Banks Revolver header + cooling issues

91 H.O., AW4, 5.5" lift, 33x12.50x15, 4:56 gears, blah,blah,blah


Ok so i installed the Banks Revolver header on my heep and after tightning the belt up, afew days later the water pump bearing starting making noise. Replaced it! That one leaked! Replaced again and did upper and lower coolant hoses too. Drove for a few weeks but could never get the jeep to run just below the 210 mark like it used to at highway speeds. Temp started going higher in traffic and back down at speeds. (still above 210 but NEVER to the next line)

Get home friday and coolant started shooting out of a freeze plug and noticed another was leaking a little to. (NEVER over heated) Thought OK "air in the system" Tear the intake and exhaust back off and replaced all 5 on DS of the block with brass plugs, and new 195 superstat. Thought this has got to do it!. Well not exactly. Still can't get it below the 210 always just a hair above.

Back to the Banks header. When installing it i had to move the cross over pipe atleast 1" closer to the block/oil pan than the stock one. Could this be where the added heat is coming from? Or should i be looking other places?

I do have the ZJ fan clutch upgrade (still seams tight) and the stock electric fan does work at keeping temps from creaping above 216. I can get the temps below 210 with heater running so i know heater core is good. Could this be a clogging radiator? Or just the added heat from the header being closer to the motor?


Oh and i have a trans cooler in front of mechanical fan bypassing the radiator. Has been this way for a yr though with no cooling issues.

If a MOD thinks this is OEM please move. I placed here because maybe mod related?

Good headers will tend to lean out the engine because they flow more exhaust. Larger injectors or a way to add more fuel might be the trick... I would reset the computer and discharge the capacitors, and let it re-learn... Did that on the '95, and it ran way better...

This is my DD not just trail rig. Miles add up quick. I did think about that to.. Ok i thought maybe i have a lazy Bosh O2 sensor. Its only a few yrs old though. Maybe time to change?

I don't think the crossover pipe is to blame. When I had mine redone it ended up really close to the oil pan and I don't have any issues. If you didn't flush the system when you changed out the water pump I would now.

i dont think it's your crossover pipe. mine's well bashed and pretty much touching the oilpan. i dont get warm at all, my electric fan almost never turns on.

aquino#s194 said:

If you didn't flush the system when you changed out the water pump I would now.

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Yeah it wouldn't be a bad idea. I did one a not to long a ago though.. Might just be better off having a shop do it good and right the first time.

Vanimal said:

i dont think it's your crossover pipe. mine's well bashed and pretty much touching the oilpan. i dont get warm at all, my electric fan almost never turns on.

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I figured this might be what i would hear.. Sometimes it best to think out loud and get input from others though. :wave1:

I agree with JaVeLiN about the better flowing headers leaning out the present air/fuel curve. By disconnecting the battery and discharging the capacitors you will allow the ECM to relearn your driving habits. I would drive more agressively for a couple days so that the ECM will have a better a/f curve in memory.
When the engine a/f is running lean the combustion chamber and engine will run warmer.....

Well i did have the battery disco'd when i did the freeze plugs for about 9 hrs and last night disco'd it again and held +/- together for about a min. I would think either one would have done that. Maybe bad or lazy O2 could be the problem?

I'm gonna pull the temp sensor in the block and see if it just needs a good burp befor i throw any more $ at this.




This is leaning toward OEM tech now. I'll have a mad move. Thanks!

OK so just an update. Just installed labaron hood vents last night in hope to see a good drop in temps. Not the drop i had hoped but a little better. 70-75 on the freeway and temps are about 211. Slight temp creep going up hills and drop on down hill. Like i said.. Its better but with a ZJ fan too i would have thought below 210 would be normal. Gonna run a pressure test this weekend to see if i have a leak that just isn't showing.

I do have a NEW lower radiator hose without the spring in it. Could be the problem? Doesn't seem to suck closed at high RPMS though.

CharlesS said:

The vents will drop engine compartment temperatures, but generally do little for engine operating temperature.

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Very true. The biggest improvement when I redid my cooling system was a new rad + plus the ZJ fan clutch, it solved my overheating problem. Vents did nothing for my coolant temps. When I swapped out my cracked stock header for an APN one, my average coolant temp rose from what it normally was, but is still below 210.

This puzzled me a bit since I thought for whatever misguided reason that a uncracked, aftermarket header would make everything cooler, but since temps are well within spec I'm not worried about it.:dunno:

I'm with CharlesS on this issue.

Did you short the disconnected positive cable to ground for 30 seconds and turn the headlights on then off when you re-connected the battery to reset the PCM?

Lurch said:

When I swapped out my cracked stock header for an APN one, my average coolant temp rose from what it normally was, but is still below 210.

This puzzled me a bit since I thought for whatever misguided reason that a uncracked, aftermarket header would make everything cooler, but since temps are well within spec I'm not worried about it.:dunno:

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The reason why the engine runs warmer is the aftermarket header will scavenge more exhaust from the engine than the stock tubular exhaust manifold. This causes the engine a/f ratio to lean out. You would expect that the ECU and O2 sensor would compensate for the changes, but unless you do a full ECU reset allowing the computer to relearn your driving style and create a new a/f map; the engine will continue to run leaner.
The newer style 4 hole fuel injectors should easily compensate for this change.

merdock69 said:

I'm with CharlesS on this issue.

Did you short the disconnected positive cable to ground for 30 seconds and turn the headlights on then off when you re-connected the battery to reset the PCM?

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Is this the correct way to do a full reset?

CharlesS said:

The reason why the engine runs warmer is the aftermarket header will scavenge more exhaust from the engine than the stock tubular exhaust manifold. This causes the engine a/f ratio to lean out. You would expect that the ECU and O2 sensor would compensate for the changes, but unless you do a full ECU reset allowing the computer to relearn your driving style and create a new a/f map; the engine will continue to run leaner.
The newer style 4 hole fuel injectors should easily compensate for this change.

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Is above, the correct way to do this? I guess some better injectors are in my near future then. Damn! Its always something with this thing.

I'll try my old O2 sensor to to see if that could be it to.

Never mind on the reset instructions. I found this. http://www.quadratec.com/jeep_knowledgebase/article-89.htm

I guess what i thought was reseting the ECU was doing nothing at all... Damn i'm still a newb. Learned somthin new today!

how new are the newer 4 hole injectors?

Ummmmm... I never said i had them.. I NEED to get them though

I had a similar issue with temperature creep and it was the water pump. Nothing about the pump looked bad, even after I pulled it off the engine. It was just a cheap pump from the previous owner. I had the problem for a while as I checked and rechecked everything else. I put on Napa pump TFW 42004 and it fixed the problem right away.