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Overheat

chickenbot

NAXJA Forum User
Location
frisco
93 4.0l AX-15 NP231

I believe I found my overheating issue.. I have replaced my entire cooling system and was still baffled. My cat wasn't getting super hot. I could not figure it out for the longest time. On Friday it gave me a new symptom. After it warmed up, it fell on its face above 2k rpm. So here I am thinking fuel or clogged cat. I start with the easiest and take the cat off.. EMPTY!! There was nothing in there. No matrix. So I go hit my muffler and it sounds like i just unburried it from the beach. That's where the heat was. I'm running a straight pipe at the moment until I can get a new cat, muffler, and tail pipe. Since I have straight piped it, I have gotten back all my power and now it doesn't go over 160. Yes I am going to put the OEM thermostat back in.

Just putting it out there in case anyone else is having the same problems. An easy test is just to take out your o2 sensor and see if it clears up the bog down.
 
O and btw come to find out that it has been so bad for awhile w/o falling on its face that I had blow by and it blew out my rear main seal and my oil pan gasket.
 
Interesting. Running a stock muffler? Wondering if, should that happen to my cat some day, whether it would block up my flowmaster or just pass on through...
 
O and btw come to find out that it has been so bad for awhile w/o falling on its face that I had blow by and it blew out my rear main seal and my oil pan gasket.

That didn't happen.
 
I've seen a plugged up rear CCV orifice exacerbate leaky seals but never seen a plugged exhaust blow them out before, I agree.

I have also experienced a disintegrating cat vomiting its guts into the muffler and making the jeep gutless. Happened on both my 91 MJ and 98 XJ. It's slightly less easy for the chunks to plug a glasspack since it's straight-through, but still happened on my 91. At least it was easy to get a stick up there and knock the chunks loose so they could fall out the rest of the way.
 
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