My 97 Maxima has almost 200k on it now and has developed a number of small oil leaks. One results in oil dripping onto the exhaust and causes a burning smell whenever the engine is hot. I have a spare car and some extra time on my hands, so my first plan was going to be a replacement of the front and rear valve cover gaskets. While I'm in there, is there anything else that I should replace? My engine has oil seeps/leaks all over and it is filthy so I can't really determine the source(s) of the leaks. Thanks in advance!

 

Sparkplug seal. PCV valve grommet.

 

Upper Intake Manifold Gasket, PCV Valve and Grommet. Clean TB, MAF, IACV. Replace knock sensor if you never done so.

 

i thought the uim gasket could usually safely be reused and does the pcv valve grommet go bad?

 

install NWP spacers(or budget spacers). clean EGR since the one person didnt mention that. polish/paint/powdercoat ****.

 

Pcv valve hardens and crumbles into the vc. Replace the TB gasket if you remove it.

 

all things stated above along with the hose running between the 2 valve covers....i just did this and mine was cracked and split like crazy from the heat. i cant remember what size i ended up buying though. Also replace the coolant hose on the back of the UIM with a longer one so next time you remove the UIM u can have better access to it and wont have to cut it....

my 2 cents....

 

on the hose. I bought a foot long piece from AZ and looped it back there. I pretty much bring it forward when I need it off now and don't need someone to hold it up.

 

Thanks for all the advice. For those of you that replaced the small hoses, can you specify which ones I will need from the catalog here: http://www.courtesyparts.com/maxima-...1808_1812.html

I am trying to order all the parts I need before starting to tear things apart.

 

The coolant hoses are 14056NA and 14056NB on that diagram. The blowby hose is 11826 on the Crankcase Ventilation drawing, number 118 under Engine Mechanical.

 

Thanks again to everyone that provided advice in this thread! I replaced both my valve cover gaskets this weekend along with all the miscellaneous items mentioned above. No more oil leaks! The only additional part I needed was item 11826+B in this pic (http://www.nissanpartszone.com/diagr...on-118a001.png) but I bought some tubing from AutoZone to replace it.

For reference, here are the threads I found helpful in describing the work:
http://forums.maxima.org/4th-generat...l?ref=esp-link
http://forums.maxima.org/4th-generat...im-w-pics.html
http://forums.maxima.org/4th-generat...pair-info.html
http://forums.maxima.org/4th-generat...e-removal.html
http://forums.maxima.org/4th-generat...placement.html

 

Not to revive a dead thread, but I was doing coils and plugs, and on the last plug (rear driver) just an absolute mess of oil!!! So in my cart I have a Mahle valve cover gasket, PCV valve, throttle body gasket, upper intake gasket. EGR gasket.
the IACV is expensive, so I will wait on that. What other sensors or gaskets should I swap while I’m in there??
I will clean the throttle body too. I have been having a slight miss at idle. So my guess is packs and plugs. And then the drenched pack and plug in oil!!! I also have both bank 2 O2 sensor codes. I bought those to change too.
thanks again gang.

 

You can take the iacv valve apart. Use carb cleaner as a cleaning solvent. Then reassemble.

Good that you are taking care of things while you have the uim off.

Our fuel injectors tend to leak. You could replace with new ones if you need to do all the work quickly. Otherwise, look up Injector RX in Houston. They do a great job with rebuilding them . They charge 18 each. The rear 3 injectors are buried under the uim. The front ones can be replaced when they fail. I had all 6 rebuilt.

The egr system tends to clog. especially the tube which bolts onto the uim. Clean the system with carb cleaner. It can be done separately later. But much more difficult.

Might as well clean the throttle body with tb cleaner.
The knock sensor is easy to replace while the uim is off, a bear if you don't.

replace all fuel lines.

the vacuum lines can get hard and brittle. I bought about 2 feet of hose to replace it.

there are 2 water hoses which connect to the tb. Those leak sometimes. Your discretion about now, or later, or not at all.

This seems like quite the list. And a pain.
Your car will run better and be more reliable once it's all done.

You will need to remove the UIM again in the future if you don't do it all at this point.

 

ok!!! Thank you. I planned on cleaning EGR and IACV for sure. Like I said, the car misses a little at idle. I was going to inspect whatever rubber I could see. I probably would have overlooked the fuel lines and I will inspect the injectors. Possibly even take them off and send them to Houston. I’m in Colorado. Does the knock sensor need to be OEM? I got this car at auction with 118k miles and I want it, but it has turned into a non maintained nightmare 😂 it’s a 1999 gold i30t

 

People have used aftermarket knock sensors with mixed reviews. The choice is yours, but since you have a 99 it’s not as easy to replace a bad knock sensor. Usually the intake manifold has to come off to get to it. If you’re doing the rear valve cover then you definitely should take care of the rear injectors.

 

should I just replace the injectors? I’ll look into the knock sensor. This all started with rockauto having a sale on coil packs and shocks lol

 

You can buy new injectors or have them rebuilt like JvG suggested. A lot of people here have rebuilt their OEM injectors rather than buying aftermarket injectors. The front injectors are easy to access, so you can replace those whenever you feel like or when they go bad. For peace of mind I’d do all six at the same time.
Only use OEM coil packs. The car may not run right with aftermarket coil packs.

 

Oem injectors are high quality, built to last.
the plastic cap at the end fails after 20 years. The rest is still good. The spray tip cam get clogged
The rebuild restores them to like new condition.
I sent mine to Injector RX. I was impressed about the results. 18 dollars per injector is more affordable than replacing them with iffy after market ones. The whole purpose of what I recommend is reliability. I doubt you enjoyed removing the uim.

 

I got oem coil packs . Denso I think. The ones I pulled were hanshin I think. I am going to send injectors to injector RX! Cheaper than 60$ each new!

 

after pricing new injectors, I am going to send to injector RX. Cheaper than new (non OEM). I am going to park the Infiniti in the garage and start tearing her apart. I am working 6 days a week alternating nights and days. So it will be a slow process. I need something to replace my corolla that has been burning oil for 50k that I abuse 😆 it is a year that came with faulty piston rings from the factory it’s been a good car. I travel soooo much for work that I only drive old Japanese cars hahah!

 

What about o rings and clips? New aftermarket, oem new?

 

The rebuilt injectors come with new o rings, already installed.

Which clip's are you referring to?

I don't recall any of what I'd call clips.

By the way. Put engine oil on the O rings and also the sides of the hole they live in when you install them.

Glad that you see that rebuilt OEM injectors are 2/3 less expensive than new ones. That savings is more than enough to pay for the rest of the project.

I'd send them the that company asap so they will be ready for installation after you do other things like the egr system. Like the housing the egr lives in , and the tube I mentioned.

you will need gaskets for both sides of that tube. Also for the egr valve you will need to remove.

 

some cars have injectors that have little metal clips the thickness of a small paperclip. if you didn't see any when you took of your injectors, then yours probably didn't come with them.

 

The 4th Gen Maxima has white plastic caps which tend to disintigrate. No metal clips .

 

Don't know if you have completed this job yet, but I did this exact job last weekend. Your list looks good to me. I made the mistake of not having an extra EGR gasket or throttle body gasket and both needed to be replaced. One thing you may want to add to your list is the crankcase ventilation hose. Its part number 11826-31U00. When I took mine off it split on both ends.