davidpingu
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Here’s a guide for anyone who wishes to remove their inlet manifold. I put this together because it’s handy to know you’re on the right track if you’ve never done this. I did this for the first time a couple weeks back but couldn’t find a guide to help.
I’d rate this as about a 6 out of 10 for difficulty. I don’t think it’s as bad as some make out but there are several things that can go wrong if you’re not careful, you have the wrong tools or you rush.
Lessons learned for me was allow plenty of time. I’d say 6 hours minimum if this is your first time. (Just to clarify it can be done in less than an hour but allow lots more time if you’ve never done this before as it’s not a job to be rushed)
The below is an extensive list of items and not everything is absolutely necessary but it WILL make your life easier if you prep well enough for this. Good prep will ensure you have everything covered.
There’s plenty of shortcuts you can take but this is for anyone who wants to do the job spot on so just use this guide as little or as much as you like depending on how bothered you are ha ha!
Ok first, the ideal list to do a perfect job:
Ok so I think that’s a pretty extensive list so once you’re happy with the above you can get started.
Step 1. Find the engine
Ok so remove the two bolts holding the VTEC plastic cover in place
Next disconnect all 4 injector plugs and unscrew the earth wire attached down to the inlet. (Word of advice, always screw these back in so you know what bolts and nuts go where!)
Unclip the plastic rail from the fuel rail at the little plastic clips and at this point if you follow the cables down you’ll see a bolt holding the loom in place. Remove this as well so as there’s more movement in the loom and replace the bolt.
Disconnect the fuel line from the rail at the elbow joint on the right. It should pop straight off by compressing the green clip in. It’s normal for it to leak a bit of fuel as this comes off.
Unscrew the two nuts holding down the fuel rail and the rail and all injectors will gently pull away. (store this somewhere safe away from any sparks/flames!!!)
There are also two black metal brackets that the VTEC plastic cover screws down to. I removed these to help with access.
Unclip the throttle cable line and anything else attached to the inlet
Now start disconnecting all your breather hoses. This big one is simple to pull off. Obviously if a different manifold is going on you’ll want to remove the pipes from the inlet side. As mine was going back on I removed some of the pipes from the other end, whichever was the easiest option.
Two of the breather hoses (circled below) were really awkward as they were welded on. I gave up and used a Stanley blade to slice down the side of them so they’d come straight off. If you do this make sure it’s only if you ordered replacement breathers. The one you really want to watch is the funny shaped one at the back on the right that comes out of the inlet to a plastic T piece. From what I was told you do not want to snap this plastic T piece as it’s expensive and awkward to replace. This is another reason I didn’t keep pulling at it too much as I didn’t want to break anything. Cutting the pipe along the edges made it much simpler.
Remove your airbox (obviously mine looks a little different to yours but just take it back to the throttle body and remove the appropriate sensor and breather hose from the airbox)
Now you’ve got access to the throttle body unclip the 3 top plugs and then the 4th is underneath for the IACV and sheathed in rubber. You can pull the rubber back and then unclip (this one I found a bit fiddly just due to access but bear with it)
Remove the two bolts holding on the plate that the throttle cable is going through then disconnect the throttle cable by sort of bringing the cable round so you can see the lug at the end of the cable. This pushes out to the side. It’s hard to describe but you should be able to work it out and you can then move the throttle cable assembly aside.
There’s a few hoses attached to the TB which we’ll come on to in a minute but I found it easier to now disconnect the TB from the inlet. Remove this by undoing the 4 size 12 nuts and bolts (one in each corner). The nuts especially are quite fiddly so take your time and don’t lose them!
The bolts when replacing can snap. It may be unlikely but I was unlucky so depending on if you decide to replace these with new bolts, move the old ones to the side for replacement.
Sometimes the TB can take a bit of work to get it away from the inlet so use something blunt (a bolster is ideal and give it a few gentle taps with a hammer aka ‘the persuader’ and it should come away.
Remove the small breather hose from the top of the throttle body and then the two water hoses located a little further down. These I had trouble with getting off which is why I said remove the TB first so as you can move it around a little more for getting better access at the hoses. I used the thin nose pliers to wiggle the hose at where its attached to the metal bit back and forth being careful not to damage the pipe then I used a thin flat head screw driver to try and work the hose off. You can also spray a little WD40 in there while working them off. This can seem to take ages but bear with it!
When the hoses come off they will leak coolant. Zip tie them so they are held upright to avoid losing too much coolant.
Ok so throttle body should now be free and can be removed. All breather hoses should now be removed and fuel rail is off. The only thing stopping you removing the inlet now is the bolts themselves. Depending on each bolt will depend on what extension pieces you will require but as a guide, most of the top nuts and bolts will require the ring spanner due to clearance. The two bottom corners are a little awkward for access but you can get a socket on them and the most tricky one it the bottom middle bolt, accessible through the gap in the centre of the inlet. This one you will need the elbow on an extension for. Make sure the socket is on it properly, it’s not one you’d want to round off!!
Ideally I’d say start with each corner bolt first to avoid too much stress on the inlet. They can crack if stressed at the edges so loosen the edges first before doing the centre last.
Another thing to note is a couple of these bolts you can’t get your fingers too, especially the bottom centre one so this is where the tweezers came in handy to remove the bolts once loosened right off and also to place them back later ready to be done up too.
At this stage I’d say remove all the bolts but just loosen off the two nuts on the top two studs but keep them finger tight for now. Once all the bolts are removed the inlet is still being held from the underneath by two brackets. You’ll need to jack the car up enough to get right underneath so please use an axle stand!! I think you’ll have more access my jacking from the driver’s side rather than the passenger side but this is one area I can’t give much advice on because when I looked underneath mine there were no supporting brackets so someone had removed these previously. It should just be two bolts though. It’s a little awkward for access but the torch will come in handy here. At this stage it may be worth considering removing these brackets altogether. They won’t fit with any other manifold other than the standard PRC so if you’re going RBC, RRC etc just remove them now. Even if you are sticking with your original they aren’t really needed and will save the struggle getting back underneath later. You’re also saving a bit of weight
So let the car back down and now you just need to concentrate on those two remaining studs. Remove the nuts and you’ll find there isn’t the clearance to slide the inlet off the studs so these need to come out too. The way to do this is to screw one nut back on part of the way down (back to front is easier so the collar is facing outwards, the reverse of how it usually goes on) then screw another nut on after it and screw them against each other. The outer nut should stop the inner nut from unscrewing so that now when you turn the inner nut anti clockwise it should remove the stud. Hope that makes sense!! Just try and support the inlet as you are removing the studs to help preserve the threads. Also take note of which way the studs go in as they are threaded both ends.
Once both the studs have come out the inlet should lift straight out.
That’s mostly my guide finished as you’ll now know everything just goes back together in reverse but I just wanted to add a few more helpful tips first.
1. If the inlet isn’t going straight back on, block the inlet chambers off with some clean rags and cover over with a plastic bag to stop moisture getting in.
2. Clean all surfaces! This includes the head where the inlet will mate back up to. I used carb cleaner whilst the rags were still blocking the inlet ports and a Stanley blade to scrape all the crap off. This will save valuable time later by avoiding any air leaks. Same with the inlet manifold itself. Clean the contact surfaces and finally the TB surface as well.
3. While your TB is off give it a good clean around the butterfly and especially the IACV! Wish I’d done this as when it went back together I spent over a week looking for an air leak when it turned out to be a sticky IACV.
So for those of you who are interested, remove the IACV from the TB by the two screws. A perfect fit screw driver is needed here as these are tight and you won’t want to round them! Once the IACV is taken off you’ll need to remove the black motor to clean it properly. There is no head available on the market that I know of that will remove these screws, they aren’t your typical torx drive heads. You can undo them using your mole grips. It’s tricky but bear with it. Once you remove the motor you can spin the paddle within the IACV to feel how stiff it is. You want this to spin as smooth as possible so spray some carb cleaner over the paddle and keep spinning it around till it feels nice and smooth. Get an old toothbrush or a bit of rag in there too and remove as much dirt as you can. Finally the PTFE in a little WD40 will just help keep it staying smooth. You can now re-attach the motor to the IACV (be careful as it will only fit properly one way so keep spinning the motor part around till it seats down properly) Reattach the IACV to the TB.
4. Replace as many bolts as you can afford to avoid bolts potentially snapping and don’t do the bolts back up over tight or you will crack your manifold. Once the studs are back in, tighten up from the middle bolts outwards.
Yes it’s a long post but I hope people find it detailed enough. Feel free to add anything to this I might have missed out. It’s easily done!
Cheers everybody!
I’d rate this as about a 6 out of 10 for difficulty. I don’t think it’s as bad as some make out but there are several things that can go wrong if you’re not careful, you have the wrong tools or you rush.
Lessons learned for me was allow plenty of time. I’d say 6 hours minimum if this is your first time. (Just to clarify it can be done in less than an hour but allow lots more time if you’ve never done this before as it’s not a job to be rushed)
The below is an extensive list of items and not everything is absolutely necessary but it WILL make your life easier if you prep well enough for this. Good prep will ensure you have everything covered.
There’s plenty of shortcuts you can take but this is for anyone who wants to do the job spot on so just use this guide as little or as much as you like depending on how bothered you are ha ha!
Ok first, the ideal list to do a perfect job:
- A decent socket set. Mostly 3/8 drive I found the easiest size to work with but you’ll need a couple sizes of extension bars and also the elbow type attachment for awkward angles (you’ll definitely need the elbow and extension bars so don’t attempt without!) Think it’s just sizes 10 & 12 sockets you will need.
- 2 Size 12 spanners (preferably one being a ring spanner)
- Flat head screwdriver – smaller fine tip type is ideal
- Narrow nose pliers
- Long tweezers (available in halfrauds I believe)
- Mole grips
- Torch
- Stanley knife with a spare blade
- Car jack & axle stand
- Some zip ties
- Can of carb cleaner
- WD40 or the equivalent
- A good assortment of Phillips/cross head type screw drivers
- Some clean cloths and kitchen towel
- Two breather hoses (i’ll show you in the pics further on which ones these are) the part numbers are: 17131-PRB-A00 and 36283-PNA-G00. There are also a couple of water hoses that go in to the throttle body you could replace. I didn’t bother with those so I don’t have the part numbers I’m afraid! There are also other breather hoses you will remove but again I didn’t replace these due to the fact they were easy to remove and avoid damaging.
- 2 spare nuts, part number 94050-08080
- 5 spare inlet bolts, 95701-0802808
- 2 spare studs (I didn't replace these so no part number)
- 2 spare throttle body bolts (no part number again)
- Inlet manifold gasket (optional but advisable)
- Throttle body gasket – You’ll definitely need one of these
Ok so I think that’s a pretty extensive list so once you’re happy with the above you can get started.
Step 1. Find the engine
Ok so remove the two bolts holding the VTEC plastic cover in place
Next disconnect all 4 injector plugs and unscrew the earth wire attached down to the inlet. (Word of advice, always screw these back in so you know what bolts and nuts go where!)
Unclip the plastic rail from the fuel rail at the little plastic clips and at this point if you follow the cables down you’ll see a bolt holding the loom in place. Remove this as well so as there’s more movement in the loom and replace the bolt.
Disconnect the fuel line from the rail at the elbow joint on the right. It should pop straight off by compressing the green clip in. It’s normal for it to leak a bit of fuel as this comes off.
Unscrew the two nuts holding down the fuel rail and the rail and all injectors will gently pull away. (store this somewhere safe away from any sparks/flames!!!)
There are also two black metal brackets that the VTEC plastic cover screws down to. I removed these to help with access.
Unclip the throttle cable line and anything else attached to the inlet
Now start disconnecting all your breather hoses. This big one is simple to pull off. Obviously if a different manifold is going on you’ll want to remove the pipes from the inlet side. As mine was going back on I removed some of the pipes from the other end, whichever was the easiest option.
Two of the breather hoses (circled below) were really awkward as they were welded on. I gave up and used a Stanley blade to slice down the side of them so they’d come straight off. If you do this make sure it’s only if you ordered replacement breathers. The one you really want to watch is the funny shaped one at the back on the right that comes out of the inlet to a plastic T piece. From what I was told you do not want to snap this plastic T piece as it’s expensive and awkward to replace. This is another reason I didn’t keep pulling at it too much as I didn’t want to break anything. Cutting the pipe along the edges made it much simpler.
Remove your airbox (obviously mine looks a little different to yours but just take it back to the throttle body and remove the appropriate sensor and breather hose from the airbox)
Now you’ve got access to the throttle body unclip the 3 top plugs and then the 4th is underneath for the IACV and sheathed in rubber. You can pull the rubber back and then unclip (this one I found a bit fiddly just due to access but bear with it)
Remove the two bolts holding on the plate that the throttle cable is going through then disconnect the throttle cable by sort of bringing the cable round so you can see the lug at the end of the cable. This pushes out to the side. It’s hard to describe but you should be able to work it out and you can then move the throttle cable assembly aside.
There’s a few hoses attached to the TB which we’ll come on to in a minute but I found it easier to now disconnect the TB from the inlet. Remove this by undoing the 4 size 12 nuts and bolts (one in each corner). The nuts especially are quite fiddly so take your time and don’t lose them!
The bolts when replacing can snap. It may be unlikely but I was unlucky so depending on if you decide to replace these with new bolts, move the old ones to the side for replacement.
Sometimes the TB can take a bit of work to get it away from the inlet so use something blunt (a bolster is ideal and give it a few gentle taps with a hammer aka ‘the persuader’ and it should come away.
Remove the small breather hose from the top of the throttle body and then the two water hoses located a little further down. These I had trouble with getting off which is why I said remove the TB first so as you can move it around a little more for getting better access at the hoses. I used the thin nose pliers to wiggle the hose at where its attached to the metal bit back and forth being careful not to damage the pipe then I used a thin flat head screw driver to try and work the hose off. You can also spray a little WD40 in there while working them off. This can seem to take ages but bear with it!
When the hoses come off they will leak coolant. Zip tie them so they are held upright to avoid losing too much coolant.
Ok so throttle body should now be free and can be removed. All breather hoses should now be removed and fuel rail is off. The only thing stopping you removing the inlet now is the bolts themselves. Depending on each bolt will depend on what extension pieces you will require but as a guide, most of the top nuts and bolts will require the ring spanner due to clearance. The two bottom corners are a little awkward for access but you can get a socket on them and the most tricky one it the bottom middle bolt, accessible through the gap in the centre of the inlet. This one you will need the elbow on an extension for. Make sure the socket is on it properly, it’s not one you’d want to round off!!
Ideally I’d say start with each corner bolt first to avoid too much stress on the inlet. They can crack if stressed at the edges so loosen the edges first before doing the centre last.
Another thing to note is a couple of these bolts you can’t get your fingers too, especially the bottom centre one so this is where the tweezers came in handy to remove the bolts once loosened right off and also to place them back later ready to be done up too.
At this stage I’d say remove all the bolts but just loosen off the two nuts on the top two studs but keep them finger tight for now. Once all the bolts are removed the inlet is still being held from the underneath by two brackets. You’ll need to jack the car up enough to get right underneath so please use an axle stand!! I think you’ll have more access my jacking from the driver’s side rather than the passenger side but this is one area I can’t give much advice on because when I looked underneath mine there were no supporting brackets so someone had removed these previously. It should just be two bolts though. It’s a little awkward for access but the torch will come in handy here. At this stage it may be worth considering removing these brackets altogether. They won’t fit with any other manifold other than the standard PRC so if you’re going RBC, RRC etc just remove them now. Even if you are sticking with your original they aren’t really needed and will save the struggle getting back underneath later. You’re also saving a bit of weight
So let the car back down and now you just need to concentrate on those two remaining studs. Remove the nuts and you’ll find there isn’t the clearance to slide the inlet off the studs so these need to come out too. The way to do this is to screw one nut back on part of the way down (back to front is easier so the collar is facing outwards, the reverse of how it usually goes on) then screw another nut on after it and screw them against each other. The outer nut should stop the inner nut from unscrewing so that now when you turn the inner nut anti clockwise it should remove the stud. Hope that makes sense!! Just try and support the inlet as you are removing the studs to help preserve the threads. Also take note of which way the studs go in as they are threaded both ends.
Once both the studs have come out the inlet should lift straight out.
That’s mostly my guide finished as you’ll now know everything just goes back together in reverse but I just wanted to add a few more helpful tips first.
1. If the inlet isn’t going straight back on, block the inlet chambers off with some clean rags and cover over with a plastic bag to stop moisture getting in.
2. Clean all surfaces! This includes the head where the inlet will mate back up to. I used carb cleaner whilst the rags were still blocking the inlet ports and a Stanley blade to scrape all the crap off. This will save valuable time later by avoiding any air leaks. Same with the inlet manifold itself. Clean the contact surfaces and finally the TB surface as well.
3. While your TB is off give it a good clean around the butterfly and especially the IACV! Wish I’d done this as when it went back together I spent over a week looking for an air leak when it turned out to be a sticky IACV.
So for those of you who are interested, remove the IACV from the TB by the two screws. A perfect fit screw driver is needed here as these are tight and you won’t want to round them! Once the IACV is taken off you’ll need to remove the black motor to clean it properly. There is no head available on the market that I know of that will remove these screws, they aren’t your typical torx drive heads. You can undo them using your mole grips. It’s tricky but bear with it. Once you remove the motor you can spin the paddle within the IACV to feel how stiff it is. You want this to spin as smooth as possible so spray some carb cleaner over the paddle and keep spinning it around till it feels nice and smooth. Get an old toothbrush or a bit of rag in there too and remove as much dirt as you can. Finally the PTFE in a little WD40 will just help keep it staying smooth. You can now re-attach the motor to the IACV (be careful as it will only fit properly one way so keep spinning the motor part around till it seats down properly) Reattach the IACV to the TB.
4. Replace as many bolts as you can afford to avoid bolts potentially snapping and don’t do the bolts back up over tight or you will crack your manifold. Once the studs are back in, tighten up from the middle bolts outwards.
Yes it’s a long post but I hope people find it detailed enough. Feel free to add anything to this I might have missed out. It’s easily done!
Cheers everybody!
