Pulsating air pressure
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
Pulsating air pressure
Is there some truth to the mechanics' story I've heard about taking the oil filler cap off while the engine is idling and feeling the pulsating air pressure coming from the filler hole as a sign there is a problem with valves or rings? I have a 4 cylinder engine that is puffing out quite a load of air pressure and was wondering if anything specific could be targeted with that.
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
No blue smoke, sometimes some black carbon at startup, no puddles of oil droppings after parking, smells good at idle but has 200,000 miles on a 2007. Need to keep checking oil to keep the level within limits. Otherwise seems to have decent pulling power and response.
Race Director
Joined: Apr 2009
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Likes: 2,754
From: Charlotte NC
COMPRESSION RINGS are shot or darn near worn out.
Each pulse of air you are feeling is the blow-by of that specific cylinder that just fired...and some of the combustion pressure is seeping by the rings and getting into the crankcase and getting out that oil fill cap hole.
I have had so many engine that the owner want a tune up and when I pull out the fresh a air tube in the valve cover and place a dollar bill over it ..IF the dollar bill does not get sucked to the grommet and it is puffing away from it. It is shot and let them know they need a new engine. AND this IS ASSUMING that the PCV SYSTEM is working.
And this is ALSO assuming that ALL gaskets that seal up the crankcase are good. Because if you have no gasket on your valve cover...then the PCV will draw air from the path of least resistance.
BUT If I was feeling significant are coming out of the oil fill cap hole..I would think the engine is on its last leg.
DUB
Each pulse of air you are feeling is the blow-by of that specific cylinder that just fired...and some of the combustion pressure is seeping by the rings and getting into the crankcase and getting out that oil fill cap hole.
I have had so many engine that the owner want a tune up and when I pull out the fresh a air tube in the valve cover and place a dollar bill over it ..IF the dollar bill does not get sucked to the grommet and it is puffing away from it. It is shot and let them know they need a new engine. AND this IS ASSUMING that the PCV SYSTEM is working.
And this is ALSO assuming that ALL gaskets that seal up the crankcase are good. Because if you have no gasket on your valve cover...then the PCV will draw air from the path of least resistance.
BUT If I was feeling significant are coming out of the oil fill cap hole..I would think the engine is on its last leg.
DUB
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
COMPRESSION RINGS are shot or darn near worn out.
Each pulse of air you are feeling is the blow-by of that specific cylinder that just fired...and some of the combustion pressure is seeping by the rings and getting into the crankcase and getting out that oil fill cap hole.
I have had so many engine that the owner want a tune up and when I pull out the fresh a air tube in the valve cover and place a dollar bill over it ..IF the dollar bill does not get sucked to the grommet and it is puffing away from it. It is shot and let them know they need a new engine. AND this IS ASSUMING that the PCV SYSTEM is working.
And this is ALSO assuming that ALL gaskets that seal up the crankcase are good. Because if you have no gasket on your valve cover...then the PCV will draw air from the path of least resistance.
BUT If I was feeling significant are coming out of the oil fill cap hole..I would think the engine is on its last leg.
DUB
Each pulse of air you are feeling is the blow-by of that specific cylinder that just fired...and some of the combustion pressure is seeping by the rings and getting into the crankcase and getting out that oil fill cap hole.
I have had so many engine that the owner want a tune up and when I pull out the fresh a air tube in the valve cover and place a dollar bill over it ..IF the dollar bill does not get sucked to the grommet and it is puffing away from it. It is shot and let them know they need a new engine. AND this IS ASSUMING that the PCV SYSTEM is working.
And this is ALSO assuming that ALL gaskets that seal up the crankcase are good. Because if you have no gasket on your valve cover...then the PCV will draw air from the path of least resistance.
BUT If I was feeling significant are coming out of the oil fill cap hole..I would think the engine is on its last leg.
DUB
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
rings could be stuck
one method is run it hard to get rpms up and then coast letting engine slow you down.
this will exercise the rings up and down.
seafoam additive will clean carbon and deposits and rings.
read directions on bottle/can.
be prepared for a lot of white smoke, A LOT.
one method is run it hard to get rpms up and then coast letting engine slow you down.
this will exercise the rings up and down.
seafoam additive will clean carbon and deposits and rings.
read directions on bottle/can.
be prepared for a lot of white smoke, A LOT.
Le Mans Master
Joined: Apr 2001
Posts: 5,436
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From: Sarver Pa
2021 C1 of the Year Finalist - Modified
At 200k miles , I would NOT advise running it hard. Maybe put some new plugs in it, keep the oil clean , might run a lot longer. What engine is it?
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
It's a Scion tC my kid uses mostly for short trips. He likes it because it's kind of trick but it's seen better days lol.
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Race Director
Joined: Apr 2009
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From: Charlotte NC
At 200K miles..I would not waste my time putting anything in it to clean it up. The engine is on a its last leg. Any of these 'snake oil' remedies may work...but in an engine with 200K...lets gets real...it does not have a lot of time left on it...in my opinion
Do as you wish and I hope it lasts for you.
DUB
Do as you wish and I hope it lasts for you.
DUB
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I have two cars that both have over 200000 miles and are still going strong, both Toyota.
so I wouldn't say the mileage is as big of a factor as how it's been treated and it's state of tune.
your scion does sound like it has excessive blowby. I would try cleaning up the Rings to see if it has an effect. It may only be one, or a couple of cylinders with an issue.
certainly a compression check or leakdown check will indicate the degree of the problem.
so I wouldn't say the mileage is as big of a factor as how it's been treated and it's state of tune.
your scion does sound like it has excessive blowby. I would try cleaning up the Rings to see if it has an effect. It may only be one, or a couple of cylinders with an issue.
certainly a compression check or leakdown check will indicate the degree of the problem.
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
At 200K miles..I would not waste my time putting anything in it to clean it up. The engine is on a its last leg. Any of these 'snake oil' remedies may work...but in an engine with 200K...lets gets real...it does not have a lot of time left on it...in my opinion
Do as you wish and I hope it lasts for you.
DUB
Do as you wish and I hope it lasts for you.
DUB
It’s not my car in the first place but was curious about what was the cause of the air pressure. Cars are making the 200k mark today with advanced oils though so don’t discount them. In the future they could invent oils that are far superior to what we have now. Times they change!!!
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
It’s not my car in the first place but was curious about what was the cause of the air pressure. Cars are making the 200k mark today with advanced oils though so don’t discount them. In the future they could invent oils that are far superior to what we have now. Times they change!!!
Still remarkable mileage.
DUB
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
Since we are talking about engine mileage, my 2001 Pontiac Grand Prix 3.1L V6, bought new, that my daughter has been driving the last few years, is coming up on 210,000 miles. The engine uses zero oil between 5,000 mile oil changes (Mobil1 0W-40 European Formula, not GM specified 5W-30, Mobil 1 oil filter) and has no noticeable power loss from when it was brand new-NONE. The engine is incredible! These GM 3.1/3.8 AMERICAN MADE MOTORS go, seriously, easy 300,000 miles if maintained and I know of some at 400,000 miles. Just about any motor (the days of the Japanese motors being the longevity mileage kings has long passed) in the last 20 years if maintained properly will go 200,000 miles..no problem.
My 2008 Chrysler 300 3.5L V6 has 155,000 miles and the same story (Mobil 1 0W-40 European Formula/Mobil 1 Filter, NOT Chrysler specified 10W-30)....zero oil issues or burning oil....I personally know another 300 owner with the 3.5L V6 with over 300,000 miles on his engine and still going.....I expect 250,000 miles out of this engine as well.
My 2008 Chrysler 300 3.5L V6 has 155,000 miles and the same story (Mobil 1 0W-40 European Formula/Mobil 1 Filter, NOT Chrysler specified 10W-30)....zero oil issues or burning oil....I personally know another 300 owner with the 3.5L V6 with over 300,000 miles on his engine and still going.....I expect 250,000 miles out of this engine as well.
Last edited by jb78L-82; Jan 14, 2018 at 06:30 PM.
Thread Starter
Racer
Joined: Aug 2011
Posts: 429
Likes: 24
From: Charlotte NC
Since we are talking about engine mileage, my 2001 Pontiac Grand Prix 3.1L V6, bought new, that my daughter has been driving the last few years, is coming up on 210,000 miles. The engine uses zero oil between 5,000 mile oil changes (Mobil1 0W-40 European Formula, not GM specified 5W-30, Mobil 1 oil filter) and has no noticeable power loss from when it was brand new-NONE. The engine is incredible! These GM 3.1/3.8 AMERICAN MADE MOTORS go, seriously, easy 300,000 miles if maintained and I know of some at 400,000 miles. Just about any motor (the days of the Japanese motors being the longevity mileage kings has long passed) in the last 20 years if maintained properly will go 200,000 miles..no problem.
My 2008 Chrysler 300 3.5L V6 has 155,000 miles and the same story (Mobil 1 0W-40 European Formula/Mobil 1 Filter, NOT Chrysler specified 10W-30)....zero oil issues or burning oil....I personally know another 300 owner with the 3.5L V6 with over 300,000 miles on his engine and still going.....I expect 250,000 miles out of this engine as well.
My 2008 Chrysler 300 3.5L V6 has 155,000 miles and the same story (Mobil 1 0W-40 European Formula/Mobil 1 Filter, NOT Chrysler specified 10W-30)....zero oil issues or burning oil....I personally know another 300 owner with the 3.5L V6 with over 300,000 miles on his engine and still going.....I expect 250,000 miles out of this engine as well.