comanche Trouble finding new exhaust manifold, Serious blow by, and low mpg

[EagleScout]

'89 Renix 2wd Comanche with 4.0 6cyl and Aisin AX-15 manual 5 speed MFI 242

 

 

What advice can y'all offer on replacing/repairing the exhaust manifold on a 89' renix comanche? I haven't torn it all apart yet, but I'd like to be readied for the worst if it winds up as more than the perfunctory gasket replacement we're most familiar with. Exhaust fumes were noticed emanating from underneath the hood when parking my vehicle directly after 15 minutes of highway driving in heavy rain. I heard no distinct, loud, or obscene sound, but upon parking the smell of fumes was noticed as immediately as the now visible tendrils of fumes escaping on the driver's side from the crevice a closed hood rests inside. 

The vehicle was promptly parked awaiting its trial so as to prevent damage to my catalytic converter, the rest of the exhaust, system, vapor canister, EGR, system or throttle body.

The replacement parts seem either too cheaply made, probably won't bolt on squarely, could need serious modification to correctly fit, and may require parts, such as a drill and tap; or they're strictly for a 91' + MJ/XJ though I'm in no way opposed to using the existing replacement gasket options. I'm experiencing hellacious blow-by and will be replacing the valve cover gasket and following Cruiser54's valve cover mod most likely tomorrow.

 

As a side query what solution has worked for you replacing the air intake?

[Dammerung]

'89 Renix 2wd Comanche with 4.0 6cyl and Aisin AX-15 manual 5 speed MFI 242
 
 
What advice can y'all offer on replacing/repairing the exhaust manifold on a 89' renix comanche? I haven't torn it all apart yet, but I'd like to be readied for the worst if it winds up as more than the perfunctory gasket replacement we're most familiar with. Exhaust fumes were noticed emanating from underneath the hood when parking my vehicle directly after 15 minutes of highway driving in heavy rain. I heard no distinct, loud, or obscene sound, but upon parking the smell of fumes was noticed as immediately as the now visible tendrils of fumes escaping on the driver's side from the crevice a closed hood rests inside. 
The vehicle was promptly parked awaiting its trial so as to prevent damage to my catalytic converter, the rest of the exhaust, system, vapor canister, EGR, system or throttle body.
The replacement parts seem either too cheaply made, probably won't bolt on squarely, could need serious modification to correctly fit, and may require parts, such as a drill and tap; or they're strictly for a 91' + MJ/XJ though I'm in no way opposed to using the existing replacement gasket options. I'm experiencing hellacious blow-by and will be replacing the valve cover gasket and following Cruiser54's valve cover mod most likely tomorrow.
 
As a side query what solution has worked for you replacing the air intake?

You could probably find an 89 xj or something around that range and swipe its manifold. Pick n pull places usually have a few old xjs because those damn things are so popular.


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[cruiser54]

Or have yours welded while it's off. 

[dasbulliwagen]

The manifold on these isnt always the issue.... they like to break the very front and rear manifold bolts off in the head and then create a leak. Its likely your manifold is good still. I wouldnt buy one before pulling it off and making sure about any broken bolts. My truck has both of them broken, and at least the front one is leaking, but its not bad enough for me to want to fix it until I have to really dig into it. 

[cruiser54]

And, I have a few good used ones along with EGR tubes.