The problems keep coming. Overheating

[Ecomike]

Starting in 91 the ECU turns the E-fan on and off. Not sure what the programmed on-off temp was in 91

 

[yossarian19]

Good to know, Ecomike.
As somebody else (Joe? ) said first, though, fan shouldn't matter if it's on the highway running hot.

 

[SBpunk]

I picked up a new relay for the fan. Going to try it out later and see if it helps with the eFan.

Coolant is looking good. I think it was sucking down coolant from the bottle because there was so much air in the system that was burping out. Makes sense to me anyway. Air works its way out and pulls more coolant in to replace the space. Just to be safe I have some IR dye and flashlight / goggles I'm going to use in it. It'll help me find any leaks so I can either patch them up or blow up the jeep if its got a cracked head lol.

As far as the o2 sensor leak. What do you guys suggest for fixing it? Its almost like the o2 sensor I put in was too small and its leaking right out of the threaded area. I figure JB weld but then getting a new one in will be impossible. Only other option I can think of is putting in a new header / down pipe which will get expensive and kind of a pain.

 

[Ecomike]

As far as the o2 sensor leak. What do you guys suggest for fixing it? Its almost like the o2 sensor I put in was too small and its leaking right out of the threaded area. I figure JB weld but then getting a new one in will be impossible. Only other option I can think of is putting in a new header / down pipe which will get expensive and kind of a pain.

You got me on that one, but sure sounds like a big part of your problem. I usually let the muffler shop guys do that stuff, but I almost don't even use them anymore.

 

[8Mud]

O2 sensors usually have a ring seal. I've seen two types, a flat copper washer and folded steel compression type ring seal/washer, that looks just like a spark plug washer/ring seal.

Maybe your washer/ring seal fell off or it never had one and it was something they missed in quality control.

I've heard them called O2 sensor crush gaskets, seals, ring seals, washers or just plain old gasket. They have an 18 MM hole in the center and are usually 1.5 MM thick.

I always paint the O2 sensor threads with (true) copper paste, being real careful not to paint the first 3/16" or so of threads, don't want to get that stuff on the sensor probe. Copper paste dries hard and makes a seal, but doesn't really bond and you can get O2 sensor back out of there again.

 

[yossarian19]

Leaking o2 sensor threads, or any exhaust leak before the probe, can cause funky stuff. Running hot... well, maybe? I'd think if it was running hot it would also have a running lean code.

 

[Ecomike]

O2 sensors compare internal exhaust O2 concentration to the immediate external O2 concentration. So if the exhaust is leaking near or at the sensor the outside O2 concentration drops and fools the sensor. It may not throw a code. It sees the differential concentration and can drive the engine leaner by mistake.

Leaking o2 sensor threads, or any exhaust leak before the probe, can cause funky stuff. Running hot... well, maybe? I'd think if it was running hot it would also have a running lean code.

 

[Digger87xj]

Re: Re: The problems keep coming. Overheating

I picked up a new relay for the fan. Going to try it out later and see if it helps with the eFan.

Coolant is looking good. I think it was sucking down coolant from the bottle because there was so much air in the system that was burping out. Makes sense to me anyway. Air works its way out and pulls more coolant in to replace the space. Just to be safe I have some IR dye and flashlight / goggles I'm going to use in it. It'll help me find any leaks so I can either patch them up or blow up the jeep if its got a cracked head lol.

As far as the o2 sensor leak. What do you guys suggest for fixing it? Its almost like the o2 sensor I put in was too small and its leaking right out of the threaded area. I figure JB weld but then getting a new one in will be impossible. Only other option I can think of is putting in a new header / down pipe which will get expensive and kind of a pain.

Sounds like maybe the threads are damaged? You can have a shop replace or rethread the O2 bung.