# 02 Altima 2.5 SL head gasket leak



## Pooch2 (Dec 24, 2016)

I have a 2002 Altima 2.5 SL with 63,000 miles on it and I believe the head gasket is blown. I have to put coolant in it about every 3-5 days and there's no heat unless I'm moving down the road. Temp guage does not show overheating. I also have P0300 and 420 codes showing up. What's the best step by step method to verify the head gasket is blown and best way to repair it? Ball park figure on parts, labor? TIA


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## quadraria10 (Jul 6, 2010)

Why are you saying head gasket? From what you are describing I would be checking the manifold gasket. Re ballpark prices-- depends upon what is required, who is doing the work and where its being done. Were the 15 year old o2 sensors ever changed. What about plugs, when is last time they were changed. Are you burning coolant or do you have a leak somewhere?


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## rogoman (Dec 16, 2004)

Pooch2 said:


> I have a 2002 Altima 2.5 SL with 63,000 miles on it and I believe the head gasket is blown. I have to put coolant in it about every 3-5 days and there's no heat unless I'm moving down the road. Temp guage does not show overheating. I also have P0300 and 420 codes showing up. What's the best step by step method to verify the head gasket is blown and best way to repair it? Ball park figure on parts, labor? TIA


The first thing you need to do is run a compression test on all cylinders; standard - 181 psi, minimum - 153 psi, differential limit between cylinders - 14 psi. Once you find the bad cylinder, you can run a leak-down test on it. The leak-down test is especially good as it will quickly show if there is a blown head gasket because the test uses compressed air which will show as air bubbles in the radiator fill tube.

The P0300/P0420 codes could be indicative of a major problem with the QR25DE engines from the years 2002 - 2006. The common problem with those engines is the pre-catalytic converter breaks down and bits of catalyst substrate get sucked back into the combustion chamber and score the cylinder walls. The QR25DE uses the variable valve timing for EGR rather than a conventional EGR valve. It opens the exhaust valve slightly during the intake stroke to accomplish this. The catalytic converter, which is part of the exhaust manifold, is so close to the head that the bits of debris get sucked in past the exhaust valve with the exhaust gases. Nissan claimed the reason for this was the ECM programming. A recall for 02-04 QR25DE equipped Sentras and Altimas was initiated years ago to correct this problem. An updated ECM was provided, updated manifold heat shields and several other things and in some cases, replacement of the exhaust manifold assy. and engine short block. At this point, Nissan probably won't do much for you if this is the issue, especially if the vehicle has already had the campaign performed (we still hear about oil burning QR25DE's on vehicle's that have had the campaign performed). You can test to see if this is the issue by performing a compression test to the engine and comparing it to the service manual specs. If it is under spec, you will likely find burnt oil on the inlet side of the catalyst media when you remove the manifold (you might need a telescoping probe to view it) unless it has been recently replaced. Head gasket failures are also not uncommon. A cylinder leakdown test would be helpful. 

If the pre-cat checks out OK, then you might consider replacing the up-stream and down-stream O2 sensors. Always use OEM components not some cheap aftermarket types. Also replace the spark plugs.


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## Pooch2 (Dec 24, 2016)

quadraria10 said:


> Why are you saying head gasket? From what you are describing I would be checking the manifold gasket. Re ballpark prices-- depends upon what is required, who is doing the work and where its being done. Were the 15 year old o2 sensors ever changed. What about plugs, when is last time they were changed. Are you burning coolant or do you have a leak somewhere?


I have read several threads about bad head gaskets with this particular engine and the P0300 code. It keeps making the check engine light come on and when I have codes read at the auto parts store, that what they tell me.I can't find any leaks anywhere and several times the car started with a big cloud with of steam and I checked the radiator and it's down to the top of the fins usually. Where is the antifreeze going if I can't find any leaks? The 02 sensors have not been changed as far as I know, plugs 20,000 miles ago.


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## smj999smj (Jan 1, 2006)

These engines will blow the occasional head gasket. Do as rogoman suggests to confirm. Price quotes will vary from shop to shop. Use this to give you a general idea: www.repairpal.com/estimator


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