Temp question

[DAKOTAKIDD]

I have a 91 eco diesel 1.6 idi.  I always run my fan (factory dual) and the needle sits around the 1/4 mark.  When I go up a steep grade or hill and have to push the pedal down a little more, the needle could rise to around the half mark.  I don't know how far it will go cause the usual grade I climb comes to and end so I can't find out.  I am assuming it will continue to rise but I am unsure.

Is this normal for this car?

Also I am going to change the coolant soon.  Right now its the green stuff in there but I need to know what the proper stuff that is used.

Any ideas would be awesome.

Thx

[maxfax]

All of mine have always liked to get a tad warm up hill..   Generally like yours they'll rise from a quarter to half..  Never went over though..


There was a service bulletin issued years ago stating to use the red antifreeze (VW G 012 A8D A1) which requires a thorough flushing of the system as it doesn;t mix well with others..   Generally though good quality standard green antifreeze is fine..

[DAKOTAKIDD]

Thx man!!

[Peter]

of nearly 25 yrs of driving the VW diesel...the valvoline green coolant (because of the iron block) (look at there web site for more info)...not knowing the history of your car, at first guess if my temp gauge ran only at the 1/4 mark and then rose another 1/4 going up a hill..I would change out the rad/reserviour cap for a new one and if that did not change anything then the thermostat (87-92C) wahler or VW brand..better still change them both out while doing the coolant change...the older cars will show a fluctuating temp gauge (about 20F) when going up a hill(s)..which is normal...many of the more modern cars, so as not to create any concern for the driver will not show any movement on the temp gauge until it gets 20f and hotter...some cars like the new subaru forester Don't even have a temp gauge...just an idiot light that will flash, hopefully when it is not to late

[DAKOTAKIDD]

My cooling system is holding pressure just fine.  Builds pressure and holds it.  So I don't think that will help.  When I flush the coolant, I am going to get the rad pressure tested. 

If I am missing something obvious about how rad caps work,   please let me know

Thx 

[jtanguay]

My cooling system is holding pressure just fine.  Builds pressure and holds it.  So I don't think that will help.  When I flush the coolant, I am going to get the rad pressure tested. 

If I am missing something obvious about how rad caps work,   please let me know

Thx 

the expansion tank cap just has a built in relief valve.  you're on the right track with getting the coolant system flushed.  don't cheap out at this stage, because its such a PITA to do! i used prestone super heavy duty flush on mine, and was very impressed.  the liquid that came out was a nice chocolatey brown (yum) and after that i've never had more heat coming out of my vents! i did run into problems with the thermostat though... and it was a $30 one from the vw stealership, and so i will never buy another one for any vw EVER. the $10 canadian tire one worked flawlessly! as for coolant, i've never tried the stuff that changes colour, but i like the idea (idiot proof-no litmus paper required lol). i think there might be a good reason to go with diesel specific coolants, but i think its more crucial if you have a (wet) sleeved block. maybe someone else can chime in on that one.

i've also used a coolant additive that stabilizes the temperature, and it does what it says it does. worked great! uphill climbing barely moved the needle, whereas before it would move quite a bit. among one of the best reasons to have a coolant additive, is protecting your heater core. after i swapped out the bad thermostat, i drained the coolant (with the additive) and with my rebuild 1.9TDI i just had regular coolant added, and within a few months the heater core blew on me the additive might have helped keep it on life support for a while longer.

[mystery3]

i've also used a coolant additive that stabilizes the temperature, and it does what it says it does. worked great! uphill climbing barely moved the needle, whereas before it would move quite a bit. among one of the best reasons to have a coolant additive, is protecting your heater core. after i swapped out the bad thermostat, i drained the coolant (with the additive) and with my rebuild 1.9TDI i just had regular coolant added, and within a few months the heater core blew on me the additive might have helped keep it on life support for a while longer.

To what additive are you referring?  Stuff sounds great. My 81 caddy reads normally around the halfway mark and going uphill for about 10 minutes it reads around the 3/4 mark which I don't really like, lately this has also been with high ambient air temps 90F or so.

[jtanguay]

i've also used a coolant additive that stabilizes the temperature, and it does what it says it does. worked great! uphill climbing barely moved the needle, whereas before it would move quite a bit. among one of the best reasons to have a coolant additive, is protecting your heater core. after i swapped out the bad thermostat, i drained the coolant (with the additive) and with my rebuild 1.9TDI i just had regular coolant added, and within a few months the heater core blew on me the additive might have helped keep it on life support for a while longer.

To what additive are you referring?  Stuff sounds great. My 81 caddy reads normally around the halfway mark and going uphill for about 10 minutes it reads around the 3/4 mark which I don't really like, lately this has also been with high ambient air temps 90F or so.

the stuff i bought is called tow-kool (i highly recommend it-it's easy on the wallet). its meant for vehicles that are pulling a heavy load, and IIRC is compatible with just about any coolant. another side benefit of using an additive like this, is the lubricating of the water pump. this could probably extend water pump life at least by two-fold.

another option is to go with Evans coolant, which seems to be amazing stuff. you can run it with no pressure in the cooling system which is such a great idea IMO. virtually all issues related to blown hoses etc. would be eliminated. that and overheating issues too! the only problem is that it might burn a hole in your wallet (initially, but apparently it lasts a VERY long time. again, one of those investment things...)