żLubrication issues on four cylinder "Duke"?
03-07-2002, 06:45 PM
#1
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Thread Starter
żLubrication issues on four cylinder "Duke"?
First, the data:
'84 Pontiac "Iron Duke" (base engine in ThirdGen). Flat tappets, pushrods, standard stuff.
Lubrication level is adequate (synthetic, of course).
PCV system is clean and operating.
EGR system is clean and operating.
ECM shows no stored DTCs and operating parameters are normal.
Engine makes no unusual noises, doesn't consume nor leak oil.
Compression readings are: 121/123/106/118. Should be close enough to call good, right?
Engine and car operate normally, start, run, make power, etc.
Symptoms/Problem:
After about five minutes of running at highway speed (3,000 RPM) the CCV filter starts to flow oil mist or liquid into the air cleaner snout, saturating the air filter and wetting the entire insde of the air cleaner. TBI unit is now very well-oiled. This produces copious amount of blue smoke from the exhaust. Oil discharge is so rapid that some oil is actually sprayed out the CCV filter/rocker cover seal and onto the engine, producing even more smoke. There is likely oil mist or liquid being ingested by the PCV system at this same time, but I haven't positively determined that.
No unusual noises are produced and oil pressure remains steady during this phenomenon.
Dropping the transmission out of gear or disengaging the clutch to lower the RPMs will stop the smoke in about 20 seconds (probably long enough to clean out the air filter and TBI unit). The smoke won't return until another 1-2 minutes of 3,000 RPM operation are completed. This cycle can be repeated endlessly.
Oil level is not notably lower, so the rate of consumption is not very high. We all know that it doesn't take a lot of oil in the chambers to make quite a bit of smoke. Oil and filter were changed 50 miles ago, but this occurred before the change as well.
My guesses at diagnosis:
I presumed the engine was having an oil drainback problem. The head was removed about 3,000 miles ago for valve work/porting/etc. I supposed that the head gasket may have had some restrictions at the oil drains, but don't recall any fitment or alignment problems when I reassembled it. My guess was that the oil that was being pumped up to the rockers was not draining back fast enough, and the rocker cover was filling with liquid oil until the CCV and PCV were the only outlet for the oil. To satistfy my curiosity, I temporarily plugged the CCV filter and drove it again. The smoke still occurred, but I presumed it was oil that was being introduced through the PCV system.
To satisfy my curiosity, I removed the rocker cover and push rod cover from the side of the engine. My inspection revealed that all the drains through the head are clear, flowing freely, adn are more than large enough to drain back a normal amount of oil. The drains from the push rod cover/lifter area are about the size of a nickle, clear as can be, and drain back directly to the sump past the camshaft. Everyting is clear, which negates my theory of inadequate drainback.
I suspected that I wouldn't find a lot of sludge since it runs synthetic oil, but thought I might find an errant piece of gasket or something from the previous teardown - no dice, nada. Clean as a whistle and no "chunks" or debris.
Since the cam and lifters were out at the teardown as well, I was beginning to wonder if the new lifters were pumping an excesive amount of oil to the valve train, but recall that this occurred before the teardown as well (with the old lifters).
I'm beginning to wonder about all the possible causes and am discounting them one at a time. An oil pump that sucked air may foam the oil excessively, possibly causing these symptoms, but should also result in lower oil presure and at least some valve train noise.
A crank dipping in a high oil level may do the same thing, but there are only a little over four quarts in the sump, the level mark is nearly dead-on, and it has done this before and after a few oil and filter changes.
I'm still wondering about the lifters, but doubt it is the problem.
I would appreciate and listen to any theories on the cause of this phenomenon. In other words, HELP!?
'84 Pontiac "Iron Duke" (base engine in ThirdGen). Flat tappets, pushrods, standard stuff.
Lubrication level is adequate (synthetic, of course).
PCV system is clean and operating.
EGR system is clean and operating.
ECM shows no stored DTCs and operating parameters are normal.
Engine makes no unusual noises, doesn't consume nor leak oil.
Compression readings are: 121/123/106/118. Should be close enough to call good, right?
Engine and car operate normally, start, run, make power, etc.
Symptoms/Problem:
After about five minutes of running at highway speed (3,000 RPM) the CCV filter starts to flow oil mist or liquid into the air cleaner snout, saturating the air filter and wetting the entire insde of the air cleaner. TBI unit is now very well-oiled. This produces copious amount of blue smoke from the exhaust. Oil discharge is so rapid that some oil is actually sprayed out the CCV filter/rocker cover seal and onto the engine, producing even more smoke. There is likely oil mist or liquid being ingested by the PCV system at this same time, but I haven't positively determined that.
No unusual noises are produced and oil pressure remains steady during this phenomenon.
Dropping the transmission out of gear or disengaging the clutch to lower the RPMs will stop the smoke in about 20 seconds (probably long enough to clean out the air filter and TBI unit). The smoke won't return until another 1-2 minutes of 3,000 RPM operation are completed. This cycle can be repeated endlessly.
Oil level is not notably lower, so the rate of consumption is not very high. We all know that it doesn't take a lot of oil in the chambers to make quite a bit of smoke. Oil and filter were changed 50 miles ago, but this occurred before the change as well.
My guesses at diagnosis:
I presumed the engine was having an oil drainback problem. The head was removed about 3,000 miles ago for valve work/porting/etc. I supposed that the head gasket may have had some restrictions at the oil drains, but don't recall any fitment or alignment problems when I reassembled it. My guess was that the oil that was being pumped up to the rockers was not draining back fast enough, and the rocker cover was filling with liquid oil until the CCV and PCV were the only outlet for the oil. To satistfy my curiosity, I temporarily plugged the CCV filter and drove it again. The smoke still occurred, but I presumed it was oil that was being introduced through the PCV system.
To satisfy my curiosity, I removed the rocker cover and push rod cover from the side of the engine. My inspection revealed that all the drains through the head are clear, flowing freely, adn are more than large enough to drain back a normal amount of oil. The drains from the push rod cover/lifter area are about the size of a nickle, clear as can be, and drain back directly to the sump past the camshaft. Everyting is clear, which negates my theory of inadequate drainback.
I suspected that I wouldn't find a lot of sludge since it runs synthetic oil, but thought I might find an errant piece of gasket or something from the previous teardown - no dice, nada. Clean as a whistle and no "chunks" or debris.
Since the cam and lifters were out at the teardown as well, I was beginning to wonder if the new lifters were pumping an excesive amount of oil to the valve train, but recall that this occurred before the teardown as well (with the old lifters).
I'm beginning to wonder about all the possible causes and am discounting them one at a time. An oil pump that sucked air may foam the oil excessively, possibly causing these symptoms, but should also result in lower oil presure and at least some valve train noise.
A crank dipping in a high oil level may do the same thing, but there are only a little over four quarts in the sump, the level mark is nearly dead-on, and it has done this before and after a few oil and filter changes.
I'm still wondering about the lifters, but doubt it is the problem.
I would appreciate and listen to any theories on the cause of this phenomenon. In other words, HELP!?
03-07-2002, 07:44 PM
#2
TGO Supporter
i had a burnt piston cause a similar/same problem on a 1/2 ton chevy truck. side of the pistion was flame cut about .040 x 1/2". caused smoking, but not all the time, oil saturated TBI, PVC valve, breather filter. have you done a leak down test? i'm guessing this only happened after you had the head off so my idea about a burnt piston doesn't really apply to your little engine.
03-07-2002, 07:47 PM
#3
Supreme Member
Vader needs help with something? Jeeze, this has to be difficult! Really sounds like either a pcv for egr problem to me, but you said those are both operating fine. I'd discount the oil level and pump, since those would tend to cause problems at all rpm ranges, unless your oil pressure is displaying incorrectly. I would try disabling the egr, but I guess you know how smart I am.
03-07-2002, 07:48 PM
#4
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Re: żLubrication issues on four cylinder "Duke"?
Originally posted by Vader
In other words, HELP!?
In other words, HELP!?
3-7-02: Vader asks for help.
Anyways, totally unrelated vehicle, same sorta problem. You could putter around town all day long and oil consumption and burning were not issues. Soon as you did something like drive on the freeway (relatively high RPM's), it would start sucking oil out of the crankcase like mad. I know this setup isnt on your Fiero, but anyways I'll give you the quick rundown.
88 Mazda P/U. 2.2L 4 banger. The aforementioned oil use problem. After rebuilding the engine (which helped, a little) and checking everything, twice, it would still do this. 100 miles and the aircleaner was soaked in oil. No, its not an oil bath aircleaner setup dammit. So I think, think, think. PCV gets disconnected. No help except now all the seals are leaking. Hmmm. This thing has some sort of funky Ford-esque Mazda designed 'smog pump' system on it thats attached to the aircleaner. Theres 3 hoses, one is some sort of vent tube, the other 2 are part of the 'smog pump'. The other 2 run down to the most screwed up cast iron fitting in the exhaust you have ever seen. Up on the aircleaner end has 2 reed valves that have apparently failed somehow. I block off the entire system, and drive the truck. Guess what? No more oil problems.
How the setup on your car could be recreating this, I dunno. Its just an idea. The low compression (looks that way to me anyway) could be causing the problem as well from excess crankcase pressure at speed. Try driving it and while you are doing 30MPH, just climb under the hood and pop the oil cap and tell me if theres too much crankcase pressure
Well, just hold the RPM's up and have a friend pop the cap after you stop driving. Also, inside the rocker cover, does the PCV have a baffle setup? Those cheapie chrome valve covers you can get for various cars sometimes create an oil use problem because theres no baffles.Thats my .01
Good luck.
03-07-2002, 08:51 PM
#5
Moderator
Thread Starter
Thanks for the replies men.
Ed,
The pistons and rods were out when the head came off. #3 bore had 0.003" wear, 1, 2, & 4 were closer to 0.0014-0.0018. The pistons looked good, and the bores only got new rings (not pistons). Since #3 is running a little lower cranking compression, it may be because of the extra wear. I'll guess it's time for a leak-down test and I'll get those numbers back to you if they don't make sense to me.
- - - - - - - - - - - - - - - - - - - - - - - -
Max,
No air injection on an '84 151 - cat converter, PCV, and EFE only. I'll simulate the conditions in the shop when I get it buttoned back together. I'm going to slide out the new lifters just for grins, split the clips, and look at the metering discs/orifaces just for grins.
The cranking compression is low, yes, but I'm almost certain it isn't from any wear leakage. The little P.O.S. now has a Comp 260H cam (.489"/.489" - 212°/212° - 110° LSA) instead of the factory .390 lift cam. I'm thinking the extra overlap is hurting cranking compression, so a leakage test is the way to go. Like I said, I'll post those numbers.
I went with the cam and "unswirled" the valve bowls to free up the top end flow. It obviously isn't a torque engine, and the car is geared at 4.10 final drive with no OD. I knew it would be running at some RPMs and cammed accordingly. Cam is timed straight up since it uses gears instead of a chain/sprocket. Actually, I think Comp ground it at +4°, and that's where it is. Vacuum is also a bit lower, but the MAP doesn't seem to care.
If I am getting blowby, I'm gonna be P.O.ed at myself for not installing a V-8 from the outset.
I'll keep you posted - just keep the speculation coming.
Ed,
The pistons and rods were out when the head came off. #3 bore had 0.003" wear, 1, 2, & 4 were closer to 0.0014-0.0018. The pistons looked good, and the bores only got new rings (not pistons). Since #3 is running a little lower cranking compression, it may be because of the extra wear. I'll guess it's time for a leak-down test and I'll get those numbers back to you if they don't make sense to me.
- - - - - - - - - - - - - - - - - - - - - - - -
Max,
No air injection on an '84 151 - cat converter, PCV, and EFE only. I'll simulate the conditions in the shop when I get it buttoned back together. I'm going to slide out the new lifters just for grins, split the clips, and look at the metering discs/orifaces just for grins.
The cranking compression is low, yes, but I'm almost certain it isn't from any wear leakage. The little P.O.S. now has a Comp 260H cam (.489"/.489" - 212°/212° - 110° LSA) instead of the factory .390 lift cam. I'm thinking the extra overlap is hurting cranking compression, so a leakage test is the way to go. Like I said, I'll post those numbers.
I went with the cam and "unswirled" the valve bowls to free up the top end flow. It obviously isn't a torque engine, and the car is geared at 4.10 final drive with no OD. I knew it would be running at some RPMs and cammed accordingly. Cam is timed straight up since it uses gears instead of a chain/sprocket. Actually, I think Comp ground it at +4°, and that's where it is. Vacuum is also a bit lower, but the MAP doesn't seem to care.
If I am getting blowby, I'm gonna be P.O.ed at myself for not installing a V-8 from the outset.
I'll keep you posted - just keep the speculation coming.
03-07-2002, 11:51 PM
#6
Moderator
Thread Starter
Some more evidence?
Removed the lifters. Didn't find anything to support my hypothesis - they looked pretty much like new, since they mostly are (well, 3,000 miles anyway). They also look like any other lifter I've had apart - a standard ball in the lower restrictor and disc check valve on top with no unusual oriface sizes.
I pulled the plugs to do the leakdown test, and discovered that I'll have to bring MY leakage tester back to MY garage tomorrow - if I can get it back.
However, I did discover something possibly revealing. The #3 plug does look a little lean. The rest are fairly normal. This may be related to the #3 hole being honed a little larger than the rest, but I also fit the rings a little tighter in that cylinder (less filing for the same end gaps - about 0.018" IIRC).
Any more clues?
Removed the lifters. Didn't find anything to support my hypothesis - they looked pretty much like new, since they mostly are (well, 3,000 miles anyway). They also look like any other lifter I've had apart - a standard ball in the lower restrictor and disc check valve on top with no unusual oriface sizes.
I pulled the plugs to do the leakdown test, and discovered that I'll have to bring MY leakage tester back to MY garage tomorrow - if I can get it back.
However, I did discover something possibly revealing. The #3 plug does look a little lean. The rest are fairly normal. This may be related to the #3 hole being honed a little larger than the rest, but I also fit the rings a little tighter in that cylinder (less filing for the same end gaps - about 0.018" IIRC).
Any more clues?
03-08-2002, 11:53 PM
#7
Moderator
Thread Starter
UPDATE -
Max,
I forgot to mention that yes, the rocker cover has baffles for both the PCV and CCV air inlet filter. The compression is lower than I would expect on a larger engine, and this thing has a design CR of about 8.2:1, so I wasn't really concerned about the apparently low numbers.
Ed,
I'm thinking you are correct. It's likely blowby. I got my leakdown tester back and put it to work. At first I didn't believe the numbers, so I pulled the #1 on the old (fresh) Impala and, surely enough, it was leaking at about 8% on a cold engine. I thought maybe the tester oriface got partially plugged when I loaned it out. Anyway, the #3 isn't my problem - they all are. I'm getting at least 35% and at worst about 42% leakage on all holes. Oddly, the #3 was the best one at 35% (maybe the tighter rings).
When I tore it down I got lazy and didn't pull the block - only the pan. I honed the bores lightly, measured them as fairly straight, and installed new cast ring sets w/SS oil rails. I went to synthetic after about 500 miles and is has been on that since. I am thinking it is possible the synthetic has prevented the rings from getting a good seal, but that isn't likely - I just should have bored it. That's what I get for taking the short cut.
What really gets me is that it doesn't consume a drop of oil between changes. I actually slightly overfill it with five quarts, and with the weenie little filter that fits, and it checks at about Ľ" above the "FULL" mark - the same place it is when I drain it. Then again, it didn't use any oil before, and I replaced the rings anyway.
So, since you were correct, you win the grand prize - or you and Max can fight over it (which one sets stuck with it?). When do you want to come and pick it up? It's my last one, and my wife says I already have too many toys. I'm also getting ready to move, and the old saying was never more painfully apparent - "You never know how much crap you have until you have to move it." Amen.
Lemme know - I'm about done with 'P' cars.
Max,
I forgot to mention that yes, the rocker cover has baffles for both the PCV and CCV air inlet filter. The compression is lower than I would expect on a larger engine, and this thing has a design CR of about 8.2:1, so I wasn't really concerned about the apparently low numbers.
Ed,
I'm thinking you are correct. It's likely blowby. I got my leakdown tester back and put it to work. At first I didn't believe the numbers, so I pulled the #1 on the old (fresh) Impala and, surely enough, it was leaking at about 8% on a cold engine. I thought maybe the tester oriface got partially plugged when I loaned it out. Anyway, the #3 isn't my problem - they all are. I'm getting at least 35% and at worst about 42% leakage on all holes. Oddly, the #3 was the best one at 35% (maybe the tighter rings).
When I tore it down I got lazy and didn't pull the block - only the pan. I honed the bores lightly, measured them as fairly straight, and installed new cast ring sets w/SS oil rails. I went to synthetic after about 500 miles and is has been on that since. I am thinking it is possible the synthetic has prevented the rings from getting a good seal, but that isn't likely - I just should have bored it. That's what I get for taking the short cut.
What really gets me is that it doesn't consume a drop of oil between changes. I actually slightly overfill it with five quarts, and with the weenie little filter that fits, and it checks at about Ľ" above the "FULL" mark - the same place it is when I drain it. Then again, it didn't use any oil before, and I replaced the rings anyway.
So, since you were correct, you win the grand prize - or you and Max can fight over it (which one sets stuck with it?). When do you want to come and pick it up? It's my last one, and my wife says I already have too many toys. I'm also getting ready to move, and the old saying was never more painfully apparent - "You never know how much crap you have until you have to move it." Amen.
Lemme know - I'm about done with 'P' cars.
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03-09-2002, 12:28 AM
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Car: 87 IROC
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Vader...
I was looking at those plugs just before you made this post and I was thinking to myself "I wonder if that #3 is actually the one in good shape and the other three are the problem... a little late I guess... glad you got her figured out...
zroc
I was looking at those plugs just before you made this post and I was thinking to myself "I wonder if that #3 is actually the one in good shape and the other three are the problem... a little late I guess... glad you got her figured out...
zroc
03-09-2002, 12:41 PM
#9
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Z,
Good call. I guessed I convinced myself that it COULDN'T be a compression problem, and ignored the symtoms. If I didn't know the history, I would have thought "blowby" right away. Sometimes you need to step away from the trees to see the forest...
C'mon Ed/Max - still no takers? At least it LOOKS good....
Good call. I guessed I convinced myself that it COULDN'T be a compression problem, and ignored the symtoms. If I didn't know the history, I would have thought "blowby" right away. Sometimes you need to step away from the trees to see the forest...
C'mon Ed/Max - still no takers? At least it LOOKS good....
03-09-2002, 01:05 PM
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A common cause of "mystery blowby" is severly worn exhaust valve guides... they will leak exhaust into the crankcase like leaky rings would, instead of leaking oil into the runners like the intake valves do... you get good compression readings, good plug readings (those don't look too bad to me considering the nature of your malfunction) and heavy blowby under relatively high loads and/or RPMs...
03-09-2002, 06:37 PM
#12
Supreme Member
I owned one of those engines in an 88 Grand Am a million years ago. Seemed they were very senstitve to the PCV system workign correctly. Lots of heavy pulsing in a 4 cylinder. Make sure the PCV valve and it's line to the manifold are clear.
Yank the filler cap on top of the valve cover. Put your hand over it and run the engine to 3000. Do you feel pressure building up? If so, your PCV system is pooched and you need to figure out why. GM oil control systems hand handle a sh1tload of blowby before they start to puke if they're working right.
Yank the filler cap on top of the valve cover. Put your hand over it and run the engine to 3000. Do you feel pressure building up? If so, your PCV system is pooched and you need to figure out why. GM oil control systems hand handle a sh1tload of blowby before they start to puke if they're working right.
03-09-2002, 08:27 PM
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Your not alone...
Id probably hafta say its blowby from teh valves... My 305 does teh same thing (albiet not nealy as bad). Completely goos the filter and the tb unit. Getting a new crate 350, though, so im not gonna bother to fix it. Keep us updated, thoiugh. I would like to know what causes this. I do want to use this 305 in another car.
03-10-2002, 09:51 PM
#15
Vader-
Don't worry even the best of em assume that something isn't the problem and that ends up being the problem. I have a friend who owns a shop and he had two master techs who wanted to break out wiring diagrams and tear into a car because it wouldn't run, but my friend the owner told them to check the fuses and sure enough it was just a simple little fuse, and the problem didn't occur again go figure. so don't feel to bad and rememer K.I.S.S. Good luck.
Don't worry even the best of em assume that something isn't the problem and that ends up being the problem. I have a friend who owns a shop and he had two master techs who wanted to break out wiring diagrams and tear into a car because it wouldn't run, but my friend the owner told them to check the fuses and sure enough it was just a simple little fuse, and the problem didn't occur again go figure. so don't feel to bad and rememer K.I.S.S. Good luck.
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