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Are your certain your cooling fans are operating at low and high speeds?

Aftermarket thermostat quality = ?

Paul
 

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2002 Focus ZX3 (Zetec) 95k miles (as of 05/2021;)
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Discussion Starter · #3 ·
Forgot to mention that temp is when driving a steady 80mph.

I'll double check the fans.

I saw a note else to check temp of upper and lower hoses from thermostat housing.
They are both hot. (I guess if the top one is cold the thermostat is not opening?)
 

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If the stat was not lined up to put the bleed hole facing straight up you can trap a lot of air in the motor.

The fans should be on past about 220-225 degrees.
 
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2002 Focus ZX3 (Zetec) 95k miles (as of 05/2021;)
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Discussion Starter · #5 ·
Forgot to add I used a vacuum coolant tool to refill after I drained the coolant.
One of these to be specific:

Pulls a vacuum in the whole coolant system and then refills via the vacuum. Works like magic. (well assuming it worked right..)
 

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2002 Focus ZX3 (Zetec) 95k miles (as of 05/2021;)
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Discussion Starter · #6 ·
More details.. when I drive a steady 70mph the temp is 220-225, but steady 80 its 238. (Did a 100 mile drive today). Never got any warmer than 238. When driving more reasonable speeds 210-225 range.

Just curious are there better aftermarket radiators? Would that help if I want to drive long distance at approx 80-85mph?
 

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Stock radiator/water pump/thermostat should be more than adequate if they are in good working condition/meet specification.

Paul
 

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I'm questioning the 238 number, if true the gauge begins to go up around then and should be started. The high fans should be kicking in around 230-235 as well. Both my '00 and '02 begin to creep the needle away from the middle around 220+ and right when low fans kick on.

You need to positively verify you not only have low fan but high as well. The cars should not budge needle at all even at 90 mph.

If that stat hole lined up right there is never any need to special bleed a Focus, they self bleed by the time the stat opens and why all the extra hoses are on them. I haven't bled mine endless times and no need to.
 

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2002 Focus ZX3 (Zetec) 95k miles (as of 05/2021;)
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Discussion Starter · #9 ·
I'm questioning the 238 number, if true the gauge begins to go up around then and should be started. The high fans should be kicking in around 230-235 as well. Both my '00 and '02 begin to creep the needle away from the middle around 220+ and right when low fans kick on.

You need to positively verify you not only have low fan but high as well. The cars should not budge needle at all even at 90 mph.

If that stat hole lined up right there is never any need to special bleed a Focus, they self bleed by the time the stat opens and why all the extra hoses are on them. I haven't bled mine endless times and no need to.
238F is from live ODB2 FwT info. Not from gauge. The dash temp gauge stays dead in the center of it's range.

When I replaced the thermostat housing, it came with an already installed thermostat. I didn't touch that.
 

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'238F is from live ODB2 FwT info.'

I understand that and do the same using a better quality scanner. Some cheap scanners interpolate the numbers slightly differently. The gauges ARE set up to be moving the needle by 238 as it is NOT a normal temperature, Normal is around 210-225F (100-110C) max and again high fan goes on at 230+ which is an indicator of higher than normal temps. I have LEDs set to both fan speeds on my two cars to know exactly when they switch on and off. The dash gauge needle is highly damped and stays in the middle from around 175-225F or so. It's really more of an idiot light than a gauge. The OEM stat is 195 and all engines run at roughly 10-15 degrees hotter than the temp the stats are marked for. These are set to run slightly over boiling at it removes water from the oil to greatly lower sludge buildup.

If you are willing to trust Chinese to set that stat correctly then do what you will. I don't and never will. The stat has zero locators and can be set anywhere in 360 degrees. The stat gasket as well has to be spaced half and half overlapping the stat edge equally on both sides and you are trusting in that too. If lapped wrong it can block off your bleed hole.
 

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2002 Focus ZX3 (Zetec) 95k miles (as of 05/2021;)
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Discussion Starter · #11 ·
'238F is from live ODB2 FwT info.'

I understand that and do the same using a better quality scanner. Some cheap scanners interpolate the numbers slightly differently. The gauges ARE set up to be moving the needle by 238 as it is NOT a normal temperature, Normal is around 210-225F (100-110C) max and again high fan goes on at 230+ which is an indicator of higher than normal temps. I have LEDs set to both fan speeds on my two cars to know exactly when they switch on and off. The dash gauge needle is highly damped and stays in the middle from around 175-225F or so. It's really more of an idiot light than a gauge. The OEM stat is 195 and all engines run at roughly 10-15 degrees hotter than the temp the stats are marked for. These are set to run slightly over boiling at it removes water from the oil to greatly lower sludge buildup.

If you are willing to trust Chinese to set that stat correctly then do what you will. I don't and never will. The stat has zero locators and can be set anywhere in 360 degrees. The stat gasket as well has to be spaced half and half overlapping the stat edge equally on both sides and you are trusting in that too. If lapped wrong it can block off your bleed hole.
Gotcha.
Unfortunately not anywhere I can take it apart until next week.
If I keep in under 75 mph it stays < 225F. So I won't push it until I have a change to take it apart and inspect it.


Can I get the low and high speed fans to trigger by letting the car idle while parked?
 

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Discussion Starter · #12 ·
Ok just took a drive.
Temp idles at 205 ish after the drive.
When I turn the A/C on the high speed fan definitely turns on.

Top host from thermostat housing definitely get's hot.
Is all that sufficient to decide thermostat and fans are working properly?
 

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Can't say,. Shouldn't be going to realtime 238 which should be moving needle toward the red. If needle not moving likely OK.

The fans wildly change their times on and off depending on the time of year, in winter they may not come on for a month at a time.
 

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More details.. when I drive a steady 70mph the temp is 220-225, but steady 80 its 238. (Did a 100 mile drive today). Never got any warmer than 238. When driving more reasonable speeds 210-225 range.

Just curious are there better aftermarket radiators? Would that help if I want to drive long distance at approx 80-85mph?
With my 2003 I run a Scangauge and I also have an LED setup that goes on when the fan does. With the AC off...the fan will come on at the higher 238 (?) number and then runs until the temp gets down to the 200 (?) number....like clockwork. I can watch the actual numbers using the Scangauge. Can't recall the exact numbers...but they are in that range.

I'd say that at 80 you should have enough airflow that the temp should stay at the lower number. I've messed around with blocking air intake to some extent as part of an MPG improvement scheme...similar to the automatic vanes in the intakes of some newer cars. Need to be very careful doing this since if you mess with the airflow you can easily cause overheating. I'd check and make sure there are no mods in this area. If you have some kind of skirt on the front...this might be an issue?
 

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Discussion Starter · #15 ·
With my 2003 I run a Scangauge and I also have an LED setup that goes on when the fan does. With the AC off...the fan will come on at the higher 238 (?) number and then runs until the temp gets down to the 200 (?) number....like clockwork. I can watch the actual numbers using the Scangauge. Can't recall the exact numbers...but they are in that range.

I'd say that at 80 you should have enough airflow that the temp should stay at the lower number. I've messed around with blocking air intake to some extent as part of an MPG improvement scheme...similar to the automatic vanes in the intakes of some newer cars. Need to be very careful doing this since if you mess with the airflow you can easily cause overheating. I'd check and make sure there are no mods in this area. If you have some kind of skirt on the front...this might be an issue?
I'm also using a scanguage to read the Fwt.. :)
How did you set up a LED to indicate when fan activates?
It's hard to get it up to 238 standing still ?

The car is bone stock, I'm the original owner so there shouldn't be anything blocking the airflow.
It's possible the thermostat included with the thermostat housing isn't working correctly.
I hope it's not the water pump I replaced (recently) with a timing belt service.

I ordered a Motorcraft thermostat and I'll swap that in and see if that makes a difference, probably next week.
 

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Make SURE the stat bleed hole faces straight up.

238 is NOT correct for normal switching on low fans and you need to be able to see when high fans come on too like I have. I suspect a temperature scaling issue with your software. That is NOT a normal running temp and incorrect if the gauge is not moving up by then. if it is HIGH fans coming on then you are running around with no low and why it overheats. The 238 is much closer to a high fan on temp.

I tapped into the low and high fan relays to get my LED light power. Green for low and red for high.
 

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I'm also using a scanguage to read the Fwt.. :)
How did you set up a LED to indicate when fan activates?
It's hard to get it up to 238 standing still ?

The car is bone stock, I'm the original owner so there shouldn't be anything blocking the airflow.
It's possible the thermostat included with the thermostat housing isn't working correctly.
I hope it's not the water pump I replaced (recently) with a timing belt service.

I ordered a Motorcraft thermostat and I'll swap that in and see if that makes a difference, probably next week.
Used some light zip-line (?) 2 conductor wire...found the + lead on/from fan and ran this from there to an LED mounted above the Scangauge right above the steering column....after the LED you need to find a ground. LED needs to be suited for 12V use. I used a length of split vac tubing to act as a hood...so sunlight wouldn't make it look like it was on.

I've learned over time that you mostly want the OEM thermostat...I've removed perfectly functioning OEM thermos for aftermarket questionable thermos. Lure of the brand new?
 

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I change the stat every 100K miles or so and use a good quality one, you don't want to save money there. Standard temp will be 195 plus the normal overhead of 15 degrees or so is a normal temp of 210 and it goes up from there to 220 to trigger low fan. Then the cycling on/off of around 210-220ish.
 

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Depending on your ECU Code your Fans dont come on till 228-235 deg so if you are not getting hotter then that that it would be normal , after you hit 53mph your fans turn off and dont come back on till 48mph

If you know your ECU code I can tell you the exact Fans turn on Deg for the low and high speed Fans

Tom
 

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Discussion Starter · #20 ·
Thanks @amc49 I'll keep the alignment in mind when I install the new Motorcraft thermostat I ordered. (probably next week).


@1turbofocus - How do I find the ECU code?
 
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