Runs warmer when colder..

[maxfax]

YEah that probably makes no sense, but I've noticed this for the last few years that in colder weather the engine temp is slighly higher..   After installing an aftermarket gauge at the water oulet on the head for the upper rad hose I have confirmed..  The engine runs up to 10 deg F warmer in cold weather..     Not really worred about it as it's done this with several thermostats & water pumps now and hasn;t been a problem.. I haven't taken notice yet if traveling at higher or lower speeds changes this at all.. 

 Just curious if anyone else has noticed this??   My though was that maybe the cold air blasting in there doesn;t allow the thermostat to open as quickly.. 

[theman53]

I noticed this too. I just thought I was nuts, but it definately did. I thought that maybe it was running the heater having the extra coolant cooling down in the heater core letting the overall temp get hotter Who knows, but I am for sure with you on that.

[rabbitman]

Yup, same here, I don't know why either....

[Zulfiqar]

bad voltage regulator in dash cluster - over here it gets so hot that cds melt if left on dashboard - replaced the VR because in summer when I filled up I got 3/4 tank and its overflowing out of the filler, and the temp needle stayed a little behind from half, in winter or a cold night I got full tank readings when full and proper slightly proud of half mark on the temperature gauge..

[maxfax]

Maybe we're all nuts..    I'm just glad I'm not the only one who has noticed this..

I considered that running the heat was doing it..  The temp sender for the gauge is on the outlet going to the heater.. Heat on, more coolant flowing, hotter reading..   That was shot when I added the WVO since it flows coolant constantly with or without the heat on..

I considered a possible electrical problem..  Especially since I first noticed this when I drove home at night (with lights on)  versus my drive to work during the day..

With an additional mechanical temp gauge on the outlet to the upper rad hose that shoots both of those therories..

Unfortunatly in extreme cold this no longer applies..  It hurries me to get up to operating temp...  I think this winter if we see some crazy cold I'm gonna try shutting off the flow to all the WVO crap and see what happens...

[theman53]

No that is what I mean. If you have something like a heater core WVO system going all the time added to the cold air the radiator would have to work less with the coolant being more consistant. Then the t stat wouldn't have to open up as fast giving a hotter read? I know mine wasnt a VR because when spring rolls around it goes back to normal.

[jtanguay]

well i have a theory. heat rises right? since the thermostat is practically at the lowest point in the system, there is a big lack of heat there, so the colder it is outside, the longer it will take to open the thermostat.

to confirm this, insulation must be applied to the bottom of the water pump where the lower rad hose connects to (and maybe the lower rad hose itself?!). if this doesn't work, then i'm out of ideas

[smutts]

Aye, they all do that, but scoobied as to why. Libbybapa's probably on the money. VW watercooleds are the only ones I know that regulate the coolant temperature going into the engine instead of leaving it.  

[dieselweasel]

I noticed the same thing, engine coolant runs hotter when ambient temps are colder.  Last winter it got really cold some days and it left me scratching my head as to why it would get up to 100C on a -20C day yet not get that hot on a +30C day.  I think I was so concerned about it because I had just done the head gasket last Christmas;  I was worried that air was getting in the cooling system.  I changed the thermostat, gauge temperature sender, and swapped in a spare cluster to test but found the temperature still the same.  I finally concluded this behaviour was normal based on the position of the thermostat.  I don't think this would happen if the stat was at the coolant outlet of the head.  Anyway, nice to know that others have noticed this also. 

[Rabbit TD]

I'm glad this came up again.  I posted about this last year but without this much response.  I watched for it this past winter and summer with my new T/D.  Exactly same setup other than this one has the turbo but it even has the temp sending unit and thermostat that was in the other engine but it acts totaly the way you would expect an engine to act as far as temp and speed is concerned.  This pretty much eliminates a resistance issue which I thought it might have been for me at least but nothing was changed in that respect and the T/D motor acts nomaly according to ambient temp. and the N/A one had the other strange phenomenon.  Same thermostat in the same place too by the way so who knows

[maxfax]

 Even with the contstant flow for the WVO crap mine ceases to do this when the weather get's warm as well..

I think Libby hit the nail on the head... I kept a close eye on both temp gauges last night..  The first observation is that the mech gauge responds MUCH faster than the factory one .. THe temp would slowly climb to about 210 deg F, then rather quickly drop back to 200.. IT did this about 6 times in 25 miles...

Having this discussion with my father last night and he reminded me that my old Mustang II did the same thing..   It had the German 2.8 v6 with the thermostat on the bottom hose..  Now to make it really interesting, the GM Quat 4 and newer GM 2.2 liter also has the thermostat on the lower hose, yet it's not so noticable on those..   Could be though that the temp gauges on those aren;t as sensative..

[jtanguay]

Even with the contstant flow for the WVO crap mine ceases to do this when the weather get's warm as well..

I think Libby hit the nail on the head... I kept a close eye on both temp gauges last night..  The first observation is that the mech gauge responds MUCH faster than the factory one .. THe temp would slowly climb to about 210 deg F, then rather quickly drop back to 200.. IT did this about 6 times in 25 miles...

Having this discussion with my father last night and he reminded me that my old Mustang II did the same thing..   It had the German 2.8 v6 with the thermostat on the bottom hose..  Now to make it really interesting, the GM Quat 4 and newer GM 2.2 liter also has the thermostat on the lower hose, yet it's not so noticable on those..   Could be though that the temp gauges on those aren;t as sensative..

its about time GM starts putting the t-stat down below... the way it is now the gauge has to read full operating temp before it starts to put out hot air on a really cold day... whereas my VW starts to put out heat with the needle just barely moving...

[maxfax]

It's such a better design having the t-stat on the inlet to the engine..   Virtually no chance of an air/steam pocket forming behind the t-stat when refilling..  And at least you can be sure the block and head are full of coolant before starting...  At least now alot of the makers are putting an air bleed in there somewhere...

[maxfax]

So I've toyed with this topic a bit more..  I installed a restricter in the bypass hose between the head and waterpump..

By the electric gauge it's bat to it's normal temp.. The mech gauge only shows 5 deg fluctuations now.. And darn is the heat HOT!!

[maxfax]

I actually kind of expected it to run warm to hot after doing that..  The fact that it ran a tad cooler kind of threw me..
Unless the combo of the heater core and all the WVO crap coupled with the colder than usual conditions last night made up for it..  The restrictor cut it down to a half inch hole, might have been just enough under the conditions...  I need to monitor for a few days...

I've toyed with the idea of using the bypass to circulate coolant through the WVO system, and connect the heater back they way it's supposed to be... Of course when the t-stat opens that'll be shot to hell anyhow.. T-ing into it may be an option, havend sorted that all out yet.. I've always had cirulation problems when it comes to having both the cabin heat and the wvo heat running at the same time..   Even with the additional aux water pumps, and various configuations of having them in series and paralell... Rather agrivating having next to no heat,  cold wvo, and a temp gauge reading 210....