QuestionQUESTION: Hello, My father-in-law & I are working on my beetle which overheated (big time) a couple of weeks ago. After a lot of time & money it is STILL too hot! So far, the new parts are...water pump, thermostat, thermal radiator switch, radiator, timing belt,. What else could possibly be wrong? What are we missing? I need my vehicle back to get to work! Thank you so much.
ANSWER: Tim; When you refilled the radiator/cooling system with coolant, did you vacuum refill the system to eliminate all of the air pockets inside the cylinder block, and the cylinder head?
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QUESTION: By the way, I just read your instructions. Here's the deal...
1998 VW Beetle - AEG 2.0 - 117,000mi - Manual Transmission
The water pump impeller was melted and I also replaced the coolant hose flange as there was a significant leak in it. I cannot detect any coolant in the oil, nor have I seen any white smoke in the exhaust. The fuses and fuse housing on top of the battery look fine (nothing melted underneath).
It is only overheating (the light/alarm comes on) after a very short drive. It seems to be fine when idling; however, I did successfully drive it about 1/2 mile without any issues. I tried the same thing later that day & the alarm went off again (after only 1/2 mile).
In response to your answer/question: No, I couldn't find any special information on how to refill it. Does it require a tool?
We have also replaced the aux. fan control module due to a problem with the fans. This did not resolve the issue. They are running at low speed but not high speed. I shorted (as suggested in the Bentley manual [red-red/white for low speed and red-red/yellow for high speed]) across the thermal fan control switch harness to rule out the possibility of low coolant or an air bubble. The fans run fine at low speed, however, do not run, nor is there voltage at the fans when I attempted to short it for high speed operation (red-red/yellow). Sorry about the light description earlier. I am really frustrated with this.
ANSWER: OK Tim;
Thanks for the additional information. Don't treat the Bentley book like it was the bible, and don't take everything I say as gospel either. Everybody has a different way of doing the necessary repairs. However, YOU SIMPLY CANNOT refill the cooling system in a Volkswagen without a vacuum assist tool. There are no provisions for releasing trapped air through a vent, and fitting anyplace on the cooling system.
The name of the tool I personally know of is "AirLift." It has a conical shaped rubber fitting that fits into the reservoir, 2 other fittings that attach to the conical part, and it requires shop air to operate...ie., you have to have a compressor to pull the vacuum into the radiator, engine block, and cylinder head. It will require one gallon of fresh coolant..recycle the stuff you've already paid for once...I know this is an added $22.00 expense, but the stuff that's in the system now has been overheated now how many times? It's left behind some crust and lost some of it's ability to perform. Mix the 1 gallon of fresh coolant with one gallon of water first, and have the 2 jugs of coolant ready, and standing by. Apply a little petroleum jelly to the conical thing where it contacts the reservoir to minimize the possibility of vacuum leaking at the fill position. Pull the vacuum down to about 1.5, to 2 Atmospheres, and let it sit there for about 3 to 5 minutes. If the needle in the vacuum gauge drops in a way that is fairly rapid, there is a leak, the system needs to be pressure tested, and you need to save your fresh coolant until the leak is repaired. But, if the system loses only a small portion...10, to 12, maybe even 15% of the vacuum it can be attributed to the seal around the neck of the conical thing, and you should proceed to refill your cooling system at that time. Insert the filtered end into the first jug of coolant mix, and the other end on the fitting at the conical thing, release the vacuum, and watch the coolant level in the jug. If someone is there to help out even better, because one of you can watch one, and the other can watch the other..sorry. Anyway when the first jug approaches empty, there should still be lots of vacuum showing in your gauge. Stop the flow with the valve, and insert the filter screen into the fresh jug. Release the valve, and watch again as the system completely fills. It should actually over fill itself using this method. However, just leave the extra coolant in the system as the water half of the mix will begin to evaporate, and over time the level will go down.
Don't have an emotional reaction to things that you have no control over. This car is just a thing, not a close member of your inner circle of friends. I know you're frustrated. I would be too. I'd probably have thrown a wrench through the windshield by now, but once you get frustrated, and emotional, you lose the ability to work on the car, and fix it. So, Bentley manuals are great tools, like the wrenches, and sockets, and screwdrivers in your tool box, but you wouldn't use a 15mm socket to remove a 10mm hex head bolt. I personally believe that Bentley is just the wrong tool to use to refill the cooling system. How much sense does it really make to run an electric fan on the outside of the radiator to ensure that there are no air pockets inside the radiator? Did I misread that or did they actually publish that rubbish? Why would you willingly short a fuse, or relay that carries that kind of current? It's rated at 30 amps, isn't it? With a 280 Amp(DIN) battery, you should have welded some sculpture. It's like using a 550 CCA battery to make absolutely certain the relay, and/or fuse never works again, except to ALWAYS pass current.
Please forgive me, I didn't mean to spank you in public, I'm just awestruck by the inaccuracy of the book I tell people to read, and use all of the time.
You seem like a talented, smart, and reasonable fellow, Tim, and I know it's a lot more money to spend on a tool that you may only use once or twice, but without it you are never going to cure your overheating problem, and if you get frustrated enough you might just "give the car away," only to have some young guy with a vacuum assist tool remove that airlock, and start driving your car for another 100,000 miles.
This is one thing I am absolutely sure of. The air bubbles and air pockets have got to go, and this is the only way I've seen work.
Please forgive my little departure from the subject at hand, and good luck, Tim honestly. If you have any need to get back to this forum, I'll be glad to hear what you have to say, or ask. Thanks for your patience.
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QUESTION: Right as usual Rocky!
It seems to have been air causing the overheating. I have put nearly 140 miles on her with no temp light and am ecstatic!
Early on in my troubleshooting I discovered that the fans were not spinning (no doubt, at the time, due to a plugged radiator, which was later confirmed, not allowing hot coolant to trip the thermal switch). I troubleshot the issue as if the fans were the problem at which time I learned that I could (using a fused jumper) test the wiring and aux. fan control unit. After purchasing a thermal switch I also acquired a thermal laser gun and was then able to determine that the coolant wasn't circulating properly, replaced the water pump and radiator etc. (later) but were baffled how after replacing 2 bad parts the overheating continued. Naturally (being a poor frustrated weekend technician) I placed the blame squarely on the fan's controller module, replaced it, then asked this forum for help and the rest is available in the writing above. I still cannot get the fans to run at high speed using the test in the book and am a bit nervous that they may return my headaches later when the weather gets hotter.
I do feel as though my previous question may have unwittingly corrupted your view of Bentley Publishing, however and I wish to explain. The Manual does explain the fan testing procedure, but I am not sure why I said that this was to rule out air pockets; maybe it made sense at the time or maybe I meant to revise that sentence later. Either way, I hope I didn't contribute to anyone throwing away any books because of it.
You are truly a talented technician and your help with this issue has been the best!
Thanks again!
AnswerHey Tim; Thank you for your kind accolades. I am greatful to any reader who can follow what I have said, and make heads or tails of it. I talk with my hands a lot, and without the gestures am afraid no one can understand me.
No problem with Bentley publishing either. I think they are the best available resource out there. They are far better than any other alternative I personally have found. I referred to the excerpt as rubbish, only because it made no real logical sense. No matter though, you are back on the road, and that's what matters here!!! Have fun, Tim, and I hope your car runs long and hard.
