Re: Need help with fluctuating coolant overflow tank level. (dmkozak)

If your "low coolant light" is going on when when it shouldn't, you can clean the contacts inside the expansion tank to eliminate that, or perhaps you park on a slope of some kind that effects your reading when it cools at night. But it sounds normal, just use the full mark on your expansion tank (when the engine is hot) as your true guide. Then you know without a doubt it's good. We know that when the car is cold it will always read lower than when it's hot, right?

 

Re: Need help with fluctuating coolant overflow tank level. (okanagan45)

Thanks. First, the coolant light is NOT coming on. It went on once, and since then, has not come on at all, even when the coolant level is a good 1/4" inch below the MIN mark.
Second, many times the coolant level is the same when cold as when hot. Many times the coolant level remains at the MAX mark when cold as when hot. So, it doesn't always lower when cold.
Third, the car gets parked in a level garage overnight. No slope. And, it's a home, so, same space every night.

 

Re: Need help with fluctuating coolant overflow tank level. (dmkozak)

SAME thing happened to me about a month ago. I started up my car one morning and got the chime alarm and shut the car down. I pop the hood to see the tank BONE DRY. SO I filled it back up with collant and it has never done it sense. Very very odd. There was no leak under the car and it wasn't that cold out.
Beats the hell outta me.

 

Re: Need help with fluctuating coolant overflow tank level. (dmkozak)

You are describing exactly what's happened to me.
I filled it once and now 4 months later it has tripped the sensor again.
I haven't filled it again and the light has since turned off.
Looking at the reservoir, there seems to be a few white deposit.
Guess I'll take it in.
Oh, car has clocked 24,000 miles.


Modified by Astralplane at 8:52 AM 12-14-2004

 

Count me in on this, happened to me a month ago as well in my 12V VR6!

 

Re: (bodyboarder20)

This is perfectly normal. ESPECIALLY for VR's. The amount of coolant in your tank will fluctuate day to day depending on temperature outside, engine temperature, what the cooling system was doing when you stopped the car etc. Usually every year when it begins to get cold you will need to add some coolant (light will come on). The system has been losing a small amount of coolant all year but the cold weather finally reveals the problem.

This is another one of those VR quirks. VR's run hot. With the MKIV's vw did something about it and added the auxilary radiator (no it is not an intercooler or oil cooler), in general, the cooling systems on these engines, like the engines themselves, are somewhat unique.

 

Re: (rs4-380)

Quote, originally posted by rs4-380 »

This is perfectly normal. ESPECIALLY for VR's. The amount of coolant in your tank will fluctuate day to day depending on temperature outside, engine temperature, what the cooling system was doing when you stopped the car etc. Usually every year when it begins to get cold you will need to add some coolant (light will come on). The system has been losing a small amount of coolant all year but the cold weather finally reveals the problem. This is another one of those VR quirks. VR's run hot. With the MKIV's vw did something about it and added the auxilary radiator (no it is not an intercooler or oil cooler), in general, the cooling systems on these engines, like the engines themselves, are somewhat unique.

If the fluctuations were small or somewhat regular, I'd more likely think this was the case. However, the level varies from below the MIN mark to the MAX mark randomly and without any reference to the temperature or the weather. Plus, I live in Phoenix, so, while we're now about 35 degrees cooler than we were in the summer, our temp does not vary as much as elsewhere in the country and the car is garaged overnight. The garage temp is usually in the low '70's, so the temp variation experienced by the car may only be 10 degrees daily.

 

Re: (dmkozak)

it depend on more than just the temperature, the termostats behavior can affect it alot.
You are not losing coolant, you know this by the fact that at times the coolant in your resevoir rises. Trust me, just add some water or G12 when it is at one of it's low states, and forget about it.

 

Re: (rs4-380)

Right, the car is not losing coolant.
Yesterday morning the coolant level, cold, was 1/4" below the MIN mark. I took it to the dealer. They ran a pressure test, which showed no problems. This morning, after the system was fully pressurized yesterday for the pressure test, the coolant level, cold, was 3/4" above the MAX. So, just by pressurizing the cooling system, the coolant level rose from 1/4" below the MIN to 3/4" above the MAX.
I'm thinking the system is somehow losing pressure. Then, it repressurizes itself, then slowly loses pressure, etc., etc. Any one have any ideas? Thanks.

 

Re: (dmkozak)

Bump for some help. Thanks.

Modified by dmkozak at 6:00 AM 12-16-2004


Modified by dmkozak at 6:01 AM 12-16-2004

 

Re: (dmkozak)

Same thing happened 2 me last year. I started my car and coolant light came on. Popped the hood and the globe was empty. Had it towed to the dealer on their dime. they did a leak down test and found nothing. They flushed the system and it was good to go. Happened again this year about a month ago. Took it to a better dealer and they did a leak down and found nothing. The service writer said if it happens again they would start replaceing crap under waranty. ie. water pump, hoses and such. Doesnt bother me. But when it does happen bring it to the dealer so they can note the problem. That way when your out of your waranty its still on the books and they will fix it under your waranty.

 

Re: (Slvr6Dub)

Coolant Migration can lead to nasty problems. I suggest you folks check out http://www.tdiclub.com, there is a huge thread on this.

 

Re: (MXTHOR3)

Quote, originally posted by MXTHOR3 »

Coolant Migration can lead to nasty problems. I suggest you folks check out http://www.tdiclub.com, there is a huge thread on this.

It would be a bit more helpful if you could provide us with a direct link, seeing as you must be a member to search their forums. Until then, personally I am going to take you statement (which could mean any number of things) with a grain of salt seeing as the TDI's and VR's share absolutley nothing in common.
I could say the same thing about blown headgaskets, but that is obviously not the problem, and does nothing other than cause people to worry.

 

Re: (MXTHOR3)

Quote, originally posted by MXTHOR3 »

Coolant Migration can lead to nasty problems. I suggest you folks check out http://www.tdiclub.com, there is a huge thread on this.

Thanks. However, my electrical connection is bone dry. And, I have the latest overflow tank with the connection higher up on the tank. I'm pretty sure I con't have a coolant migration problem.
Wondering if I have a system pressure loss problem where the system holds pressure but a very tiny leak results in a small loss of pressure over long time?

 

Re: (dmkozak)

Guys,
I've had the exact same problem when I first hit around 70k. Soon as I started up, the light came on, bone dry. Luckily the dealer was right next door to the Arby's I was at, so I coasted over and got some G12 replacement. Then it didn't happen again for like 6 months. Around 85k, it started acting up again. This time, I noticed some white crusted powder around my expansion resevoir and under the engine. When G12 dries, it dries white and slightly pinkish. So I refilled, and again no problems until around 103k.
Then...I started noticing visible leakage coming from the passenger's side of the engine. After pulling off the spash guard underneath, the bottom of the engine was *covered* in dried G12. Replaced the water pump, and now at 112k with no problems at all.
Moral? Check the water pump.
Fae

 

Re: (FaelinGL)

Except, you were losing coolant. I'm not. Some days my coolant level is down, and some days its up. Now, if I didn't have the system vacuum needed to suck the the cooled coolant from the overflow tank back into the radiator, I could see how the level could rise. But, in the morning, the level is always less than it was when the car was last driven. So, the difference is being sucked back into the radiator.
The tank was never dry. When the light went on, the level was only about 1/4" below the MIN mark. Lots of people post the same story you've posted. But, that's different than my story.
Still wondering how the level can go up and down at random from day to day.

 

Re: (rs4-380)

Quote, originally posted by rs4-380 »

it depend on more than just the temperature, the termostats behavior can affect it alot. You are not losing coolant, you know this by the fact that at times the coolant in your resevoir rises. Trust me, just add some water or G12 when it is at one of it's low states, and forget about it.

absolutly, the best way I guess I can describe the coolant level is there is a level when the car is cold, and when its hot. When the car is cold the level will be low and not pressurized. and when the engine is hot the tank and the system is pressurized and the coolant is running throught the system and is circulating and will appear to have more coolant.

 

Re: (CorradoG60)

Okay. Now the overflow tank amount expands when the coolant is hot because the tank "catches" the vapor from the coolant which has reached the temperature where the liquid converts to atmosphere (like when water water boils). Then, when the coolant vapors cool in the overflow tank, they return to the liquid state, increasing the amount of coolant in the overflow tank. So, when the coolant is hot, there's more coolant in the overflow tank.
Then, when the coolant cools, the system pressure (and vacuum) sucks and pulls the cooled coolant from the overflow tank back into the radiator and block to replace the coolant which was hot enough to vaporize, flow to the overflow tank and return to liquid as it cooled in the overflow tank. So, in a completely sealed and fully functioning cooling system, the cold level in the overflow tank would always be constant. When cold, you'd have the block and radiator full of coolant, and the "excess" coolant would be in the overflow tank.
If the amount in the overflow tank decreases over time, you're losing coolant. If you're not losing coolant, then the only way the cold tank amount could decrease is if the system vacuum sucked or pulled more cooled coolant into the radiator or block than vaporized when hot. If you don't add coolant, the only way the overflow tank amount could increase, when cold, is if the system vacuum doesn't pull or suck the cooled coolant from the overflow tank back into the radiator or block.
So, the only thing I can think of that would cause the cold levels to go up and down, at random, would be a system that doesn't always reach the same pressure level when fully pressurized. The question is how could this happen, what could cause a change in pressure levels when fully pressurized?
Does the thermostat affect the system pressure?


Modified by dmkozak at 1:46 PM 12-19-2004

 

Re: (dmkozak)

Monday morning bump.

 

I got one this morning. It was nine degrees. I put a bit more coolant in it and all is well. Oh well