Author Topic: Cooling system thoughts (Read 10121 times)

BellCityDubber · « **on:** July 16, 2006, 07:57:10 am »

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

burn_your_money · « **Reply #1 on:** July 16, 2006, 08:07:01 am »

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)

jtanguay · « **Reply #2 on:** July 16, 2006, 08:43:38 am »

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: .

tylernt · « **Reply #3 on:** July 16, 2006, 09:50:09 am »

Quote

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.

BellCityDubber · « **Reply #4 on:** July 16, 2006, 07:38:45 pm »

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

burn_your_money · « **Reply #5 on:** July 16, 2006, 07:44:46 pm »

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.

tylernt · « **Reply #6 on:** July 16, 2006, 07:55:06 pm »

Quote

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.

nkb · « **Reply #7 on:** July 16, 2006, 08:30:34 pm »

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.

tylernt · « **Reply #8 on:** July 16, 2006, 08:59:55 pm »

Quote

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...

BellCityDubber · « **Reply #9 on:** July 16, 2006, 09:21:59 pm »

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?

jtanguay · « **Reply #10 on:** July 16, 2006, 09:44:57 pm »

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

LeeG · « **Reply #11 on:** July 16, 2006, 10:25:03 pm »

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.

MaxHedrm · « **Reply #12 on:** July 16, 2006, 11:05:53 pm »

Quote

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.

jtanguay · « **Reply #13 on:** July 16, 2006, 11:27:23 pm »

Quote from: MaxHedrm

Quote
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.

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.

BellCityDubber · « **Reply #14 on:** July 17, 2006, 05:01:58 am »

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??