HELP with intake manifold ADVICE

[THE LOVELESS]

I was told my intake manifold was cracked by shop and I don't know what to replace it with. What kind of manifold do I need? from what I've read which is little I need a dual-plane i think? Also, from what i've looked I can't find one for the 1990 wrangler sahara 6cylinder model online or at a couple auto parts stores either. So I guess what I'm asking is 2 questions, 1) what route should I go with replacing my cracked intake manifold and how easy would it be to do it myself? 2) does anyone know where I can find an intake manifold for my model jeep (1990 YJ sahara 6cylinder)? Is there a certain brand or whatnot you would suggest? Thanks for the help I try to drive my jeep every day as my dd but I don't think I should be driving it with my manifold messed up like this. ANY THOUGHTS??

[OhioYJ]

Are you sure you have cracked intake manifold? Usually the straight six motors crack exhaust manifolds. If you had a crack in the intake I'd imagine your Jeep would be screaming RPM wise all the time from it sucking air.

If its the exhaust manifold cracked, don't sweat it, every last Jeep on the road today with a straight six will go through at least one manifold in its lifetime, maybe more... :D

On the exhaust manifolds, if you have the cash, Banks. If you want to go the cheaper route, throw a stock manifold back on it.

[DalTxYJ]

Originally posted by OhioYJ:
On the exhaust manifolds, if you have the cash, Banks. If you want to go the cheaper route, throw a stock manifold back on it. About a month ago I had to replace mine because the crack spread nearly all the way around. I drove it about a year before this happened.
I went with the stock because the original worked fine. It was I think about 325.00 for the stock Manifold. I didnt have time or a place (raining alot) to do it myself and spent about 250.00 more for them to do it.

[THE LOVELESS]

I checked the paperwork that I got from the shop and it says "Advise . Inspection revealed leaking intake manifold," and when they told me about it I remember them saying it was cracked. With that established what do you think I should do about it YJ? Or what do you think in response to the questions I asked in the first post?

DalTXJeep, I live in dallas, nice coincidence I never see anyone on here from here. anyway, you said you drove it about a year before that happened, did it happen all at once? or did you drive it around a year while it was leaking til the crack got more severe? I ask because up til I found out it was cracked I was using it as my daily driver, I always just thought it drove like ****, not that there was necessarily something really wrong. So should I just keep driving it until it doesnt run or what? Can I replace myself? How expensive? Also I cant seem to find a intake manifold for my model jeep anywhere online, any ideas? THanks guys

[THE LOVELESS]

anyone please feel free to share your thoughts, I would like everyone's opinions

[OhioYJ]

If your intake manifold was cracked or leaking, your Jeep wouldn't idle, it would be screaming from all the excess air coming in.

Is your Jeep loud or louder than you think it should be?

If it is the intake manifold after all, I would just go to a junk yard and get one, as these usually don't have any problems, or crack.

[THE LOVELESS]

I didn't think it sounded especially loud or anything. Sometimes it has problems idling right at first but it usually idles fine after running for 5-10 minutes. I'm still pretty sure its supposed to be the intake manifold thats supposedly "cracked" but the shop hasnt called me back yet and maybe it could just be that its leaking from worn out gaskets?

[Devildog]

You can check your manifold yourself with wd 40. If there is a crack and you spray it near it the engine will idle up.

[OhioYJ]

Well thats the thing, if it were cracked or you had a leaking intake gasket, typically it does one of two things. A small leak typically will just give you a lean condition. If its a larger leak, or crack the motor will idle way high as it has air seeping in. I worked on a 360 today that was idling at 2500 RPM due to a cracked manifold.

I prefer to use carb cleaner rather than WD though, the carb cleaner will have the reverse affect, the motor will idle down.

[Knuckelhead]

Originally posted by OhioYJ:
every last Jeep on the road today with a straight six will go through at least one manifold in its lifetime, maybe more... OEM 2000+ won't... :cool:

[jeepin4life]

why won't 2000+

[OhioYJ]

2000 forward are the new style, its basically two separate headers, one header for the front three cylinders, another header for the back three cylinders.

[edudley]

Do you have a Check engine light on? A crack in the intake will cause the system to suck air and run lean. This will usually result ina check engine light. The ODB1 system on your 90 should do this if the leak is very bad. This would be a tough diagnosis to make from a visual inspection for any mechanic. Try the WD 40 trick it does work. If it turns out to be true you should be able to find one in a junk yard pretty easily. They are not to bad to replace if you have some mechanical backgound and decent hand tools. Good Luck

[THE LOVELESS]

I will try the WD40 trick tomorrow, I've got carb cleaner also Ohio so I'll try both probably. I havent seen any check engine light on or anything like that, and It doesnt idle too bad, it was idling somewhat higher like 1300-1400 til i took it to the shop to fix the accelerator pump but they fixed it back down to around 700-ish for me while they had it so thats no longer really an issue. I don't know what else to say about it, seems like the jeep should run stronger and such but yeah. Whats a good way to locate junk yards without knowing where they are first? I live in Dallas but have never been to one and was wondering if there was an easy way to find them for your city. Thanks yall

[SHARPSHOOTER]

Clifford Performance has always made intakes for the 4.2L. They sell header and intake sets, or just one or the other.

Run a search on them and call them up. From what I found, they offer a performance intake and header combo for $599.99, or just the intake (performance) for $289.99.

Their performance intakes i think have a 4barrel opening, so you'll need an adaptor. But this is good if you have a mc2100, or ever plan on getting one.

But call the folks at clifford up. From what I remember reading, they are very helpful and dedicated. They can better give you an Idea than what their website will say.

[Knuckelhead]

Originally posted by OhioYJ:
2000 forward are the new style, its basically two separate headers, one header for the front three cylinders, another header for the back three cylinders. http://i42.photobucket.com/albums/e333/knuckelhead/header1.jpg...

[Devildog]

A split manifold on a 6 cylinder doesnt sound to bad with a set of duals. Till you let off of it ;)

[DalTxYJ]

Originally posted by THE LOVELESS:

anyway, you said you drove it about a year before that happened, did it happen all at once? or did you drive it around a year while it was leaking til the crack got more severe? I ask because up til I found out it was cracked I was using it as my daily driver, I always just thought it drove like ****, not that there was necessarily something really wrong. So should I just keep driving it until it doesnt run or what? Can I replace myself? Sorry Loveless as I havnt been online in a few days. No it didnt happen all at once it was over time. It wasnt running bad but I know it was giving some false readings to the puter. Mine is a daily driver as well.
The new OEM ones they put on are new designs they said. They have like a crinkle/flex look where they are notorious for cracking and "supposedly" the new design is made not to crack anymore. So I would go with the OEM replacement.
Mine ended up trashing my cat. conv. and when it plugged up I think the backpressure made the crack go all the way. IMO

[Knuckelhead]

Originally posted by Devildog:
A split manifold on a 6 cylinder doesnt sound to bad with a set of duals. Till you let off of it ;) OEM uses a Y pipe... :cool:

[THE LOVELESS]

I have another question- I noticed that while my engine is running I guess its leaking oil onto the top of the motor and so as the engine heats up the oil is "burning" away? or maybe just heating up and making steam or smoke or whatnot but it doesnt stop it just always does it. I was thinking it might just have to do with the possibly cracked manifold or maybe just with crappy gaskets for the manifold but I wasnt sure. My buddy seemed to think it was a big deal that there was oil constantly on top of the engine just burning off and that it never actually all burns off. I was just wondering what you guys thought about this.

[SHARPSHOOTER]

Are you sure that your valve cover gasket isn't leaking? That can leak onto your exhaust manifold and smoke.

Oil will be in the top half of your motor to lubricate all your valves etc... You fill the motor with oil through the top of your motor.

I'm still running my stock manifold on my '87 4.2L. I thought my exhaust manifold was cracked, but it ended up being the gasket once I had it all pulled apart. Your intake and exhaust manifolds are held on by most of the same bolts. Order up some gaskets and replace your valve cover gasket while your there too...

A crack &/or bad gasket will sound like an annoying tick.

SHOP TIP: Grab a peice of small tubing about 3' long. Hold one end to your ear and search around your engine compartment with the engine running. This will help you isolate any sounds (Front of block, rear of block, valve cover, exhaust manifold, etc...)