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Discussion Starter #1 (Edited)
my 99 sentra used to do just 1.5 mile to work for 6 years. Now it goes 75 miles one-way to work. It used a lot of engine oil. I have to add 1 qt per week.

There is no leaking on the ground. the tail pipe is black. I am thinking the oil got burned. Any idea to save this engine? replace PCV? switch to 10W-40? change oxygen sensor? Replace some gaskets?

I used to change oil every 4 month when it ran very few miles (~3000 miles per year). I didn't see much oil consumption at that time. Now it will do 30k miles per year. It runs OK, occasionally gives me P1448 code.
 

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Discussion Starter #2 (Edited)
I just flushed the coolant. the coolant looks right. the front seal was replaced a few years ago.

I monitored the gas mileage, on mostly highway, it is 30-31 miles/G, with the high oil consumption.
 

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Sup Mod keeping the peace
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Replacing the PCV is probably the easiest to try. Make sure there are no external oil leaks. What's left are worn rings or worn valve stem seals. A good way to test for oil burning is to first fully warm up the motor. Stand behind the car. Have someone rev the motor to 4,000 RPM and hold at that RPM for about 15 seconds. If you see a lot of blue smoke come out of the tailpipe, the motor is burning excessive oil.
 

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That and the little gasket under the valve cover probably hard/brittle/leaking...
I've been told a dozen times over what it's called, and every time somebody else brings it up, I forget...
 

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NF Mod/Nissan Master Tech
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I agree with jdg. I call it a PCV baffle gasket, but the parts catalog simply refers to it as "gasket-rocker cover." The part number is 13271-4M501. It's part code "13270N" on the part diagram:

Part Detail
 

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Discussion Starter #6
Thank everyone for suggestion. I will first replace PCV. Then do the blue smoke test.

smj: my GA16 rocker cover looks different than your picture. The PCV faces back to the firewall, not upward. Does it have the baffle gasket?

it looks more like this:link
there is a O-ring like thing, called "INSULATOR-PCV VALVE", 11810E, **812-41B00, on my 99 GA16DE. I guess this thing functions the same as your baffle gasket: to seal the PCV on the rocker cover.

I guess this is a deal-only parts. I will take a look around the PCV port to see if any oil leak from there. If yes, I will order that insulator to replace it.
 

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You've got a '99.
The picture/detail is for a '96.
der....
 

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Yup to above posts, that pesky 'inner gasket' as it is called here, is an easy thing to replace, and usually comes with the larger valve cover gasket (which, in order to check the small one, would be a good idea to replace while you are doing the check, or at least have at hand in case you hurt the old one). When you pull the valve cover and go to put stuff together again I think it is important to note that there are a couple of places to add some silicon goop, one is at the ends/corners of the hump over the distributor drive, I think the other is at the other side of the engine where the timing cover is, there are how-to's on this forum, sry 'bout the crappy memory).
When I first got my '95 it quickly developed the 'mystery oil usage', and I began to leave huge clouds of smog when doing long right-hand corners. The folks here set me straight on that silly little piece of rubber.
Good luck!
 

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Discussion Starter #10 (Edited)
that pesky 'inner gasket' as it is called here, is an easy thing to replace, and usually comes with the larger valve cover gasket.
is the 'inner gasket' the rectangular thing in the picture? Link This part is from Rockauto. and also on AAP web.

I did see black oil deposit outside my engine head, just below the plastic rocker cover. It is almost all around the valve-cover gasket.

Please confirm that rectangular gasket is the right parts. I am going to replace both gasket. Thank you.
 

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I had to buy mine from the dealer. I bought the vc gasket from AAP, but it didn't come with the rocker gasket.
 

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I remember years ago they never included the baffle gasket with the valve cover set, but I guess they've smartened up over the years!
 

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Discussion Starter #14
Car cannot start!!

I got a new PCV. take the old one out. there is a lot of oil in the PCV and tube. Then I want to test if the PCV tube is ok. So I start the engine with PCV tube open. It has strong suction. The engine runs very unstable, cycling from 1000 rpm to near dead.

Then I put on the new PCV, add some engine oil to the right level. Start the car and move it to another parking spot. Then this afternoon, after sitting there for 5 hours, I cannot get it started!!! :balls:The engine turns, the starter is OK, but it just won't run. I switch to the old PCV, but still the same thing.

There was a heavy T-storm this afternoon for 1 hr. but this shouldn't be the problem. I need this car on Monday to go to work. urgently need your help!
 

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Start the car and move it to another parking spot. Then this afternoon, after sitting there for 5 hours, I cannot get it started!!!
That's where you messed up...a quick run of the engine without letting it warm up, then shutting it off.

Don't ask me why these engines do this, I just know they do. A quick run just like you said to move it from one parking spot to another, or back it out of the driveway or whatever, and the plugs get fouled out.
You can try pulling the fuel pump fuse, cranking it over until you're sure all the gas is out of the fuel rails and try to dry the plugs off and see what happens.
Or you can pull the plugs out and let them dry out for awhile and see what happens...
Or just go out and get a new set of NGK plugs, which should fix the problem.
Like I said, it sounds really stupid, and I don't have a good reason why this particular problem happens, it just does.
 

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Discussion Starter #16 (Edited)
Still not start.

I got 4 new NGK V-power plugs, replaced the plugs. pull out the fuel pump fuse, let it run for 10 sec, 3 times. Then put it back on. The car is shaking, but not start.

I can feel the pulse on the fuel line. So the fuel supply is good. The starter is fine as the car is cranking.

for the old plugs, 3 and 4 are dry and normal wore. 1 and 2, especially 2, got a lot of oil on it. they have a lot of carbon deposit on it. I also saw lots of oil in the PCV itself. Is PCV supported to be dry? I guess this is why I have high oil consumption: oil sucked into PCV and then went into cylinder 1 & 2 as the PCV hose goes to here. then oil got burned.

Any ideals? Will idling engine with PCV hose open to air break any sensor or vacuum? But I did start the car and move it 50 feet. It was normal at that time.
 

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Sounds to me like you've created a big ol' vacuum leak somewhere on the engine that isn't allowing it to run properly.

Now, where and how might you have created such a massive vacuum leak???????????
 

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Discussion Starter #18
I test the crankshaft position sensor: it has right resistance.

I opened the distributor, sometimes, oil leakage in the distributor can mess up camshaft position sensor. but the distributor looks dry, no oil at all.

I also drain oil near to 'low' mark as it was a little bit higher than 'high' mark.

still not working...

looked the engine bay, didn't see any hose open.
 

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I test the crankshaft position sensor: it has right resistance.
Only means is not definitely broken. Still might not be putting out a good enough signal.
Back track your steps. Probably knocked something loose. Might've been just holding on good enough to move the car one time.
How's the spark?
 

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Discussion Starter #20
update:
the car was back from mechanic last Monday, with a new distributor. It cost me $500+. Don't know how the distributor got messed up.

today, I took of the valve cover. found that inner gasket. It is hard as a rock. I actually broke it into pieces when I took it off. Hopefully the new gaskets will fix the oil consumption.
 
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