Is Oil Consumption tied to Catalytic Converters/Intake/Seals?
#1
06-03-2007, 11:06 AM
Join Date: Jun 2007
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Is Oil Consumption tied to Catalytic Converters/Intake/Seals?
All,
I recently started shopping for used Maxima's (having owned 2), and came across an 02 modle with the VQ35 engine. As usual, I began checking the forums and stumbled onto the oil consumption concerns (note: these are consistent from the introduction of this engine in 2002 across all Nissan/Infinit models - and do not appear to be limited to the 'rev up' engines, etc.). In reading this (and based on years of hotrodding experience with American V8's) it almost sounds like a really high vacuum issue (generally a good thing as it indicates a strong combustion chamber seal) that is pulling oil past the valve guides, or past a gasket like the intake gasket. It doesn't take too much oil dilution for too long to screw things up either (i.e. rings don't seat correctly, etc.). Sometimes engine designers "solve" this by simply shielding the points of entry. As an example, valve springs will have oil shields to keep the splash away from the valve stem seals, etc. Other times, the seals themselves can be improved (i.e. better intake gaskets, PC seals on valve stems, etc.).
On another note, I see Nissan acknowledged issues with oil consumption caused by the catalytic converters on their 2.5 liter engine (i.e. Altima, Sentra SE-R, etc.). In that situation, those engines apparently do not have traditional EGR valves which recirculate exhaust gas back into the combustion chamber to be 'reburned'. Instead, they rely on the overlap of the valve timing from the exhaust and intake stroke to 'pull' a bit of the exhaust back into the combustion chamber (so far, so good). The problem is tha thte catalytic converters are very close to the exhaust manifolds onthese cars, and more importantly have an issue where the ceramic internals are starting to break down. As a result, little bits of ceramic debris are being pulled back into the combustion chamber, and are in turn scoring the walls of the cylinder. Obviosuly, if the converter isn't replaced at the same time as the engine (i.e. the root cause in this situation), then the new engine will just experience the same thing. Anyone heard of a similar cause with the VQ35 cars? Just my thoughts, sorry if this has all been covered before.
Later,
Chris
I recently started shopping for used Maxima's (having owned 2), and came across an 02 modle with the VQ35 engine. As usual, I began checking the forums and stumbled onto the oil consumption concerns (note: these are consistent from the introduction of this engine in 2002 across all Nissan/Infinit models - and do not appear to be limited to the 'rev up' engines, etc.). In reading this (and based on years of hotrodding experience with American V8's) it almost sounds like a really high vacuum issue (generally a good thing as it indicates a strong combustion chamber seal) that is pulling oil past the valve guides, or past a gasket like the intake gasket. It doesn't take too much oil dilution for too long to screw things up either (i.e. rings don't seat correctly, etc.). Sometimes engine designers "solve" this by simply shielding the points of entry. As an example, valve springs will have oil shields to keep the splash away from the valve stem seals, etc. Other times, the seals themselves can be improved (i.e. better intake gaskets, PC seals on valve stems, etc.).
On another note, I see Nissan acknowledged issues with oil consumption caused by the catalytic converters on their 2.5 liter engine (i.e. Altima, Sentra SE-R, etc.). In that situation, those engines apparently do not have traditional EGR valves which recirculate exhaust gas back into the combustion chamber to be 'reburned'. Instead, they rely on the overlap of the valve timing from the exhaust and intake stroke to 'pull' a bit of the exhaust back into the combustion chamber (so far, so good). The problem is tha thte catalytic converters are very close to the exhaust manifolds onthese cars, and more importantly have an issue where the ceramic internals are starting to break down. As a result, little bits of ceramic debris are being pulled back into the combustion chamber, and are in turn scoring the walls of the cylinder. Obviosuly, if the converter isn't replaced at the same time as the engine (i.e. the root cause in this situation), then the new engine will just experience the same thing. Anyone heard of a similar cause with the VQ35 cars? Just my thoughts, sorry if this has all been covered before.
Later,
Chris
Thread
Thread Starter
Forum
Replies
Last Post
