Drewjharper1900

Alright so i have never taken apart/put together the intake/exhaust. Today i took on the task of replacing my freeze plugs and while i had it all apart i installed an apn header. Everything went great until i started the engine and realized that i had a massive vac leak between the intake and the block that brought my rpm's to 3,500. So i went around a few times, re-torqued the bolts, started the engine, let it heat up and cool a few times and torqued the bolts some more. Slowly but surley the rpm's started going down. They got all the way down to 1,000rpm and then stopped. I cant get em to go down any more than that. So i have decided that im gona have to take it all off and give it another shot. Ive got a few questions for you guys.

1. My dad is saying that i need to run a tap through the bolt holes and get new hardware. Has anyone ever done that? Does it really help?

2. I dident use any copper gasket spray/sealer on it. Do i need to?

3. Do i need to apply a little rtv around the intake/exhaust holes?

4. Any other tips or things i missed?

I followed this write up

https://www.cherokeeforum.com/f51/je...91-98-a-80445/

1997 jeep cherokee
4.0l
140,000 mi

freegdr

check and make sure all surfaces are same thickness between header and manifold also sounds like header tightening up b4 intake to me

BotakBeng

.sorry double post.

BotakBeng

1)?
2)No need for sealant (i had confirmation from APN as well as Felpro)
3)No
4)Make sure this is connected

There should be a vacuum line from the throttle body to the intake manifold on your 97.

DFlintstone

Oh..just doesn't seem right "battleing" for better idle. Something's a miss. Something in the bolt holes keeping them from "going home"..had it happen, but pretty rare. They are the same bolts & washers, so they are not too long. Yea like freedgr mentioned, would hope the header is not thicker and holding it out. Then, any chance just maybe, something snuck in there, a wire? Any little thing could hold it from seating. Idk. I usually put a thin bead of silicone both sides on an intake. Probably shouldn't, don't need to. With all the bolts backed of a bit you might try to "feel" the fit, see if it rocks somehow. Sounds like a "palm on forehead" issue. Piece of a zip tie in there or something.

Drewjharper1900

Thanks for all the tips. All vac lines are hooked up.

And i forgot to mention that i can spray throdle body cleaner at bolt # 8 and 9 and it makes the rpm's drop. So its deffently leaking between the intake and the head.

cruiser54

My money's on the fact that the intake is being held away from the head either by a locating dowel or the APN header. Some filing will be in order for sure, usually near #6 exhaust runner/flange..

DFlintstone

Hey,,,Make sure it's not a lower injector O ring. I got tricked by that. Idle would change when I sprayed back there, also had exhaust leaking. While I was changing the gasket I found one O ring funky right there, it was so close I had thought is was the gasket. Maybe partition that with cardboard and give'r another squirt.

Drewjharper1900

I replaced all the o-rings when I changed the header.

ZINGGG

Agreed with this.

I hate to tell you but you may be taking it all apart again. If and when you do, definitely pick up some copper spray. And make DANG sure the intake and exhaust are sitting flush on the head. When I put on an APN header, I actually had to grind the intake manifold right above the first header runner because it was making contact and not sitting completely flush.

Good luck

cruiser54

Correct. Especially since the idle is so high. That indicates a massive leak.

DFlintstone

I had gotten one ****-eyed some time before. Had I known that the spray was being sucked in there, as opposed to going in the intake I might have put off changing the gasket. I was playing "one squirt short", if a correct diagnosis.

ZINGGG

This would definitely be a good place for you to start before pulling everything apart again.

If you're sure you did something correct the first time, check it again. And after you check it again, check it another time. It's very easy to overlook something.

Drewjharper1900

Ill deffently go back and check the orings then.

Funny thing is, my rpm's dropped by 100 or so today. Still a little high, but the did drop. Maybe the gasket is getting hot and filling in the gaps?

AND! now my ac wont turn off de-frost and the cel popped up. Im getting more and more confused.

Drewjharper1900

Alright just kidding about the ac. Just went outside and moved around my vaccume ball and now ac works.