jeepmarine312 Posted July 24, 2013 Share Posted July 24, 2013 so my mj felt like it was running hot, ended up it wasnt, but yeah, so it felt like it was and so i went to change the thermostat, when i took off the housing, there was no thermostat in it at all, so i put one in and sealed it up, let it all dry over night and crap, then i drove with water in it. on the way home it started steaming like crazy and i pulled over. so i took the thermostat back out cause it wasnt letting enough coolant through. now it sealed back up and perfect, no leaks from the housing or the block or the water pump or anything, but the reservoir at the top side of the hood near the passanger side just pours coolant. filled it all up today, let it run and suck the coolant in to the rad and everything, then topped it off, went to parts store and when i came out coolant all over the ground from the reservoir, no coolant will stay in at all, but why? it didnt do this before it overheated that day after adding thermostat. now its back like it was and this is happening...? Link to comment Share on other sites More sharing options...
JeepcoMJ Posted July 24, 2013 Share Posted July 24, 2013 you have a blown head gasket. only compression going into the head would cause that. you no longer have a t-stat in reducing the flow and causing boil-off. you could have a cracked coolant reservoir or bad reservoir cap, but I've never seen one leak with no t-stat in. Not having the t-stat doesn't allow it to develop the pressure to cause it to overflow. Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 24, 2013 Author Share Posted July 24, 2013 but with a blown head gasket wouldnt i have milky oil or the leak coming from the block? the only leaking is from the reservoir. Link to comment Share on other sites More sharing options...
mnkyboy Posted July 24, 2013 Share Posted July 24, 2013 You only get the milky oil if coolant is mixing with oil. You could just be blown between a coolant port and a combustion chamber which would over pressurize the cooling system. Link to comment Share on other sites More sharing options...
jeepsouth Posted July 24, 2013 Share Posted July 24, 2013 If you "drove it with water in it" like you said ,and just water that could be the problem. Also if you didn't properly vent all the air out of the system you can get the coolant puking out after a short drive also. What did the temp. gauge read assuming you have one? Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 24, 2013 Author Share Posted July 24, 2013 ok here's how it went, took off housing and there was no thermostat in, so i put one in, the one the auto store gave me, filled with water and drove, drove fine till on the way home. heard a pop sound, not a loud one like a motor component blowing but a little pop, and i saw steam pouring from hood. so i pulled over and opened hood. steam shooting out of reservoir. reservoir cap popped off. got towed home so not to take any risks, when the tow truck came he started it to go up the tow ramp and no issues occured. got home, and took thermostat out. resealed properly, let dry over night, and then next morning filled it with coolant. let run for a min or two. then turned off and topped off resevoir with coolant. drove back to auto store to show my friend my truck. when we walked out coolant was all over the ground. opened hood and it was coming out from either the bottom of the tank or from the line that connect to the port on the bottom of the tank. tank= reservoir. reservoir was empty. filled with water to get back home. got home and have not started her since. before i put the thermostat in she ran fine, i didnt know that mj's ran at 210 normally so i thought i was running hot. i do not have a temp gauge i just have that dumb warning light that tells you once its too late, but it never came on. i don't think its head gasket because no milky oil, no leaks from the block at all, none in the back or front, or sides. only from either the tank or that line. no smoke on starts, no smoke at all from tailpipe. no difficulty starting, or running. just dumping coolant out of the reservoir. i was thinking maybe it is the cap for the reservoir. I'm thinking that the thermostat was restricting to much flow and the pressure built up and the only place to go was back through the reservoir, and since the cap shot off, I'm thinking that it will no longer hold pressure like it used to. and thus it is dumping the coolant. but thats just my thoughts. what yall think? Link to comment Share on other sites More sharing options...
jeepsouth Posted July 24, 2013 Share Posted July 24, 2013 Had to replace my thermostat not too long ago ,and until I properly bled the system my pressure bottle cap would pop off also (brand new bottle/cap). I went with a cap that is meant for a Volvo something or other (sorry can't remember right now)as others on here have done. Also I jacked up the rear of my truck as high as I could ,and took out the temp sensor at back of cyl.head(4.0 liter) then refilled Through pressure bottle opening slowly until coolant only came out at the temp. sensor hole. Do this when engine is cool. Lowered truck ,and filled pressure bottle to half ,put cap back on-good to go ever since. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 24, 2013 Share Posted July 24, 2013 Some aftermarket thermostats are not marked, so you might have put it in upsidedown. The pellet on the thermostat should be facing toward the engine. I have had problems with aftermarket thermostats being bad right out of the box. For that reason I always use a thermostat from the dealer. They also have a hole with a jiggle valve that allows flow even when closed and helps bleed air from the system. Link to comment Share on other sites More sharing options...
Eagle Posted July 24, 2013 Share Posted July 24, 2013 filled it all up today, let it run and suck the coolant in to the rad and everything, then topped it off, went to parts store and when i came out coolant all over the ground from the reservoir, no coolant will stay in at all, but why? it didnt do this before it overheated that day after adding thermostat. now its back like it was and this is happening...? There's your problem. The surge bottle is NOT supposed to be topped off. It's an expansion tank, not an overflow recovery bottle. It should be filled to no more than the halfway mark when cold. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 24, 2013 Share Posted July 24, 2013 It's very possible that the bottle IS the problem. If you don't replace it, at least replace the cap with a 703-1396 from Napa. The old one "popped" off because they are chinese pieces of crap. Here's what the FSM says about filling your cooling system: Only fill to the top of the little pipe inside the bottle. Check this out from the FSM This system does not have a radiator pressure cap. Instead the pressure cap is mounted on the coolant pressure bottle. System coolant flows directly through a fully pressurized Hot-Type expansion bottle. Coolant flows through the pressure bottle at all times during engine operation whether the engine is cold or at normal operating temperatures. Larger coolant volume caused by thermal expansion during engine operation is absorbed by the expansion chamber in the bottle. Air trapped in the system is purged through the pressure cap vent valve during maximum coolant expansion.. Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 24, 2013 Author Share Posted July 24, 2013 thank you guys. went to the JY and found a good bottle. much better then my current one. so i grabbed it, gonna try it tomorrow. anyone have a pic by pic of how to do the bleed thing? Link to comment Share on other sites More sharing options...
cruiser54 Posted July 24, 2013 Share Posted July 24, 2013 thank you guys. went to the JY and found a good bottle. much better then my current one. so i grabbed it, gonna try it tomorrow. anyone have a pic by pic of how to do the bleed thing? It's not necessary to bleed it. good bottle, and a good cap will be fine. Get that Napa cap!! Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 25, 2013 Author Share Posted July 25, 2013 i would just like to bleed it to be careful you know... Link to comment Share on other sites More sharing options...
cruiser54 Posted July 25, 2013 Share Posted July 25, 2013 i would just like to bleed it to be careful you know... Not necessary. Did you read the quote from the Factory Service Manual? Did you know I was a Service Manager and Shop Foreman at a Jeep dealer since when these were new, and I nor my techs EVER bled/burped a Renix cooling system? Link to comment Share on other sites More sharing options...
Eagle Posted July 25, 2013 Share Posted July 25, 2013 Fill it (to the halfway mark, as indicated), then drive it. Check it after it cools down, and add coolant as necessary. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 25, 2013 Share Posted July 25, 2013 Fill it (to the halfway mark, as indicated), then drive it. Check it after it cools down, and add coolant as necessary. Yup. Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 25, 2013 Author Share Posted July 25, 2013 just do that over and over and it should stop eventually or once all the air is out? Link to comment Share on other sites More sharing options...
cruiser54 Posted July 25, 2013 Share Posted July 25, 2013 Do like Eagle says and drive it. You shouldn't have to add more than once. But use the Napa cap!!! This whole thing of bleeding/burping Renix systems is an old wive's tale that has lived on in perpituity. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 25, 2013 Share Posted July 25, 2013 Thats really interesting. I always thought burping the cooling system was a big deal on the renix's. Link to comment Share on other sites More sharing options...
Eagle Posted July 25, 2013 Share Posted July 25, 2013 I burp mine, and I learned how to do it from a racing buddy who was a Jeep shop foreman and service manager when my '88 was bought new. I do it so I won't have to remember to check the coolant level later, but it's not a big deal and I'm sure most shops don't (didn't) do it. Back to your original post and overheating. You may still overheat after replacing the coolant bottle and cap. If your truck doesn't have a fairly recent radiator, it's probably clogged and not doing a lot of cooling. You reported that there was no thermostat -- people typically remove the thermostat because they think that's a "cure" for overheating. It's not. Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 25, 2013 Author Share Posted July 25, 2013 it only overheated after i added the thermostat. before that i had no problems whatsoever. drove to hilton head, SC and back from Grovetown, GA. and she went fine the whole time. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 25, 2013 Share Posted July 25, 2013 it only overheated after i added the thermostat. before that i had no problems whatsoever. drove to hilton head, SC and back from Grovetown, GA. and she went fine the whole time. Check to make sure you didn't install it upside down. Also, do you have a part number for the one you installed? Link to comment Share on other sites More sharing options...
jeepmarine312 Posted July 25, 2013 Author Share Posted July 25, 2013 i aint got it no more, i took it back out and tossed it, i was frustrated, upset, angry, sad... lots of not good emotions at the time... Link to comment Share on other sites More sharing options...
Eagle Posted July 25, 2013 Share Posted July 25, 2013 it only overheated after i added the thermostat. before that i had no problems whatsoever. drove to hilton head, SC and back from Grovetown, GA. and she went fine the whole time. Modern automobiles NEED a thermostat to run properly. Many people simply don't understand that the purpose of the thermostat is to keep the temperature UP, not down. A properly-functioning radiator and cooling system are capable of keeping the temperature well below the temperature needed for optimum combustion -- in fact, often below the minimum temperature for the electronics to switch over to to closed loop operation, meaning the system is reading and reacting to all sensor inputs. For the Renix-vintage Jeeps, that switch-over takes place at somewhere between 170 and 180 degrees F (I used to know more exactly, but I haven't thought about it for a long time). Removing the thermostat could have you running in open loop mode all the time. The vehicle will run ... but it will be always running on a pre-mapped air/fuel curve that's far richer than optimum for an engine at normal operating temperature, and the fuel mileage will suck. Removing the thermostat is NOT a fix -- it's a temporary bandaid that just masks the symptoms of an underlying problem. Link to comment Share on other sites More sharing options...
Egm89 Posted July 25, 2013 Share Posted July 25, 2013 I had the same issues with mine, but I do have a thermostat, what I didnt have was a good bottle cap, the first one was kinda bad, and the second one that I bought from the JY had a little crack, so I whent to napa bought the one that yall said, and it seems to work ok, been a couple days w/o issues. Link to comment Share on other sites More sharing options...
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