Topic: New issues with the Jeep

[sharpxmen]

water won't come out if you have the radiator cap on, if you take the cap off it will start leaking until the level in the rad comes down to the level of the hole.

what does it exactly behave like (the gauge)?

[jfrabat]

water won't come out if you have the radiator cap on, if you take the cap off it will start leaking until the level in the rad comes down to the level of the hole.

what does it exactly behave like (the gauge)?

Two things are happening, and they alternate.  One is that the gauge will not even reach the first mark past 100* in the dial, and will stay there.  The other, the gauge will oscillate between about 160 and 180* as in the video I attached.

<a href="http://www.youtube.com/v/4nN_ie6kBcI" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">http://www.youtube.com/v/4nN_ie6kBcI</a>

[sharpxmen]

Two things are happening, and they alternate.  One is that the gauge will not even reach the first mark past 100* in the dial, and will stay there.  The other, the gauge will oscillate between about 160 and 180* as in the video I attached.

I'm checking the FSM to see if i can find the ohm values for the coolant temp sensor - I'll come up with a way to test this.

EDIT:
get a 1 to 2 kohm resistor, put one end to ground and the other stick it into the temp sender connector (after unplugging it from the sensor), see if it does the same, if it doesnt then it's the sender or the harness at the sender (terminal, wire, crimping, corrosion,etc), if it does then it's the harness and/or circuit to the gauge or the gauge itself. At 1kohm should display about 190F at 2kohm should be about 150, idea is to have something that you know it wont vary at all and see if you still get the problem.

of course best to do this with the engine started so you get the vibrations. You work for Sony so most likely you're wiring savvy and probably understand what i meant above.

the other thing you can do is to measure the coolant sensor resistivity (ohm) with the engine running, see if it varies like the gauge does, if it is then it's the sender.

This is not a thermostat issue, it will not vary like that up/down 30F at a rate of 2 or 3 times/second.

EDIT2:
your oil pressure is also wrong unless the engine was cold.
 

[jfrabat]

EDIT2:
your oil pressure is also wrong unless the engine was cold.
 

Yeah, but usually that gets fixed with the oil pressure sensor change (I have it, I just haven't replaced it yet).  But I think it is also unusual that I need to change that out at least once a year!

By the way, I work in MARKETING!  So no, I am not electronically savvy AT ALL!  But I think I understand what you mean.  I'll try it with my multimeter and see if I can read the resistance.  But I doubt it's the sensor; it would be much too odd to have 2 sensors acting the exact same way...  (I just replaced it a week and a half ago and it's still doing the same thing).

[sharpxmen]

Yeah, but usually that gets fixed with the oil pressure sensor change (I have it, I just haven't replaced it yet).  But I think it is also unusual that I need to change that out at least once a year!

By the way, I work in MARKETING!  So no, I am not electronically savvy AT ALL!  But I think I understand what you mean.  I'll try it with my multimeter and see if I can read the resistance.  But I doubt it's the sensor; it would be much too odd to have 2 sensors acting the exact same way...  (I just replaced it a week and a half ago and it's still doing the same thing).

well, then should be from the plastic piece on the sensor and up to the gauge, only thing is to determine where. Stick a needle in the wire and put the multimeter on it (needle would be best) to ground and measure resistance - unplug the connector in the gauge cluster when you do this, if it does the same then it's either the crimping/connector or the sender.
If it doesn't do it then go to the connector that goes to the cluster and do the same for the wire that goes to the sender (still unplugged from the cluster) and see if you get the behavior there - if you do it's the harness, if you don't it's the connector to the cluster or the cluster itself (the gauge).

also, if you have a piece of harness with the connector you can plug that in the sender and test the same, if you're clear cut and solder that piece.

[Jeffy]

Well Mopar doesn't make sensors they are outsourced.  Have you put a thermometer into the radiator to get a temp?  Maybe get a cap with the temp gauge on it.

[jfrabat]

Maybe get a cap with the temp gauge on it.

Can't say I have seen those before...  To be honest, I never know they existed!

[sharpxmen]

Well Mopar doesn't make sensors they are outsourced.  Have you put a thermometer into the radiator to get a temp?  Maybe get a cap with the temp gauge on it.

at 150F the temp in the rad would be lot less (the thermostat won't be open).

[jfrabat]

The thermostat IS opening, so THAT is not the problem (I turned the Jeep on without the cap and let it get to operating temperature, and you can see the coolant flowing when the thermostat opens); my doubt is that if he used silicone, maybe some of it is interfering with the flow of coolant to the sensor, and that is what is causing problems.  Or maybe the water pump is dying on me, who knows...

[Jeffy]

The thermostat IS opening, so THAT is not the problem (I turned the Jeep on without the cap and let it get to operating temperature, and you can see the coolant flowing when the thermostat opens); my doubt is that if he used silicone, maybe some of it is interfering with the flow of coolant to the sensor, and that is what is causing problems.  Or maybe the water pump is dying on me, who knows...

I think that's a bit of a stretch.

BTW; the sender for the gauge is not the one at the thermostart.

[sharpxmen]

Jeffy is correct, the gauge sender is close to the firewall in the cyl head, so if you replaced the one in the thermostat that's the one for the pcm.

[grumpygy]

Have to agree since I busted the back one and it took a bit for me to figure out it was the one for the Gauge.

[jfrabat]

Oh REALLY!  Well, that explains A LOT!!!!  OK, where is the sender for the gauge exactly?  And is there a part number?

[sharpxmen]

Oh REALLY!  Well, that explains A LOT!!!!  OK, where is the sender for the gauge exactly?  And is there a part number?

driver's side on cyl head towards the firewall close to the valve cover, you can't miss it, only thing with a wire in it in the cyl head

EDIT:
you can see it in this picture, top left of cyl head as the picture is taken - yours will look different as mine is autometer, stock has a connector going to it.

[jfrabat]

OK, I will order it then...