My 95 has just under 220k on the clock, and has some CELs. I went ahead and am replacing all the injectors (just cuz that's how I roll ). In doing so I have removed the intake plenum and it is a nasty mess inside. I have also removed the intake itself cuz it too is nasty. I thought I read in the manual to not clean these due to some special coating (but can't seem to find that blurb now of course). Well if that is the case, it's not doing a very good job cuz both of these internally are gritty, gooey messes inside, so my plan is to clean them in a solvent tank unless someone says otherwise here. In addition to that, I am cleaning up the throttle body, IACV, EGR and EGR tube (tube was completely plugged at the one end). Even though they are not leaking at the moment I also plan to replace the valve cover gaskets since I am already in here. So my questions are these:

1. Is it okay to clean the intake plenum, intake manifold and throttle body with a solvent?
2. Are there any other things I should be cleaning and/or replacing while I've got this thing tore down to this point?

Thank you!

 

I've cleaned mine with carb cleaner. I think could get a better clean with seafoam though.

 

1. Yes.
2. Change PCV valve of course. Maybe change knock sensor(test it first). Replace IM gasket, EGR tube gasket, throttle body gasket, and fuel filter while youre under the hood. General cleaning and degreasing.

 

Thanks. Yes, forgot to mention that PCV and fuel filter are already on the list of to-dos, along with all related gaskets. There seems to be a surprisingly little amount of grease & oil on the outside of the engine for a rig with this many miles (and I don't think it was taken care of all that well really).

 

While this item may not be in the vicinity of the intake, I'd take a look at the oil pressure sender unit located next to the oil plug underneath, just to make sure its not starting to sweat oil.

 

You do not want to use carb cleaner for the throttle boddy. Pick up some throttle body cleaner.

 

I have some TB cleaner, but what is different about it? Is there some coating that needs to be worried about?

 

TB/Choke cleaner is fine. Go to town with a tooth brush and some clean rags/towels.

+1 on preventive maintenance man. I would seafoam the car once you get it put together as well. And put seafoam in your gas to clean your fuel system as well.

 

I hate to say it, but I am not convinced seafoam really works. I seafoamed the D30 on my 96 Taurus and despite all the smoke that came out when I later took apart the intake both the primary and secondary runners were still pretty gunked. The catalytic converters clogged up too after seafoaming.

I tried it on my max after I first got it, huge amount of smoke just like the Taurus, right after seafoaming all 3 of my O2 sensors went out.

After doing some research I later found out apparently some people have tried seafoaming brand new rental cars and stuff and it still makes a huge smoke cloud even though a brand new engine should be clean.


Honestly, I think the best bet is to just take it apart and have the intake hot tanked or clean it by hand.

 

Just replaced one O2 sensor...would be PISSED to have to replace all 3 of 'em after putting some crap in that's supposed to clean stuff up. Sounds like the stuff just makes black smoke so it SEEMS like it's working, huh? My plan is to simply clean it by hand. It's already apart so that makes more sense to me anyway. Really surprised how much soot and crap is in the INTAKE stream from the TB to the valves. You'd think that it would be pretty darn clean, but I guess it's from the EGR dumping crap in there that clogs it all up. Anyone successfully bypass the EGR to keep it from doing this (yeah, I know it's all for emissions, but really)?

 

I use seafoam every 20k. Did it ever occur to you that your O2's were possibly on their way out already and seafoam finished them off?

I have been seafoaming my car since it has 26k every 20k. Never had any issues after seafoaming, and actually, my car idles better and the throttle response is slightly better.

If I was doing what you were doing ChiknNutz, I'd do the following (some of this was stated already):

• Clean Throttle Body, replace gasket
• Clean IACV, replace gasket
• Clean EGR Tube, replace gasket
• Replace Air Filter with ONLY Nissan (if using drop in paper filter)
• Replace Fuel Filter with 95' 300ZX filter
• Replace Valve Cover Gaskets with Nissan OEM
• Replace Knock Sensor with Nissan OEM
• Replace Spark Plugs with NGK V-Power Copper Plugs (BK5R-11E I believe)
• Check all hoses
• Seafoam car through the Upper IM
• Pour a FULL bottle of seafoam into the gas tank
• Replace PCV valve
• Suck out all old power steering fluid with turkey baster, replace with AMSOIL ATF
• Top off other fluids
• Flush Coolant and replace with Toyota OEM fluid (50/50 mix)
• Clean factory grounds

I'd also pour seafoam into the oil and drive 100 miles then drop the pan and clean it all out and refill, check the exhaust, etc. but doing the above will get your car ready for spring/summer and most likely boost your MPG at least 1-2 miles per gallon.

I have had ZERO issues with seafoam on this Maxima and my last one (97 GXE).

 

Thanks for that list. Most of that is on mine already, so cool. One question is about the Knock Sensor...since this is about a $100 part, why do I want to replace it if it is still working...other than it's a PITA to get at later? Is this something that goes out eventually and just needs to be replaced? I like to be proactive, but also don't want to simply throw $$$ at it needlessly. Still, thanks for the info.

 

Yes, it does go out.

I would do it as preventive maintenance. But that is just me. I replaced my PERFECTLY fine functioning one at 60k when I was doing my 00VI. These probably last a good 100k or so. I did mine cause I had access to it. Rather, TJ_Maxx had access to it lol.

 

i got my replacement knock sensor off ebay for like 35 shipped, just fyi.

 

anybody done the seafoam in the oil thing? I havent sea foamed either car yet but was debateing it. My SE has had BG MOA, and BG carbon fighter its whole life at least once every 10k. I'm sure it couldnt hurt to seafoam it but never heard of putting it in the oil.

 

just write seafoam in the search for 4th gens and u will have a days worth of reading to do.

 

Since you have the manifold off, might as well replace it with a MEVI and add some NWP spacers.

 

I did.

Put it in, drive it 100-200 miles (I drove 210). Drain oil. Drop oil pan. Clean off the old gasket off the oil pan. Spray down the inside of the oil area with choke cleaner/similar solvent. Put nice thick RTV Silicon line on the rim of the oil pan. Re-install.

I haven't had any issues with mine after doing this 3 weeks ago. Becareful not to strip one of those bolts on the pan though. I stripped one and had to re-tap, etc. PITA. But my Maxima is known for that. I can always remove 90% of something and then all hell breaks loose lol. Always.

 

I'd do the spacers for the heat drop but 00VI's and MEVI's are over-rated lol. I'm glad I de-00VI'ed. I had nothing but problems with that thing on my car.

 

Seafoam is the coolest thing. Its hilarious when you floor it down the block and it seems like the whole place was just starting on fire with all that smoke.

 

That's only if your car is dirty. My car never smokes very bad. My 97 the first time I did it smoked A LOT more.

I did my first one at 26k, second at 45k, third at 55k, fourth at 76k. None of them smoked much, but that's probably cause I keep everything as clean as possible.