on our LS5 we have just started to burn some light oil out of the right (passenger) bank .. notice it at idle only ... the heads were done early spring and had 500 + miles on them before this started ... I pulled the plugs and they all look good ( burning even in all cylinders) .. I pulled one from the driver's side as well and saw no diff. IS it possible that this condition is being caused by a faulty PCV valve? The PCV valve is the orginal from 71 .. the car has 25k miles .... thoughts anyone??
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Re: C3 oil burning pass side .. PCV ??
How do you know it is burning oil on one side? Smoke? What is the actual rate of consumption?
If excess oil was being ingested though the PCV system it would should up more or less evenly on all eight cylinders. The change interval on the PCV vavle is probably 30K miles in your maintenance schedule, but these all metal valves can usually be used almost indefinitely. Since they are all metal, they can be soaked in carb. cleaner. If you shake the vavle and it rattles, it's probably okay. At least the valve is not jammed with goop. Also, push on the valve plunger with a small screwdriver to make sure the spring is not broken.
Check the hoses and fittings upstream and downstream of the valve for oil - not just a film, but liquid. If liquid oil is passing through the system it could indicate that the liquid vapor separators in the valve covers are somehow defective - possibly a broken spot weld.
Duke -
Re: C3 oil burning pass side .. PCV ??
Duke,
We notice smoke from the right bank only .. .. the quantity of smoke will increase to a "maximum" the longer the car is idling .. a quick hit of the throttle will usually clear it up for a short period of time ( maybe 20 seconds or so) .. I pulled all the plugs on that bank and really can not see anything major on any one plug .. they look like they are all burning a "little" rich .. I pulled one from the other side ( that is not smoking) as well and it looks identical to the passenger bank ( a little rich) .. I can not exactly say what the oil consumption rate is but I am "guessing" at about a 1/3 quart in 800 miles or so ..
I have checked the PCV itself and it does rattle .. I have no yet checked the spring but will do so ... I disconnected the PCV hose going into the carb to see if this is any liquid oil in the hose .. I turned it upside down and "tapped" it on the intake manifold .. no liquid came out .. the inside of the hose does feel oily .. but I would expect that to be normal
AT first thought I felt that the smoke might be from idling rich .. so I adjusted the fuel/air mixture again ..
( exactly as recommended by the manual) .. obsoletely nothing changed in the volume of smoke .. so I had a mechanical look at it when we were at KY motor speed way during the caravan . he said it was burning oil and he thought it might be a valve seal .... he was absolutely convinced it is oil and not fuel ... so I have been on the oil hunting trail since then ...Comment
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Re: C3 oil burning pass side .. PCV ??
I would supect something is amiss with one or more of the new vavle seals on the smoking bank.
DukeComment
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Re: C3 oil burning pass side ..
Since I can not see anything on any of the spark plugs that would indicate which cylinder is burning oil .. is there some mechanics trick that I do not know of to find the bad seal?..Comment
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Hate to be the bearer of bad news but...
identical thing with my '63 a couple of years ago. My mechanic thought it might be bad rings et al. He said for some reason the passenger side was the first to go. Pulled the engine and, sure enough, found a cracked ring. The engine was not original (or correct) and already 30 over so I put in a crate.DickComment
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Re: C3 oil burning pass side ..
Not sure what kind of valve seals your BB has, but if they are just the
O-rings
between the valve stem and retainer as is the case with the OEM SB seals a
vacuum cup can be used to test them merely by removing the rocker arm.
(See a
service manual.) If the seals are the positive type that mount to the valve
guide or umbrella seals that ride on the valve stems, the vacuum cup test
won't
work. It takes a lot of oil to show up on plugs, but over a longer mileage
interval, oil ash deposits will build up on the insulator, which can be
used to
make an educated guess.
Chances are a valve seal was either defective, improperly installed,
damaged or
not installed. To be sure before you investigate the valve seals I would
recommend a compression or leak down test to be sure it's not a ring
problem.
DukeComment
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Re: Hate to be the bearer of bad news but...
Is the smoke blue or black. Generally, if the smoke is black, it is a fuel/air mixture problem (as I had recently been expereincing with my '72). Sometimes a few carb adjustments are warranted. Sometimes a carb rebuild. If the smoke is blue/gray and/or coming from only one bank, then generally it is oil comsumption. If it were me, I would do a compression check on all 8 cylinders. It could be a broken ring, which generally would be uncovered with a compression check. If the compression is good, then pull the intake and valve covers and check the valve seals and guides. Oil comsumption can usually be tracked down by driving the car and keeping an eye on the spark plugs. If any one plug starts to "carbon-up" badly, then you have a problem in that cylinder somewhere (as you apparently already know). Good luck. And keep the faith, remember afterall, they are 30-40 year old "bitches with attitudes"
Kevin #39927Comment
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Re: Compression Test Results
Here are the results of the compression test:
1) 162
2) 160
3) 160
4) 162
5) 162
6) 162
7) 159
158
Next is the leak down test.Comment
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Re: Compression Test Results
Can't get much more uniform than that...you said 1/3 of one quart in 800 miles = 2400 miles per quart sure sound fine on a vintage BB to me. Really makes me wonder if it's oil or something else....I don't remember if you had a 4 speed or Turbo400, I had a vacuum modulator let loose once on my 81 PU and since the vacuum connection is in cyl 8 runner it sucks the oil from the tranny and burns it up in number 8 resulting in oil out the right bank. Course, this would not apply to a 4 spd...CraigComment
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