After replacing the top radiator elbow, as it was broken, I am trying to find the best way of bleeding the coolant. There seem to be 2 ways either a vacuum bleed for which I don’t have the tools or allowing the engine to get warm with the expansion tank top off. I have tried the second method and the engine temperature is stable at 90° but the heater is coldish. I have raised the front of the car up so to try to encourage the air to find the highest point but I guess there must be a better method?
How to bleed coolant system
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I have always started the car, filled the radiator, turned the heat on high, fan on low, leave the radiator cap off and let the car run, as the air escapes, the water level goes down, top it off. Do this till you don't see anymore air bubbles coming out.
Due to limited space in the engine bay, the highest engine point is usually the cylinder head which can be below the level of the coolant reservoir. V.W and other manufacturers recommend vacuum bleeding cooling systems and ABS brakes. This avoids the risk taken when an engine has to be run for the coolant around thermostats to be hot enough for them to open and get flow. The most important engine temperature sensor is fitted in the cylinder head and a secondary sensor near the water pump usually drives gauges. Surrounded by air locks and water, the cylinder head may be partially filled and its temperature much higher than measured by the gauges. There are cheap vacuum bleed kits on Ebay, but most require an air line and make a lot of jet engine noise. I bought a cheap kit to use the adaptors with a small 12V vacuum pump.
Perhaps i need to run it a bit longer but why have the fan on low? I know you have to have the heater valves open hence it needs to be on high but what difference does the fan make?
Your solution is interesting. Can you post a photo of it set up or point me in the right direction?
Loads of these on Ebay to choose from. Most work on the same principle with small changes in color, style and price. As I said, using an air line works, but sounds like a jet engine and you need the compressed air supply. I can't remember which Ebay seller had the 12V vacuum pump, you don't need anything huge and something up to 10 amp max current draw and clips on the battery should be fine. I'm surprised nobody thought about what I did and sells a complete 12V bundle?
I use a Gunson pressure bleeder kit for ABS brakes which replaces the master cylinder cap. Fit, fill reservoir with fluid, pressurise to about 10-15 psi and just go around opening brake bleeders - soo simple and easy. Warning: They use pressure from the spare tire and our skinny tires are at a very large pressure. I let air out down to 15 psi before using this kit: I have no connection with either company or product.
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I use a Gunson pressure bleeder kit for ABS brakes which replaces the master cylinder cap. Fit, fill reservoir with fluid, pressurise to about 10-15 psi and just go around opening brake bleeders - soo simple and easy. Warning: They use pressure from the spare tire and our skinny tires are at a very large pressure. I let air out down to 15 psi before using this kit: I have no connection with either company or product.
I’ve got the eezibleed kit which is simple to use but yes you do need low pressure. That vacuum kit looks good and I have been looking at them but that seems a good value kit. Just got to find a vacuum pump or compressor to use it. I doubt my tyre inflater would work!
Well having left it overnight the level in the expansion tank had gone down which is good. So I topped it up and ran it and now have heat coming out of the heater! It gets a bitter hotter if I raise the revs so I may still have a tiny bit of air in it. Pleased so far!
From what I remember when I tried it you need about 60-80 psi of continuous free air to pull vacuum through their Venturi and it uses up a lot of cfm air capacity, that's why it sounded like a jet engine and annoyed my ears! The 12 Volt vac. pump was a fairly quiet diaphragm type with a bit of vibration when sat on top of the engine cover.
I thought about what you said, Tip of the Day: Some decent tire inflators can be 1 or 2 mini piston types, particularly those sold for larger van tires. They must have an air inlet probably covered by a filter and that might be usable to pull sufficient vacuum for these kits? You must make sure there's a small reservoir so no fluid gets sucked into the vac. pump. You don't need much vacuum to get air bubbles to rise from nooks & crannies in the coolant system.
Small amounts of residual trapped air should eventually work its way out after a few drives. It's the first phase of coolant fill and getting air locks in the cylinder head you want to avoid.
Well today the expansion tank is at the max level where I left it and I get heat after a few minutes through the vents. So that seems a success. Just got to sort the slam panel, wing, bonnet, front bumper, headlight out and get them painted.
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