Intake Manifold Maintenance Suggestions

[Pwnin O'Brien]

So since the weather has gotten nice, I have decided that tomorrow I will start some major maintenance on my upper intake manifold. When I had the throttle body off last week I noticed some fresh oil lining the upper manifold. I will also be completing some other routine maintenance items while I have the manifold off. If you have any suggestions as to other jobs I should complete with the upper intake manifold off, please let me know.

Here's a list of the jobs I will be completing on the upper intake manifold:

Replace PCV valveInstall in-line oil catch can (and extend hoses so catch-can is easily accessible)Clean upper and lower manifoldsLoctite power valves and swirl valves

Also, does anybody know if it will be possible to reuse any of the gaskets? I would like to try to keep costs down but I want to do the job right and prevent any further headaches.

EDIT: Also, the thread title is incorrect and should read 'Intake Manifold Maintenance Suggestions' since I am performing maintenance on both the upper and lower manifolds.

[Mikey178]

Not that I have done this but I currently have my qx4 in the shop for repair and the mechanic thought he could take the intake manifold off and be able to reuse the gasket but it led to leaking. Had to get new ones.

I'd suggest changing both intake gasket and throttle body gasket. Not sure of the cost for them tho.

[Pwnin O'Brien]

I'm going to see if I can remove the upper IM collector without removing the throttle body. Since I did the throttle body bypass I don't need to remove the TB to access the coolant lines so I think I can remove the upper IM collector and throttle body as one piece, I'm hoping.

[racerken]

If I were to do it again, I'd replace the intake manifold collector to intake manifold gasket.I would also take the car to the car wash and lightly spray the area to remove as much dust as you can. Don't know about Jersey but the snow and road salt in Michigan plays havoc on filters.

I didn't understand what you meant by the trhottle bi-pass. I had to remove my throttle body because the coolant lines would not allow me to lift the unit. Ha, I even pulled the coolant line thinking that it would just dribble out... Wrong, I ended up spraying myself.
Modified by racerken at 6:34 AM 3/24/2010

[Pwnin O'Brien]

If I were to do it again, I'd replace the intake manifold to intake manifold gasket.I would also take the car to the car wash and lightly spray the area to remove as much dust as you can. Don't know about Jersey but the snow and road salt in Michigan plays havoc on filters.

I didn't understand what you meant by the trhottle bi-pass. I had to remove my throttle body because the coolant lines would not allow me to lift the unit. Ha, I even pulled the coolant line thinking that it would just dribble out... Wrong, I ended up spraying myself.

The throttle body bypass is taking the TB coolant lines off the TB (or upper IM collector in my case) and joining them together so the coolant no longer heats up the throttle body or upper IM collector (thus preventing saturation, keeping the TB and IM cooler for more HP). This means they are completely independent of the IM.

Is there a specific reason why you would replace (instead of reuse) the gasket between the upper and lower IM collectors? Did you get an air leak?

[racerken]

I've got a bracket in the front

My engine service light came on after changing plugs and i did notice:1. dust all over the place which I really didn't take time to clean because I ran out of time to remove the wire harness to the fuel injectors so all of these wires were in my way. I think some dust or junk is corrupting the seal.2. It's just good practice to change a soft seal such as the o-ring types.3. another poster recommended it so its making me stay up late at night. I may spray some engine start to check rpm change.

On another note, I just ordered the OBD.com diagnostic tool so I should be able to tell you what codes are making the 'service engine' light active.

[Pwnin O'Brien]

Can anybody tell me the significance of the power valves and why they are necessary? Why don't the manual R50's have them?

[Pwnin O'Brien]

So I got the upper intake collector, lower intake collector, fuel rail, and the intake manifold off the engine. The intake manifold gaskets were shot to hell so they will have to be replaced. The swirl valves have several millimeters of carbon buildup on them and the back of the power valves had a fine layer of carbon and oil buildup as well as the swirl valve runners. I think I will be able to reuse the other gaskets once I clean them up. Right now I'm trying to clean all of the carbon from the manifolds and get them back to factory clean. I've already found an in-line filter for the PCV line I just need to figure out a good mounting solution. I really hate Nissan for the way they designed the PCV valve and the line connecting to the lower intake collector.

Once I have the parts cleaned up I'm going to back out the screws for the power valves and apply some loctite 271 to the threads and re-torque them. I'm not sure if I'll be able to do the screws on the swirl valves since the neutral position of the swirl valves is open. I pulled each fuel injector from the fuel rails and I'm trying to find out if I should have them cleaned or if I can clean them myself. I would like to get them ultrasonically cleaned but I doubt any shop in my area does that and I really don't want to send them out.

My intake valves look fairly clean (from what I could see), I didn't see any buildup on the stems and I didn't really stick my head down in the engine to get a good look at the actual valve seats. I also just bought my first can of Seafoam and I'm going to try it once I get the car back together. I'm also trying out a brand new oil by Pennzoil, it's their new Pennzoil Ultra and I've been reading on BITOG that it is superior to Mobil1 EP, I'll post up the results once I'm finished, which is hopefully sometime this weekend.

[Pwnin O'Brien]

Here are some pics I took during the tear-down if anyone's interested. I didn't take any pics with the intake manifold and fuel rail removed but I will for reference.

[Pwnin O'Brien]

Some more pics with the intake manifold removed. I took a better look at the valves and they are really clean. I just need to clean the ports a little and remove the old gasket material. I'm also going to replace the fuel injector o-rings as a few look a little worn and most have carbon deposit build-up.

[Pwnin O'Brien]

I found out what the power valves are for. The power valves provide higher torque in the low-end while sacrificing some HP. When the power valves open (in higher RPM's) it provides more HP and less torque. I'm assuming that the M/T Pathfinders did not have this system since the shift points are controlled by the driver and it could cause the VIAS system to wear prematurely (this is just a guess), especially if the driver waits until the last second to shift in every gear. This is the reason why the M/T Pathfinder has a higher HP rating, it lacks the low-end torque that the VIAS system provides.

Technically you could remove the power valves to gain some HP but you would lose that low-end torque.

[RyanEvh]

What's that part labeled as 1 in the diagram on the upper right? I've never been able to figure out what it is.

[Pwnin O'Brien]

What's that part labeled as 1 in the diagram on the upper right? I've never been able to figure out what it is.

In racerken's diagram (for the 2005 Pathfinder upper intake collector) the part labeled #1 is the surge tank for the VIAS system. It essentially is a vacuum tank which operates the power valve actuator and opens the power valves for more HP. When engine speed is over 5000RPM's, the surge tank will become a vacuum and then that vacuum is used to operate the power valve actuator which opens the power valves, shortening the intake manifold length.

[racerken]

Thanks for the pictures. Now that is alot of work.

So is it back together?

Let me know if you have any error codes.

[Pwnin O'Brien]

Thanks for the pictures. Now that is alot of work.

So is it back together?

Let me know if you have any error codes.

Unfortunately the weather decided not to cooperate so I have all of the parts waiting to go back on and tomorrow is supposed to be nice so hopefully I'll have it back together tomorrow. I'm sure since the battery has been disconnected for so long I will have to do all of the relearning procedures.

[racerken]

I just purchased gaskets for the intake manifold collector to manifold (x3) and throttle to collector.

collector to manifold = 19.44 x 3 = 58.32throttle to collector = 15.97

ouch.

[Pwnin O'Brien]

I just purchased gaskets for the intake manifold collector to manifold (x3) and throttle to collector.

collector to manifold = 19.44 x 3 = 58.32throttle to collector = 15.97

ouch.

I actually was about to post some news on gaskets. I needed to replace my intake manifold gaskets so I went to the dealer and he quoted me $40 PER GASKET! I said f*** that, I went to Advance Auto Parts to see if they sold any gaskets for the R50 and I purchased all five gaskets for the intake manifold and upper/lower collectors for a grand total of $35. They are Fel-pro gaskets and they are EXACTLY like the factory gaskets, absolutely no difference.

[ugharin]

I purchased all the non-OEM gaskets too but from autozone around a month or so back actually for around 38.50 or so. Never got around to doing the power valves. Got too much going on and cant find the time for it. Got 82k miles on my truck and maybe if I wait for an year or so perhaps, I could also do the sparkplugs, wires, as well as the injectors, throttle body cleanup etc all together.

Thanks for all your write ups btw. They are of immense help.

[Pwnin O'Brien]

So I finally got everything back together and started the car up and got no DTC's (I did have to do the idle re-learn procedure). The engine was running a little funny after the re-learning and it had erratic idle. I popped the hood a heard a vacuum leak. I listened for a little while and then find out it's the new in-line filter for the PCV valve leaking. I take the thing apart and find out it has a manufacturing defect. I went to my local Home Depot (it was a Husky in-line air tool filter) and returned it. While in the store the lady asked me if I wanted to try other new ones to see if one worked, it turns out all of the new ones in the store all had the same defect. Now I'm wondering if I should just forget the "cheap" solution and go all out and get one of those Greddy (or some other brand) hardcore stainless steel oil catch-cans and be done with it.

The first drive after I fired up the engine already collected some oil from the PCV valve; that just shows you how much oil gets sucked into your intake.

[qx4dude]

If you dont mind me asking, what is the PCV valve and how do you know when it needs replacing?

[Eikon]

Pwnin- I edited your thread title for you.

Do me a favor if you would... send me an email. eikond at gmail.com

[Pwnin O'Brien]

If you dont mind me asking, what is the PCV valve and how do you know when it needs replacing?

When the detonation occurs in the cylinder and the gasses expand (pushing the piston down, thus turning the crankshaft), some of that gas gets pushed past the piston and into the crankcase. These blow-by gasses can build up and need to be vented from the crankcase or you could blow seals and gaskets (or blow the oil dipstick from the tube). The PCV system vents all of those gasses to ensure they don't build up. The PCV valve exhausts those gases from the crankcase and routes them back into the intake manifold so they can be burned and pushed out of the engine. If your PCV valve is broken (in the closed position; the neutral position of the valve is closed), you can get erratic idle (the RPM needle will "bounce" when you come to a stop or let off of the gas pedal) and those gasses will try to exhaust another way.

The rocker covers on the R50's have a baffle which is to prevent oil from being exhausted through the PCV valve. A little oil being sucked out the PCV valve is normal (it helps lubricate the PCV valve) but excessive oil blow-by can cause build-up in the intake manifold and sludge on the power valves and swirl valves. The baffle on the R50 actually collects oil and sludge (if the vehicle isn't maintained properly), usually pushing that stored oil and sludge out out of the PCV valve at startup, causing a nice white puff of smoke at startup.

Some people say that you can see if the PCV valve is bad by shaking it and if it clicks then it is good (I can't comment if that is actually true). The only issue is that if you are going to go through all of the work to test the PCV valve on the 3.5L R50's you might as well just buy a new one for $16 from the dealer and replace it.

[Pwnin O'Brien]

Also, here is a list of parts I purchased for this job as well as any tools required for the job:

Tools Required--------------------------#2 Philips-head screwdriverNeedle-Nosed pliersTorque wrench (you need to do both in-lbs and ft-lbs)Breaker bar (not necessary, but it makes removing difficult bolts much easier)10mm socket12mm deep socket12mm ratcheting wrench (w/elbow)

Parts--------------------------Loctite 271 (Red): $6Intake Manifold Gasket Set: $35Two 4ft. sections of PCV tubing: $1.40 per footFour injector hose clamps: $1.85 eachKobalt Large In-line air filter: $23Chore Boy stainless steel scrubber (3-pack): $1.00New PCV valve from dealer: $16.00Lots of parts cleaner and brake part cleaner

I'll take some pictures of the PCV catch can setup tomorrow or the following day, I just need to figure out some sort of mounting system for it.

[racerken]

Here was my problem:

I had to remove the intake manifold collector to access the spark plugs (to change them).I did not have gaskets for the throttle valve or the intake collector.After resetting the Service light it came back on after about 1 day.My mileage also was down to 12 mpg.Idle was up to 950rpm.

I figured that i as leaking vacuum so i ordered gaskets and a pcv valve just to be sure. Anyway, since I'm couch bound after foot surgery, can't stand for too long... had to find a short term fix...

So I shot carb cleaner all over the mating surfaces thinking that the gunk and liquid would help form a seal until I could properly change all gaskets...

As pwnin recommended, I reset my accelerator pedal released position learning and reset the throttle valve closed position learning.

All is perfect now.Stop and go traffic mpg is up to 15 mpg.

Hey pwnin, I used used to control blow-by + oil loss by having (v8 configuration) a can in the middle with left/right manifold in, return to intake, with a drain back to the oil galley, with steel wool in the can. The oil return had a filter to keep steel wool out particles out of the oil.

I guess if you had some welding experience you could build a air oil baffle but steel wool does the trick since it picks up oil and is not affected by the heat.

[Pwnin O'Brien]

Glad to hear everything is back to normal. For the Kobalt filter I removed the filter element and actually stuffed it with a stainless steel scrubber (Chore Boy brand) so the oil has something to condense onto. This way, I don't have to worry about small strands coming loose and getting sucked into the engine. I have collected a decent amount of oil for only having driven the car four times since I finished it. It looks like the most oil is collected during WOT, otherwise it only collects small amounts during normal driving.

It's also pretty ridiculous that you have to remove the IM collector just to change the spark plugs on the R51's.

[Pwnin O'Brien]

Here are some pics of my oil catch can setup. You can't really see where the hoses go due to the horrible placement of the PCV valve and the PCV inlet on the lower intake collector. You can also see the stainless steel scrubber inside the Kobalt filter case, this allows the oil vapors to condense and collect more oil that would otherwise make its way back into the intake. If you need any details about my setup feel free to ask. Also, my zip-tie mounting system is temporary until I can find something better.

Let me point out that while it looks as though the arrows on top of the filter look like they are pointing int the wrong direction, the two hoses cross right after the brake booster vacuum hose bracket; the arrow points from the PCV valve and into the lower intake collector PVC inlet. I had to do it this way because it was just how the 90 degree bend pieces screwed onto the filter case.

[racerken]

OK, two things:

1. I think you have a clean engine compartment disorder. I'm going to clean mine out when I swap all the gaskets.

2. That Kobalt filter is a great idea and I am strongly considering going down this path when I run into a vacuum leak which I'm sure will inspire me. How often do you have to flush out the accumulated oil?

BTW, what was the name of the website that offers low price dealer parts?

[Pwnin O'Brien]

OK, two things:

1. I think you have a clean engine compartment disorder. I'm going to clean mine out when I swap all the gaskets.

2. That Kobalt filter is a great idea and I am strongly considering going down this path when I run into a vacuum leak which I'm sure will inspire me. How often do you have to flush out the accumulated oil?

BTW, what was the name of the website that offers low price dealer parts?

1. Thank you, but I assure you, it is much dirtier than those picture suggest. I wish it were as clean as those pics make it look.

2. Do you know if oil blow-by is a big issue on the 4.0L? Most engines do have blow-by oil but this mod was really meant to stop the large amounts of oil that the 3.5L rocker covers blow through the PCV valve. Of course, anybody could complete this mod to guarantee that their intake plenums and intake manifold are completely free of oil, and also to prevent the burning of oil and extending the life of the catalytic converters.

I purchased the large Kobalt filter to lengthen the time between having to drain the oil out of the the catch can. I'm not really sure when I'll have to empty the oil out but at the current rate it could be as much as once a month. I have driven 80 miles since I added the catch can and it has accumulated a little less than a teaspoon of oil. I was hoping that I wouldn't have to empty the catch can until the next oil change, and that may still be the case, I'll update this thread when I do empty it.

A site for really cheap factory Nissan parts is EverythingNissan.com; they are one of the cheapest OEM Nissan parts sites I've found (well, it's a NICO advertiser, so NICO found it), they're even cheaper than CourtesyParts.

[racerken]

2. Do you know if oil blow-by is a big issue on the 4.0L?

Heard from the car company that makes this car:--------------------------------------------------------------------------------------------------------As far as your technical question goes, I spoke with one of our powertrain engineers, and they have not received any complaints in the field regarding this issue; however, they did disassemble a high mileage engine +200K miles, and found oil in the intake manifold in that unit. It is now clear to them how the oil got there. This particular engine was used on a farm, and did not get regular maintenance, but they did not find any significant wear on the friction parts. They seem to think that maybe the piston rings were stuck, i.e. they did not expand properly which allowed more oil blow by into the combustion chamber. Not clear what is going on with your unit. Also, I believe your engine has Pt tipped spark plugs, which are good for 100K. Any reason why you decided to change at 56K? Also, with respect to the amount of disassembly required for spark plug #1, see previous comment. --------------------------------------------------------------------------------------------------------

He was responding to my issue of having to clean-out oil from the inside of the collector which was not a substantial amount... As for the plugs, I was just shooting off things to do in order to increase my gas mileage.

Pwnin, when you open your oil cap while runing the engine, is blow-by puffing out? Mine does not.
Modified by racerken at 5:44 PM 4/13/2010

[Pwnin Obrien]

Pwnin, when you open your oil cap while runing the engine, is blow-by puffing out? Mine does not.

That's a great question, I'm not sure, I'll have to check and post my results.