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Sedans Nissan Altima Nissan Altima Engine Failures
497 messages, Last post on Nov 21, 2009 at 8:01 PM
You are in the Nissan Altima Forum. Your Hosts are pat & karens
Hi all, I am new on this forum and hopefully someone can help me out. I am replacing my intake manifold gasket and have run into some kinks. I am using the Haynes manual as reference for my install. Do I have to take the head & timing chain off to get to the intake manifold? The manual did not make mention of the timing chain so I am at a loss. I am trying to separate the plenum from the head to get to it. Can this be done. Please advise.
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Replying to: kynymac (May 27, 2008 10:26 am) First, unbolt the upper manifold and Plenum (all one piece). Second, unbolt the lower intake manifold from the back of the engine. There is a bracket under the lower intake that has to be removed. To see all the pictures of how to take it apart and put it together, look at the links in messege #182. See Teardown Photos #DSC06971 through DSC06980, and see Rebuild Photos #DSC07265 through DSC07270. Good luck, E.D. in Sunny Florida |
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Replying to: pdupuy (May 02, 2008 6:20 am)
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Replying to: puds2002 (Jun 12, 2008 11:47 am)
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Replying to: smoothride4me (Jun 12, 2008 3:03 pm) |
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Replying to: electricdesign (Jan 31, 2008 7:12 pm) My question is since the emission is not checked where I live is it better to remove the CAT? Thanks Onuchukwu Chuma.ndiboy  yahoo.com 2348033974181. |
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Replying to: electricdesign (Jan 19, 2008 9:33 pm) I was expecting to see this cat stuff in one bit, but to no avail.One thing that is not clear to me is the whitish brown material in the container.Is it the stuff that is blocking the exhaust? Then there is another hole there, probably after the plug was removed, please I need more clarification now that I have seen the pics. The pre cat, I must confess i didnt see it.I tried looking into the manifold when it was lowered but i couldnt identify anything I could call the cat.I thought the cat will be something big that I will easily see. I need these things to be clear because I will like to remove the one in my Altima 2002 car,especially the pre cat,early before any problem starts.Mine is around 76,000miles now. ED,I need early and fast response,thanks and God bless you.I want mine to run like your daudhters car!!!!!! I love the car,stay in Nigeria, so if the car develops a problem,it gonna be terrible. Chuma.
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Replying to: ndiboy (Jul 25, 2008 1:31 pm) I'll be glad to help clear things up. Yes, you have a good Idea to remove the pre cat before the problems start, especially since you don't have emissions inspections. The best way to refer to the pictures is by NUMBERS, since there are about 700 pictures or more. The pre cat is built into the exhaust manifold. The top of the exhaust manifold, as it is being removed, is shown in teardown picture DSC06900. The bottom of the exhaust manifold is shown in teardown pictures DSC06930 through DSC06934, it shows views looking up inside the bottom of the exhaust manifold. Normally you would see the precat there, but in those pictures it is gone, the exhaust manifold is EMPTY. If the precat was there, you would see a screen in the bottom that holds the precat material above it. In this case the screen failed and the screen and all the precat material got blown out of the exhaust manifold and was blown down the exhaust pipe into the SECOND cat. When the material got blown down to the SECOND cat, it plugged up the second cat. That is when I had to remove and unplug the second cat. And yes, that brown and whitish material IS the contents of the SECOND cat plus the contents of pre cat. What happened now is that both cats are hollowed out, the pre cat and the second cat, giving a wide open exhaust, of course it still goes through the muffler, like a regular exhaust. Looking at the unplug cat photos, photos DSC06096 & DSC06097 show the old cat material that was removed from the second cat. This contains the material from the pre cat (first cat) and second cat. Then photos DSC06098 through DSC06100 show the hollowed out inside of the second cat after the contents have been removed. Photo DSC06087 shows the inside of the second cat BEFORE the contents were removed, the cat is plugged in this picture. What you see is the screen that holds the cat material in place, but the material had got wet and compacted, and the exhaust gas could not flow through it. The cat normally works by allowing the exhaust gas to pass through the cat material and then through the screen and then on to the muffler. The purpose of the screen is to hold the cat material in place. Once ithe cat pluggs up, it's no good anymore unless you unplug it or replace it. Unplugging the second was fairly easy once I had it off the car, just use a hammer and a metal punch or small diameter piece of pipe to hammer the stuff out. If you look into the bottom of the pre cat, you should see a screen just like in photo DSC 06087, unless the material has already blown out. You could clean out the pre cat the same way, break the screen and material out with a piece of small diameter pipe and a hammer. I think you should be able to hollow out the pre cat from under the car by removing the exhaust pipe and breaking out the material through the bottom opening, but be careful to not damage the oxygen sensors. It is best to remove the second oxygen sensor before you attempt to break the material out of the pre cat. You can run the engine for just a few seconds to blow the loose material out of the precat. After the pre cat is hollowed out, the service engine soon light will come on shortly thereafter, because the SECOND oxygen sensor will read the SAME as the FIRST oxygen sensor. To avoid this, you will need to add the O2 cheater at the SECOND oxygen sensor to make it read differently and for the light to stay off. Hope this helps, Good Luck, E.D. in Sunny Florida USA
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Replying to: electricdesign (Jul 25, 2008 6:49 pm) You mean the hollow in the cat unplug pics DSC06098-100 is all that the exhaust gas needs to move out?. Before I go further, I want to let you know someother things.I have been really afraid for this car because before and since I bought I have been reading a lot about it, Camry and Accords on the net, reviews etc The reviews have been that of mixed feelings for all the cars so I decided to go with this with this innate fear.The engine looks new and clean for a 73,000miles car so I was wandering is this not one of those the engine has been worked on and sent to Nigeria?. One sunday morning,about 2 months ago, I started the Car and after some seconds i heard a sound like something has dislodged inside the bonnet and i thought it was the cat since I have read several reviews of it coming off and damaging the engine.I was already looking foward to the engine dying but the noise stopped as if the stuff has dislodged and off we drove to church and till now nothing has happened.I change the oil every 3months with 4litres, and the filter every 6months and the oil level remains the same. Is there a way of knowing if the pre cat has been removed? Do they remove it before sending the cars to Nigeria? When I bought the car, the service engine light was on and I complained because of the reviews I read on the net about it.Later since it was not giving any problems and many cars down here show that, I ignored it.I changed the oil and filter, it still remained but after taking it out on a journey of about 500km I noticed the SES light has gone off.It remained off until about 3 mths later when it came on.I always turn the fuel cap several times after refuelling.I serviced it again ie changed the oil,the light remained.Now I travelled again about the same distance as the previous one and noticed that the SES light has gone off again(2weeks ago), and has remained off till now.My question now is can one use the light to gauge when to change the oil? I am presently on a cross country journey in the Niger Delta area and will be here in the next one month so I will try and remove the pre cat when I get home. Since you said the engine is good when you had a look at it,will you recommend it for somebody? since every car has its own fault. The noise I heard that sunday,can it be the pre cat dislodging?My only observation is that when the car is idling, if you rev it there is a little drag between the idle tachometer level(0.5) and 2.0, but its not felt when the automatic gear is engaged.You know this car so much that If I were in your position, I will erk out some living from it. Thanks for your concern and prompt response, its highly appreciated and looking foward to response to the questions raised above. Chuma.
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PART ONE of TWO Q. "Pics DSC6932-34 contains a whitish ring like a loop opposite the O2 sensor ,I wander what that is." A. There are two whitish rings in picture DSC06932, they are the outer ring support for the screens. The lower screen ring is in place just above the oxygen sensor. The outer ring is all that is left, the screen is blown out, missing. You can also see the upper screen ring, with missing screen, it has blown loose and is visible at an angle. It is suppose to be out of sight farther up at the top of the precat, but because it has blown loose, you can see it in the picture. --------------------------------------------------------------------------------- - - -------------------------------------- Q. "You mean the hollow in the cat unplug pics DSC06098-100 is all that the exhaust gas needs to move out?" A. No, that is the SECOND CAT hollowed out. I needed to hollow out the second cat because it became totally plugged up. Your first priority is to hollow out the FIRST CAT (the pre cat), that is where the problem arises that destroys the engine. Your second cat is probably ok If the second cat is not plugged, I would recommend that you leave it alone. Only hollow out the SECOND CAT if you need to. --------------------------------------------------------------------------------- - - -------------------------------------- Q. "The engine looks new and clean for a 73,000miles car so I was wandering is this not one of those the engine has been worked on and sent to Nigeria?" "Since you said the engine is good when you had a look at it,will you recommend it for somebody? since every car has its own fault." A. The Nissan 2.5L I4 engine is a very good and solid engine design. The basic engine is very reliable, the only problem was this exhaust systen flaw that was messing up some of the engines, and the root cause of the whole thing is that the computer was allowing a slightly too rich mixture in the exhaust, which in turn causes the deterioration of the pre cat. The real solution is to have the computer memory "reflashed" or "upgraded" to eliminate the root cause of the problem. But on a used car, it is also good to hollow out the pre cat because it is likely that damage to the pre cat is already being done, and that damage to the engine is likely to follow, if something is not done about it. --------------------------------------------------------------------------------- - - ------------------------------------- Q. "One sunday morning,about 2 months ago, I started the Car and after some seconds i heard a sound like something has dislodged inside the bonnet and i thought it was the cat since I have read several reviews of it coming off and damaging the engine.I was already looking foward to the engine dying but the noise stopped as if the stuff has dislodged and off we drove to church and till now nothing has happened.I change the oil every 3months with 4litres, and the filter every 6months and the oil level remains the same." A. Over here we have "Hoods" instead of "Bonnets". You could have the second big problem that those engines have, the "Butterfly valve screws coming loose and getting sucked into the engine" I have not had this problem yet. When I had my daughters engine apart, the screws were still tight. These are also called "Power Valve" screws, they are located inside the INTAKE manifold. Two small screws hold each butterfly valve onto the shaft, there are 4 butterfly valves (one for each cylinder), total of 8 screws. There are know to come loose and fall out. when they do, they have no place to go but get sucked into the engine. Once in the engine, they bounce around inside the clyinder, and can cause much damage, or if you are lucky, maybe not to much. It is just a matter of how the screw happens to bounce around in the cylinder, before finally getting blown out past the exhaust valve. The bouncing screw can bend or break the spark plug, score the clyinder walls, crack the head, crack the piston, or crack or bend the valves or valve seats. To fix these, the intake manifold has to be removed, then the screws removed and then cemented tightly back in place or cement new screws back in place. --------------------------------------------------------------------------------- - - ----------------------------------- Q. "I change the oil every 3months with 4litres, and the filter every 6months and the oil level remains the same." A. I would suggest that you change the oil filter at each oil change. How often you change oil depends on the miles, type of driving, and road conditions. Idling is harder on the engine, as well as dusty roads. Our Altima is driven in mixed City and Highway on clean roads, so I change oil and filter every 5,000 miles, using high quality Mobil One Synthetic Motor oil 10W-30 and a Purolator "Pure One" synthetic motor oil filter. 5,000 miles works out to be about every 4 months for us. It gets a new air filter every 15,000 miles and an Automatic Transmission Fluid Flush every 60,000 miles. --------------------------------------------------------------------------------- - - ---------------------------------------- Q. "Is there a way of knowing if the pre cat has been removed? Do they remove it before sending the cars to Nigeria?" A. The only way to know for sure is to pull the exhaust pipe loose from the bottom of the exhaust manifold and look up inside and see if it is there. It is most likely that yours would still be there. --------------------------------------------------------------------------------- - - ---------------------------------------- Q. "When I bought the car, the service engine light was on and I complained because of the reviews I read on the net about it.Later since it was not giving any problems and many cars down here show that, I ignored it.I changed the oil and filter, it still remained but after taking it out on a journey of about 500km I noticed the SES light has gone off.It remained off until about 3 mths later when it came on.I always turn the fuel cap several times after refuelling.I serviced it again ie changed the oil,the light remained.Now I travelled again about the same distance as the previous one and noticed that the SES light has gone off again(2weeks ago), and has remained off till now.My question now is can one use the light to gauge when to change the oil?" A. The check the SES Light, you need to read the codes with a Code Reader or Scanner, or have them by someone. Once you know what the code is, you use logical thought and mechanical skill to determine what the problem is and how to repair it. There are a lot of codes and it must be diagnoised properly. --------------------------------------------------------------------------------- - - ---------------------------------------- God Bless E.D. in Sunny Florida, USA |
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