so i switched to an open cooling system

last night i finally did the swap. I was tired of exploding bottles and constant overheating on the trail. Went with a 94 radiator and heater switch into my 87. New hoses as well. My only problem is that my temp guage continues to read zero or 100 whatever the the lowest the switch can get. I have got a 195 thermostat and i cant even get it to open up. Then engine feels cool even after a 10 to 15 minute drive. Is this normal?? I expected the swap to help out a bit but not quite this much. Maybe it is because i tested it at night??? It was about 60 degrees outside (cold for tucson). My other question is the switch i took out of the radiatior, is that the temp switch for my dash guage or a just a fan switch? The only other sensor i thought might be for the temp gage is a sensor on the intake manifold. All help would be appreciated.


Thanks
Mike

mnaemark said:

My other question is the switch i took out of the radiatior, is that the temp switch for my dash guage or a just a fan switch? The only other sensor i thought might be for the temp gage is a sensor on the intake manifold. All help would be appreciated.Mike

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Temp sensor for the guage is on top of the headed in the very back on the intake side.

And if I'm not mistaken the sensor for the electric fan is on the radiator itself. I only know about 1 or 2 people who have the closed system so I have not had alot of experience with it, only replacing the plastic turtle with an aluminum one. Never really looked at where the sensors are, the closed system is not a bad thing, there is nothing wrong with the closed system as long as everything it good.

The sensor in the radiator is for the e-fan. The temp sensor for the gauge is on the back of the head next to the firewall.

How are your hoses set up? Are you sure you're forcing the coolant to go through the t-stat or is there a hose you thought you needed that you don't and it bypasses the t-stat?

i know there is nothing wrong with the closed system. The closed system was just wrong for me. I left the lower radiator hose in the same spot and the upper radiator hose in the same spot. I used this drawing to hook up my heater core lines ect
I found it in a tech article on off-road.com about the swap. Is this correct??? In the meantime im going to go find that sensor and see if it actually is working. Thanks for the help

-mike

It somehow fixed itself. Drove it around for a while and then the temp guage started to work. Maybe an airbubble or something??? Anywho thanks for the help

-Mike

The sensor on the intake manifold is the MAT sensor, leave that one alone or you will run rich.

I personnaly like the closed system but hate those cheap bottles. My wife's Ford Windstar is a closed system also but it has a very stout stock bottle that is clear and is re-enforced inside so that it won't expand and bust. I think I'm going to retrofit one of those in and also plumb all of the heater hoses with copper and just have short rubber connections to eliminate all of the custom fit hoses and reduce the chances of hose failure

I'll do a write up when I do the bottle and plumbing swap.

mnaemark said:

It somehow fixed itself. Drove it around for a while and then the temp guage started to work. Maybe an airbubble or something??? Anywho thanks for the help

-Mike

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It takes a while for the system to push out bubbles, it takes a few trips to push them out.. Just make sure that you keep the bottle at a decent level for a few weeks, the system will pull in more fluid from the bottle as it cools off and the fluid loses heat- compresses.

It takes a few hours for the system to stabilize itself and it has to get hot first, then cool off to push the bubbles out, all it takes is getting it hot and letting it cool off, but just make sure your bottle is topped off, you don't want to lose the vacuum or you will get air back into the system.

hope that helps.

Hey all i did the exact same cooling system swap in my MJ due to the exploding plastic bottle and overheating on the trail. My temp guage never gets above 210 even when im stuck in traffic. I am using the original pressure bottle as my overflow return to save space, i just drilled a hole in the cap just big enough for the hose. It was well worth the money. I also have a 3 row all metal radiator.

I have heard about this open and closed system but dont know which one I have. I have a 94, how can I tell which it is that I have?

Andrew

xrayjeeper83 said:

I have heard about this open and closed system but dont know which one I have. I have a 94, how can I tell which it is that I have?

Andrew

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94 is open. Closed system has no cap on the radiator.

Cool good to know

Thanks
Andrew