Plenum Removal Question

[OwnerCS]

Here's in the home stretch on removing the plenum.

From the picture below, I believe I need to remove bolt at (A).

Should both (B) and (C) be removed or just (C)?

There seems to be a line behind the part where I need to gain access for releasing the hose clamp.

[tfitzs01]

Definitely remove C, and both B bolts to gain access to the EGR valve and to remove it. The plenum at this port should be cleaned thoroughly. Also make sure the rubber hose that connects to the egr diaphragm via the metal tube from the EGR is replaced as well. Ask Autozone for some of their spare hose bits. You just need an inch of hose.

[tfitzs01]

plenum-removal-90-93-q45-step-by-step-w ... 67568.html

This is the writeup I used as well. Great article

[OwnerCS]

Thanks neighbor! I was following a different example. MIke's examples are GREAT!

I've got a bunch of tools, but no cresent wrenches. Here I go to the store..

So far no hose casulties today. I took a heat gun/hair dryer looking device to warm up the hoses a little and they all came off without a hassle.

[tfitzs01]

you could use a pair of Channellocks (tongue and groove pliers) to do the job, I did not use the crescent.

I replaced three hoses. One hose was back-ordered a week. It was the exhaust recirculation hose under the TB

[Infinitiguy19]

Only B and C as shown in your picture need to be removed. The bolt (A) is for the EGR temperature sensor which you do not have.

[OwnerCS]

Thanks everybody. I got it off. :-) I had to cut the back hose.

We need to engineer something to give more room for reaching into that area.

[Infinitiguy19]

What hose did you have to cut?

When I cleaned the Auxiliary Air Control valve/Idle Air Control Valve last year(I think?) I used some radiator hose grease. I took it off again a couple of days ago and the hose just came right off after undoing the clamp. I would use that stuff on all the plenum hoses but I think grease and rubber end badly (The rubber hoses degrade when mixed with grease)?

[Lokim]

Use Sil-Glyde. A tube is about $6 at Napa and works great on all hoses and won't degrade the rubber.

[tfitzs01]

I second the syl-glyde...

Also, if you are replacing injectors, make sure that they are screwed down evenly. (e.g. One turn of each screw at a time.)
I screwed up two o-rings last week because of poor diligence to that simple fact! Repeating a removal after a muck-up is like punching yourself in the face after a root canal.

[Lokim]

I second the syl-glyde...

Also, if you are replacing injectors, make sure that they are screwed down evenly. (e.g. One turn of each screw at a time.)
I screwed up two o-rings last week because of poor diligence to that simple fact! Repeating a removal after a muck-up is like punching yourself in the face after a root canal.

Amen!

[lino]

Repeating a removal after a muck-up is like punching yourself in the face after a root canal.

[OwnerCS]

The hose I had to cut was from Step 20 in Mike's instructions.

"Step 20- Disconnect IAC Exhaust Gas Inlet This is the toughest part of the plenum removal- And as bad as disconnecting it is, reconnecting this hose is worse. This is the last connection and can be seen by lifting the front of the plenum a few inches and looking to the center rear. Move the plenum around until you can get enough space to back off the clamp with a pair of pliers." This is the absolute word on that one.


Here are some additional questions:

1) With a timing chain replacement planned for mid-September as a separate operation, would you remove the valve covers and reseal as part of this operation?

2) Did you use any lubricant like Sil-Glide on the injector o-rings?

3) Is there a way to remove the Infiniti emblem and side bars from the plenum top without damaging them? I would like to get the plenum bead blasted at a local machine shop.

[Lokim]

1) Yes.

2) A MUST! You don't want to tear the o-rings.

3) I don't know, but if you can't, just use a layer of blue masking tape and three layers of duct tape over that. Trim to fit and blast away!

[Q451990]

There isn't a ton of overlap between the timing chain guide job and the rocker covers, but if it jumps time, then you would remove the covers to retime the engine. The plenum job and the rocker covers have very little overlap, except for the stuff that you remove on the driver's side for the throttle body... and if I remember correctly, the EGR valve and it's tube should be removed to make it easier to get that cover back on.

Use a smear of motor oil on the injector o-rings and the inside of the rails to lubricate them. Infiniti starting including this advice in their later FSM instructions. I like it because it's already native to the engine bay, and I assume if Infiniti recommends it - it's the way to go.

The center emblem on the plenum is just stuck on there with double-sided foam tape. The other parts are part of the plenum.

Heath

[goody90q45]

......The center emblem on the plenum is just stuck on there with double-sided foam tape. The other parts are part of the plenum.....

With the engine hot it will pop off without damage with gentle but steady prying under one of the long edges with the tip of a small screwdriver.

I fill my pockets with them when I go to the salvage yard. They make nice refrigerator magnets.

[OwnerCS]

Thank you. I used the heat gun to warm the plenum before lifting them off with a putty knife.

Should the 2nd part of the intake lports (connected to the head) be removed and sent out for bead blasting with the plenum?

[goody90q45]

The lower intakes should be removed to clean the interior surfaces. They're probably black.

Are you bead blasting the interior to clean or the exterior for shine?

[OwnerCS]

While I like the looks of an outwardly shiny engine, I am really going for clean and protected internals.

Yesterday the plating guy referred me to another service he says can do better with nickel plating the insides of the injector rail and fuel lines.

I will be researching threads for information on cleaning the EGR and IAC valves.

The good news about all this is the old injector screens were clean as a whistle. That was a nice surprise.

Also the first thing before I started the job was to evacuate the fuel system (3) times -- following a recommendation from an airplane and yacht mechanic that is known for cleaning up some bad fuel contamination problems. I did not find any contaminants in that process either.

Now I have it filled with 100% premium. Luckily, I found a station a few miles from home that sells real gas -- for the time being.

I aim to cut open the old fuel filter when I have some spare time -- which might be a while from now.. :-)

[qship96]

While I like the looks of an outwardly shiny engine, I am really going for clean and protected internals.

Yesterday the plating guy referred me to another service he says can do better with nickel plating the insides of the injector rail and fuel lines.

I will be researching threads for information on cleaning the EGR and IAC valves.

The good news about all this is the old injector screens were clean as a whistle. That was a nice surprise.

Also the first thing before I started the job was to evacuate the fuel system (3) times -- following a recommendation from an airplane and yacht mechanic that is known for cleaning up some bad fuel contamination problems. I did not find any contaminants in that process either.

Now I have it filled with 100% premium. Luckily, I found a station a few miles from home that sells real gas -- for the time being.

I aim to cut open the old fuel filter when I have some spare time -- which might be a while from now.. :-)

Total waste of time, energy, and money........No need to "plate" anything, as proven by my 258K miles troublefree plenum and injector rails that have never been cleaned or disassembled.......many better uses of your resources in known trouble areas of these old Q

[Q451990]

QShip - are you saying you have 258,000 miles without your plenum having ever being removed and cleaned, or are you just referring to the injector rails?

I would save the money and just clean it with brake parts cleaner. I would also skip removing the lower intake runners and clean them with BPC as well. My method to keep from getting a lot of gunk into the engine is to stuff the runners with a few of sheets of paper towels, clean a little with a toothbrush, bottle brush, etc - then pull the paper towels and replace them with fresh ones. I pack them down pretty solidly and then pull them out with a "grabber" or some people call them "lady fingers." I always make sure I use a few full sheets with no missing corners or holes so that when I pull them out I can unfold them and make sure I got everything out.

The outside of the plenum is painted or coated with a gold-ish color paint. There is some debate on this point, so I think maybe the later models were not - but the earlier ones are. So I like to clean the outside by misting it with BPC and then letting it dry without too much rubbing. I think I went through about 10 cans of cleaner, which I let drain into a 5 gallon bucket as I cleaned and evaporate outside for a day or two.

Here are a few pictures of my nice clean plenum and runners.





Heath

[qship96]

plenum has only been off 1x in its life,at 203,000 miles when T3 did the underplenum job{hoses/knockers}....seriously doubt they took 1 extra second to clean it- other than that, it has never been touched, same for egr and injectors & rails....runs smooth, like new still. I have always run a true synthetic group 4 or 5 oil at short intervals{ 5-6K}though {Redline for the last 160,000 miles} so that may explain the lack of buildup introduced from PCV system?

[OwnerCS]

I’m glad to be doing this as I found an exposed wire running between two sensors – looks some varmint chewed off the wire insulation. I’ve got a working cat on duty to keep that from happening around here.

I am laughing out loud here..

I remember a poster on one of the Honda forums reporting that a squirrel chewed up the wiring harness on his fairly new vehicle. I’m glad the wire wasn’t touching any other parts.

[Q451990]

plenum has only been off 1x in its life,at 203,000 miles when T3 did the underplenum job{hoses/knockers}....seriously doubt they took 1 extra second to clean it

If it was anywhere else but T3, I'd agree with you - but I'm pretty sure that it is their SOP to clean everything that's off. They even spent a good bit of time cleaning my rocker covers on my Q and they only had 47K of buildup on them. Possibly less than that since it was their second reseal. Pretty sure they cleaned the plenum on my old Q when they had it off too.

looks some varmint chewed off the wire insulation.

Dennis used to joke that the insulation for the knock sensor subharness was made out of recycled Big Mac wrappers! For some reason they always get that one... I had one that was stripped too, but I think it was from incompentence by a dealer tech. that had worked on the car, it was all around one of the cable tie tie-downs, like the wire had been pulled really hard and the insulation was stripped as a result.

Heath