CJ running hot!

[liljeeplover]

I have a 1980 CJ7 with a AMC 304 v8 4spd. i just put a temp gauge in it because someone thought it was running hot. the temp gauge only goes up to 240 and that is what it is running at, maybe further because thats as far as the temp gauge goes. I have put a new radiator on it a couple months ago. and this morning just installed a 6 blade fan because it only had a little 4 blader. I was thinking maybe taking out the thermostat? any suggestions. the water pump is working. Thank you.

 

[mylittlecj5]

is it a mechanical gauge you installed? If it is electric, I'd think its messed up, but a mechanical gauge is pretty reliable.

Some ideas...

Is there coolant mixing in with the oil? Either in the oil pan or in the radiator. Does it seem to lose coolant after its run a while? That would indicate a bad head gasket or crack in the block/heads.

Start the engine and stick a meat thermometer in the radiator cap (take it off while the engine is cool, Duh), see what it says. Does it match the gauge?

Is the radiator new, or new to you? Is it plugged? Look in the radiator and see if you can see any coolant flowing after the engine reaches operating temp.
Feel the outside of the radiator and see if you can feel a cool spot or area on the OUTSIDE of the radiator (don't stick your hand in by the fan on a running engine)

Feel the hoses (upper and lower) and see if one of them is cooler than the other by touch. Is the lower hose collapsing internally when it reaches operating temps or high RPMs?

Pull the thermostat as a last resort, check it by immersing it in a pan of water set to boil, and watch it till it opens, then use that meat thermometer to see what temp the water is at. Its possible that it is in upside down, check that just before you pull it out of the engine. (pellet side into the coolant)

 

[CJ]

Welcome to the site liljeeplover!

Do everything MyLittle said... All good advice.

Check the lower hose (suction) and make sure it is not collapsing when running, there should be a spring in it. If it collapses no water flows.

Taking out a thermostat is an easy way to see if it is working but your CJ will most likely run hotter (eventually) without a thermostat in it then with it in. Let me explain. Without a thermostat, the water in the radiator will pass so quickly through that there will not be sufficient time for the water to cool by the air passing by it. Always run a thermostat...

BTW - IMHO - Thermostats are so cheap, it's always a good idea to change them out when you suspect an overheating problem.

 

[liljeeplover]

it is an electric gauge that i put the sending unit to the head of engine. nothing mixed in with coolant and not leaking coolant. radiator is brand new not used. thats all the info i have right now. ill wait on pulling the thermostat and do your suggestions

 

[liljeeplover]

ok thanks for all the help i am changing the thermostat in the morning. ill let you know how it goes thanks again!

 

[liljeeplover]

it is in the intake manifold sorry bout the confusion guys. i did change thermostat today.. i only drove it for about 10 minutes. by the temperature gauge which like i said reads max 240.. sat at 235? is that still too hot? i have no checked fan clutch and a mechanic did install the gauge and sending unit so it should be correct. when i boiled this thermostat for about 8 minutes it opened up about 1/2" is that ok?

 

[gert]

is the motor old? sometimes they can collect rust in the bottom of the block which will prohibit cooling the motor if a large quantity settles in the bottom you would have to flush the system. what is the condition of the water pump? Some times it can cause over heating if the water pump does not circulate enough water thru the engine. these ideas i am sugesting are more of your long shot type of problem/fixes. Good luck

 

[kicknjeep]

if i'm not mistaken there is actually a drain plug towards the bottom 10"'s or so behind the motor mount . you can flush the motor and hopefully drain the rust from the block. maybe someone can help out with pics..

 

[gert]

If you buy the prestone coolant system flush and do it by the instructions on the back of the bottle it tells you to run the motor a few hours with the prestone in it and then splice into your heater hose with a garden hose and let all of the junk flush out of the top of your radiator (with motor running) and there will be a lot of junk come out. It does work I have done it on about four motors now.

 

[JHOFF]

Definetly don't pull out the thermostat, it will actually cool worse. Do you have a fan shroud on there? If not that is probably a lot of it. As big of a fan as you can get too, a 17 or 18 inch flex fans work well.

 

[CJ]

Definetly don't pull out the thermostat, it will actually cool worse. ~~~

Exactly... Have to give the coolant time stay in the radiator so the transfer of heat can take place...

 

[Thorwon]

Another thing to check is the water pump. I have changed two (on different vehicles) in the last year that had no pump vanes left, they had disintegrated.
I spent three days trying to find a reason on the first one, I started with the pump on the second one.
The odd thing is I could see the water flowing in the rad.

 

[Thorwon]

Liljeeplover did you get your over heating issues worked out?

 

[sweetpeet]

Welcome to the site liljeeplover!

Do everything MyLittle said... All good advice.

Check the lower hose (suction) and make sure it is not collapsing when running, there should be a spring in it. If it collapses no water flows.

Taking out a thermostat is an easy way to see if it is working but your CJ will most likely run hotter (eventually) without a thermostat in it then with it in. Let me explain. Without a thermostat, the water in the radiator will pass so quickly through that there will not be sufficient time for the water to cool by the air passing by it. Always run a thermostat...

BTW - IMHO - Thermostats are so cheap, it's always a good idea to change them out when you suspect an overheating problem.

is a 160 Degree thermostst any better than a 195 Degree? what's the difference?

 

[CJ]

Hello sweetpeet and welcome to the site!

The difference between the two is at what temperature the stat opens up and starts allowing the water to flow.

Which one is better really depends on your application.

 

[sweetpeet]

Hello sweetpeet and welcome to the site!

The difference between the two is at what temperature the stat opens up and starts allowing the water to flow.

Which one is better really depends on your application.

well i guess im just trying to keep it from exploding. but seriously i just want to keep it as cool as possible.

 

[trw]

perfect thread! I too am having overheating troubles with my AMC 304 after just having installed a new radiator and hoses.

the first day I drove mine after the install, it ran great, the temp gauge remained low all day long and the amount of heat in the engine bay was normal. 4 days later, the temp guage steadily got hotter and hotter as I kept driving the CJ, with every stop and start it seemed to run hotter as heat built up under the hood and things began to get scorching hot (couldn't even open the hood), idling in park with a high idle, the motor cooled down slowly to more normal levels, but as soon as I put it in D and idled just a short period, the temp spiked up again.

One thing I did notice was that the coolant was dirty again only after 4 days of driving, considering the coolant I flushed out was pure water and rust before, I suspect I have a lot of flushing ahead of me.

oh and I run a 160* T-stat too, the previous owner put it in to thwart the overheating issues, but he didn't know TAKING CARE of the Jeep would have prevented that

 

[Old Dog]

is a 160 Degree thermostst any better than a 195 Degree? what's the difference?

every engine has a heat range where it was designed to run the best, for our jeep s thats 195. If you put a 160 in it it either won't run efficiency because it's not up to the right temp or more than likely the cooling system won't be able to keep up with it and it will overheat because the tstat will stay open.

 

[2BAD4U]

is a 160 Degree thermostst any better than a 195 Degree? what's the difference?

What Old Dog said is very true plus a 160 will only put out luke warm heat out of your heater in the winter
A 180 is a good compromise, but I wouldn't run a 160 unless it was in a racing engine.

 

[Thorwon]

perfect thread! I too am having overheating troubles with my AMC 304 after just having installed a new radiator and hoses.

the first day I drove mine after the install, it ran great, the temp gauge remained low all day long and the amount of heat in the engine bay was normal. 4 days later, the temp guage steadily got hotter and hotter as I kept driving the CJ, with every stop and start it seemed to run hotter as heat built up under the hood and things began to get scorching hot (couldn't even open the hood), idling in park with a high idle, the motor cooled down slowly to more normal levels, but as soon as I put it in D and idled just a short period, the temp spiked up again.

One thing I did notice was that the coolant was dirty again only after 4 days of driving, considering the coolant I flushed out was pure water and rust before, I suspect I have a lot of flushing ahead of me.

oh and I run a 160* T-stat too, the previous owner put it in to thwart the overheating issues, but he didn't know TAKING CARE of the Jeep would have prevented that

I think you may need a ground strap from your engine to the frame and tub. Or at least clean all of your battery cable conections.
You could be "burning" your coolant by not having a good ground. Most of the times I've seen the coolant turn brown it's been a electrical issue.
Once the coolant is burned it will not transfer heat very good and it will also freeze at a much higher temp.
I do recommend a 180 t-stat, that's what I run in my AMC 304 with no problems.