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The Don.
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6,151 Posts
Discussion Starter #1 (Edited)
Hey guys,

I've finally started getting around to fixing some of those problems with my car. One of those problems was a intake manifold gasket leak that I've uncovered and wrote about in this thread,

http://www.nissanclub.com/forums/general-nissan-altima-discussion-1993-2001/231751-poor-mans-vacuum-leak-detector.html?highlight=poor+man+intake

I've gotten good, since I was about one year of age, in tearing down and breaking things apart - so I've heard from my parents. Most of those stuff never became whole again...but hey I learned. Hopefully I won't have any leftover parts when I'm done with the intake manifold gasket repair.

My adventure in adulthood is to find a way to do the near impossible - replace the intake manifold gasket without dropping the motor or removing the cylinder head. I've read other threads on how some had gone about it but nothing sounded straightforward to me. The approach I am taking offers a different alternative for undertaking this task. I haven't been taking any pictures but I will go on writing about this as I move along...specifically noting the challenges.

The first thing you should keep in mind is that your car will be "out of commission" for some time. So don't expect a quick turnaround unless you are a master mechanic, which I am not. My car has been in summer hybernation for about three weeks now since I can only do maintenance work only during the weekends and I am in no hurry.

The approach I am taking is simple in concept, first remove the intake manifold collector before moving on to the intake manifold. Why?? Because it stands in the way at getting clear access to the center of the intake manifold bolts. Besides you want to take advantage and replace the PCV, IACV, knock sensor, gaskets, and anything in that area that is in a bad state.

Here is what I had to do so far, in no particular order,

- Remove the air intake duct system.
- Remove the passenger side intake manifold support brace near the IACV.
- Remove the oil filter.
- Remove the starter.
- Disconnect the EGR passage tube.
- Remove the throttle body and associated hoses and linkages.
- Remove the driver side intake manifold support brace. It is located to the right of the throttle body. Very important!
- Remove the five nuts/bolts holding down the collector to the manifold.
- Disconnect some of the plugs from the underside wiring harness.
- Disconnect the throttle body and IACV coolant hoses.

Give the intake manifold collector a good whack with the handle of a hammer or something similar and she will drop a couple inches. Here is how it looks like from the engine,



Location of the braces;





WOW!! All that just to remove the intake manifold collector. Had to stop at this point, but I'll see what is needed next to fish the collector from the throttle body side or work it loosely around while I work with the intake manifold.

It has repeatedly been said by others that you need a rachet with a swivel head. Heed that advice because without one you are just begging for additional headaches. Also get a 1/4" socket adapter and a few different size socket drive extensions as well. They will come in very handy.

Oh, and don't forget to get yourself an engine gasket kit ahead of time. Did I say that this was an intake manifold gasket replacement? :brow:
 

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white on rice
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1,565 Posts
nice work, keep the info flowing!!!
 

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The Don.
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6,151 Posts
Discussion Starter #5 (Edited)
Another update...

Well I am finally learning how to also become an daily early morning mechanic instead of weekend shade tree mechanic, and I'm loving it, less interruptions.

My attempts of removing the intake collector from the throttle body side were futile so I opted with option number two, to simply move it around to gain clear access to the underside of the intake area.

Working from under the engine, I had FULL view and clearance to all the bottom intake manifold bolts. The two bolts underneath the intake where I have the leak seemed very loose. I had already known that my leak was localized inbetween intake runners #3 and #4. I initially thought, "Well hell, I probably just needed to tighten those bolts and that was all". But something stood out around that area, as I was removing the bolts, that caught my attention. There was a noticeable black patch in that area close to the intake gasket material. Was is carbon deposits? I ran my fingers through it expecting to bring up some sort of chalky charcoal looking substance, meaning it was coming from within the intake and was blowing out, i.e. intake backpressure issues. But that wasn't it. Looking at it closely it ressembled the baked state of engine oil similar to what you see inside the valve cover from cooked engine oil. I thought, "Could it be the valve cover gasket leakage that cause this?" But the topside of the intake and all around looked clean. So I went back down there to get yet another closer look...and there I saw it. That black baked engine oil had left a trail that was leading to the driver side. And, what were my previous leakers over there?

1. The old distributor which had a bad bottom o-ring and which I ran like that for some time.

2. And the half-moon gasket piece of the valve cover which had dried up liquid gasket and leaked in that same area as well.

Do you 'see' what I see?!? Nissan Techs and Engineers listen up! Remember all those complaints from a bunch of people that turned out intake leaks around intake runners #3 and 4, well maybe it is due to the engine oil getting to the intake gasket material. That material, like paper, absorbs engine oil and with high engine temperature will cause it to break down and eventually either harden or crack. Hench the leak. What do you guys think? Sounds very plausible, doesn't it?

Anyway, going back to were I left off... I removed all the bolts but the intake manifold wouldn't budge. I thought I hit a brick wall. :banghead: I started checking around and couldn't see any more bolts to remove but something still held it tight. Got to counting the bolts I removed and it was showing 9 instead of 10. :smack: I was a bolt short and it is the one underneath the throttle cable bracket. Had to get ready for work so there she stands waiting for me to continue...

Anyone else planning of doing this work? It's so much fun...NOT...
 

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cool, if you can take pictures of the process, that would be awesome! I really hope to never need to do it hehehe :D
 

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The Don.
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6,151 Posts
Discussion Starter #9 (Edited)
Intake leak pokes it ugly eye!

I've added some pictures. You might want to pull them up while reading along.

So continuing on where we left off with the teardown,



You need to disconnect the brake booster vacuum hose from underneath the intake. Also need to disconnect and set aside the water cock bracket and attached hoses from the firewall and disconnect the cable wire to it. The cable wire has a small metal clip that locks it down. Make note on how it is attached since it will have an affect on the heater core heat output if misadjusted. Paint a stripe or something to know how to set is back properly.



There is a big coolant hose that need to be unclipped from the bottom of the intake manifold. In addition, there is a 10mm bolt holding down this hose through the center that also needs to be removed. Move the intake collector around if you need to gain access around this workspace.



Here is the backside of the intake manifold. As you can see there is no need to remove too many components from the top of it. Most of the components are EGR related as shown. Also, if you are not using any zip bags to store and name the bolts, I suggest you put the bolts loosely back in place so you don't go insane trying to figure out what goes where.



Here is another shot showing the big coolant hose. It is held in place at the center brace by a bolt and at the end brace by a nut. The #3 intake gasket crumbled apart when I accidently brushed it with the coolant hose metal bracket. That was not the way it was when I pulled the intake from the top. There is the knock sensor if you ever wondered where it is located.

...and some additional shots off the surrounding area...



http://www.stac-consulting.com/serrano.j/altima/intake/0603070754.jpg



The PCV connects to the PCV blow-by tube so you have to disconnect one end of the hose to it. But in my case, that rubber hose was so hardened I could not bend it in any form. So I decided to just unclip it from the PCV and unscrew the PCV from the PCV breather. Either way I will have to replace both the PCV and hose is one swoop. The PCV blow-by tube has a gasket that can be replaced as part of the engine gasket kit. Notice how the lower intake manifold gasket looks in good shape despite the age.

[imghttp://www.stac-consulting.com/serrano.j/altima/intake/0603070742a.jpg[/img]

Here are the two intake buddies side-by-side. I highlighted the area I spoke about the clearly shows that engine oil trail left behind around the problem area.



If you are wondering what some of the parts are from the intake manifold collector then take a look at this picture. The IACV bypass hose basically bypasses the intake air around the throttle valve into the IACV. The IACV Air Regulator has an inlet (feed) and outlet (return) coolant lines. This is used so that a wax and spring mechanism inside the Air Regulator controls how much additional air feeds through the IACV during cold starts (fast idle).

Here is how my engine looks with both the intake and exhaust mainfold removed.

http://www.stac-consulting.com/serrano.j/altima/intake/0603070758.jpg
http://www.stac-consulting.com/serrano.j/altima/intake/0603070758a.jpg

And, how about this??? A free additional repair to add to, a busted passenger side steering boot. Can I replace the boot instead? How hard is it? Or, should I just bite the bullet and replace that entire piece since I have her guts opened.

http://www.stac-consulting.com/serrano.j/altima/intake/0603070753.jpg

Now on to the good part. Let us see what all that fuss was about when I first diagnosed this problem a year back, as mentioned above.

Here is the vacuum leak from one angle,



... and another angle...



If you notice from the picture above, the intake gasket material changed to a red'ish color in the failure point which seems to suggest that my theory about the engine oil soaking it caused it to fail. That discoloration is not visible anywhere else. So I'll hold to that theory for now.

There is one additional note I'd like to make; the EGR and PCV systems causes some really bad looking carbon deposits to heavily coat the interior of the manifold. The problems with this charcoal looking substance is that too much of it acts like the charcoal canister and absorbs and drenches the fuel vapors trapped inside. I've heard how some mechanics have mixed feelings about this because it can cause driveability problems. I've also read about some type of 'catch can' design for the PCV systems that can curtail some of this crud and that might seem like something I might read up more on. Any inputs are welcome on this as well.

So there you have it folks. This should hopefully be of aid to some of you. If this hasn't stopped you from doing it yourself and taking the car in, then at least you know what you are getting yourself into.

There is still some more work ahead for me on this so I expect to write some more. Unless, y'all are bored to death with it...

Later :wave:
 

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Registered
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lol, saw all the pictures, really painful to remove, uh? and just for a crack on a gasket... :(

since you're removing everything, will u use the opportunity to change things like the pcv valve? did u take a look at it to see if it's still in good shape? I'm wondering if mine is still cool after 140k miles on it :)

and I'm impressed by the carbon deposits, if we had no egr, then no carbon deposits would form, right?
 

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The Don.
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6,151 Posts
Discussion Starter #12 (Edited)
sonicxtacy02 said:
damn your a brave mofo... now come on down to woodbridge and help me with mine.... all the beer u can handle i swear!!!

LOL. Thanks for the offer but you couldn't get me drunk enough to do this on someone else's car. I'd probably pass out beforehand anyways. But there is plenty of info in this thread to get anyone else started.


I spent the better half of the day on the intake manifold and collector. The first order of business was to remove all that carbon deposits. I've read up on how many have done the intake cleaning with "Easy Off" oven cleaner. And let me tell you that there is probably nothing better than it. I saturated the interior runners with it and let it sit for about 5 minutes. Then I rinse it with high stream water. Dried it up and repeated the process. After about three times they started looking really nice inside. I only had a few odd spots that I was able to finish up with carb. cleaner, a toothbrush, and a cotton towel. I'll have to post some pictures so y'all can see how nice they look inside.




This next picture shows how clean the ports came out. For you nitrous folks, look how close the PCV blow-by ports are to the cylinder ports. Makes for some nice direct nitrous injection if someone could come up with something. But you'll have to designed something for the regular PCV system as well.



Make sure to also do the same thing with the EGR passage internal to the manifold and to the external pieces. Take your time and clean the EGR valve while you are at it. Put in the new gaskets from the engine kit.





I had decided to remove the EGR temperature sensor with a 14mm wrench and got a big surprise. The EGR sensing tip was covered so thick in carbon deposits that it is very likely it wasn't doing it's function or was operating well out-of-range. This sensor tells the ECU what the EGR temperature is and the ECU will then know how to control the EGR solenoid valve. I bet that everyone who removes it will find the same thing since this item is never maintained by anyone. You could either clean the sensor or buy a new one. They go for about $100 so I cleaned and reused mine for now.





I finally also got a chance to put in the new IACV I bought about 6 months ago. It was a simple replacement since the collector was out of the engine. I also put in a new PCV valve. And since the question was asked about the condition of the old PCV valve, here it goes. The old valve rattled and behaved exactly like the new one. It was working perfectly fine from what I gathered. The most you probably would have to do is simply drench it with a solvent and it will be as good as new. This thing is very heavy duty and I don't see why anyone will really need to replace it EVER. But I did, since what the heck, I bought it a long time ago and expected to do it together with the intake gasket.

My gasket kit didn't include the fuel injector grommets. They are the rubber pieces which the fuel injectors rests on. Sometimes they harden and could be a source of an intake leak. Mine were still fine so I just placed them upside-down so that the injectors would seal better. The only thing I noticed with the injectors was that #1 had a cracked plastic cap at the end of the pintle. I have some good spare injectors so I'll just replace that one.

One additional note I'd like to make. You know about the common problem where the temp gauge needle flickers (oscillates) back and forth rapidly. I used to clean the spade connector on the sensor and crimp the wiring connector and that would work for a long time. But then it would come back. Well, I finally know why it really fails. It is because the spade terminal becomes loose on the sensor itself. You can twist the spade connector on the sensor with a plier and it will lock tightly in place. But the best option probably is to buy a new one since they are cheap. I'll need to do that later.

So I am now pretty much at the point where I can start the reassembly of the entire intake system. I'll continue to keep you all posted on how it all goes from here on in.

'Til next time..js
 

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Did the carbon on the EGR sensor seem to be natural buildup over the life of the engine or excessive, possibly as a result of MAF issues (bad connections,etc)?

Seems like a number of folks have the extreme carbon buildup that plagues the EGR valves and lines and I'm wondering if it's related to the poor MAF connection issue or even due to the fact that Nissan's tend to run on the rich side....?

Good job, if I had a spare car, I'd actually like to tinker myself. Guess I'll check that sensor on my '93 if I have it....

Jeremy
 

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The Don.
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6,151 Posts
Discussion Starter #14 (Edited)
niceguy said:
Did the carbon on the EGR sensor seem to be natural buildup over the life of the engine or excessive, possibly as a result of MAF issues (bad connections,etc)?

Seems like a number of folks have the extreme carbon buildup that plagues the EGR valves and lines and I'm wondering if it's related to the poor MAF connection issue or even due to the fact that Nissan's tend to run on the rich side....?

Good job, if I had a spare car, I'd actually like to tinker myself. Guess I'll check that sensor on my '93 if I have it....

Jeremy
That carbon buildup is likely due to the times when the engine has been running rich. That happens enough times in the life of any engine, particularly during cold starts, where the engine will run rich until it has warmed up. Sudden acceleration will also do it. Not much you can do unless you have an SAFC or tune the ECU to not run rich. And yes, bad MAF will cause a rich condition as well.

The way I removed the EGR Temperature sensor was like this; put a 14mm wrench sitting vertically so it grasps the sensor. Then get something like an adjustable wrench and clamp it to the wrench horizontally. You are in essence leveraging the wrench and can easily twist the sensor to crack it loose. Then you can finally just use the 14mm wrench, sitting vertically by itself, to get the sensor off.

I can show a picture of this if someone doesn't understand what I am saying and feels the need to see it.
 

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and 93 SE 5speed LSD
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273 Posts
Hugh thanks for this thread. I'm gonna be tackling this project very soon now that I've seen this. My 93 is in need of some serious maintence, starting here.

thanks jserrano!!
 

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jserrano,
Huge thanks for this thread looks like a huge (pita) job which requires a lot of
patience/time. Good luck and good work, and again thanks for sharing and posting pics.

Glenn
 

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The Don.
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6,151 Posts
Discussion Starter #17 (Edited)
Intake Reassembly Started

Glad to hear that this thread is proving useful to many of you.

Intake Manifold Gasket Installation
-----------------------------------
The reassembly has begun. I first placed the intake collector loosely in the engine bay. Then I installed the new intake manifold gasket (aka upper gasket) and aligned the manifold in place. Loosely tightened the eight (8) bolts and two (2) nuts which was a 'piece of cake' to do since the collector was floating loose below. Remember to do a final torque from center on outwards in a criss-cross fashion.

Note: You have to keep a good eye on things. I had initially failed to move some harnesses around and had to redo the manifold installation. Just take your time.





Intake Manifold Collector Gasket Installation
--------------------------------------------
Put in the collector gasket over the two end studs. That will hold it nicely in place. Installing the collector to the upper manifold from atop is not too bad. You will still have to do some wiggling around since it tends to get caught up on one thing or another. Once you have lined up the collector with the upper manifold put in the big center bolt so the you can let it loose. Then put back the two end nuts and the remaining bolts. Again torque it from the center on outwards in a criss-cross fashion.



Other Components Installation
-------------------------------
Put in the new PCV and clamp the hoses. Install and torque the throttle body with it's new gasket. Install the injector harness and tighten the two manifold grounds. Put back the brake booster vacuum hose and clamp it down. Reinstall the IACV coolant lines and clamp it down. Install the two end manifold braces and lock them down. Installed the EGR tube passage with a new gasket.

The EGR tube passage is where the EGR tube passes the exhaust gas from the exhaust manifold over to this point. It then splits up the exhaust gas two ways; 1) goes to a separate passage inside the manifold and awaits at the end of the EGR valve, 2) goes through a small pickup tube which leads to the EGR-BPT valve. So basically the EGR valve handles the exhaust gas injection into the cylinders to lower their temperatures, and the EGR-BPT enables or disables the EGR valve based on the exhaust pressure present - low pressure disables the EGR valve while high pressure enables the EGR valve to operate.

Some of the reassembly takes a little work to get it back into place. I had a coolant hose hit the collector gasket and curled it up a little but luckly I saw it in time before final installation. Just take you time and look around to make sure you don't damage anything.
 

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'99 GXE Automatic
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391 Posts
Glenn14 said:
jserrano,
Huge thanks for this thread looks like a huge (pita) job which requires a lot of
patience/time. Good luck and good work, and again thanks for sharing and posting pics.

Glenn
Yes, thanks for doing this writeup. It's awesome and will help immensely when it comes time for me to do this repair. I was originally going to pull the motor but its a relief knowing I don't have to now!!! Thanks again!!!
 

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A pic of the EGR gas temp sensor would be appreciated if you get the chance....the Haynes manual has no clear pic of its location or description.

I looked in the general area of the Haynes manual and EGR/valve cover area but couldn't find anything like a sensor(or in the 14mm size)....

I'm curious whether or not my '93 has it....BTW, finally reconnected the KS harness and got rid of the consistent (uneraseable) KS code via Blazt. Whether it helps we'll see but back to topic....


Jeremy
 

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The Don.
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6,151 Posts
Discussion Starter #20 (Edited)
niceguy said:
A pic of the EGR gas temp sensor would be appreciated if you get the chance....the Haynes manual has no clear pic of its location or description.

I looked in the general area of the Haynes manual and EGR/valve cover area but couldn't find anything like a sensor(or in the 14mm size)....

I'm curious whether or not my '93 has it....BTW, finally reconnected the KS harness and got rid of the consistent (uneraseable) KS code via Blazt. Whether it helps we'll see but back to topic....


Jeremy
Jeremy, here are some pictures of the EGR temperature sensor.





I added these pictures to the previous threads to maintain continuity with the information.
 
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