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Discussion Starter · #1 ·
1.8 B5 here with a coolant system question/ in need of advice. My passat was overheating and it turns out the coolant flange was cracked and leaking out coolant The mechanic I took my car to (highly recommend by a "friend" of mine) said he had trouble finding the part (BS because I found online in half a second) so he said that he made one instead. I haven't seen the part he made but it sounds questionable to say the least. He then replaced what was left of the G12 coolant with NOT G12, which was green and splashed all over the place. He did empty the system first but didn’t flush the system at all. So what was left of the G12 is now mixed with what he put in. He called and asked me to look up on the internet how to bleed the system because he doesn't know how (Seriously?). As of right now there is no coolant circulation and according to mechanic the engine temp starts to rise above 190 after about 30 minutes of idle (its about 32 degrees F here). Also, the fan clutch is broken so that is playing a role in the rising temp while the car is stationary if I am correct.

So first of all he is clearly done working on my car. I want to try to fix it myself now.

My questions are;

1. Since he did not bleed the system is the heater core likely gunked up due to mixed coolant or does the heater core only fill with coolant after the system is bled (this is what my brother/previous owner told me)

2. If the heater core is intact is it ok to drive to my house so I can flush ~5x and refill with G12 and bleed the system.

I’m limited in my experience talking about cars and working on cars so please forgive any errors in my description, I’ll clarify as best I can if needed.

Thank you!!!!!!
 

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How much driving is involved to get the car from where it is now to where you'd be working on it? It sounds like the less he touches the car the better off you'll be. Maybe have him drain the cooling system and flush with water then fill with water. Then you drive it to your work area or a different mechanic and re-repair the car properly.

You can get G12 online and at some auto parts stores and also the dealer. http://www.google.com/search?q=pent....0...1ac..34.heirloom-serp..0.0.0.P8PjTwhJri0

I'd like to see what this guy "made" to repair or replace a cracked coolant flange.

I bet he can fix a pre-1980 Chevy small block or a Briggs & Stratton pull-start lawn mower real good, but a German car... not so much.
 

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x2

There is a DIY in the info base on how to bleed the cooling system. Its fairly easy and its done with the engine off. That's hopefully why the gauge shows its overheating.

As to your questions, for 1) that's not entirely correct. Some mixing could very well take place. 2) having mixed coolants in the system is a big no no, especially G12 with certain ones, hence the recommendation to flush it if a longer drive is involved.

With the viscous fan missing, dont idle it or drive it in stop and go traffic. Does the secondary fan work?

If you need to flush and fill it with water to get it home, take note. If you add cold water to an engine that's been outside in below freezing temps, the water may freeze as soon as it enters the block. You may be better off running the engine for a few minutes and then drain the mixed coolants and start adding water. Then shut it off, bleed and drive it home.
 

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The A/C fan acts as a backup, so your car should be able to avoid overheating.

x2 on the idea that you should have this clown drain the engine when cold and fill with distilled water.

I hope you aren't going to pay this guy much, if anything.

What kind of "mechanic" is this guy? Jury-rigged fixes for parts he's too lazy to buy, not bothering to look up the correct coolant, etc.
 

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Sounds like he used prestone coolant. Prestone claims their green coolant is mixable with all types of coolant, but I don't believe that. From what I heard Mixing Prestone with g12 will cause the coolant to gell. As long as you flush you all the prestone coolant out of the system and you replace it with G12 you should be fine. I believe they sell a chemical that will un-gell coolant if it has gelled but I'm not 100% sure.
 

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If you go to the dealer today, they'll probably sell you a jug of G13. If you are getting Pentosin juice from an auto parts store, it'll be a crap-shoot as to which one they stock.
 

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Sounds like he used prestone coolant. Prestone claims their green coolant is mixable with all types of coolant, but I don't believe that. From what I heard Mixing Prestone with g12 will cause the coolant to gell. As long as you flush you all the prestone coolant out of the system and you replace it with G12 you should be fine. I believe they sell a chemical that will un-gell coolant if it has gelled but I'm not 100% sure.
I've not had problems mixing yellow bottle Prestone with the OEM coolant.
 

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It might be compatible, but if it turns out not to be, is Prestone going to rectify a clogged cooling system? The safest thing is to stick with the factory recommended stuff. Second safest would be to drain then flush then replace with a less expensive and more readily available type of coolant. In last place we have mix in various types of coolant and hope the writing on the bottle isn't a stretch of the truth written by the marketing team.
 

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Discussion Starter · #12 ·
I have been super busy with classes and am just now getting ready to fix this.
Update: I drained out the green coolant and flushed 3x with distilled water. The last flush was almost completely clear and I dont see much green. after adding more water I bleed the system at the heater core and tried to drive home, about 30 miles. It overheated after about 10 minutes of highway drive time so I pulled over, let it cool for a bit, added more water to the fil line. I drove for about another 10 minutes before it overheated again. Now I see that I need to bled at the second spot under the coolant resavior to have the system completely bled (right?). Is it likely that it overheated because I only bled at the one spot and didnt fill the entire system, thus not having proper/any flow of coolant?

Also, Is it necessary to use a coolant system wash product to flush or would I be ok just with flushing with with water a few more times before adding g12?

Thanks!
 

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Just water is fine for what you're doing. You can flush with tap water. Use the distilled for the final flush and when you go to fill.

The antifreeze you mix in with the water also raises the boiling point of the mixture. This may be why you were overheating. A stuck closed thermostat, air-locked passage or failing water pump can also cause overheating.

http://www.passatworld.com/forums/b...leeding-cooling-system-heater-core-flush.html

Edit: ...and I type too slow. :D
 

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Discussion Starter · #15 ·
ok I did the flush and refilled. still get the temp light flashing. The upper radiator exit hose is cool to touch but both of the heater core tubes are very hot. When bleeding, there is flow, does that tell me I have flow from the water pump? If so, it seems that my problem must be that the thermostat is stuck closed. What do you all think?
 

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Discussion Starter · #16 ·
I just replaced the thermostat and checked the water pump. I unhooked the expansion tank return hose and stuck it in a bottle, started up the engine and rev'd and got coolant in bottle. Does that show the water pump is ok? Now I'm thinking it may be a problem with the temperature sensor? The temp light flashes almost imediately after i start the engine. the temp reads 190. So I dont know what to do.
 

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When bleeding, there is flow, does that tell me I have flow from the water pump?
NO.


I unhooked the expansion tank return hose and stuck it in a bottle, started up the engine and rev'd and got coolant in bottle. Does that show the water pump is ok?
NO.


DO NOT run the engine during bleeding; read the DIY.
Check/replace the CTS (in the coolant flange at back of the head)
 

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Discussion Starter · #18 ·
Ok, Properly bleed, with engine off, no incline etc. (embarassing, I forgot to reattach the resevior sensor to the tank, once I did, that solved the temp light flashing right after start up) I drove around a bit. The temp was steady at 190 F for about 10 mins of neighborhood driving. I took it out on the city streets and went up to 45/50 and the temp started to rise after a few minutes and then got up to 240 F before I got back home. By the way, the temp light never came on.

The upper radiator hose is hot and feels filled with coolant when I squeeze it so I think I have circulation/water pump pumping, sound probable?

I tried the water bottle method I mentioned previously bc I saw it in a video. How can I check to see if the water pump is functioning properly? Replacing it is a rather big job for a novice is it not?

Thanks!!!
 

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Discussion Starter · #19 ·
Ok, Properly bleed, with engine off, no incline etc. (embarassing, I forgot to reattach the resevior sensor to the tank, once I did, that solved the temp light flashing right after start up) I drove around a bit. The temp was steady at 190 F for about 10 mins of neighborhood driving. I took it out on the city streets and went up to 45/50 and the temp started to rise after a few minutes and then got up to 240 F before I got back home. By the way, the temp light never came on.

The upper radiator hose is hot and feels filled with coolant when I squeeze it so I think I have circulation/water pump pumping, sound probable?

I tried the water bottle method I mentioned previously bc I saw it in a video. How can I check to see if the water pump is functioning properly? Replacing it is a rather big job for a novice is it not?

Thanks!!!
 

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I drove around a bit. The temp was steady at 190 F for about 10 mins of neighborhood driving. I took it out on the city streets and went up to 45/50 and the temp started to rise after a few minutes and then got up to 240 F before I got back home. By the way, the temp light never came on.
Did it lose any (how much) coolant ?


The upper radiator hose is hot and feels filled with coolant when I squeeze it so I think I have circulation/water pump pumping, sound probable?
The pump impeller is probably broken or slipping.


I tried the water bottle method I mentioned previously bc I saw it in a video. How can I check to see if the water pump is functioning properly? Replacing it is a rather big job for a novice is it not?
To some extent it depends on the engine code, what is it ?

The only sure way that I can think of to check it, is to remove it.


It still seems that you might also have a faulty CTS, you could check it with VCDS measuring blocks.
 
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