Temperature Fluctuations.... ?

[newbie]

Ok, so first things first.
as some of you may know, my lower rad hose popped off when idling in front of a theatre a few months back.
I swapped the hose and clamps.
It did this again the other day. I left my car idling in front of my mothers house and we were there a little too long (15 minutes maybe). And I look out to see my car puking coolant in the driveway.

Its not overheating, wp/tb done about 40k ago (could they be done already??).

When I drive on the highway I run cool, around 160-170. But when Im in traffic or stop and go I can go up to 210-220, I havent gotten any warnings yet though.

It feels like coolant is flowing in the lower hose and I have no leaks or weird smoke from anywhere.

Why is this pressure building enough to pop hoses?

Im gonna change the thermostat this weekend hopefully, start with the cheap stuff..... But other than that I stumped.

any ideas ?


Side note, with my hand I can spin the drivers side fan, passenger side is hard to move.

And the car runs great, Im just scared to pop off another hose.

[D2Beetle]

If your fans are not working that could explain the wide temp difference. When the car is moving air is flowing through the radiator; when not moving, no air flow.

[newbie]

but that doesnt explain the hose popping...... does it

[MyOtherRidesAVette]

Do you have any stored codes?

The coolant system, when operating correctly, is pressurized, and could blow off a hose that is not securely attached. Is it the original factory clamp, or have you replaced the clamp(s). You should never reuse the factory clamps

You need to check the fans for operation. When idling at temp, putting the a/c fan switch on "4" should turn one of them on (the small I think). The other should come on at idle as the engine heats. May even come on and run for up to about ten minutes after you shut the engine off. They are controlled by thermo-switches. I have posted up the correct Bentley diagnostics in a thread, and they can be found here
Overheating problem

MORAV

[newbie]

just a quick update..

Though my temp on highways is 160-175 my blue engine light stays on all the time. This is on highways only, I havent driven in the city yet because I dont trust the hoses not to pop off...

Coolant is at the halfway point of the overfill, the equator on that little globe..lol...

The Light did flash blue for about 15 minutes 2 weeks ago, but when I stopped and restarted after going into a store it never came back. Now its on all the time.

I do have a cel, but I always do because of a P0420 (cat code). I dont know if there are anymore other than that now. I havent come across the extra $100 for the dealer to scan it (because they will not just scan, they have to inspect as well. )

[Smileybug]

If its always blue, I'd replace the coolant temp sensor.

[newbie]

if its the coolant temp sensor could it be that its letting my car get too hot and that's why its popping hoses ?

[MyOtherRidesAVette]

Originally Posted by Smileybug

If its always blue, I'd replace the coolant temp sensor.

x2 probably, but it's my understanding the sensor can be checked with a VAG-COM.

Get it scanned for codes even if it's a generic SAE code reader at the Corner Parts Store. Save your $100 at the Dealer and buy a VAG Checker Scanner here -
Home Page > Search > Vagchecker > ES#9951 V-Checker Scanner - Basic - VAGCHECKERBASIC
Check eBay for this item, I bought mine from another Orger for $25 when he upgraded.

Edit: SB, not implying the sensor itself can be checked with this reader (it can't), only that this reader is a good option to $100 at the Dealer or the Corner Auto Parts.

M.

[Smileybug]

That reader won't check measuring blocks and the CTS doesn't always throw a code, or one that is specific enough to know its the CTS. Not sure what it is about the CTS, but it can do some really strange things when it fails. I had two go on my Beetle. The "revised" sensor actually lasted a shorter time than the original in the car too. When the first one failed, I was getting high revs on startup and had a code for it. Second one that failed, I had no clue it was dead until I had my cat fail. Also threw a cooling system code, but I think it was that generic cooling system code. But no symptoms at all.

[Design]

it is pretty easy and cheap to swap the temp sensor too. Also pressure could be due to a clog or malfunctioning thermostat.

Did you mix coolant types? That gunk will build up in the system on and cause you problems.

[newbie]

Originally Posted by Design

Did you mix coolant types?

I wouldnt say I mixed it...
But after the first blow-off it was empty and the green stuff went in. But this was AFTER the first time it blew off. So the problem was already there beforehand.

I know I know.... but it was an emergency.....

[Smileybug]

How much of the green stuff did you put in? You will have to flush your cooling system before you cause any more problems from sludging. You can add distilled water rather than coolant until you can get some G12.

[newbie]

Update.. Drove home Friday, temp got up to 215. Shut down and maybe 10 minutes later it popped again. .
The sensor in the res works cuz the minute i start it up it beeps red.
Coolant sensor and thermostat on order....

To be honest I'm border-lining on just parting this car out.

[Design]

don't go there yet. The Sensor and the Thermostat are easy fixes. But while you are in there do a complete backfulsh of the system. You can buy a flush kit from any auto parts store or Walmart. Follow the direction as this will help clean anything that is in your system out.

If you want to do it the really cheap waynote do not allow the coolant to run off into the ground)

Pop the line off the reservoir, detach the upper hose from the radiator, do the same for the lower hose.

take a garden hose with a sprayer and spray into the upper hose. This will push the old coolant out the detached line at the reservoir. Run this until you get clean water running out.

Then spray through the radiator at the upper opening and flush the crap out of your radiator.

thermostat and sensor next.

Fill car with fluid.

[newbie]

changed thermostat and temp sensor...
All good so far, things seem to be back to normal.
Full coolant flush this weekend also.


But regardless Im selling the car now.... 3 vehicles is just too much.

[newbie]

False alarm....
Still overheating..
Realized it's because the cooling fan is not turning on.
So I'm gonna start going down the line starting with the fan switch, then relay, then the fan itself

[MyOtherRidesAVette]

Why not just diagnose it all, properly, instead of just throwing new parts at it. Could be something cheap and simply. Haven't been following the thread, and haven't now read through it, but here is the Bentley diagnosis for many things.

Bentley Cooling System Diagnostics
Overheating problem

Bentley drain and fill procedure
Beetle overheating

MORAV

[newbie]

well based off the Bentley I am not doing anything wrong...

Blue coolant light was on, heater was normal. Thermostat and Temp sensor replaced. Problem didnt go away..

So, next step.....

I noticed the A/C fan goes on but even when my temp gets up to 210 my cooling fan never goes on...
It says inspect switch and sensor so thats next on my list..

[newbie]

Ok...
I definitely have trapped air. Top hose gets HOT bottom stays cold.
This is new, last time around the bottom also got warm and the heater blew heat.

I checked the level this morning after all of yesterdays work and it was 1/2 gone... no leaks so must have been air working its way out overnight or during cooldown.

NOW

I noticed that my A/C fan works but the other does not.
Just for fun I pulled the A/C clutch fuse with the car off. Does this prevent the fan from running? because when I pulled it, the fan turned on.

[MyOtherRidesAVette]

Originally Posted by newbie

Realized it's because the cooling fan is not turning on.
So I'm gonna start going down the line starting with the fan switch, then relay, then the fan itself

Wasn't implying you had done anything wrong. I was merely suggesting you diagnose these additional items as opposed to just replacing them. And further put up the diagnostics to do this. Sorry.

M.