07 Sentra needs a new engine

engines
nissan
selling
sentra

#1

We have an 07 Sentra with 63k miles that has been burning oil (no smoke). At the 60k check up everything looked good. At 62.8k needed 3.5 quarts of oil(oil light just came on). Now the mechanic says the car needs an new/rebuilt engine $4-6k. What to do?


#2

give us a LOT more data. It’s pretty strange for an engine to go from great to junk in 2800 miles unless someone screwed something up pretty badly somewhere.


#3

Ok…took my daughter’s car to the mechanic for engine light on (code PO300 random miss fire. Replaced spark plugs, cleared code. The light returned 2 days later. Engine passed cylinder test, engine computer iis in good fuel control. Mode 6 test found no defects.
Hope this information helps.


#4

Not really!


#5

Are you sure there were no leaks. Something went seriously wrong, did the mechanic tell you where the oil was going or why the engine should be replaced


#6

Yes surprisingly there were no leaks under the car, made us very worried. We thought about going to heavier grade oil, trying an additive (CD-2 etc.)

Our shop ran 2 diagnostic tests: Compression and Leak-down tests

Compression:#1 cylinder: 180 #2: 90 #3: 180 #4: 180

Leak-down: #1: 7% #2: 70% #3: 7% #4: 7%

So based on this the engine needs a new long block/re-manufactured or a used engine??
Hence the $4k-6K range. Ouch any thoughts?


#7

Your #2 cylinder is in bad shape…Your shop can do a “wet” compression and leak-down on that cylinder to determine if its a bad valve or some calamity with the piston and rings…But the heavy oil burning points to broken or stuck rings…

This is VERY unusual in a 3 year old car with only 63K miles…I would have a little chat with a Nissan dealer and see what they have to say about it. Your warranty may be expired but they DO make exceptions now and then…


#8

As Caddyman states get ahold of the dealer.

These engines had problems with the catalytic converter breaking up and being sucked back into the engine ruining the piston rings and causing excessive oil consumption. I do not remember which years had these issues but it was very common if it has the converter in the exhaust manifold.


#9

I’d be reluctant to suggest based on the data so far that the car definitely needs a new engine. It is entirely possible for a blown headgasket to involve an oil passage, in which case oil would be drawn into the combustion chamber and burned. It can do this without an obvious cloud of smoke in the rear view mirror because much of it could be getting captured in the cat converter. That would, by the way, destroy the converter.

The readings from your #2 cylinder suggest either a headgasket breech involving an oil passage or a valve problem wherein a valve is not seating properly. That cylinder could also be pulling oil past the valve stem seal.

I think the next diagnostic step is to pull the valvecover, turn the crank by hand and see if anything on that #2 is not allowing the valves to close, and next pull the head and see what’s going on.

Generally if an oil ring is coked or a cylinder is scored it’ll be having an effect on all four cylinders. Those kinds of problems don;t usually happen to just one cylinder. Since one cylinder is so dramatically different, I’d want to look deeper before makin gany assumptions.


#10

Thanks very much for these responses. We were advised that the engine in the 07 Sentra was a new model, but we are going to start with a discussion with the Nissan dealer and go from there. If they thought the problems barteik mentions with prior Sentras were fixed maybe we can get an “exception” on the table


#11

You say the oil light came on. Now you need a new engine. Was the car driven with the oil light on? WHY does the mechanic say the car needs a new engine? Is there any mechanical noise? Does the oil light stay on now?


#12

I think 3.5 quarts of oil is all this engine holds. So it ran practically empty. I Think to get any manufacture assistance on the cost of engine replacement your oil change documentation will need to be perfect.

Not saying this is what happened but it only takes forgetting to change the oil once and letting it run low to cause sludge that can damage the engine enough to cause the engine to burn oil. After that if you forget to add oil when its low and the engine runs dry the engine will be ruined.

As The Same Mountainbike suggest have the valve cover pulled, and inspected, alot can be determined from that.

One question. When the car was new did it burn any oil to indicate that it could have been a manufacture defect.


#13

You’re thinking of the Nissan Altima.
All years from 2002 through 2006.
2006 had an additional issue of the pistons and rings being smaller than the cylinder bores in some engines that were sold, and those engines failed real quick.

Is this engine the 2.0 or one of the 2.5 engines?
Do you have all your oil and filter changes documented, or can you get them from your service facility?

These will be needed in order to take the car to Nissan for a warranty repair, which is the only possible outcome that would be worthwhile.

BC.


#14

It is indeeed a new engine; the 2.0L Sentra is powered by the (all-aluminum) MR20DE.


#15

w/ a new oil filter, the engine takes 4qt


#16

During the leakdown test your mechanic should have heard air escaping from somewhere when he pumped the cylinder full of air. Did he say where the air was coming out from?? Example: Through the throttle body (Intake valve), through the exhaust system (Exhaust valve), through oil filler cap (Rings, head gasket) That leakdown test should have told the mechanic exactly where the problem is. Did he tell you or is he just condemning the whole engine??

transman


#17

At 3.5 quarts down with the oil light on and seriously low compression on Number Two cylinder that engine has major problems and likely needs rebuilt or replaced.

The OP states it was burning oil, which at such low miles is usually caused by overheating or irregular oil changes. If the hood was never raised in that near 3k miles interval to check the oil it’s likely the oil burning, and the oil, just go away from them.