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Author: Subject: Struggling with to much cooling.
furryeggs

posted on 30/10/18 at 08:36 PM Reply With Quote
Struggling with to much cooling.

Iíve been having a few issues with getting any tempreture into the engine when driving. I noticed it first at IVA but didnít really think to much about it. To get the emmisions passed we had to switch off the test centres fan as the ecu was reading the coolant between 75-80 degrees and started over fueling the map. With it off the temps rose to 96 and ran from the thermostate temps and everything settled and passed.

Iíve double checked the map, the thermostate and my temp gauge and they are all working/reading ok, I ran the car upto temp whilst stationary and the fan came on at 96 and off at 90, which matches the gauge and ecu.

When out driving the temp gauge doesnít get to 80 degrees unless Iím in traffic then the fan kicks in as normal at 96.

I have a coolex 50mm ally rad (their 7 one), with a blow through 9Ē fan. My 2.0 blacktop on TBís and emerald is plumbed as suggested by Tiger. The bypass is blanked off, as is the heater. Thereís then 2 holes drilled into the thermostate itself to allow flow that would usually be through the bypass.

why canít i get the temps up? shouldnít a zetec be running at 90+ degrees

cheers in advance for any help

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SPYDER

posted on 30/10/18 at 09:17 PM Reply With Quote
Hi there. Ideally I would suggest re-instating the bypass flow and using an undrilled thermostat. Other than that you could investigate some sort of radiator blind, adjustable if possible.
My car used to be plumbed in a similar way to yours. Bypass etc blocked off; drilled thermostat. The problem I got was that the dynamic pressure created by the pump caused the top hose to blow off at high revs on more than one occasion. You could feel the hose expanding as you revved the engine. I fitted an external thermostat which had it's own bypass and re-instated the redundant heater flow.
A similar external 'stat could solve your problem.

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adithorp

posted on 30/10/18 at 09:50 PM Reply With Quote
It's because the by-pass circulates water back to the block uncooled. Your 2 holes in the 'stat allow it to circulate through the rad'; Effectively you've got a stat that's stuck slightly open. Even 2 tiny holes will cause enough cooling to be noticable.





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steve m

posted on 30/10/18 at 10:15 PM Reply With Quote
"When out driving the temp gauge doesnít get to 80 degrees unless Iím in traffic then the fan kicks in as normal at 96. "

I am no expert, but to me this seems to be bang on, and your cooling correct, and if it was my car, feel that there was not a problem

why do you think your under cooling (a very rare thing with our style of cars ) ?

steve





Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at




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SPYDER

posted on 30/10/18 at 10:41 PM Reply With Quote
If he is running a normal Zetec 'stat, 88 or 92 degree IIRC, then the coolant should warm up to that temperature fairly readily. It would seem that the flow through the holes in the 'stat is seemingly enough to overcool the water and keep it substantially below the opening temp. How big are the holes OP?
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coyoteboy

posted on 31/10/18 at 12:41 AM Reply With Quote
As said in a few answers - drilling holes in stats is going to cause over-cooling at low loads. This is why bypasses are designed in by the OEM, so you don't need such a kludge.





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steve m

posted on 31/10/18 at 07:48 AM Reply With Quote
when were your figures taken ? in August or two days ago ?

As the ambient temperature is considerably different

I doubt I could even get the fan to come on in this temp, even leaving it running for an hour stationary





Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at




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beaver34

posted on 31/10/18 at 10:33 AM Reply With Quote
are you on a standard or aftermarket ecu?

if aftermarket can you adjust the cold start temp lower so it isnt chucking in as much fuel

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furryeggs

posted on 31/10/18 at 01:17 PM Reply With Quote
3mm holes and Emerald K3 ecu
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adithorp

posted on 31/10/18 at 01:55 PM Reply With Quote
There's your problem.





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snapper

posted on 31/10/18 at 08:36 PM Reply With Quote
I would cover some of the radiator the old fashion way, tape some cardboard over the radiator in strips either side and keep adding till temps are where you would like them.
When you have the temps in the right place you can fabricate some ally sheet which is easily removable for hotter days.

I do think however itís a flow/thermostat proble and an easy solution is to replace the thermostat, see what one with no holes does then start with a smaller single hole and slowly build if required





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02GF74

posted on 31/10/18 at 09:51 PM Reply With Quote
I'm happy to be proved wrong but would be surprised if it is due to the two 3mm holes, thats smaller than the diameter of a straw.


First step is to get a new thermostat at the required temperature and check it opens correctly, an IR thermometer is recommended for accuracy. If you need to have a hole, start with one 1 or 2 mm, should be enough for bleeding.





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Irony

posted on 1/11/18 at 08:52 AM Reply With Quote
Why would over cooling bother you? Over heating kills engines quickly not over cooling. Now I know hundreds of people will immediately shout at me and state 'over cooling a engine will reduce its life expectancy and promote accelerated wear' or 'engines are designed to run at certain temps etc'. But in reality what does it matter? Most engines these are designed with 250000km but thats in a tin top. Are you really bothered if you 'possibly' reduce life expectancy?

If I get 20K out of my V8 I'll be happy. I did build it out of bits though.

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coyoteboy

posted on 1/11/18 at 03:00 PM Reply With Quote
2*3mm diam is about enough area to flow ~200cc/s at full choked flow. I'm guessing the pressure from the stat would be lower, but you're still looking at hundreds of watts of cooling capacity given the specific heat capacity of water.

Overcooling potential problems:
over-fueling
bore wash (due to overfueling)
incorrect timing
drivability problems (due to fuel vaporization being poor)
increase clearances = decreased life and more rattle

Why would you not just change the stat to check it, stick the bypass tube in and know it's right?





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DJT

posted on 1/11/18 at 03:43 PM Reply With Quote
I tried without a bypass with no success, e.g. no stat, 3mm hole in stat. Even the tiniest hole will flow a significant amount of coolant, enough to overcool. In the end I did it properly utilisting the bypass exit in the stat housing. Has been faultless since and is self bleeding.







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AlexXtreme

posted on 1/11/18 at 05:15 PM Reply With Quote
Agree 3mm holes x 2 is the problem and I had the similar though perhaps 2 x 2mm. Change the stat and I think I put 1 x 2mm hole and it now worked fine.
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02GF74

posted on 1/11/18 at 06:13 PM Reply With Quote
quote:
Originally posted by coyoteboy
2*3mm diam is about enough area to flow ~200cc/s at full choked flow.


I am sceptical - where did you get that figure? It does not feel right.

If I get time, I will try this with a short length of garden hose (mains pressure I would expect to be more than that produced by the water pump but I could be well wrong here). I find it hard to believe I will get 2.6 gallons or 12 litres in a minute from two 3 mm holes.





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SPYDER

posted on 1/11/18 at 09:20 PM Reply With Quote
I think your thermostat isn't fully closing.

Like coyoteboy says "Why would you not just change the stat to check it, stick the bypass tube in and know it's right?"

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coyoteboy

posted on 2/11/18 at 12:59 AM Reply With Quote
quote:
Originally posted by 02GF74
quote:
Originally posted by coyoteboy
2*3mm diam is about enough area to flow ~200cc/s at full choked flow.


I am sceptical - where did you get that figure? It does not feel right.

If I get time, I will try this with a short length of garden hose (mains pressure I would expect to be more than that produced by the water pump but I could be well wrong here). I find it hard to believe I will get 2.6 gallons or 12 litres in a minute from two 3 mm holes.


Choked flow calcs for 2 bar pressure difference across a 4.25mm diam hole. To be fair, 2x3mm may provide slightly lower but you think you can't half fill a teacup/mug in a second from an average tap pressure through a straw? I think a waterpump at idle will probably push less (say 1 bar). Let's re-run it... 3mm holes allow ~250l/hr at 1 bar pressure difference. So
500 litres/hr - 138ml/second (seems reasonable)
Each litre of water can carry 4200 Joules per kelvin.
At 60C temp difference that's 250KJ/litre.

250000*.138 = 34KJ/s (kW)

So assuming all bits were 100% efficient (i.e. the water flow isnt the limiting factor), it's got 34kW cooling ability with that leak, assuming the rad returns ambient water temp.





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furryeggs

posted on 2/11/18 at 08:26 PM Reply With Quote
Well itís all gone tits up this morning, been in the garage to start swapping over to use the by pass. Started the car to pull it outside to sort out the garage, gave it a little blip and woosh, Iíve now got coolant blowing out from behind the timing cover. Iíve pulled the belt, idlers and alternator off and removed the cover and theres nothing obvious that i can see.

There's no water in the oil, no sludge in the cap and when the engine stopped the coolant stopped. Is there a plug/ blank behind the timing belt anywhere, it seems to be coming from the the middle to left hand side on the front of the engine as you look at the crank. no sign of any other leaks anywhere and theres still coolant in the bottle.

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SPYDER

posted on 3/11/18 at 02:40 PM Reply With Quote
Water pump bleed hole?
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rusty nuts

posted on 3/11/18 at 02:50 PM Reply With Quote
Beg ,borrow or steal a cooling system pressure tester but make sure it has an adaptor to fit your rad cap.Pity your not closer, you could borrow mine
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furryeggs

posted on 3/11/18 at 07:41 PM Reply With Quote
quote]Originally posted by SPYDER
Water pump bleed hole?


It seems to be a good 10" away from anything water pump related?

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