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Discussion Starter #1
All,

I am very confused on what the issue could be. My car is over heating when i rev the engine or take it for a spin.

I can let the engine idle for an hour and the temp is normal. if i rev the engine for 10 minutes (around 2500rpm) it climbs up to red.

It has 130k miles on it.

I have replaced all hoses. I have flushed the system entirely twice, i have taken the radiator out and had it inspected (no blockages or gunk inside and has good flow)

I flushed out the heater core. It has good flow.

I replaced the thermostat (tested it in boiling water to make sure it works, my fans are kicking on (also replaced the resistor just in case)

The water pump seems good because it is cycling the coolant around the engine and there is pressure in the system.

No leaks. Not losing coolant anywhere.

The heat is up around 90*F coming out of the vents.

New Coolant reservoir cap.

I have followed the instructions in the Haynes repair manual on replacing coolant.. I feared i might have an air bubble, so i filled all the hoses up, engine block, and radiator, on the last time i drained the system, trying to eliminate any air pockets. I have left the cap off the coolant tank for up to 2 hours. Engine idles fine, i had a few bubbles to start, but by the end no bubbles.

I put the cap on, the system starts circulating... i can see the coolant in the tank go up and down like it is supposed to. All hoses are hot..all of them have pressure in it.

But as soon as i start reving the engine, the temp rises.. goes to red. i let off the engine.. it comes back down after a minute or 2. Both fans are kicking on. First the at idle fan and then the high speed fan eventually kicks on.

I have no coolant in the oil or in the piston area (spark plugs just got replaced and look brand new still.)

Im looking for help! I have used your forums for years (as i have had 5 ford focus cars.. This one has be baffled.

I dont think it is the head gasket nor do i think it is the water pump. I think i am missing something simple.. Help!
 

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Be clear here. BOTH fans work all the time, both are either on low or both are on high. The way they work.

Has engine ever been run longterm with no antifreeze in it? If so sometimes the block builds up enough scale and deposit in it that temperature cannot get from metal into the coolant fast enough, that is a motor issue. Overbored blocks can do the same if you happen to be unlucky.
 

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The water pump seems good because it is cycling the coolant around the engine and there is pressure in the system.

I put the cap on, the system starts circulating... i can see the coolant in the tank go up and down like it is supposed to. All hoses are hot..all of them have pressure in it.


I dont think it is the head gasket nor do i think it is the water pump. I think i am missing something simple.. Help!

Like amc I'd want to know if both fans work at each speed.

Water pump doesn't create pressure in the system, that's only from expansion due to heat.

Unlike a car with a radiator top reservoir, where you can see coolant circulate, I don't know a way to see if the pump is actually circulating coolant in this type system.

Coolant in the tank would normally go up & down slowly, rise as the temps increase then drop as it cools off. I wonder about up & down as it runs if that's what you're seeing.
 

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Discussion Starter #4
Both fan work at both speeds. To the best of my knowledge the car has never been run without antifreeze. There was no leaks in the lines when i got it and the coolant was filled correctly when i got it. This is a stock engine and it hasnt been bored.



If i take the hose off the top of the water pump and start the engine, it will shoot out coolant at a good rate. The only part that can move coolant is the water pump, correct? I hope that is a good enough test..lol. because your right. you can't see it circulate in this system.
 

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I like your test, messy but effective.

Guessing an intermittent there would be a real stretch.

I'd be using a thermometer on the head, with the trip odo in test mode to see temps, just to try to confirm correlation of sensor temp. with actual at this point.
 

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Fans ever been replaced? I highly suspect some Chinese replacements as having motors that do not run full speed.You would have high and low, just slower. Hard to tell that. Any evidence of corrosion in the cooling system? That is an indirect indicator of how clean block passages might be. Anybody ever changed plastic parts that upon viewing some of it was missing? Piece might get stuck in a critical passage. Water pump is the only thing that moves the coolant. Maybe temp sensor is stuffed. I have improved things on cars simply by cleaning the sediment off of them before, if thick it can affect the temps seen there. I would be trying like the daylights to establish the needle beginning to climb in to the red and then do whatever I could to determine the fans were on THEN and on high fan if the needle is on the way up. Two long pieces of wire and a cheap bulb and you have the makings of a fan test light, wire it quickly to the relay output (you can simply stuff the bare wire ends in the relay slot and shove relay down on top of it). and run the light inside car, that'll tell you when fan working. Is a/c condenser clean and not full of crap, you got an air flow issue at speed maybe, anything blocking front grille opening like a bra? Dunno what water pump looks like internally but if say a blade broken off or summat, you get the picture. It would still shove water out but not enough. As he says with temp sensor, if it has left the real world to give wonky numbers a problem.
 

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Discussion Starter #8
I will have to try to put the car in Test mode and watch the temps there. I was thinking on replacing the temp gauge sensor (the resistor is technically the temp sensor on this car and i replaced it) Fans are Factory and comparing them to another Focus, they seem to be spinning fast enough. You can def hear them ramp up from low speed to high speed. I havent found much inside the coolant system. I have replaced all hoses (they were not bad, and Flushed Radiator and heater core, and they were not bad either. ac condensor and radiator have been taken off and cleaned (they were not bad, but since i took the radiator out to flush it, i figured i might as well clean it off.)

I will be working on the car this weekend. I will give you all updates. Thanks for all the help so far! I just hope it isnt a head gasket. or the water pump.. If i am doing one, im gonna do both, but i really dont think that is the issue. I'll keep you posted!
 

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Discussion Starter #9
ok guys. I tried to put the car into test mode and i was able to get it in. But i only had like 5 options to cycle through until i was back at my reset odometer. I didnt see a temp options or anything that resembled a temp option...

So i replaced the temp sensor.. still nothing in test mode resembling a temp.

Next i did a compression test on the engine.. I was getting a solid 180psi out of each cylinder. This appears to be perfect and no valve/lifter/head gasket issues.

Next i took out the thermostat and refilled the system and let it run. It definitely ran much better, but still overheated. When it got to the point of almost red on the gauge (it idled perfect so i was revving the engine at a consistent 2000 rpms) and when i let off just before the red line, it cooled back off within about 30 seconds.

I am starting to think that maybe there might be a flow issue from the water pump. Like at idle there is enough to push coolant through, but in a high revving situation, that the pump isnt pushing water fast enough. It is the only thing left i can think of.

What is everyone else's thoughts?
 

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Kinda back to the beginning, but did the low speed & high speed fans kick on during this process? High speed would have to run for a bit to start the temps down again once it gets to the top of the gauge.

How's it acting when driven, always get the low fan soon and continue increasing temps to the top of the gauge?
 

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Discussion Starter #11
Yes. they did. The low speed fan kicked on first... and only the low speed one kicked on during idle. the needle on the gauge never went above 50% in idle for about 45-50 mins. Im currently not driving the car with all of this going on. Thats why I am pressing the accelorator to about 2000 rpms to get temp to rise. Once the needle on the gauge moves past 65-70% the high speed kicks on and brings the temp down. It then turns off and the low speed one is still on for a bit. if i keep holding the accelerator once the high speed kicks on the needle goes up to almost the red bar and then i let my foot off the accelerator and the needles comes down pretty quickly (about 30-40 seconds it comes back down to where it should be (about 50% or half way)..
 

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All that seems normal, except for the fan on not seeming to be able to control the heat.

Idling high for that long is unusual operation, if you hadn't mentioned the car getting hot this way when driving I'd be wondering if there was a problem.

Partial blockage of the radiator or the water pump guess you had are all I can think of at the moment, I'd be using the cheap IR thermometer I picked up for another purpose to check the radiator & see if it's all heating evenly. Looking to see if the outlet is cooler than the inlet might be another way to see if it's doing what it should.
 

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Discussion Starter #13
ok guys. i got a water pump and timing set... when i pulled the water pump off the impeller was shattered... i cleaned out all the metal fragments and put a new water pump in and new timing components.. everything is working as it should bow.. thanks for all of your help!!
 

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Tx for the update!

When nothing else is left to try....

It happens, just not often without bearing damage & seal seepage.

Worst impossible problem to date was a heater that didn't work - checked & flushed but still no heat. Owner took the whole system apart again finally & found a plastic cap in a heater hose. Apparently had been used by a mech. to plug the hose when working on the car & missed/forgotten when assembled (pushed in & invisible).
 

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If your fans are kicking on my guess is the water pump. Water pumps are made with a scored shaft, the idea there is that when the shaft breaks, you want a controlled break not something that jams the belt pully and tears the housing apart. Shafts break due to unbalanced forces - when your barreling down the road and the engine is running and air bubbles go through the water pump impeller, you get what they call "unbalanced radial thrust" and over time that fatigues the shaft. Also when the bearings wear out you get more vibration this also fatigues the metal shaft eventually leading to breakage.

It could also be belt slipping on the pump.

Your pump is moving water when there's no load on it because perhaps the 2 broken ends of the shaft are rubbing against each other, but when you reconnect the hose and the pump has to exert some force to force the coolant through the radiator, then the shaft ends start slipping or the drive belt slips or whatever, and your not getting flow.
 
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