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Engine Specific Info and Questions => IDI Engine => Topic started by: BellCityDubber on July 16, 2006, 07:57:10 am
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Hey guys
seeing as summer is in full swing, I've noticed that my temp gauge (the one where the shift light in a mk2 normally is.. top centre) goes pretty much to the 2nd from highest mark on the gauge... I would assume that this is normal operating temps am I right?
I was wondering about making cooling system tweaks on my TD... perhaps a lower temperature fan switch (would anyone have a part #?) and maybe a vr6 radiator if it will fit (would it?)
can anyone shed some light on these ideas?
thanks
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I might be wrong but I always thought the hotter the better your economy and preformance (except for when you get to temps that could warp the head or blow the headgasket)
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If only our gauges showed the actual temp in deg. C, but yes, hotter = better... to a certain point of course :lol:
I think second from the last is ok. If it ever spikes higher than that (hill climb) ease off the pedal, or risk warping engine parts. If you can find a thermostatically controlled oil/air cooler then go for it. It will definitely help keep the temps from skyrocketing quickly.
The bigger the radiator in the winter time, will mean a cooler engine for you brrrrrr :lol: .
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I was wondering about making cooling system tweaks on my TD... perhaps a lower temperature fan switch
Yes you can do this (I did), but the thermostat and rad fan switch need to be matched to each other. T-stat should be about 15 degrees cooler than the rad fan.
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So Diesels are expected to run hot eh?
my gauge points to 2 lines before the top of the gauge, would this be normal operating temps?
If so, what kind of temps would be "too hot"? anything high than that I would assume
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Andrew, that may be the case in sunny AZ but up here if the rad is too big you have to put a piece of cardboard or something in front of it in the winter or your car will never warm up.
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Andrew, that may be the case in sunny AZ but up here if the rad is too big you have to put a piece of cardboard or something in front of it in the winter or your car will never warm up.
Interesting. If your thermostat is totally closed, then that should never happen because water never flows through the radiator. Unless the little hole in the t-stat that prevents airlock is letting cold coolant through. Or there is enough heat transfer from the air going past the radiator to cool the bypass hose and the head itself.
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supposed to run hot?? damn my car hardly goes past the 70deg mark... i worry when it gets to the half mark!! i guess i have some work to do.
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The only thing that cardboard is doing is keeping the colder outside air out of your engine bay. It's not changing the temp of the coolant in your radiator one iota.
You know, one thought does occur to me. At the water neck on the cylinder head, some mixing of cold coolant in the top rad hose does occur with the hot coolant coming off the head. Not a lot, to be sure, because there is no through-flow but maybe an eddy forms as the hot coolant makes a 90* turn to go down into the bypass hose that picks up a little bit of cold coolant from the top rad hose. Same way that the glow and gauge senders on the drivers side water neck read accurately even when the heater valve is closed and no coolant is flowing there.
Not sure how pronounced this effect is. We would need some scientific measurements to know if it was significant...
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Awesome info guys... I'm totally digging it..
my grandpa had a piece of pegboard infront of the rad, so I decided to remove it while I was doing my headlight conversion....
I guess the best thing for the TD would be to just leave it alone... if it aint broke.. type deal huh?
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I wouldn't really trust the thermostats myself, unless it was brand new. My dad drives a 99 Daewoo and his thermostat is broken. Reason I know is because the engine never gets up to temperature. Rad is always hot too.
I had to use the cardboard trick in the winter a few times... my old jetta had a bad thermostat too :( I had to go at least 120 to get the heater to give off 'warm' air. Any slower, and all i got was this lukewarm bs that was probably stealing the heat from my body!!! :lol:
Thats why I say stick with the smaller rad. You might have different experiences though. If you're really good at fabricating parts/pieces, i would recommend the bigger radiator and a piece of metal to partially block off a portion of the rad during winter time. Heck you might not even need that if your thermostat is working perfectly.
Good luck if you choose to undertake this project :)
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I used to live in the cariboo, Where I lived it got down to -40 (-40C = -40F thats where F and C cross over). At that temp your car wont start if it wasnt plugged in, your shocks are rock hard, the foam in your seats doesnt compress when you sit on it.
But even at -40 if you need cardboard to get heat, then you got a bad thermostat.
A lot of people will partially block off the grill, mainly to help keep the heat in when you shut off for a few minutes to go into a store.
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I wouldn't really trust the thermostats myself, unless it was brand new. My dad drives a 99 Daewoo and his thermostat is broken. Reason I know is because the engine never gets up to temperature. Rad is always hot too.
I had to use the cardboard trick in the winter a few times... my old jetta had a bad thermostat too :( I had to go at least 120 to get the heater to give off 'warm' air. Any slower, and all i got was this lukewarm bs that was probably stealing the heat from my body!!! :lol:
Uhhh ... so replace the thermostat. Duh. :P
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I wouldn't really trust the thermostats myself, unless it was brand new. My dad drives a 99 Daewoo and his thermostat is broken. Reason I know is because the engine never gets up to temperature. Rad is always hot too.
I had to use the cardboard trick in the winter a few times... my old jetta had a bad thermostat too :( I had to go at least 120 to get the heater to give off 'warm' air. Any slower, and all i got was this lukewarm bs that was probably stealing the heat from my body!!! :lol:
Uhhh ... so replace the thermostat. Duh. :P
bought the vehicle in the summer. didn't have the luxury of a nice heated garage like some. I've learnt my lesson touching cold metal before. :lol: and will not pay a garage to do it for me.
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okay, yeah, so I dont live in the arctic... I dont EVER see 40 below..
I think I should be good...
but if I were to change the thermostat, would a lower temp thermostat and lower temp fan switch be a good idea? someone said they were supposed to match up or something??
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but if I were to change the thermostat, would a lower temp thermostat and lower temp fan switch be a good idea? someone said they were supposed to match up or something??
I changed out my t-stat and rad fan switch to lower temp versions. I did it because I have warped too many cylinder heads from overheating. You will see a reduction in fuel economy, but that's a hit I'm willing to take.
My thermostat is 169*F and my rad fan switch is 186*F. I think. Memory not too good. :P Anyway, my gauge never makes it to halfway.
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i just bought a manual rad fan switch :) it will turn on at any temp i want :)
from 0C-120C :D
my current idea for its use will be a homebrew water intercooler :). it will be nice for those days where the pump doesnt need to be run, etc.
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I changed out my t-stat and rad fan switch to lower temp versions. I did it because I have warped too many cylinder heads from overheating. You will see a reduction in fuel economy, but that's a hit I'm willing to take.
My thermostat is 169*F and my rad fan switch is 186*F. I think. Memory not too good. :P Anyway, my gauge never makes it to halfway.
I've already turned up my fuel and boost so economy is slowly going out the window as it is...
would you happen to know part numbers for the lower temp rad fan switch??
on the lighter side, I changed my oil cooler (finally) and it appears that the oil in my coolant bottle is of no more... :D
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Stock 2-prong (1-speed rad fan without A/C) is 197*F, part 201-0809. A cooler one (179*F) is 201-1545.
I only found one 3-prong (2-speed rad fan with A/C) switch of unknown temp, which is 201-1266.
The above numbers come from Autozone but I got all my stuff at Bow-wow, if that helps.
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The above numbers come from Autozone but I got all my stuff at Bow-wow, if that helps.
Eh??
canadian up here eh.... we aint got no aw-toe-zone :D
we get partsource, crappytire, princess auto... maybe the stealership but that's about it.
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http://www.autopartsonlinecanada.com seems to be a pretty good source for us canadians. Prices are... okay I guess. Shipping is fantastic!
I bought my 0C-120C relay at http://www.rxauto.com. They primarily make this head gasket sealer stuff... but I picked this thing up as it will have MANY uses :).
A quick search revealed the source for these thermostats, but they're website is pretty crappy.
http://thermostat.en.ec21.com/5/1/Industrial_Thermostats.html
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Eh??
canadian up here eh.... we aint got no aw-toe-zone :D
Lol. Well, the good news is you should be able to find a Bow-wow since I know they have a Canadian website.
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Eh??
canadian up here eh.... we aint got no aw-toe-zone :D
Lol. Well, the good news is you should be able to find a Bow-wow since I know they have a Canadian website.
yup.. found it.... by looking at their canadian website... but it'd only take me a week to drive to BC :p
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I wouldn't really trust the thermostats myself, unless it was brand new.
If your thermostat works properly, you wouldn't even need a rad until it opens. I had one winter where I couldn't get a Honda Civic to put out any heat. I went through 4 different 195 degree thermostats from various jobbers, and couldn't even get the windshield to defrost completely. I finally went to a Honda dealer and asked for a 195 degree thermostat. They only sold one rated at 160 degrees. I tried it anyway. Instant normal heater function. Soooo... just because your thermostat says 195 doesn't mean it will actually keep your engine at that temperature. By the way, the pot of water on the stove test showed that each of the 195 degree thermostats was opening within 10 degrees of the rating, so I can't really explain why I was having all the problems.
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By the way, the pot of water on the stove test showed that each of the 195 degree thermostats was opening within 10 degrees of the rating, so I can't really explain why I was having all the problems.
The T-stats most likely were not closing at the proper temp.
Some T-stats once heated up won't completly close until
the motor is stone cold. Which can cause the motor to
take a really long time to heat up.
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guess the moral of this thread is... trust the stealer for good t-stats. lol
I thought I would post this so people know about the fan operating temps etc.
(http://img466.imageshack.us/img466/6486/untitled1hs6.jpg)
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Interesting. If your thermostat is totally closed, then that should never happen because water never flows through the radiator. Unless the little hole in the t-stat that prevents airlock is letting cold coolant through. Or there is enough heat transfer from the air going past the radiator to cool the bypass hose and the head itself.
Yes and really cold ass air is also reaching the oil filter. -30C at 100kph equals to about -60C with wind factor :shock: Even the oil temperature is lower.
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-30C at 100kph equals to about -60C with wind factor
Wind chill describes the temperature a person will sense at a given speed/temp. Its the sensation of heat loss and is related to moisture evaporting from your skin.
To your radiator, -30C at 100kph equals -30C, unless your radiator is wet on the outside.
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-30C at 100kph equals to about -60C with wind factor
Wind chill describes the temperature a person will sense at a given speed/temp. Its the sensation of heat loss and is related to moisture evaporting from your skin.
To your radiator, -30C at 100kph equals -30C, unless your radiator is wet on the outside.
Well the wind chill for -30C @ 100kph is -54C.
regardless of whether or not your radiator can 'sweat', 100kph wind is still going to cool it faster than as if it were parked.
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Well the wind chill for -30C @ 100kph is -54C.
regardless of whether or not your radiator can 'sweat', 100kph wind is still going to cool it faster than as if it were parked.
Right, but that's mass flow of air through the radiator, not a lower temperature of the air.
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for the experimentaly minded, here is a way to prove that wind chill only affects something that is wet:
Take 2 apples, peel one. Go for drive and hold both out your window. The peeled one will get colder until the surface is dried out. the other wont change temperature much at all.
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There is also different factors that decrease the rad temp. First off, its metal, so it conducts heat quite well. The fast moving air flowing through the rad will be somewhat pressurized (at about 100km/h), and allows for greater heat removal, on the molecular scale. If its cold + humid, it can cool down even more. Of course the pressure I'm talking about is pretty small, but does make a difference.
To explain, the molecules slamming into your rad are being somewhat compressed to eachother, allowing them to absorb more heat than they would going at a slower speed.
Of course the temp differential is nowhere near as great as the 'wind chill'
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If its cold + humid, it can cool down even more. Of course the pressure I'm talking about is pretty small, but does make a difference.
Actually, humid air is less dense than normal air, so it doesn't cool quite as well as dry air, which is fairly counter-intuitive.
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If its cold + humid, it can cool down even more. Of course the pressure I'm talking about is pretty small, but does make a difference.
Actually, humid air is less dense than normal air, so it doesn't cool quite as well as dry air, which is fairly counter-intuitive.
I wonder how that works? Water can hold 4 times the amount of heat that air can hold. The moisture in the air will be as cold as the air, and as such will be able to absorb 4 times the amount of heat. Isn't that how water injection works?
Yes air below 0C can be humid too... Us poor Canadians know all about that! The cold won't kill ya, its the humidity!
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If its cold + humid, it can cool down even more. Of course the pressure I'm talking about is pretty small, but does make a difference.
Actually, humid air is less dense than normal air, so it doesn't cool quite as well as dry air, which is fairly counter-intuitive.
I wonder how that works? Water can hold 4 times the amount of heat that air can hold. The moisture in the air will be as cold as the air, and as such will be able to absorb 4 times the amount of heat. Isn't that how water injection works?
Actually, we're both wrong. (or both right :))
Humid air is less dense than dry air (h20 has a lower molecular weight than n2; gas density at atmospheric temperatures - i.e. where the Ideal Gas Law applies - is based on molecular weight), therefore, for a given speed you'll get a more MASS flowing through your radiator which helps your cooling.
However, humid air has a higher heat capacity than dry air. It's not four times as much - that's LIQUID water vs. air - but more like 1.5 to 2 times as much on a mass basis. But again, that's on a MASS basis, not a molar basis - which is what we care about for gasses.
On a *molar* basis, water vapor has a slightly higher heat capacity than N2, but not much. (I don't have time to do the exact calcs)
So: I think it's probably a wash and they cool your radiator just about the same. :)
Wikipedia has some of the heat capacity data here: http://en.wikipedia.org/wiki/Specific_heat_capacity but they're measuring the Cp of H20 vapor at 100C and N2 at 25C, so you can't compare them as heat capacity is dependant on temperature. Same for the Air Cp's listed: one is dry air at 0C and the other is humid air at 25C.
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Well my explanation only applies to cold air (with is more dense). In hot weather, dry is definitely better. I also stated that the moisture in the air will absorb 4 times the heat. The air won't :)
This post has gone really scientific :)