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g8ter55 06-24-2013 04:06 PM

Help overheating issues
Well to start my gas or temp guards don't work. Did some digging and found two wires were crossed on the back of the fuel gauge, maybe S and A. According to Johns troubleshooting page on these gauges I put these wires back and the temp gauge started working, I think. It's says I'm overheating in about 1-2 minutes. So I changed the thermostat, still same. I took my fluke IR gun and ran the jeep for a bit then shot the back of the block where the sensor is and read about 220 and then shot the thermostat housing and shot about me this is fine and not overheating?? Anyone agree ?? Anyways I was going to replace the water pump and took a look at a new one and basically it really doesn't look like it can go bad. Also, after idling for 20-30 minutes it never blew off into overflow res, another Reason I don't think it's over heating. No water in oil, no coolant leaks otherwise... Any suggestions?

LeePrather 06-24-2013 06:38 PM

I got rid of the electric gauges except for my fuel gauge an went mechanical. It's a lot nicer to see a temp than just h or c. Mine stays around 190-200 and the temp sensor is in front of the manifold. You might try to flush the radiator first before replacing the pump. Also, a lot of guys on here will recommend a rod-out on your radiator. When you fill up the radiator make sure you run it with the cap off to bleed the system. Air in the system made mine shoot up to 240 before I bled it and now it stays 190-200 no matter what

walkerhoundvm 06-24-2013 06:46 PM

Are you sure about the connections in the back? It sounds like you're grounding out the gauge - causing it to shoot up to hot quickly. Have you tried a new temp sensor for the block?

Either that or your gauge is already shot and you need either an aftermarket one or a used one via a used speedo cluster.

82JeepCJ7 06-24-2013 10:10 PM

The sending unit in the intake for the water temp could be bad as well. Test it with an ohm meter.

Temp *F Ohms
70 = 413 Ω
100= 246 Ω
150= 92 Ω
180= 56 Ω
190= 49 Ω
200= 43 Ω
210= 36 Ω

g8ter55 06-25-2013 06:32 AM

I followed johns wiring diagram repeatedly to make sure that the wiring on the back was ok. I definitely believe I have grounding issues causing my gauges to not function. My tub is not in the best shape and I have to chase the grounds first. My main goal is to make sure this thing isn't actually overheating. I don't know if those temp ranges i shot are ok to operate in... I will bleed the radiator and system with the cap because I haven't yet and I'll pull that sensor and ohm it out. I have a spare radiator that has been sitting for a long time but I could take it over to the radiator shop and have them pressure test and flush it to eliminate a radiator issue. Also the parts store near me has a fan clutch in stock which I might change.

walkerhoundvm 06-25-2013 06:51 AM

Those temperatures sound normal.

Simple things first - swap out the temperature sensor for a new one ($8 maybe?) and see what you get. Radiators are a bit more involved ;)

g8ter55 06-25-2013 08:45 AM

Yea the zone has one for 8$. It would be nice to see the flow rate thru the radiator to make sure it's not an issue. Another thing I just realized is that the guy I bought this jeep from took off the hoses that run through the manifold and just routed them to and from the HC. I doubt that should be an issue but any thoughts on if I should be running it with the coolant through the manifold?

LeePrather 06-25-2013 08:55 AM

I'm no rocket scientist, but doesn't it defeat the purpose of having a radiator and cooling if it doesn't go through the manifold? You are saying that the radiator runs straight to the heater core?

walkerhoundvm 06-25-2013 08:58 AM

Running coolant through the manifold helps stabilize temperatures throughout warm-up and once the engine is hot. It's just part of the equation, though - there is your manifold heater plate on the base of the intake, your EGR, a hot air collector from the exhaust manifold to the air filter - all of these things try to maintain some consistency with the air temperature so that it's atomizing fuel as optimally as possible.

Short answer: yes, routing the coolant through the intake is a good thing. Be careful, though, sometimes POs do things for reasons we could only guess at - like maybe your intake is cracked internally and it was blowing coolant into the cylinders...a little something I found out when I tried to reconnect my coolant hoses a few years ago.

^^Edit^^ Lee- coolant still runs through the engine once your thermostat opens up, so the engine is still cooled. Routing through the intake is a separate branch of the cooling; it's constant and serves the purpose noted above.

g8ter55 06-25-2013 09:29 AM

Yea I mean obviously its used to regulate the air and fuel temp introduced to the motor and since the guy went out of his way to disconnect them only makes me wonder as well. I figured I'd hook up a hose and run water through it while the jeep was not running to see if there is a leak somewhere. Actually I would almost say that it might cool better without the manifold hooked up , Less Flow restriction - less Heat load. I do wonder if it would have a direct relationship on why I can't get the thing to idle very well. I have a rebuilt weber 32/36 Dgev carb and can't get the thing to idle smoothly. But that's a different issue I'm having, the carb only has two adjustments, mixture and idle. I'm going to change the cap, rotor and wires to see if that helps.

Back to the cooling... I'm going to ohm the temp sender out and see what I got. Either way I might just replace it and then look to the gauges and grounds afterwards. I going to go out on a limb here and say that if it WERE overheating it would be blowing off into the overflow?? Correct? Not necessarily?

Deeznutz73 06-25-2013 10:23 AM

Just got done doing this myself. The PO on mine had a two prong fuel gauge and had it spliced in all wonky. It worked, but bounced a lot. Anyways, It took me a minute to get my temp gauge squared away. Best bet is to start at the sender itself and ohm it when the engine is running or after it is at "normal temp". That should tell you if your sender is good. If it's shooting to over temp in a minute or two, definitely a grounded wire. Even after I fixed mine, I was driving down the freeway and my temp gauge maxed out super fast one day, I just did the 4.0 head swap so I freaked. I was about to pull the thermostat to get home but noticed the sender wire hit the exhaust manifold and shorted out.

Also if you can pop the cap when it allegedly is overheating without it puking everywhere, it's definitely not overheating, or at least the excessive water temp isn't getting into the radiator. I have a 73' but a late model "wet" manifold that I don't have the lines hooked up yet so that shouldn't be an issue.

I used this site to help check my gauges and sender unit:

Check the sender first like you said, then ohm the gauge and trace the wiring. If it is over heating, flush your heater core, and finally replace your water pump. I doubt it's that but you never know!

g8ter55 06-25-2013 12:33 PM

thanks i will check that sender later on today first thing as well as trying to flush any possible air bound up in the block. the more i think about it i know standard type rtd's will either open or go to max range if they are bad...typically. i was just freaked out myself because dont really want to blow a head gasket messing around.

LumpyGrits 06-25-2013 03:52 PM

The temp sender for the gauge is in the head back by the firewall on the D/side.
That sender in the pic. I believe is for the CTO unit.

Balvar24 06-25-2013 04:04 PM

Sounds like you're electrical temperature gauge is not working. Fix it, or go to a mechanical one.

Not all jeeps had jacketed manifolds. My 79 doesn't. No big deal.

g8ter55 06-25-2013 09:09 PM

i will try some of these things and let everyone know what i came up with. thanks for all the help, i really appreciate the time

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