Blue exhaust smoke at start up + oil consumption. PCV valve?
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RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, Blue exhaust smoke at start up + oil consumption. PCV valve? in Past Cadillac Vehicle Discussion; My '79 Phaeton with the 425 has been poofing blue smoke at start up, and has used half a quart ...
  1. #1
    Benzilla's Avatar
    Benzilla is offline Cadillac Owners Connoisseur
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    Blue exhaust smoke at start up + oil consumption. PCV valve?

    My '79 Phaeton with the 425 has been poofing blue smoke at start up, and has used half a quart of oil since my oil change about one month & 434 miles ago. I know my valve covers leak a little oil, but it didn't used to use hardly any oil at all. I never had to add more than half a quart between oil changes. Also, while I was looking around in there, I found a small pool of oil on top if the intake manifold by the pass. side valve cover. Of course it never seems to leak in the driveway, oil just goes down.

    I was wondering if part of it might be the PCV valve? I'm going to check my records, but I really don't think I've ever had it done, and it has the original hose clamps on it.. at 220k. Should I go ahead and change it? I was hoping that's whats causing the blue smoke. Pretty sure I had the compression checked a few years ago & it was fine.

    Any other ideas? Also, where could I find a good tutorial on changing the valve cover gaskets? I know it sounds pretty basic, but there's a lot of stuff around them that would need to be moved! Checked my factory service manual, and it was pretty vague.

    Any other ideas?

    Thanks,
    Ben

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    sven914 is offline Cadillac Owners Connoisseur
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    A bad PCV valve can cause the oil to get sucked into the intake, so defiantly replace that.

    A compression test does not always find internal oil leaks. You might have a problem with worn valve guides. To more accurately find worn valve guide problems, you should use a vacuum gauge. The needle will be shaky at low RPM, but will steady out as RPM's are increased.

    Also keep in mind, that is completly normal for a high mileage engine to lose or burn a quart of oil every 1000 miles.

  4. #3
    brougham is offline Cadillac Owners Master
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Blue smoke right when you start after it's been sitting a while is typical of bad valve seals. Burning a quart every 1000 miles also seems to be normal for northstars. You're driving in true Cadillac fashion .... kind of.

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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Thanks for the advice. I heard that as a rule of thumb, you should replace your PCV valve every 24,000 m.i. to prevent problems.. if this is original, then damn! I thought it was supposed to be changed whenever a shop does a "tune up"? Also, do I need to replace the plastic grommet going into the valve cover, or should the valve come out & go back on without a problem?

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    brougham is offline Cadillac Owners Master
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    You don't have to replace the rubber grommet it pushes into unless it's dried up from age and oil or breaks. Which it might be being 30 years old.

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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Ok, the one on the 425 seems most like a plastic than rubber, which is why I was wondering.

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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Went out & bought a PCV valve. It was funny, because I drove the Phaeton, and the guys behind the counter at Advanced Auto actually came out to the parking lot to look at it, lol. Also, when I pulled up, a guy pulled out cash & asked how much I wanted for it right there.

    Anyway, while I was in there, I picked up a can of this stuff.



    Anybody ever use it? Should I put it in or not? Thought it sounded like it was worth a shot. Is there any reason I *shouldn't* use it?

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    outsider is offline Cadillac Owners Connoisseur
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    I've tried it before...didn't make a difference in my engine (307) but I've heard good things about it.

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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Went ahead & put the Restore in. I'll let it work through for a few hundred miles before I make a verdict.

    Ran out of daylight to put in the PCV valve, but I'll hopefully do it tomorrow before the rain hits, then report back.

    Thanks for all the help guys!

    Ben

  11. #10
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    HUF
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Quote Originally Posted by Benzilla View Post
    Went ahead & put the Restore in. I'll let it work through for a few hundred miles before I make a verdict.

    Ran out of daylight to put in the PCV valve, but I'll hopefully do it tomorrow before the rain hits, then report back.

    Thanks for all the help guys!

    Ben
    When you take off the old PCV valve, shake it to see if it works. It should click just like the new one does. Sure, replace it no matter good or bad.

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    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Those grommets harden with age and exposure to engine heat. That's why yours seem like hard plastic. You could get them from GM several years ago, I'm not sure if they are still available.
    If your going to replace the valve cover gaskets, take pics of your engine on either bank. That way you have something to go by when putting it back together.
    When you pull the cover, look around for for oil seals, small o-rings. They dry out over time and if the guides get sloppy things don't travel in a straight line anymore. Usually the exhausts go first. Due to the heat produced, you get more wear. If throughout the history of the car the oil was changed regularly, the wear will be minimal, but with the milage you describe, over 200K, some wear is to be expected.
    Check that your oil return passages aren't blocked up. Excess oil held up in the top of the engine can cause blue smoke at start-up, but it wouldn't stop after the engine warms up. It would reappear at low engine speeds. Pennsylvania oils have a tendency to build sludge because of their parafin content.
    Hope this helps.
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Just got back in from replacing the PCV valve. Easiest repair I've ever done, lol. Five minutes, tops. Old one still rattled... somewhat. Looked like it had been there a while though. Perfect timing too, it started raining right after I got back from a quick test run. I'm excited to see if I'll notice any difference within the next few hundred miles from the Restore engine stuff.

    Thanks for the tips on the valve covers, too. BTW, should I get a torque wrench for re-attaching the valve covers? I seem to remember something like that from when I had the ones on my Cutlass done a couple years back.

    Where are the oil return passages? If they are blocked, what should I use to unblock them? I've really never been inside the engine, so that's the like last frontier for me, lol.

    Ben

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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    You don't need a torque wrench for valve cover gaskets. The key is to not over tighten them. Snug, then about 1/4 turn will be enough. Oil return passages will be in the top of the heads, towards the outside (exhaust side). You can clean them out with pipe cleaners or a small bottle brush.

    Ben, don't feel bad. I am dealing (actually, not dealing) with the same problem on my 65 Impala. Blue smoke at startup, and blue smoke when the throttle closes on decelleration from highway speeds. No PCV on this car, so it is either restricted drains or bad valve seals. It is likely the latter. If I do the seals this summer, I will put up a how to.

    Jason.

  15. #14
    csbuckn is offline Cadillac Owners Master
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    Same head, 4 drainback holes that drain down at the pushrod guides.

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    sixtycyclehum is offline Cadillac Owners Member
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    Re: Blue exhaust smoke at start up + oil consumption. PCV valve?

    While working on the PCV system, the breather filter (other valve cover) is supposed to be cleaned every 15,000 miles and replaced every 30,000 miles. Good luck finding one, carb cleaner will clean it out ( remove it for cleaning of course).
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