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bought a 89 Comanche last week got it home and had a coolant leak which turned out to be a small crack in T-stat housing when i replace it i put in straight water to test for any other leaks now it blows water out of  the bottle it didnt do that before i know the cap is bad but could straight water cause this with the new 195 stat i put in ? i did bleed air out at back of head temp sender hole... thanks for replies..

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You may still have air trapped in the system.

 

You have an '89. That plastic coolant bottle on the firewall is not an overflow catch bottle, it's part of the pressurized cooling system. That crappy plastic cap is the pressure cap. If it won't hold pressure, you have a double problem.

 

First, "anti-freeze" not only protects against freezing, it also raises the boiling temperature of the coolant. At sea level, the boiling point of plain water is 212 degrees F. The boiling point for a 50/50 anti-freeze mix is 223 degrees F. at sea level. The boiling point goes down as elevation increases, but I don't remember by how much. So by running plain water, you're allowing the system to reach a boil 11 degrees earlier than if you ran 50/50 anti-freeze.

 

Second, pressure also acts to raise the boiling point. If the pressure cap can't hold pressure, then you're stuck with 212 degrees as your maximum temperature before it boils. If there's any air trapped in the system, it will be "burped" out rather violently. I've always had to "burp" my XJs and MJs with the closed system. The way I do it is to fill the system, then start the engine with the cap off the bottle. Let it idle for a few minutes, until it starts to boil. (Stand away from the bottle when doing this or you WILL get scalded.)

 

When it boils, shut off the engine. As soon as the boiling subsides and the system starts to pull coolant (water) back out of the bottle, add coolant (water) to keep the level at the halfway point. When it settles down completely, double check that the bottle is filled to the mark (halfway), then start the engine and repeat. I usually have to go through three to five cycles to get the majority of the air out.

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Thanks for the advice on bleeding air out have done 4 cycles so far each time it was better and no more coolant leaks except the cap will replace that but still have a oil leak to deal with

When you get the new cap (and now), be sure not to overfill that plastic tank, or you'll blow it up. We cal that a "closed" system because there is nowhere for expanding coolant to go -- no overflow catch tank/bottle. Expansion of hot coolant is taken care of by compressing air in that bottle. It should be filled halfway when cold -- no more.

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washed engine got under it with it at idle have a steady drip from center of oil pan at the rear main guess that tells me whats next to do any body know easy way of fixing it ?

 

Ask Cruiser for his leak synopsis.  It's not  automatically rear main leak right off the bat.  Some other "looking" is in order.

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washed engine got under it with it at idle have a steady drip from center of oil pan at the rear main guess that tells me whats next to do any body know easy way of fixing it ?

 

Ask Cruiser for his leak synopsis.  It's not  automatically rear main leak right off the bat.  Some other "looking" is in order.

 

thanks,, I'm all for looking for leak other then rear main because both trans lines are in the way of getting oil pan off

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Tip 15 in my link below, but here it is for ya:

 

 
 
 
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
 
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. 
 
 Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it? 
 
  A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
 
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
 
 First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
 
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first. 
 
Revised 02-26-2013
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I'm a big fan of the mid 90"s Mopar coolant reservoir, it has a different shape, but it is made of HEAVY duty nylon and has a real pressure cap.

 

Mid 90's is an open system. I thought we were discussing the OP's closed coolant system problems.   :hmm:

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I "burp" the cooling system on mine by jacking the rear of the truck up reeeeeal high (till the engine tilts forward) and cracking the coolant temp sender (for the gauge) at the back of the cylinder head.  Works the first time and no burns  :yes:

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