Quick exhaust manifold question.
#1
Junior Member
Thread Starter
Join Date: Apr 2011
Location: Knoxville, Tennessee.
Posts: 47
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0
Quick exhaust manifold question.
Hey guys thanks for reading. I have a question, if you all don't mind. Today I started pulling all the stuff on the driver side of the motor so that I can fix (what I believe to be) a cracked exhaust manifold. After I pulled all the important stuff off the intake and took off the air box, I was looking at the exhaust manifold and saw some open port thing sticking out under the intake pointed towards the air box section. It looks like the end of an exhaust pipe just sticking out of the header. So I was wondering if this was a normal thing? And If not, could it be the reason for my awful gas mileage and horrid noise? Thanks guys!
#3
Junior Member
Thread Starter
Join Date: Apr 2011
Location: Knoxville, Tennessee.
Posts: 47
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0
#4
CF Veteran
That thing you described reminded me of an old Cherokee "Pioneer" that my sister asked me to fix for her many moons ago. There was some kind of a rotted crossover tube that ran from under the manifold near the collector, down and under the engine and up to - I can't remember - on the passenger side. I think it might have been related to the choke. Sorry for the very sketchy/vague memory but, as they say, memory is the second thing that goes as we age - and I already forgot the first!
#5
Junior Member
Thread Starter
Join Date: Apr 2011
Location: Knoxville, Tennessee.
Posts: 47
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0
Thanks man I appreciate it, I was kinda hoping I would be able to fix the crack without buying a new manifold. I'm not sure if this is something some sketchy mechanic did as some sort of quick fix, or if it's actually factory. Although, I don't think I've seen anything like this coming off a Cherokee header (not that I'm familiar with Cherokees by any means). But I would assume any open spot on the manifold would throw the compression of for the o2 sensor.
#6
Registered Users
Join Date: Jul 2011
Location: 92392
Posts: 618
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Its there because theres suuposed to be a flex pipe thing that goes to the front of the stock renix air box. You will notice theres also a cirlce there, and a valve type thing. It provides hot air and "helps the engine warm up quicker"...
late 80 engineering I know it works but it kills performance!
Every renix era rig is like that!
Heres some more info if you want to know more.
http://www.google.com/imgres?q=jeep+...:429,r:13,s:18
late 80 engineering I know it works but it kills performance!
Every renix era rig is like that!
Heres some more info if you want to know more.
http://www.google.com/imgres?q=jeep+...:429,r:13,s:18
#7
CF Veteran
Is there a crack or is it just that tube thing? Maybe you can simply crimp/seal it off and you'll at-least make it quieter - no doubt your mileage will also improve...
Take a few extra minutes to look and see if there's a corresponding unterminated fitting elsewhere - like maybe at the base of the carb or the choke housing on the passenger side.
Take a few extra minutes to look and see if there's a corresponding unterminated fitting elsewhere - like maybe at the base of the carb or the choke housing on the passenger side.
Trending Topics
#8
CF Veteran
Join Date: May 2008
Posts: 3,018
Likes: 0
Received 13 Likes
on
13 Posts
Year: 1988
Model: Cherokee
Engine: AMC242
Hey guys thanks for reading. I have a question, if you all don't mind. Today I started pulling all the stuff on the driver side of the motor so that I can fix (what I believe to be) a cracked exhaust manifold. After I pulled all the important stuff off the intake and took off the air box, I was looking at the exhaust manifold and saw some open port thing sticking out under the intake pointed towards the air box section. It looks like the end of an exhaust pipe just sticking out of the header. So I was wondering if this was a normal thing? And If not, could it be the reason for my awful gas mileage and horrid noise? Thanks guys!
It is not connected to the exhaust, and won't contribute to a leak. It's simply a sheetmetal duct that allows the engine to draw air ducted over the exhaust primaries, which heats it. The reason to heat intake air on cold starts is to help wit fuel atomisation, which helps with combustion efficiency.
#9
Junior Member
Thread Starter
Join Date: Apr 2011
Location: Knoxville, Tennessee.
Posts: 47
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0
That is the "intake preheater," and is there for emissions control (it's a holdover from carburetted engines.)
It is not connected to the exhaust, and won't contribute to a leak. It's simply a sheetmetal duct that allows the engine to draw air ducted over the exhaust primaries, which heats it. The reason to heat intake air on cold starts is to help wit fuel atomisation, which helps with combustion efficiency.
It is not connected to the exhaust, and won't contribute to a leak. It's simply a sheetmetal duct that allows the engine to draw air ducted over the exhaust primaries, which heats it. The reason to heat intake air on cold starts is to help wit fuel atomisation, which helps with combustion efficiency.
#10
CF Veteran
Join Date: May 2008
Posts: 3,018
Likes: 0
Received 13 Likes
on
13 Posts
Year: 1988
Model: Cherokee
Engine: AMC242
Thanks a ton man. You guys never fail to provide good answers. I got to looking at it after reading Kamaran's post and saw what you guys are talking about. I guess I should probably replace that tube that runs off of it. Is there any certain type of material for the flex hose that needs to be used? Is it subjected to high temperatures?
You can usually find pre-pack foil hose (I think it's actually heavily aluminised Mylar...) at most parts houses, back by the fuel filters. There are three or four inside diameters available, and the prepacks are about two feet long extended (collapsed, about a third of that. They're on the shelf in the collapsed state - you stretch them out like an accordion.)
As I mentioned, they're a holdover from carburettor days. They're not strictly necessary on fuel-injected vehicles, because the EFI system adapts to intake air temperature, and the fuel is atomised much closer to the cylinder. It's one of the few cases where CA smog has agreed with me - mine's been missing for years, but I never get downchecked on biennial smog tests for it.
Nylon zip-ties won't cut it for securing it at the exhaust end, but will work at the airbox. Secure the exhaust end with a small steel hose clamp instead, or you can use safety wire as a twist-tie. The fit isn't quite snug enough to stay put on its own (the OEM hose comes with a toggle band clamp inbuilt, but I don't know if you can even get the OEM part anymore! I've never looked.
#11
Junior Member
Thread Starter
Join Date: Apr 2011
Location: Knoxville, Tennessee.
Posts: 47
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0
Thanks guys. Also, I have another quick question if anyone doesn't mind. I'm trying to remove the intake manifold to get to header. I've removed all the bolts along the top of the manifold but I can't seem to get to any of the ones on the bottom side. They're blocked by the exhaust manifold. Any ideas? Thanks.
#12
CF Veteran
Join Date: May 2008
Posts: 3,018
Likes: 0
Received 13 Likes
on
13 Posts
Year: 1988
Model: Cherokee
Engine: AMC242
Thanks guys. Also, I have another quick question if anyone doesn't mind. I'm trying to remove the intake manifold to get to header. I've removed all the bolts along the top of the manifold but I can't seem to get to any of the ones on the bottom side. They're blocked by the exhaust manifold. Any ideas? Thanks.
The Craftsman version should cost less than the Allen version, but either will make the job much easier.
While you're there, pick up one in 7/16" or 11m/m to make replacing the CKP easier as well (trust me on this.)
Thread
Thread Starter
Forum
Replies
Last Post
lilshortwun
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
09-23-2015 10:31 AM
Calikingcrawler
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
3
09-21-2015 02:27 AM
Azzy
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
0
09-08-2015 10:49 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)