overheating

[E.T.]

I was driving home yesterday and got stuck in a traffic jam on the freeway. Outside temps were about 100*. I had the windows down the whole time, but once I was back to normal speeds, I turned on the AC. It blew cool for a few minutes, then turned warm. I looked down and notice the temp gauge was almost maxed out.

Did a quick search on here and found some posts about a bad fan relay being the possible cause. I didn't check to see if my fan is running when the ac is on (will do later), but if this is the problem, how do I fix it. I guess there are two relays? So do I just need to change the 2 fuses? Any place special I need to get new ones, or will Radioshack carry those?

Thanks:happy160:

 

[dude1116]

I was driving home yesterday and got stuck in a traffic jam on the freeway. Outside temps were about 100*. I had the windows down the whole time, but once I was back to normal speeds, I turned on the AC. It blew cool for a few minutes, then turned warm. I looked down and notice the temp gauge was almost maxed out.

Did a quick search on here and found some posts about a bad fan relay being the possible cause. I didn't check to see if my fan is running when the ac is on (will do later), but if this is the problem, how do I fix it. I guess there are two relays? So do I just need to change the 2 fuses? Any place special I need to get new ones, or will Radioshack carry those?

Thanks:happy160:

Did it stop overheating when you got moving? In that case, I would assume it was something with the fan. Not sure though...

 

[E.T.]

Here's the weird thing...I didn't turn it on until after I'd been moving for a while. The whole time I was sitting in traffic, it was off and the temp was in the normal range.

I popped the hood last night while it was parked and running, and the radiator fan was not spinning. Then I turned the AC on, and the fan was spinning, but I couldn't really hear it over the engine.

 

[rockymountain]

you should be able to hear it well if its on the high setting. It has a low and high. It moves a lot of air when its running full speed. You can feel it when it kicks on if you stick your arm out the window. If it's warmed up and the AC on when its hot outside it should be running at full speed.

 

[E.T.]

you should be able to hear it well if its on the high setting. It has a low and high. It moves a lot of air when its running full speed. You can feel it when it kicks on if you stick your arm out the window. If it's warmed up and the AC on when its hot outside it should be running at full speed.

I'll have to try the arm out the window thing. It didn't seem to be blowing that hard though. Could it be that it's only running on the low setting?

I didn't have any trouble today with the AC on, but it's only in the 80s and I didn't drive very far.

 

[trent.brown]

To reitterate what dude said, If you are overheating while driving down the highway, the vehicle moving will push enough air through the radiator ruling out your fan.

So if its not overheating while you are stopped, the fan is probably doing its job.

My guess would be a faulty thermostat getting stuck closed.

 

[E.T.]

To reitterate what dude said, If you are overheating while driving down the highway, the vehicle moving will push enough air through the radiator ruling out your fan.

So if its not overheating while you are stopped, the fan is probably doing its job.

My guess would be a faulty thermostat getting stuck closed.

Could the stat do this intermittently? Is that something I can change myself?

 

[HoosierJeeper]

It could, but I'd think you'd get a code. It's easy to DIY I think. Part isn't more than $15-20 from Rockauto

 

[E.T.]

It could, but I'd think you'd get a code. It's easy to DIY I think. Part isn't more than $15-20 from Rockauto

OK, maybe I will just keep an eye on it. This is the one and only time it's happened so far. Although my drive to work is less than a mile, I haven't had any trouble this week since it's been in the 80s. Temp needle has stayed near the middle.

 

[E.T.]

OK, so here's my coolant bottle. This looks way low to me...what do you think?

 

[jmnetus]

Yes, that appears to be quite low - see the cold fill arrow.

I don't have personal experience with how low it can get before you start having overheat issues, but I think I would start with the low coolant here.

 

[E.T.]

Well, I got the proper coolant and added a 50/50 mix. It took about 2 qts to get up to the line. Hopefully that solves my problem. I can't believe I let it get this low! During the winter, I had to get the heater core flushed because my heat wasn't working. I wonder if it didn't get filled up enough then? At any rate, I went for a little drive and the temp needle didn't even cross the halfway mark.

 

[E.T.]

Is there anything that would cause the temp to increase only during freeway driving with the AC on?

Since filling the coolant, the Jeep has been fine. Temp needle has stayed right about in the middle during city driving. However, yesterday I was on the freeway running AC and noticed that the temp needle climbed to a little over 3/4. At this point the AC was still blowing cold.

So to sum up, normal temps in city with AC, but temp needle rises on highway with AC. Any ideas, or is this normal?

 

[rockymountain]

Is there anything that would cause the temp to increase only during freeway driving with the AC on?

Since filling the coolant, the Jeep has been fine. Temp needle has stayed right about in the middle during city driving. However, yesterday I was on the freeway running AC and noticed that the temp needle climbed to a little over 3/4. At this point the AC was still blowing cold.

So to sum up, normal temps in city with AC, but temp needle rises on highway with AC. Any ideas, or is this normal?

Once the engine is warmed up the needle should never move.

You may have air in the lines, a faulty thermostat or a water pump going south.

Have you checked the radiator to see if its clean and not obstructed? Running a hose over it would help clean it off. Do you smell coolant?

 

[E.T.]

Once the engine is warmed up the needle should never move.

You may have air in the lines, a faulty thermostat or a water pump going south.

Have you checked the radiator to see if its clean and not obstructed? Running a hose over it would help clean it off. Do you smell coolant?

Radiator looks clean, and I didn't notice any unusual smells.

Is there a way to check the thermostat and water pump to make sure they're working properly?

 

[E.T.]

I'm just going to go ahead and replace the t-stat. Found one at Napa for 23 bucks with the gasket. How much coolant is going to pour out when I disconnect the lower rad hose?

 

[tjkj2002]

I'm just going to go ahead and replace the t-stat. Found one at Napa for 23 bucks with the gasket. How much coolant is going to pour out when I disconnect the lower rad hose?

All of it.

If your only overheating at speed then you have a coolant flow problem like a plugged radiator.Since you stated you had to have the heater core flushed to get heat last winter that would also be a huge red flag saying your radiator is partially plugged also.

 

[E.T.]

All of it.

If your only overheating at speed then you have a coolant flow problem like a plugged radiator.Since you stated you had to have the heater core flushed to get heat last winter that would also be a huge red flag saying your radiator is partially plugged also.

OK. One thing I didn't try doing is burping the system, so I might do that to see if it helps.

If the radiator is plugged, is that something I could clean out myself with a hose, or is it best just to take it to a shop and have them do it?

 

[E.T.]

All of it.

If your only overheating at speed then you have a coolant flow problem like a plugged radiator.Since you stated you had to have the heater core flushed to get heat last winter that would also be a huge red flag saying your radiator is partially plugged also.

You might have called this one. After a very short drive home from work (about a mile) I let it cool off a bit, then tried the "burping" procedure. I didn't see the fluid level drop at all, or any bubbles. After idling for a bit, I turned it off and felt the upper rad hose, which was very hot. I reached down and felt the lower rad hose, and it was cold. Does this sound like a blockage somewhere in the radiator, or is that bottom hose normally cool?

 

[E.T.]

Well I made an appt to get it flushed next week. Tonight I poked around under there some more and look what I found (see pic). Does this mean I need a new radiator?