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I had made a thread a while ago in which I outlined a possible engine build due to some burning oil issues. It has been a while since then and I have new information so I wanted to start a clean thread.
Since the other thread I have replaced my valve stem seals with a set of FelPro's to hold me over until winter when I would like to build an engine for my car anyways. I just went on a drive and did some hard boosted pulls and low a behold, she's still drinking oil and puffin that blue smoke . I also now noticed it blows blue smoke after doing a boosted pull, engine braking for a couple of seconds then lightly getting back on the throttle, something I either never noticed before swapping out the valve stem seals or just wasn't there. The original condition where it would smoke while idling and at a stop after hitting boost is still there as well. If I load up the car in neutral while parked I can also see a little bit of blue smoke coming out of the exhaust.
While replacing my valve stem seals I did notice some play of the valve within the valve guide. Sadly I don't have any way of accurately measuring it and what would be the beast way to measure that kind of stuff? I feel like calipers would not fit down there. I did however take a video of the movement, and although its not a measurement, I figured it would be better than nothing and hopefully if the play was THAT bad someone would be able to tell.
When installing the valve stem seals I used the included straw that made sure they didn't get caught on the keeper slot in the valve and I also oiled the inside of the seal so it would slide nicely on the valve. I used a fair amount of pressure on the seals when installing them and I heard most of them click but some of them didn't make a click when pressing them on. I pushed as hard as I felt safe with pushing on those seals and never saw them to be seated any lower than the others, deformed, or messed up from pushing too hard. I also feel like if a valve stem seal wasn't fully seated I would be seeing a LOT more than just the small clouds I am seeing now.
I had previously pulled the downpipe off and checked it too see if it was oily at all from the turbo but it seemed fine at the time. Tomorrow I am going to pull it off and check again after work however.
Basically, I am looking for any suggestions on next steps. Did I bung up the valve stem seal install? Are my valve guides bad? Time for the scrap yard?!? Any thoughts and considerations are greatly appreciated!
Side Note: I used the Flying Miata Valve Seal compressor tool and it works REALLY well. Although I am sure it may take longer than using the Bluepoint tool I have seen most people use on here, I felt better not doing any hammering towards the head
Blow-by (rings or inadequate crankcase vent or both)
turbo oil drain
That was my original thinking and prompted me try two different catch can setups on the intake side. The first was just a can intercepting the line that went from the PCV to the intake manifold and I added the little check valve that I have seen others use to ensure no boost can push past the PCV. At that point, I actually saw some oil spray out of the exhaust side breather so I got rid of the check valve. I was assuming that the check valve, PCV valve, and catch can collectively were restricting the flow of blow-by out of the crankcase enough that more was going out of the exhaust breather and taking oil with it. I also ran a line from the exhaust side breather to a small compressor filter so I would not have to worry about oil hitting my turbo manifold.
I currently have a temporary setup that is VTA where I capped the intake manifold port for the PCV line, put a fitting in place of the PCV valve, and ran the line to my catch can which is just VTA right now. So now I have two catch cans that are VTA with no PCV valve right now. I get some clear fluid in the intake side catch can but only a very minimal amount of oil. The exhaust side catch can doesn't collect any oil and sometimes has a very minimal amount of clear fluid in it.
As far as the turbo oil drain goes, I have it like this right now:
Everything before this is downhill and that is as downhill as I can get it without removing the AC compressor. If you guys think removing the AC compressor and having the line run at more of an incline would solve the problem I would be okay with doing that. This is the way the drain has been routed for the car's whole turbo life (2 years now) and it has only become an issue in the past 6 months so it makes me thing the drain routing is okay.
I have a eBay turbo on the car which has a built in restrictor which has been enough until now. The hole is roughly the size of the 1/8 pop rivet that most people have said work for them. Maybe I need a smaller restrictor than what is on there now due to a change in tolerance within the turbo? I change the oil every 2k-3k miles with synthetic 5w30 (street car) as an added data point.
Compression test was done and wet and dry were close, which I was told and assumed meant more oil was getting into the cylinders than it needs on a regular basis: Dry: 1: 165 2: 160 3: 162 4: 165 Wet: 1: 170 2: 150 3: 165 4: 170
A test has not been done since the valve stem seals were replaced.
Originally Posted by cpierr03
Valve guides are the first thing I'd think of, assuming the obvious has been checked (rings w/ compression test and over-pressurized turbo feed/drain)
I am thinking it may the valve guides as well. Are you able to tell if they look super out of spec from the video at all? Wish I had a measurement to know for sure :((
Turbo oil feed pressure has been fine until now, maybe I need a smaller restrictor now?
I pulled the downpipe last night as well as a lot of the intercooler piping and did not see anything horrible:
Turbo compressor outlet (dark stuff is oil residue):
Turbine outlet:
And downpipe:
In this downpipe picture, in the wet looking spot on the right, you can actually see a small hairline crack. It doesn't seem to be leaking badly but I will try and patch that lightly with my little flux core welder.
The oil residue in the compressor outlet and downpipe doesn't seem like enough to cause the smoke I am seeing. It is not a lot of smoke but I still feel like that isn't enough oil, but please correct me if I am wrong. There were not any other oil markings in the intercooler piping and the intercooler wasn't noticeable filled with oil. Could oil be vaporizing and traveling through the air (hence it not catching on the piping and getting caught in the intercooler) and then burning up in my engine? Or is this just a stretch? Maybe I could disconnect the intercooler piping post intercooler and see if the air coming out has an oily smell/or is discolored? But I could not hit boost and decel with the piping disconnected like that for testing.....
Any opinions on the issue being with the turbo? Or ways to test it? Or does it seem fine?
Last edited by c.buffm; 06-18-2021 at 10:56 AM.
Reason: Additional Info
Ebay turbos are hit and miss. I have seen them be perfectly suitable for a long time and moderate mower levels (<250whp) and I have seen the exact same turbo on the same setup be crap out of the box and last <6 months at the same power level.
Did you do the recommended valve cover mods? In stock form, the VC doesn't flow enough air to vent even marginal blow-by on an FI setup. Even a psi of crankcase pressure can be problematic. Do you have leaks on the RMS/FMS? These are key indicators of excessive crank case pressure.
A leakdown is the test you want to run next.
turbo seals keep pressure out of the CHRA, not oil in. Oil in the compressor housing is a real indicator of a drain/crankcase pressure problem.
Ebay turbos are hit and miss. I have seen them be perfectly suitable for a long time and moderate mower levels (<250whp) and I have seen the exact same turbo on the same setup be crap out of the box and last <6 months at the same power level.
Did you do the recommended valve cover mods? In stock form, the VC doesn't flow enough air to vent even marginal blow-by on an FI setup. Even a psi of crankcase pressure can be problematic. Do you have leaks on the RMS/FMS? These are key indicators of excessive crank case pressure.
A leakdown is the test you want to run next.
turbo seals keep pressure out of the CHRA, not oil in. Oil in the compressor housing is a real indicator of a drain/crankcase pressure problem.
I have not done any valve cover mods as I thought they were only needed when running high boost/high power and my car only makes ~200 whp on 10 psi from the eBay 2871 on it. I have seen the mod where you enlarge the hole on the intake side that runs from the middle chamber to the one where the exhaust breather is as well as the scrubbers. I am not aware of any other than those but I will do some digging.
There is sometimes a little oil on the bottom of my oil pan but I assumed that was from a poorly sealing oil pan. I actually replaced the front main seal a month or two ago and it did not look like it was leaking but I wanted to replace it anyways with the timing belt job. The oil down there could however be from the front main seal (which I am hoping I won't have to replace again now). The rear main seal could be leaking. My transmission tends to have a light oily film on it as well as the rear of the oil pan. Clutch job was done by a trusted shop about a year and a half ago and they could have bunged up the install but it could also be leaking. I do not lose a noticeable amount of oil from them however (no puddles or replacing a quart of oil every 100 miles). Would I need to replace both seals if they have been leaking due to crankcase pressure?
Also, what do you think of my drain routing? Is it downhill enough or should it not go flat the way it does in the picture?
So, if the turbo seals are fine (which I think is what you inferred?) then what needs to be addressed is: better drain, crankcase pressure preventing draining, or restrictor(?). Is this just normal excess blow-by from the added forced induction that is causing this issue or does it seem excessive to the point of bad rings or valve stem seals allowing the pressure to pressurize the crankcase within the engine? Unfortunately I do not have a leak down tester so I will try and see if I can borrow one from a friend.
Thank you a TON for your information and advice so far!
The drain doesn't look too bad, as long as you don't have restrictions through fittings, and the return line isn't blocked by the pick-up tube.
The various engine block seals don't typically "leak" in a traditional sense. That is to say that there won't necessarily be spots on the floor after being parked. Essentially every engine seal can "weep" in the presence of positive pressure. Those seals don't hold pressure in.
I am not necessarily saying anything is fine, only highlighting the usual suspects. To put things in perspective, I had a tired M45 setup at ~175whp that would weep and stopped with the VC mods. When I took that motor to 225whp it started popping the dip-stick and weeping again. The 225whp version was the compound prototype, and the turbo on that setup (a 2871 churbo) sent oil out both ends. If you have excessive blow-by right now, the VC would probably be a stop-gap to a re-ring.
The drain doesn't look too bad, as long as you don't have restrictions through fittings, and the return line isn't blocked by the pick-up tube.
The various engine block seals don't typically "leak" in a traditional sense. That is to say that there won't necessarily be spots on the floor after being parked. Essentially every engine seal can "weep" in the presence of positive pressure. Those seals don't hold pressure in.
I am not necessarily saying anything is fine, only highlighting the usual suspects. To put things in perspective, I had a tired M45 setup at ~175whp that would weep and stopped with the VC mods. When I took that motor to 225whp it started popping the dip-stick and weeping again. The 225whp version was the compound prototype, and the turbo on that setup (a 2871 churbo) sent oil out both ends. If you have excessive blow-by right now, the VC would probably be a stop-gap to a re-ring.
That is good, I was worried my drain routing wasn't good enough. It has been fine up until recently but still could be an issue that I will look into.
And what you said about seals makes sense. They are supposed to keep oil inside, not the positive pressure that I am getting. Thus, when parked they aren't leaking because there is no excessive pressure.
And yea, sorry I misinterpreted what you said regarding turbo seals, but thank you very much for highlighting those points. I plan on building a motor (hopefully this winter) and that would get rid of this issue. But, I really want to try and enjoy the car for the rest of the summer if I can. Although stop-gap type things go against what I normally like doing with issues, I am more okay with it since it won't be permanent.
I have a theory I am going to try and test out tonight regarding my catch can. I think it may be too restrictive (sub par eBay unit) and restricting the flow of blow-by out of the PCV port. I am going to bypass the catch can entirely and just run the PCV port line to an actual can for testing purposes and if that makes things better at all, I am going to buy a new VTA catch can of higher quality.
Thanks again for all the help. I will give updates as I find new things/get more information.
First off, I want to give you a HUGE thank you Ted75zcar for pointing me in this direction. I thought about what you said regarding VC mods and making sure the VC can flow enough blow-by out of the engine. I tried blowing through the lines that went from the valve cover to the catch cans and it was actually pretty restrictive. So for giggles, I took both my little VTA catch cans off and ran two straight lines from both breather ports to a (literal) can like this:
(Don't mind the oil spots on the valve cover, took the oil cap off at idle to see if there was excessive vapor coming out)
And then I went on a cruise. Much to my surprise, I could not see any oil smoke at idle when coming to a stop after driving around. I even did some pulls, came to a stop, and physically got out to check and I could not see the clouds I had seen before. However, I would still get small puffs of smoke ,visible from the passenger side mirror, if I engine brake then slightly get back on it. I checked the can after my session and there was a tiny bit of clear fluid and a little bit of oil reside as well but nothing crazy at all.
What I think I can gather from this (and please correct me if I am wrong) is that I was holding pressure in the crankcase due to the restrictive catch cans and this was more than likely preventing oil from draining optimally from my turbo. When driving around and in boost there was pressure pushing on the turbo seals (as they keep the pressure out of the CHRA) and when I stopped and idled the oil backed up in the drain would slip past the seal into the compressor housing and burn up. Thus making the oil smoke at idle. Does this theory make sense? Or am I still newb?
Now there is still the issue of the oil smoke on tip in. I believe this is more than likely from tired rings or worn valve guides. I still need to do a leakdown test to confirm this and will hopefully be able to get my hands on a tester this week from my friend. Maybe I should also try some more VC mods to get even more blow by out of the engine faster. Regardless of if this is an engine rebuild or a rebuild of the head, I am just happy I am learning and figuring things out with the help of you guys.
A leak down test will not help you pinpoint your oil consumption issue.
Your valve guides look worn to me and guides usually create smoking after decelerating using engine braking (high vacuum) and then getting back on the throttle which is what you described in your last post.
The leak down test tests cylinder sealing in regards to compression rings and valve face to seat contact points.
You could leave the oil control rings off of the piston and still see an excellent "leak down" reading with good compression rings.
It would smoke like a 1980s diesel...
Now, if you have a crappy leak down and you can hear it significantly in the oil fill hole (rings) the top 2 rings are shot and they will take the oil control rings out with them.
I normally check valve guide to stem clearance with the head off, valve and guide completely dry and the amount of clearance that appears in your vid would be too much in my book.
You're checking it wet, everything installed and on the opposite end than I do. I would think clean and dry with no seal on it you will have even more clearance.
On a perfect fitting valve guide you will feel a tiny bit of clearance dry but no clearance can be felt wet. The oil forms a hydraulic "wedge" and takes up all the clearance...
That's a nice little spring compressor.
I has TOOL ENVY!
A leak down test will not help you pinpoint your oil consumption issue.
Your valve guides look worn to me and guides usually create smoking after decelerating using engine braking (high vacuum) and then getting back on the throttle which is what you described in your last post.
The leak down test tests cylinder sealing in regards to compression rings and valve face to seat contact points.
You could leave the oil control rings off of the piston and still see an excellent "leak down" reading with good compression rings.
It would smoke like a 1980s diesel...
Now, if you have a crappy leak down and you can hear it significantly in the oil fill hole (rings) the top 2 rings are shot and they will take the oil control rings out with them.
I normally check valve guide to stem clearance with the head off, valve and guide completely dry and the amount of clearance that appears in your vid would be too much in my book.
You're checking it wet, everything installed and on the opposite end than I do. I would think clean and dry with no seal on it you will have even more clearance.
On a perfect fitting valve guide you will feel a tiny bit of clearance dry but no clearance can be felt wet. The oil forms a hydraulic "wedge" and takes up all the clearance...
That's a nice little spring compressor.
I has TOOL ENVY!
It is a VERY nice little tool. I am glad I spent the money on that one, definitely helped make the job go smoothly. I have no idea what worn valve guides look like so thank you for confirming my suspicions that there was a little too much play in them. So it seems to be the valve guides, due to the way I am able to produce the smoke, but there is still a possibility it could be rings(?). I don't believe valve guides are something I could do myself as well so I would need to find a reputable machine shop to do it for me.
I guess the question now is; where do I go from here? I was hoping to be able to enjoy my car this summer and tear it apart this winter. I did a ton of work in preparation to enjoy the car this summer and was hoping the valve stem seals would fix things but it seems that was all done for no reason. However I may have to just tear it apart yet again . The current options I am considering are:
A: Enjoy the car for the rest of the summer and get sad every time I see oil smoke in the rearview. Then, in the winter I can pull the motor and start a build which would include a head refresh.
B: Pull the head now, try and find a machine shop I can trust (not really sure what to look for but I am worried that a shop could possibly do more harm than good) and have them replace the valve guides and I am guessing valves would need to be replaced as well as grinded.
B2: Swap with a lower mileage head? BP4W head?
C: Pull the engine out now and start the build process.
I am somewhat leaning towards option A, unless you guys think that is a bad idea. Option B seems okay but would be a new experience for me. I feel like I could get the head off, get it to a machine shop and get it back on and together to be able to enjoy the car for the rest of the summer. The only thing that worries me is having someone do a bad job on it. I feel like a lot of head work can get expensive though and being a college student, I don't have super deep pockets. B2 would be a good option especially if I could complete a BP4W swap for a reasonable price, I believe it flows better than the head I have now.
Could I try running a thicker oil in hopes that it would not get through the valve guides? I am running Valvoline 5w30 full synthetic at the moment and it was changed 200 miles ago. Any opinions on the options I laid out? Any other options I should consider?
If it makes you feel better I'm having similar problems. Replaced the head on my '94 with a JDM BP4W head, installed China rods, coolant reroute and had the machine shop deck the head and pressure test it. I replaced the old seals with Fel-Pro's. New crank and rod bearings, changed all the engine gaskets and the turbo drain is not blocked or kinked. I have similar compression readings to yours and my leakdown test shows the valves leaking a decent amount but there's a ton of cruddy oil all over the valves and the seats. The there's no oil in the coolant and no leaks. The valves were lapped and looked good. The rings are original but looked good and the car made no smoke whatsoever before I did everything. I even did a "wiggle" test with the valves and got similar results between the BP05 and BP4W valves and guides. I used almost a quart in 100 miles. Smokes like crazy and the plugs and top of the pistons were pretty wet with oil. I ordered a set of oem seals and currently debating weather or not to put them in the BP4W head or just put them in the BP05 and throw the BP4W in the ocean with some batteries! Easily the most frustrating auto situation I've had in a long time.
If it makes you feel better I'm having similar problems. Replaced the head on my '94 with a JDM BP4W head, installed China rods, coolant reroute and had the machine shop deck the head and pressure test it. I replaced the old seals with Fel-Pro's. New crank and rod bearings, changed all the engine gaskets and the turbo drain is not blocked or kinked. I have similar compression readings to yours and my leak down test shows the valves leaking a decent amount but there's a ton of cruddy oil all over the valves and the seats. The there's no oil in the coolant and no leaks. The valves were lapped and looked good. The rings are original but looked good and the car made no smoke whatsoever before I did everything. I even did a "wiggle" test with the valves and got similar results between the BP05 and BP4W valves and guides. I used almost a quart in 100 miles. Smokes like crazy and the plugs and top of the pistons were pretty wet with oil. I ordered a set of oem seals and currently debating weather or not to put them in the BP4W head or just put them in the BP05 and throw the BP4W in the ocean with some batteries! Easily the most frustrating auto situation I've had in a long time.
Try and figure out what kind of engine conditions make the car smoke, That can help lead you to the possible cause (big thing I have learned here) and make sure you have ample flow for blow-by out of the crankcase.
Your rings could be bad too even with good compression numbers as the extra oil in the cylinder might help them seal more, thus give a higher compression reading. Maybe a ring got cracked or chipped on re-install?
I am also having a hell of a time tracking down a BP4W near me/ on eBay that isn't crap or very expensive.
But I had no issues with the old cylinder head. I'm gonna take it to a machine shop this week and have them measure the guide-valve clearance. If its okay or close I'm gonna put in the OEM seals and see what happens.
06-16-2021, 11:08 PM
Still Burning Oil
. I also now noticed it blows blue smoke after doing a boosted pull, engine braking for a couple of seconds then lightly getting back on the throttle, something I either never noticed before swapping out the valve stem seals or just wasn't there. The original condition where it would smoke while idling and at a stop after hitting boost is still there as well. If I load up the car in neutral while parked I can also see a little bit of blue smoke coming out of the exhaust.
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