So my car is giving off blue smoke during startup which quickly dissipates. It's consuming a decent amount of oil. I've noticed more smoke if I'm parked for 5-10 minutes. I do a lot of city driving. In the morning after sitting it seems like less but it's actually seems very inconsistent. Sometimes it will be a gigantic amount of smoke, other times not really visible (or maybe I'm just not seeing it from inside the car.) I've already swapped out the turbo for another used one because I was having overboost issues. When I took of the turbo manifold I didn't notice anything unusual in the exhaust ports or in the manifold itself. I'm thinking valve stem seals. Oil sitting on the valves makes its way down into the cylinder via gravity? From what I understand there's no vacuum in the manifold but that still doesn't prevent oil from being sloshed around and finding it's way down there? Car has 430,000km on it. Let me know what you guys think.
cloud of blueish smoke on startups.
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oilhammer
Certified Volkswagen Nut & Vendor
Valve guides, rings, combination of several things.
Good news is, the ALH is relatively easy to freshen up while in the car.
Good news is, the ALH is relatively easy to freshen up while in the car.
So less likely to be the seals but the guides you're saying. To rule out the rings a compression test is probably in order? Need to get my hands on a diesel compression gauge. Car seems to have good compression starts right up. I have an extra motor I'll probably rip the head off that and rebuild it once I can verify the lower end is solid.
oilhammer
Certified Volkswagen Nut & Vendor
Common misconception on rings: oil control rings clear the cylinder walls of oil (like a squeegee), compression rings seal high pressure on TOP of the piston against low pressure below, by pushing OUT against the cylinder walls whenever high pressure is present above them. That's why they have a little wedge cut in them on the top, and not on the bottom.
So.... you can have EXCELLENT compression and still have completely WIPED OUT oil control rings. In fact, wiped out oil control rings will allow more oil to seep up past them to where the compression rings live, which will allow them to actually seal BETTER, further blurring the actual problem. And again, since compression rings are designed to push out from pressure above, they don't really do squat to seal from anything (like oil) being pulled UP from below.
This is more of an issue with gas engines, as they run with frequent vacuum above the pistons on the intake stroke, where worn oil rings will let the cylinders suck massive amounts of oil right up past the compression rings on the intake stroke. Diesels with turbochargers don't do much of that except at extended idle, as soon as you take off, the boost comes up and the manifold is at positive pressure much of the time. Diesels will exploit worn rings more as blowby (pressure being blown down from above the piston into the crankcase).
So I guess what I am getting at it, you can (and probably do) have decent compression, as the car starts easily and runs good, so a compression test won't give you a really good window into the condition of the oil control rings.
Valve guides: they are worn out. Guaranteed. That's the first thing that wears on any VAG SOHC engine, especially with hydraulic lifters. Reason is, because when they went to hydraulics, back in the middle '80s, they didn't want to redesign the entire head, so they modified it. And to make room for the taller lash adjusting followers, they had to shorten the valve guides. Add in the increased oil feed to the lifter bores to keep them fed with oil, and you have the perfect recipe for oil being pushed right past the stem seals down into the engine. However, as you mentioned and I reiterated with the piston rings, the diesels don't "suck" the oil down past the guides the same way the gassers do. However, again at idle, the crankcase pressure can be enough to "push" the oil down. New stem seals on wallered out guides will be a very short lived fix, even if it fixes anything at all.
So.... you can have EXCELLENT compression and still have completely WIPED OUT oil control rings. In fact, wiped out oil control rings will allow more oil to seep up past them to where the compression rings live, which will allow them to actually seal BETTER, further blurring the actual problem. And again, since compression rings are designed to push out from pressure above, they don't really do squat to seal from anything (like oil) being pulled UP from below.
This is more of an issue with gas engines, as they run with frequent vacuum above the pistons on the intake stroke, where worn oil rings will let the cylinders suck massive amounts of oil right up past the compression rings on the intake stroke. Diesels with turbochargers don't do much of that except at extended idle, as soon as you take off, the boost comes up and the manifold is at positive pressure much of the time. Diesels will exploit worn rings more as blowby (pressure being blown down from above the piston into the crankcase).
So I guess what I am getting at it, you can (and probably do) have decent compression, as the car starts easily and runs good, so a compression test won't give you a really good window into the condition of the oil control rings.
Valve guides: they are worn out. Guaranteed. That's the first thing that wears on any VAG SOHC engine, especially with hydraulic lifters. Reason is, because when they went to hydraulics, back in the middle '80s, they didn't want to redesign the entire head, so they modified it. And to make room for the taller lash adjusting followers, they had to shorten the valve guides. Add in the increased oil feed to the lifter bores to keep them fed with oil, and you have the perfect recipe for oil being pushed right past the stem seals down into the engine. However, as you mentioned and I reiterated with the piston rings, the diesels don't "suck" the oil down past the guides the same way the gassers do. However, again at idle, the crankcase pressure can be enough to "push" the oil down. New stem seals on wallered out guides will be a very short lived fix, even if it fixes anything at all.
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If it runs fine and you check the oil frequently enough, you can just ignore it. Not sure what you mean by gigantic, though. Like fogging out the entire street?
If it were bad oil control rings, I'd think it would smoke all the time, not just on start-up then quickly go away.
Not unusual for an ALH to have a little smoke on start up.
If it were bad oil control rings, I'd think it would smoke all the time, not just on start-up then quickly go away.
Not unusual for an ALH to have a little smoke on start up.
oilhammer
Certified Volkswagen Nut & Vendor
No, the valves still open and close, and as long as the valve seats and valves are good, the cylinder will still make good compression.
Yesterday it pretty much engulfed my car as I'm backing out.
csstevej
Top Post Dawg
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- 2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I had a similar issue on my 01 golf , only on start up would have a blue smoke cloud rest of the day it would be fine , car had 392,xxx miles on it when I pulled the head , I had other issues , broken GP for the last 10 years and head gasket leaking due to some power mods. When I pulled the head cylinder #4 was wet with oil on top of the piston , the other 3 were dry. It was leaking down the valve guides from the exhaust stem when car was off.
Replaced the head with a serviceable head and no more smoke on startup. Car now has 447,xxx miles on it .
Replaced the head with a serviceable head and no more smoke on startup. Car now has 447,xxx miles on it .
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