Question about 1991 Nissan Pathfinder

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Burning oil how do you check if it is valve seals or piston rings

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  • kggreen Jul 16, 2010

    thank you for the information

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Most of the time, when you first start your engine and it smokes, then the smoking slows down after the engine gets hot; this is a sign of valve seals, because the seals get softer when they are hot and re-seal themselves. If your car smokes all the time, hot or cold this is sign of bad oil rings, because of the oil being forced up past the oil rings, into the cylinder.

Posted on Jul 16, 2010

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Posted on Jan 02, 2017

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Right steering clutch will not completely disengage. why do i have a loss in pressure when i pull the steering leaver to its travel end?


sounds like didnt get all the trash out --possible valve is fouled or blocked and not closing or sealing correctly and allowing blow by or leakage test valve and pressure piston rings may be causing blow by as well also new parts doesnt mean free from defects

Aug 16, 2016 | Cars & Trucks

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BLOW BY 89 TOPAZ COMRESSION WITHIN SPECS PCV VALVE IOK


Hello, You can still have Ring issues with good compression. The pistons have different types of rings on them to do different jobs. The top rings are your power rings, the bottom rings are your oil rings.

The oil rings prevent the block pressure and oil slop from being drawn up into the cylinder. The piston creates a siphon action and the oil rings prevent the oil from climbing the cylinder walls. All it takes is for the rings to rotate around the piston and have the ring ends line up.

That is why you offset the rings on installation from 90 to 120 degrees. It staggers the gaps of the rings for a better seal. Now you can get oil vapor if the compression rings line up to allow compression into the crankcase through the gaps on the piston rings.

Sometimes the valve stem seals can leak and allow exhaust into the upper block if you have valves that are not seating correctly.

Jul 16, 2011 | Mercury Topaz Cars & Trucks

1 Answer

Excessive fuel consumption on vw caravelle 2.5i


Clogged PCV Valve
The main purpose of the PCV (positive crankcase ventilation) valve is to recirculate blow-by gases back from the crankcase area through the engine to consume unburned hydrocarbons. Blow by is a mixture of air, gasoline and combustion gases forced past the rings on the combustion stroke. The PCV system usually has a tube leading from the crankcase to the carburetor or intake manifold. Vacuum within the engine intake manifold pulls blow by gases out of the crankcase into the combustion chamber along with the regular intake of air and fuel.
Worn Piston Ring Grooves
For piston rings to form a good seal, the sides of the ring grooves must be true and flat - not flared or shouldered - and the rings must have the correct side clearance in the grooves. Normally, automotive ring groove side clearance should not exceed .002-.004. As the pistons move up and down, the rings must seat on the sides of the grooves in very much the same way that valves must seat to prevent leakage. New rings in tapered or irregular grooves will not seal properly and, consequently, oil will pass around behind the rings into the combustion chamber. Worn grooves are usually flared or tapered causing increased side clearances which permit more than the normal amount of oil to pass the rings into the combustion chamber. Excessive side clearances also create a pounding effect by the rings on the sides of the piston grooves. This promotes piston groove wear and, if the condition is not corrected, breakage of rings lands may occur.
Cracked or Broken Ring Lands
Cracked or broken ring lands prevent the rings from seating completely on their sides and cause oil pumping by a process similar to that described in #7. In addition to this, they also lead to serious damage to the cylinders as well as complete destruction of the pistons and rings. Cracked or broken ring lands cannot be corrected by any means other than piston replacement and this should be done as soon as there is the slightest indication of a crack.
Worn Valve Stems and Guides
When wear has taken place on valve stems and valve guides, the vacuum in the intake manifold will draw oil and oil vapor between the intake valve stems and guides, into the intake manifold and then into the cylinder where it will be burned. If this condition is not corrected when new piston rings are installed, an engine is likely to use more oil than it did before because the new piston rings will increase the vacuum in the intake manifold. When gum or deposits on the valve stems are removed - a procedure recommended when overhauling an engine - the seal previously formed will be removed and leakage will be more pronounced. This is particularly true on overhead valve engines where loss of oil may occur on the exhaust valves as well as on the intake valves. High oil consumption caused by too much valve guide clearance can frequently be cured by reaming or nerraling the valve stem. In some cases new valves may also be required. Use of a permanently bonded valve stem seal will give added insurance against oil leakage on complete engine overhauls or on valve jobs. Large Oil Leaks Leaking valve cover gaskets, leaking crankshaft front and rear seals.

Apr 24, 2011 | Volkswagen Microbus Cars & Trucks

2 Answers

Blue smokes come out tailpipe when i start the car but stops afte


Helllo there
Symptom: Gray or blue smoke from the exhaust. You notice gray smoke coming from the exhaust when you start your car. The smoke may or may not disappear after the car is warmed. If it is, it is less noticeable. The smoke may have a bluish tint to it. Possible causes:

  1. The engine's piston rings may be worn.
    The Fix: Replace piston rings. (Generally not a DIY job)
  2. The engine's valve seals may be worn.
    The Fix: Replace valve seals. (Generally not a DIY job)
  3. Damaged or worn valve guides.
    The Fix: Replace valve guides. (Not a DIY job)
Symptom: Engine uses more oil than normal, and there is some smoke from the exhaust. The oil level is low between oil changes. It appears that the oil is being burned by the engine because of the smoke in the exhaust. You may or may not notice the engine doesn't have the same power as it used to.
Possible causes:

  1. The PCV system is not working properly.
    The Fix: Replace PCV valve.
  2. The engine may have mechanical problems.
    The Fix: Check compression to determine engine condition.
  3. The engine's piston rings may be worn.
    The Fix: Replace piston rings. (Generally not a DIY job)
  4. The engine's valve seals may be worn.
    The Fix: Replace valve seals. (Generally not a DIY job)

Jun 01, 2010 | 1989 Buick Electra

1 Answer

Fuel in Oil


Yes it could be from damage in the piston rings but the ring damage would have to be sever for this to happen(Rough running engine or missfire) You can check for bad piston rings by doing a compression check of the supsected bad cylinder or cylinders.I belive autozone rents this tool out. Another possibility is bad seals in your valves, during compression stroke the air fule mix could be leaving thro a bad seal in one of your valves. due to the compexity of this test i recomend you have your valve seals check by a shop.

Mar 01, 2010 | 1998 Dodge Grand Caravan

2 Answers

MY CAR SMOKES AND USES OIL FOULS NUMBER 2 PLUG


you have bad seals in the valves or bad piston rings.

Nov 04, 2009 | 1984 Honda Civic

1 Answer

Replaced to valves on center piston on 1990 geo


timming is not the issue, sounds like the valve seals are leaking, or the piston rings are severly worn. these engines are fairly simple to just rebuild the entire engine.....ie...seals,rings gaskets, maybe a have the head dropped off and have it checked for cracks or warpage.

Sep 22, 2009 | Chevrolet Metro Cars & Trucks

3 Answers

WHAT'S LEAKING? Is it the valve stem seals or piston rings???


Hi,
If it is the valve seals,you can replace the head,but it would be cheaper to replace the seals,If you pull the head,you can do a leak down test on the pistons to check the rings as well.


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Jan 23, 2009 | 2004 Ford Crown Victoria

1 Answer

Blowing black smoke on acceleration 2.5 exceed turbo intercooler I have a Mitsubishi 2.5 diesel with what sounds to be a similar problem except it happens when you rev the engine suddenly but stops...


1 Inspect Piston Ring Set Worn or broken piston rings. grey_line.gif 2 Inspect Valve Stem Seal Cracked or brittle valve stem seals allowing oil to enter combustion chamber. grey_line.gif 3 Inspect Head Gasket - Performance Head gasket leaking coolant into cylinders grey_line.gif 4 Inspect Fuel Injector Rich injector grey_line.gif 5 Inspect PCV Valve Plugged or damaged pcv valve. grey_line.gif 6 Inspect Engine Worn or scored cylinder block grey_line.gif 7 Inspect Piston Worn or damaged piston. grey_line.gif 8 Inspect Valve Guide Worn valve guides

Nov 26, 2008 | 2001 Mitsubishi Montero Sport 4WD

1 Answer

Flooding out


Hello thank you for choosing FixYa.com here are a few things that would cause the black
smoke and stalling.
1 Inspect Piston Ring Set Worn or broken piston rings. grey_line.gif 2 Inspect Valve Stem Seal Cracked or brittle valve stem seals allowing oil to enter combustion chamber. grey_line.gif 3 Inspect Head Gasket - Performance Head gasket leaking coolant into cylinders grey_line.gif 4 Inspect Fuel Injector Rich injector grey_line.gif 5 Inspect PCV Valve Plugged or damaged pcv valve. grey_line.gif 6 Inspect Engine Worn or scored cylinder block grey_line.gif 7 Inspect Piston Worn or damaged piston. grey_line.gif 8 Inspect Valve Guide Worn valve guides

Nov 08, 2008 | 1993 Dodge Shadow

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