Any suggestions for high consumption/leak?
 

Hello folks,
I have a 02 maxima with 136K which I love to death. Bought it when it had 50K and never had a problem except it always consumed oil. It started maybe about a quart every 3K which I was ok with using 5w30 oil. When the car had about 95K I switched to 10W 40 because consumption increased to a quart about every 900 miles. (VAlve cover gasket replaced a while back)
Now, it seems that consumption dropped to a quart every 600 miles. Now, add what seems to be a leaky rear main seal. The tranny clutch housing appears slightly wet and I dont see any other wetness anywhere.

If the rear main seal is in fact leaking at that mileage, I'm suspecting crank thrust washer issues here so just replacing the seal won't probably fix the issue and it's a big frigging job.

Any suggestions here and is there anyone's 5th gen that has a rear main seal leak like mine that can share what they did? I mean, I can either live with buying quarts of oil every 2-3 weeks depending on where I drive weekly or try to fix it but it's a big job and don't feel like pulling the trans to find out the engine has thrust bearing issues.

If it's a bad leak then fix it, but if it's just oil consumption, try Amsoil

When I switched from dino to full synthetic my oil consumption is almost not an issue since it seems to use less than a quart over 4000 miles; when before it would eat a quart almost every time I was ready for gas

Worth the $$ in my opinion

That kind of consumption is precat damage. Engine is toast.

I'm a little lost on that one. I actually did run Full synthetic up to about 100K then decided to switch back to regular oil and actually my consumption was less with regular oil. Synthetic seemed to have been slipping right by. Although what I was running was Full Synthetic 10W 30. Maybe Full Synthetic 10W40 may consume less? In other words, switching to non synthetic oil from at 10W30 weight decreased my oil consumption.

As far as precat damage,I had totally forgot about that issue that some people were having in some cars. I never even contemplated replacing the cats as I thought it was just too much money and work. Yes, an engine costs more, true. But at this high mileage now I'm not doing that. If the engine is toast then the rings are toast. Compression rings appear to be good still as the car still moves out pretty quick as per my butt gauge :)

The cat should last the lifetime of the vehicle. But vehicles wind up with issues causing catastrophic catalyst failure.
From what it sounds like your probably hitting the highway at high speeds for a few hours per week. Even with a small leak that much oil could leak out of just a small area depending on how fast you go and how far. People that don't drive far from home and don't break 60 very often could have a small leak and not lose a lot of oil. It sounds like you drive extremely far putting 600miles on your car in just a few weeks. So not sure exactly what the figures are but these Maxima s probably build up high amount of oil pressure when traveling at higher speeds.

I got leak in the same place by the rear cover plate . The whole upper oil pan has to be dropped . Half the engine has to be removed so what I suggest is taking the time to replace anything else that could leak or go bad
Good point about the crank thrust Double up on RTV right ? On both sides of the horseshoe seal

I drive 50 miles each day for 3 days out of the week so600 is more like in 4 weeks. But 600 can build earlier with weekend driving. I do hit the highway and I don't do 60. I'm on it around 70-75. I don't do excessive crazy rpms but at 70-75 the rpm's do get to about almost 2500 or so, maybe less.

Yes, correct, I forgot about the upper oil pan. It's leaking there too. There's no way I'm dropping that damn pan. I mean the car only has 140K but still it's a job I'm not doing. When I drop that, I'll have to replace the whole exhaust as it's all rotted but steady for now. Once you drop it, it's done and now a gasket change will turn into thousands.

But as far as the rear main seal, how do you double up on the seal with RTV with the trans on?
Also would using 20W 50 oil be advisable to slow down leaks? Aside from the fact that winter temps will put a toll on the starter.

An external oil leak will not have any effect on the cats. It doesn't matter how much you drive.

There's no way to RTV an oil seal from the outside. They need to be replaced when they fail. There's no way to access the rear main without removing the tranny. Even then, all you can do is look at it. You'll have to pull the upper pan to replace it.

It's probably leaking from the front main as well and that's a much easier fix. You could at least slow the leaking some by replacing that.

Yeah, I didn't think you could RTV the seals from the outside. I'm not dropping the pan much less trans. But thanks for the front main seal advice. Didn't notice anything from the front but I'll look again.

I don't blame you. I did the seals on both my Maximas this year and it's a lot of work even without a rusty exhaust. Kind of a crap design that requires the lower pan to be dropped.

You might be confusing the main cat located under the car, to the pre-cats, those butt plugs shoved right up the car's exhaust manifold. They're the ones prone to failure in the 2002-03 Maximas.

Check this thread with pictures;
https://maxima.org/forums/5th-genera...at-gutted.html

How probable is it that pre-cats will fail? Is it inevitable, or something attributed to poor maintenance and driving around with a misfire for a long time?

I'm at 115K and getting kinda nervous :ugh:

Very probable
Definitely inevitable, no matter the maintenance on the rest of the car

Good excuse to buy headers

Still going to burn though

Exactly. Or at the minimum, a y-pipe.

Get peace of mind. Everything else about the 1st gen VQ35DE is good to go for the long run.

Unfortunately 2000 cali and all 01-03s have the cats in the manifolds (3.0L has one in it). This is about half the reason for the failures. Thanks, useless govt.

😂😂😂

I haven't heard of any failures of VQ30DE-Ks like the VQ35. I would chalk that up to the longer stroke, deeper breathing VQ35.

Those cats don't break apart, afaik (never heard of an instance anyway). The cats in the Y would be too far down, I think. Also, 2000 uses EGR.

I wonder what the tune WOT is for 3.0s? That didn't help the 3.5s, b/c it's too rich from factory and just heats the cat more (and causes microexplosions in it, so I've read). So, if you combine more heat from location, more heat/degradation from fuel and probably a ****tier part, you get disaster.

Contrary to popular belief, nissan did not fix this with 6th gens (plenty of pics with the cats down in the Y pipe). They did slap EGR back in an attempt to stop engine damage, though.

Interesting......and to be fair, this is not just a Nissan thing. The 2007 or so Toyota MR2 suffers the same fate. There are probably other car manufacturers with models suffering from the pre-cats being too close to the exhaust manifold.

With high consumption leak i'm thinking that the PCV valve could be bad.

This valve is always the suspect usually when having issues.