removing intake runners on KA24DE

Post by **p00t** » Sat Aug 09, 2003 2:52 pm

I will be redoing my coolant system soon, and i want to remove the butterflys (swirl control) in my intake runners while doing that. I am pretty sure they are located in the intake manifold runners (top half of intake manifold). The thermostat is also located on this top piece (hence why coolant and this are related).

I am removing the butterflies because my car acts like they are stuck open anyway. It has semi smooth power 1500-3000, but once the car hits 3000 it feels like a little turbo has spooled up and the car really pulls. I thought (and heard) that the KA has gobs of low-end torque, but all I can feel is mushy performance at low rpms (mushy as in less throttle response, when at 3000+ the car responds accordingly with little pedal movement).

"well why dont u just fix it?" Because I have no way of "testing" the butterfly's action at different rpms.... its hidden away in the intake, and the swirl control valve is back behind/under the intake runners (almost impossible to see). When i looked i couldnt even see the sucker moving.

has anyone had experience with removing the top part of the intake manifold and maybe with removing the butterflies? I will be doing a search but i would like any extra tips or info.

so far i think that when i remove the intake runners, replace the thermostat, and replace the coolant temp sensor, i will need:

1. a top and bottom paper(?) gasket for the intake runners2. rubber gasket for the thermostat3. possibly need silicone sealant for temp sensor or water passage?

Post by **leper421** » Sat Aug 09, 2003 2:52 pm

The thermostat is not part of the intake manifold. The thermostat housing bolts onto the block. Alot of the gaskets on the KA are what I call 'make-your-own-gasket', in other words its just RTV. I'm pretty sure the intake manifold gaskets are real gaskets, but the thermo house is just RTV.

Sorry, but I dont know anything about the butterflies. The 91 doesnt have those, right? Anyone know? Cause if it does then I will remove them.

Post by **p00t** » Sat Aug 09, 2003 2:52 pm

hmm... ok the thermostat isnt on the intake? so does the intake just go around it at that point?

in reguards to the butterflies they are on all KA24DEs. I have a 1993 240sx FSM and it shows it, 91 should be identical to 93.

I was initially wrong about the function of the butterflies, I have been looking closely through the FSM and Im pretty convinced I know why it isnt working, but still not sure about the procedure to remove them. Maybe an email to McKinney will help?

the FSM says it should only be closed at idle to help swirl the air for the fuel to mix better. when ever you press the throttle it should completely open. I think the problem is that, it shuts off at idle and the butterflys close.... ok easy enough... but when most things fail they do so in the closed (off) mode...since it requires no power to keep it in that state. All it takes to screw the system up is a kinked/clogged hose, or a malfunctioning solenoid/valve. If that happens the only way the butterflies are gonna open is if the vacuum of the engine pulls them open!!! this of course wont even open them completely and adds unnessisary restriction to the intake! GHEY? YES SIR!!

if i get a few good tips i should be able to handle this by myself and I will document it along the way like the AIV removal thingy i did.

Post by **240nismo** » Sat Aug 09, 2003 2:52 pm

The thermostat does have a real Gasket, if you order the gasket set from FEL-PRO gaskets you'll see it. The thermostat is right below the lower plenum of the intake manifold attatched to the block. You'll probably have to remove your Idler pulley and belt first. The intake manifold is kinda difficult to remove if its the first time you've done it. If you have any questions you can ask me, or do a search, i ran into plenty of them the first time i did it. GoodLuck

Post by **leper421** » Sat Aug 09, 2003 2:52 pm

240nismo: Some companies may make the gasket, but my FSM says to use RTV for the thermo housing.

p00t: Page EM-6 of my FSM shows the intake side of the engine, and doesnt mention butterflies anywhere. What section should they be mentioned in? It shows the swirl control valve, but nothing about the butterflies.

Post by **p00t** » Sat Aug 09, 2003 2:52 pm

leper421 wrote:p00t: Page EM-6 of my FSM shows the intake side of the engine, and doesnt mention butterflies anywhere. What section should they be mentioned in? It shows the swirl control valve, but nothing about the butterflies.

exactly... it talks about the swirl control valve and the butterflies it actuates. but it never shows the damn things ..grrrr....

the only respresentation of the butterflies are shown on "EF & EC-6" in that nasty vacuum diagram you see that the little butterfly thing is right before the injector (almost dead center of the diagram).

since it shows it just before the injector in this diagram Im assuming its in the top half of the intake manifold :eh:

240nismo: is the ^above^ true??

Post by **leper421** » Sat Aug 09, 2003 2:52 pm

I just ripped the intake manifold off of my spare engine. The butterflies are directly before the injectors, right where the manifold meets the head.

but when most things fail they do so in the closed (off) mode...since it requires no power to keep it in that state.

They actually 'rest' in the open position.

Post by **RatedR** » Sat Aug 09, 2003 2:52 pm

240nismo: I've tried taking my intake mani off once, but I couldnt access the lower bolts for the intake manifold. Its the part that connects to the head, how'd you get access to those???? Also, should I drain the coolant before I do this again??? Thanks!

Post by **24_4life** » Sat Aug 09, 2003 2:52 pm

I am rebuilding my motor and I am porting out my intake manifold. I took out the butterflys on mine so I could port it out a bit. They are just before the injectors and it is one solid rod that runs through the whole manifold. Each butterfly is screwed on the rod so all I did to take it off was unscrew each butterfly then slid the rod out the side of the manifold. If you take it off and plan on leaving it off it would be a good idea to find something to plug the holes in the manifold that the rod runs thru. It is really easy to do and will take you just a couple of minutes to do. The hardest part was getting to those hard to reach bolts when removing the intake manifold.

To get the manifold off in the fashion in which I pulled it off you would have to drain the coolant. I unbolted the bottom half of the manifold and disconected the coolant hoses that ran thru part of it (disconecting the hoses that are attached is much easier to do with it being unbolted). You can keep the throttle body on it when you disconect the lower portion of the intake manifold you just have a few more hoses to disconect but it gets more crap out of the way. With a little shimmying you should be able to slide the lower half of the intake manifold off of the motor and then all of those lower bolts on the upper portion of the intake manifold will be easy to reach. Taking it off in halves was alot easier for me to do. Im not sure if that was how you were trying it or not. If you take it all off in one peice and you dont want to pull it out from the engine bay you could keep the coolant in the car, but there is coolant that runs thru a small portion of the bottom peice of the intake manifold.

I don't know a whole lot. This is the first time I have messed around with anything like this. That is how I pulled it off. Somebody out there probably has a better suggestion.

Post by **24_4life** » Sat Aug 09, 2003 2:52 pm

Pulling out the butterflies would lower the gas milage a bit wouldn't it? And would it have a drop in performance at the lower end? I was trying to deside whether or not to leave them in when I put the motor back together. I am pretty sure that mine were resting in the closed position. Turning the lever on the side opened the butterflies further. This was before I tinkered with anything on the manifold.

Website · Post by **s13sr20chris** » Sat Aug 09, 2003 2:52 pm

i had a customers car whose swirl control valve mechanicaly locked up in the closed position. it was an older ka24e in an s13 but it would not rev over like 4500 or so. no power at all over 2000. if yours were staying shut for some reason, you would know it. intake manifold is not too bad but not too easy either. just be glad you dont have an altima!

Post by **stash420sx** » Sat Aug 09, 2003 2:52 pm

if the butterflys are vacuum controled your engine vacuum could be messed up. check it with a vacuum gauge. should be around 17 at idle.

Post by **24_4life** » Sat Aug 09, 2003 2:52 pm

ARE THEY WORTH KEEPING?

Website · Post by **s13sr20chris** » Sat Aug 09, 2003 2:52 pm

if you are just driving the car then keep them. if i had the intake off anyway, i would remove them. they actually are a good thing to have. i just like to take stuff off.

Post by **p00t** » Sat Aug 09, 2003 2:52 pm

wow... didnt realize this thread still existed!

just alittle side info, most of the hesitating i mentioned earler was cured by regrounding the engine/chassis to battery lines. I am still going to remove the butterflies this summer when i pull my engine out for overhaul/inspection, as i slowly prep my engine for turbo.

good info here guys, thanks!

Website · Post by **s13sr20chris** » Sat Aug 09, 2003 2:52 pm

Proud member of Section_8_Racing

awesome!

Post by **bozuzu** » Sat Aug 09, 2003 2:52 pm

man, i found this section in the search and said, "damnit, 2003!" but the last post was this week! hooray! so i say to you all, what happens when you remove the cursed butterfly valves? my '97 truck has them and i contemplate removing them. i also have a website about this! here! look!

butterfly picture

and here's the whole story:homepage

i'm interested to hear what the results are removing them. increased top end power (like jwt told me)? poorer fuel mileage? rougher idle? :fruit

Website · Post by **s13sr20chris** » Sat Aug 09, 2003 2:52 pm

all that stuff.

Post by **bozuzu** » Sat Aug 09, 2003 2:52 pm

thank you for that informative, well written post. your particular attention to technical detail is impressive. we're all the more knowledgable for having read it. now we know exactly what to do. :thumbup

Website · Post by **s13sr20chris** » Sat Aug 09, 2003 2:52 pm

no prob bro.

removing intake runners on KA24DE

removing intake runners on KA24DE

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