coolant temp

[brokenwrist21]

ok, so my temperature gauge freaked out on me, the other day on my way to work. so i went down to orielly's and bought a new temperature sending unit, put it in, filled it back up, purged the air and added hyper lube coolant additive. ever since i changed the sending unit, my gauge now will not drop below 210 and it goes all the way up to about 225 before the thermostat will open and bring the temp down. i checked the coolant temp tonight when i go home with a probe in the radiator and the filler and read 180. what going on, do i have to much resistance or not enough. plus my water pump appears to be taking forever to build pressure, i can actually squeeze the upper rad hose flat and not have pressure build behind it. should i just bite the bullet and buy a new temp sending unit, replace the thermostat and water pump? i know someone out there can help me.

[Jeffy]

Well, first off which temp. sender did you replace?  The one on the thermostat housing is for the PCM.  The one ofr the gauge is on the head on the back of #4 cylinder.  If you replaced the correct sender then it might not be the right ohm range as the original.  Squeezing the radiator tube doesn't mean much unless the thermostat opens up.

Really though you need to test the system to see if there is flow.  If it flows then the thermostat and the pump are fine.  You can use a thermometer in the radiator to see how hot it gets and see when the thermostat actually opens.  It won't be as hot as in the engine block but it should be plenty hot enough that you shouldn't see too much of a difference with a probe in the upper tank of the radiator.

[sharpxmen]

should also squeeze/block the heater hose along with the radiator one to see if there is pressure otherwise would just circulate thru the heater core.

[brokenwrist21]

ok, i did the most basic of basic and free cooling system checks today. parked my jeep on an incline, started it removed radiator cap and just let it idle for almost an hour. there aparently more than one, huge air bubble stuck in the cylinder head right on the gauge sensor. it now reads between about 190 and 210 at idle, still flucuates, and same temps when driving, still flucuates there too. so for right now the problem is fixed. thanks for the input guys.

[chrisfranklin]

Well, first off which temp. sender did you replace?  The one on the thermostat housing is for the PCM.  The one ofr the gauge is on the head on the back of #4 cylinder.  If you replaced the correct sender then it might not be the right ohm range as the original.  Squeezing the radiator tube doesn't mean much unless the thermostat opens up.

Really though you need to test the system to see if there is flow.  If it flows then the thermostat and the pump are fine.  You can use a thermometer in the radiator to see how hot it gets and see when the thermostat actually opens.  It won't be as hot as in the engine block but it should be plenty hot enough that you shouldn't see too much of a difference with a probe in the upper tank of the radiator.

Jeffy, so the coolant temperature sender for the dash gauge is on back of the engine, out-of-view?  

My gauge went dead awhile back and I thought it was because some sensor got disturbed on or just to the sides of the valve cover.  

Looked at the '94 manual here and searched site.  

Looking around at parts suppliers it looks like everybody mixes up "sensor/sender" in their labeling so I don't know what I'm going to end up with - CTS or Coolant Temperature Sender that the dash gauge reads.   

[chrisfranklin]

Assuming here, when this place says "with gauge" under product description, they mean the sender they show connects with the the gauge, not something else. 

http://www.autopartsnetwork.com/shop/-part_Engine_Coolant_Temperature_Sender-make_Jeep-model_Wrangler-year_1992.html

[Jeffy]

Assuming here, when this place says "with gauge" under product description, they mean the sender they show connects with the the gauge, not something else. 

http://www.autopartsnetwork.com/shop/-part_Engine_Coolant_Temperature_Sender-make_Jeep-model_Wrangler-year_1992.html

That's usually how it's labeled.

[grumpygy]

Just in case I got a Sensor from Orielly's and Mine did the very same thing, never did get it do drop.  But did have a heat gun so I could check everything and It was dead on what it should be.

  So went to A dealer and Bought one from them, now my gauge reads correctly.

[chrisfranklin]

Figured out what the story was with my coolant temperature sender and coolant gauge function, yesterday.

The sender on mine screws in near the back of the engine, just to the right and down from the valve cover.  I pulled the plug connection to the sender yesterday and, in plugging it back in, the plastic plug basically came apart, disintegrated in my hand.   Looks like the connection inside the plug wasn't making contact with the metal tab in the sender.

Took the wire/connection that was inside the plug and crimped that and fitted it, minus plug, on the sender's tab and that got the gauge working again.  Will have to wire on a new plug or some other tab connection at some point.

[grumpygy]

Figured out what the story was with my coolant temperature sender and coolant gauge function, yesterday.

The sender on mine screws in near the back of the engine, just to the right and down from the valve cover.  I pulled the plug connection to the sender yesterday and, in plugging it back in, the plastic plug basically came apart, disintegrated in my hand.   Looks like the connection inside the plug wasn't making contact with the metal tab in the sender.

Took the wire/connection that was inside the plug and crimped that and fitted it, minus plug, on the sender's tab and that got the gauge working again.  Will have to wire on a new plug or some other tab connection at some point.

My Sending unit is what fell apart.