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Discussion Starter #1 (Edited)
Cooling problem, need help!!! *Update*

My car started overheating 2 days ago but only at idle or very, very slow driving. I replaced the thermostat and thermostat housing 2 months ago due to a cracked thermostat housing. I had my mechanic take a look at it and he thought it might be the HTS (head temperature sensor) going bad. Turns out the sensor is working fine. There are NO leaks, the thermostat is opening when it should and the fans are working as well. My mechanic said the best thing would be to take it to the dealer. The dealer dosen't have any openings till mid next week. Any help would be appreciated....
 

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Maybe your water pump isn't pushing the coolant like it used to, or maybe your radiator core is getting blocked up with minerals and other crud. A crude test (while idling) is to pinch the upper radiator hose closed with your hand, then let it loose and confirm a surge of coolant flow. You should feel a definite surge.

Your coolant expansion tank cap may not be maintaining enough pressure, letting coolant boil around the cylinders, leading to an overheat.

As a longshot, if your UDP setup reduces operation of the water pump, that could aggrevate other issues like the ones mentioned above.
 

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1fastfocus05
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i agree with him on this one...also,,,is the engine actually over heating...maybe a temp sensor went bad,,,of course the way to check is to let it idle and see if its getting extremely hot..above average...and if it gets hot really fast,,,,but more then likely its a water pump...there cheep to buy...aint so easy to install though..lol
 

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Discussion Starter #4
Thanks for the replys...
I was leaning more towards my water pump than anything I have heard. I have had my UDP on for over a year now and havent had any problems with it. I am hoping and praying that it isnt my radiator right now. That is something I can not afford in the least. Anyone else have any ideas....?
 

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What tells you that it's overheating. Is the gage going into the red. If it isn't, then you don't know for sure. Lift the hood and let it idle. Watch the gage. If the fan comes on and it's not in the red, why worry. Also, try turning the air cond on at idle while the hood is up. The fan should come on. If it does, what does the needle do. Possibly, the fan isn't coming on soon enough. Make sure it is overheating, when the fan is on, before you worry about the radiator, pump, etc.
 

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If you can borrow an infrared thermometer, you can check-out the radiator and look for "hot spots" that indicate poor flow. And, of course, and UDP is not going to help things, e.g., the original pulley is designed to assume things, such as the radiator, may lose efficiency over time and is designed with a "safety margin" to provide more than adequate flow. Reduce this and, in a sense, "you're on your own."

I would probably try a flush of the radiator system to clear out any crud as the first step. It would waste a bit of time and money if it turns out you do need to replace the water pump, but if you haven't flushed the cooling system for a while (say, two years or more), there's a reasonable chance a flush might "fix" it.

P.S. Please do not be insulted with the following comment, but sometimes I have missed the obvious and/or been careless myself. I only mention as a remote possibility. On some engines (I haven't checked the Focus), it is possible to install the thermostat backwards. And this would lead to overheating.
 

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Have you checked for codes? Anything to indicate your engine truly is running hotter, and your cooling system simply can't keep up?

Any possibility you have the beginnings of a head gasket leak?

Some other cheaper/easy possibilities:

A plastic bag, sheet of newspaper, or other road debris could be trapped up in front of your condenser/trans cooler/radiator, blocking airflow. Heck, enough dead bugs will clog things up too, depending on where you live.

All the small air bubbles left over from your t-stat replacement have finally formed one big air pocket in the coolant system; need to 'burp' it again, nose-up on an incline if possible.

Drivebelt slips on the pump pulley at slow speed.

Coolant mix is less than 50%. This sometimes results after someone flushes the system, because they miscalculate how much plain water is left in there before the mix is added.

The radiator fins have been flattened due to somebody power-washing them. Use a fin comb to open them back up.


I hope you aren't faced with something expensive -- please let us know what you find out.
 

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"Anything to indicate your engine truly is running hotter,"

Yes, it would be interesting to get a real time OBD scanner hooked up and see what temperature is on the OBD buss. I have a little thing called a "car chip," that I leave plugged into the OBD connector and it can monitor the coolant temperature every 5 seconds.
 

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Hope this can Help...

Why not use the on-board scanner function at the odometer ?
This DLC can give you many information. I had to learn to use mine because an unseen coolant leak at the water pump bearing. Not noticed it until I heard the craking noise at the engine bay and my coolant tank was empty. We replace the water pump and refill the system with plain water to check for more leaks. There were no problems but I was afraid of engine temp, air bubbles and had to keep that way for almost a week before refilling the coolant system. In the mean time I depend on monitoring the temp with the DLC even after refilling because they only used 1 gallon of coolant and an empty system must be full with 6 litters. In my 2000 SE sedan focus the primary fan come on at 110°C and only when using the A/C the second fan would come up. If you stand at the front facing the engine the primary fan is at right side just behind the radiator.

A bad conecting harness may induce a CEL on and many warnings, just check for sure.

Good Luck
 

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Discussion Starter #10
I took her in this morning to the local Ford stealership and paid $80 to have Ford help me with the problem. They said it was overheating due to a bad connection in the whole cooling fan assembly and that it needed to be replaced. They stated the fans come on, but not all the time. And to top it off, they want to charge me $660 after taxes for parts and labor to fix it. I told them I would just get the part myself and have my mechanic install it. As for the car, it not throwing any codes what so ever. The radiator looks like it is in really good condition. I ordered the parts and they should be here late tomorrow and ready to install on Wednesday.
 

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Discussion Starter #13 (Edited)

I dropped the car off today in hopes of my mechanic being able to do the install today. When I picked it up they told me the fans I have on right now are putting out a high amount of current and the resister plugs are a little bit melted.
 
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