
I thought your issue was physics-defying upper engine crankcase pressure that could float things...
Now it's shitty oil...
Maybe the shitty oil was FARTING!!
It is possible to run so rich that you fuel-foul your oil. Once had a MB with an out of cal K-Jet system that did that until I finally gave up on "Euro-Specialist" mechanics and took over tuning myself. White-blue smoke is a symptom. It's not thinned oil getting past seals, it's thinned oil getting past rings. Be aware that when you thin your oil this much, you are not protecting your engine. I'd prioritize getting tuned to a proper AFR. Either that or change your oil every day.
And, what technicalninja said. Did you do a compression test? Did you do a leakdown test? Terminology matters. Playing with out cars is a learning process.
I did a leak-down and compression test.
autocorrect took over on my phone. Sorry.
both tests were performed by simply fast. A local racecar and engine builder.
Numbers look OK. Bit high on LD but the ring/cylinder wall interface is fuel washed. I would do NOTHING to your motor besides change oil which you have already done.
Then I would adjust the base tune so I saw 13.5-14.5 just tooling around. Not under boost!!!!!!!!!
At that point you should be able to drive car to a competent tuner. I would NOT test car under boost until I could absolutely verify that I was between 11 and 12 while boosting. One full boost hit at 14.7 could trash your motor and I bet the motor is ok at this point.
When they are finished you really should see AFR dithering around 14.5-15 in non-boost operation with AFR richening to 11-12 when you get into boost.
Drive car lightly after the tune for a week and THEN re-do the compression and LD test. Wouldn't surprise me if your LDs went below 10% across the board and your dry compression will come up close to the wet numbers.
Hornetball- You've played with K-jet, cool. Most folks don't even know what that is. I once saw a Volvo with the injectors out of cylinder head, get pressurized, something was pressing the reaction plate, a spark occurred, and the Volvo became a fire breathing dragon with 4 tongues of flame shooting 10 feet out from the car. Awe inspiring! Set the car in the next bay on fire. It was so bright that after the flames were extinguished your eyes took a while to re-adjust to normal illumination. I did not create this monster, another tech got the "fire master" moniker...
Have you ever rebuilt a fuel distributor head? You're NOT supposed to open them but once you do there is NOTHING to them and they are easy to fix.
I got 1/2 way through the A&P program at TCJC and the instructors brought a "Porsche-Mooney" engine into class room. The student were advised to NEVER work on this injection as it take specialized training from Porsche to repair.
They were taken aback when I said "I've been working on those for 10 years, every VW Rabbit has one, and this set up doesn't even have Lambda control. It is the butt-simple version and a monkey could repair it."
Your little cartoon on the direct intercooled exhaust injection was funny but TRUE. Late model 2007+ turbo-diesels have a HUGE EGR system which has a cooling system based air-water intercooler in it. Looks ALOT like your cartoon and when the intercooler develops a hairline crack every shop you take it to will tell you its a head gasket...
I though HG as well but was slightly unsure so I pressure checked this puppy when I took it off the truck (first to come off for HG job). Man, I'm glad I did. I did not do a HG. I replaced the cooler which saved the customer 2K +. Would have been very BAD to say here's your 3K bill, sorry but the truck is still blowing white smoke and you need an EGR cooler to the tune of another 700...
Customers like NOT paying for un-necessary work. I have a near 100% kill ratio.
Nice to see usable comp/LD numbers on this. OP has a good chance of getting out of this unscathed.
Rick
I haven't gotten into the fuel distributor itself. Just spent a lot of time with K-Jet gauges and OEM vacuum diagrams making sure all the gozintas, gozoutas and pressures were right. Did the final idle mixture adjustment with a vacuum gauge (old school!). Found lots of leaks and incorrectly routed vacuum. You know, basics that I thought I had paid the "Euro Specialist" to do. Oh well. Anyway, the old 380SL runs like a dream. Once those old mechanical FI systems are setup, they're really nice and seem pretty durable.
I like Carter AFBs too.
This newfangled ECU autotuning stuff is just too easy. No chance of 10 foot flames though.
I haven't gotten into the fuel distributor itself. Just spent a lot of time with K-Jet gauges and OEM vacuum diagrams making sure all the gozintas, gozoutas and pressures were right. Did the final idle mixture adjustment with a vacuum gauge (old school!). Found lots of leaks and incorrectly routed vacuum. You know, basics that I thought I had paid the "Euro Specialist" to do. Oh well. Anyway, the old 380SL runs like a dream. Once those old mechanical FI systems are setup, they're really nice and seem pretty durable.
I like Carter AFBs too.
This newfangled ECU autotuning stuff is just too easy. No chance of 10 foot flames though.
You would be surprised at how often it is simple basics, proper routing, correcting stupid mistakes.
Get it all right and the vehicle magically works "better than it has in years" and your seen as a wizard. Customers will not let anyone but you touch their cars (this is a kill).
Every super strange electrical issues I've diagnosed has come back to a mistake done in the last area someone was working. That's my first question to a customer in this case is "what's the last thing done to this" and I solve a mistake that others may have taken hours to find.
It's not rocket science...
I like AFBs and Edelbrocks as well. If your froggy you can change mixture needles with it running... Best overall street performance carb IMO.
That's where my afrs are, 14.0-14.9 idling and driving.
I think my warm up enrichments are way too high, and my time based enrichments are too intense(throttle based)
They need to be map based. Will work on my tune this evening.
No smoke on accel or deccel. Plume of smoke on startup, and when hitting the throttle after having been in stop and go traffic for a half hour.
Just re-read thread
That was the original complaint and to me I'd put my money on bad valve stem seals (most likely exhaust side). I'd replace all as they are 20 years old.
Everything else was the OP trying to figure this out and not having a technical background to base his assumptions on.
I'll be surprised if changing the oil is going to do anything.
His final AFR reading are FINE for NA operation and the car has been on the MS for some time.
How did the oil get "shitty" Sounded like it was changed three week ago?? That's fast for a car running 14-14.9
The oil's black as well...
Bad valve seals merely allow a tiny amount of oil to seep into the intake or exhaust port. This is most noticeable as smoke on start up that usually clears within 30 seconds and smoke after the engine has been running under lowest intake vacuum (closed throttle) at throttle tip in.
Another symptom is the longer the car sits the worse the smoke is on start up. 4 hours nothing, overnight a cloud, 3 days a cloud that you worry your neighbors will complain about.
Valve stem seals do not have any effect on crankcase pressure ever. They would have to be MISSING valve stem seals to turn the oil black and it would take more than 3 weeks.
So, technicalninja,
Thank you for all of your help and explanations.
I changed the oil three/four weeks ago with 5w30 castrol GTX dyno oil. Knowing I'd change it out in a month (this past saturday) for 5w40 rotella T6.
Main purpose of that was to use a crappy oil since I knew I was changing all the fluids when I did my clutch last saturday.
I was told Rotella T6 has stuff in it to prevent/resist oil dilution from running rich.
I noticed last night that my accel enrichment were off and kicking in during traffic. So a throttle application to move up to the car in front of me is bringing on 12.5 - 13.0 AFR.
I changed it this morning and it stays at 14.7-15.0 AFR, at that point there's barely any load since I'm just applying throttle to move the car up a few feet to prevent a douche in a BMW, not using turn signals, from bashing his way into my lane.
Also, I worked at making all of my cruising and idling cell closer to 14.0 - 14.7 AFR. Then at 100kpa and above it'll go to a richer AFR.
The car will be going to a tuner once the new FM clutch is broken in. I'm doing a 2hr drive this weekend going to F1 in montreal, that should cover it.
I'm hoping to get tuned June 17th.
EDIT: When I did my clutch, I also looked at a few things. There is NO oil in the downpipe, and the I put acetone in the intercooler to wash it out, came out clear. My Rear main seal was installed incorrectly last time and was leaking, I used the FM tool this time and got perfect fitment of the RMS and it shouldn't leak anymore.
So, technicalninja,
Thank you for all of your help and explanations.
I changed the oil three/four weeks ago with 5w30 castrol GTX dyno oil. Knowing I'd change it out in a month (this past saturday) for 5w40 rotella T6.
Main purpose of that was to use a crappy oil since I knew I was changing all the fluids when I did my clutch last saturday.
I was told Rotella T6 has stuff in it to prevent/resist oil dilution from running rich.
I noticed last night that my accel enrichment were off and kicking in during traffic. So a throttle application to move up to the car in front of me is bringing on 12.5 - 13.0 AFR.
I changed it this morning and it stays at 14.7-15.0 AFR, at that point there's barely any load since I'm just applying throttle to move the car up a few feet to prevent a douche in a BMW, not using turn signals, from bashing his way into my lane.
Also, I worked at making all of my cruising and idling cell closer to 14.0 - 14.7 AFR. Then at 100kpa and above it'll go to a richer AFR.
The car will be going to a tuner once the new FM clutch is broken in. I'm doing a 2hr drive this weekend going to F1 in montreal, that should cover it.
I'm hoping to get tuned June 17th.
EDIT: When I did my clutch, I also looked at a few things. There is NO oil in the downpipe, and the I put acetone in the intercooler to wash it out, came out clear. My Rear main seal was installed incorrectly last time and was leaking, I used the FM tool this time and got perfect fitment of the RMS and it shouldn't leak anymore.
That was an excellent post, no strange names for anything, good info. Almost like a different person took over. There is hope
Quick note AFRs should already be rich at 80kpa IMO. OEM stuff is already open loop by 80KPA and pig rich.
14.7 is good at cruise, as you close on 100KPA it should already be below 13.5 and probably lower (don't "know" Miatas well enough yet to make an accurate AFR target at 100KPA).
GTX is not crappy. It is my go-to oil for standard daily drivers. In a turbo car I'd change it at 2-2.5K miles. (Turbos really need synthetic)
Got to get some work done.
From what you are saying your AFR's are no where near rich enough to fuel wash cylinders and ruin oil. You'd need continuous 11 to 1 or lower readings to really cause issues. Don't worry about an AFR swing when you first stab the throttle, you'll be months and months of tuning to get your AFR's to move from a cruise 14.7 to a WOT 12.5 with no overshoot. A momentary rich dip is fine.
06-02-2017, 08:03 AM
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