2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Coolant Problem

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Old Mar 8, 2003 | 07:43 PM
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From: ATX
Coolant Problem

Alright. FINALLY after three months of being lazy I got my rex up and running again after the fire. Only had to turn the key once and the thing started right up. Heh. BUT I think there may be a problem with the coolant system now. After just idling in my garage (yes with the door open) the radiator and hoses coming off the top of the UIM were VERY hot to the touch. I dont have a clue what to check for to fix this. Any pointers on what I should check? Or is there anything wrong. The reason I think something IS wrong is that my temperature gauge on the dash still was at zero, cold. And I know it had been running long enough to at least register somewhat on the gauge. Any pointers?
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Old Mar 8, 2003 | 07:46 PM
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From: Mars
Have the system flushed.
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Old Mar 8, 2003 | 07:53 PM
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From: charlotte
check to see if you left the coolant temp sending unit unhooked.

did you let the air bleed out of the cooling system properly? what year is it?
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Old Mar 8, 2003 | 08:56 PM
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From: ATX
you mean the plug that is right infront of the UIM? yes i plugged that in. What does it mean to have the system flushed? its an 88. No I didnt let the air bleed out, how do i do that?
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Old Mar 8, 2003 | 09:45 PM
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There's a bleeder screw just like the drain, up on the right side of the rad.. Open it up and add coolant until it runs out the hole, then put the screw back in and fill it the rest of the way up.

A good flushing once in a while is a good idea. Just regular maint..
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Old Mar 8, 2003 | 10:01 PM
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From: Mars
Hm.. not bleeding it would explain a whole lot
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Old Mar 9, 2003 | 11:21 AM
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From: ATX
well i opened the cap that is on top near the UIM, right behind the radiator fan and filled that until it was full. So I need to fill it from the bleeder screw? Then fill it some more, is that what youre saying?

so if i didnt bleed it would that explain why it seems to run very hot? would it also explain why the temp gauge on my dash doesnt register at all, it just stays on cold?
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Old Mar 9, 2003 | 11:24 AM
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From: ATX
the cap that i filled it from when it was cold was the yellow one in the upper right hand side of this pic.



of course i put the rest of it back together before I started her up
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Old Mar 9, 2003 | 11:45 AM
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The temperature sending unit is on the driver side of the engine, behind where the spark plugs are, but approximately at the same level. There's a spade connecter there. The wire to it kinda snakes its way accross the engine, but goes under lots of stuff, so it's easy for it to get lost. On a 90 its a single black wire with a yellow stripe, not sure if it's the same on the s4
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Old Mar 9, 2003 | 11:47 AM
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Originally posted by HeffBoost
There's a bleeder screw just like the drain, up on the right side of the rad.. Open it up and add coolant until it runs out the hole, then put the screw back in and fill it the rest of the way up.

A good flushing once in a while is a good idea. Just regular maint..
The bleeding just doesn't end from the Radiator Bleed Screw. When you are filling up your Engine with new Coolant, you use this screw as a finale. But first disconnect the Water Hose behind the Throttle Body. (The one that the other end connects to the Rear Housing). Fill Coolant up at the Thermostat Housing. Doing this ensures you will not be left with a huge air pocket back there. Once Coolant starts overflowing from that particular Hose, plug It back In. From there, proceed to the Rad Bleed Screw. Once Coolant starts oveflowing from this screw, you've... Fini!
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Old Mar 9, 2003 | 02:13 PM
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From: ATX
ok, the radiator gets hot so I believe that the water is in fact circulating through the engine. Safe to assume?

Also, the temperature indicator thing that is near the spark plugs is totally severed, so that would explain why the temp gauge in the dash isnt working correctly. I'll get that fixed.

Question though, how hot is the radiator supposed to get when just idling? Right now it is getting just to where its too hot to touch. Is that too hot, should I be worried about the temperature? I cant really tell because the gauge isnt working.....heh. Thanks guys.
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Old Mar 9, 2003 | 02:24 PM
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After the Thermostat has opened, I find It hot to a touch. Mind you, this after driving It around. I really would get the Coolant Temperture Sending Unit fixed right away. I wouldn't be dependant by how hot It Is to the touch rather what nubers I can see on my Gauge. Or In stocker form, where the needle Is.
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Old Mar 9, 2003 | 03:19 PM
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You're saying that you're worried because your radiator is getting hot?!? I'm a little confused here because people are trying to troubleshoot a problem that doesn't exist. The radiator and cooling hoses are SUPPOSED to be hot.

Though I do agree that you need to get that temp guage working before you go driving around. Connect the sender. It is located under the oil pressure sensor (under the oil filter).
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Old Mar 10, 2003 | 07:41 AM
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From: ATX
Ive never gone in and touched my radiator after driving so I was unsure just HOW hot it was supposed to be. So Aaron, that was JUST the information I was looking for. So it seems I dont actually have a problem as of yet. I need to get the temperature sending unit fixed though asap just so I can actually see just how hot is is getting. Thanks for the help guys!!!
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Old Mar 10, 2003 | 08:13 AM
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But first disconnect the Water Hose behind the Throttle Body. (The one that the other end connects to the Rear Housing). Fill Coolant up at the Thermostat Housing. Doing this ensures you will not be left with a huge air pocket back there. Once Coolant starts overflowing from that particular Hose, plug It back In.
Where does this come from? First I've ever heard this. Sounds unecessary to me.
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Old Mar 10, 2003 | 09:12 AM
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From: ATX
anyone tell me where the other end of the temperature sensing wire goes? does it go straight to the dash board? or plug in somewhere in the engine compartment? I'm going to have to rewire/replace mine because it seems it was torched in the fire. Anyone got one in tact they could sell?
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