Club 80-90 Forums

bootie3367 wrote:OIl changed and started the bleeding process.
One man band time so although I got water coming out of the bleed screw at the rad I was unable to do all the things required, every time I backed off from 2000 rpm the coolant came back at me and overflowed the tank!
So today armed with the last of my coolant I will find a friend and get this bled!

Rev the nuts off it with the cap off, as the level drops add coolant to fill up tank, replace cap, drop the revs. 5 second job if you only need to do it once. One man job.

Sounds so easy and thanks for that.
In this case I think I need to follow the wiki to the letter as there was no telling how much coolant was lost and I do seem to still get bubbles back every now and then.
Oh and I've just discovered a leak from the heater hose stub on the rear of the cyl head, the one that has the temp guage and glow plug relay sensors, better take some coolant out and sort that while I'm doing this.

The heater hose stub had a small crack in it! So, did the usual and had a look on ebay, both UK and ES(spain) all good prices, ranging from£7.90 to £13, postage as always a killer, nothing local in spain, all coming from UK or germany with a delivery time of 4 to 7 days!
Didn't want to wait that long so, on the offchance I popped into our nearest main VW dealer with the offending part................... Result, they had one in stock! The nice chap (who also spoke some english) chucked in the sensor 'O' ring for free, grand total of €16, wahaaay!
So to understand the bleeding process a bit better, I take it the 2k revs is to make sure the pump forces the coolant up to the rad or else it will just circulate locally and just get hot v quickly yes?
For me I really want to do this by the book (wiki) so this is a 2 man job, one topping up and the other watching ready to close the bleed valve yes?

Jon

I am sure Simon will not mind me posting his treatise on bleeding - I can't be bothered to check the wiki to see if it is in there, if it isn't it damn well should be!

parts in the system you need to know about.

Engine, the noisy thing in the back
Radiator, the big heavy thing at the front, 2 types, early 1.6D "CS" type with 2 switches towards the top, these are crap and if you even get the opertunity to upgrade to the later style please do. For some reason VW put the fan switches at the top of the radiator, if you have a leak and air is introduced into the system then coolant drops below the fan switches level, and they don't work! Well done VW for that one, clever boys.
Anyway, they soon realised the error of their ways and changed to a much better radiator, and they put the fan switch in a sensible location towards the bottom of the rad, much better.
The radiator, early CS or later style have a bleed screw at the top to let the air out, much like the ones on your radiators in the front room (unless your Welsh, but there are no 3 bar fires on a wedge!)

Header tank, the one INSIDE the engine bay, the one with the pressure cap, this must always be full right to the top, always, forever, period, fullstop.

header tank cap, Make sure your header tank cap holds pressure, there are a few types, the early push and twist ones (rubbish) the later screw on ones, these come in 3 flavours, Black, usually knackered by now, Blue with 2 visible round valves in the business end, usually knackered, and the best of all, the later blue ones with no visible valves, they also make quite an impressive "quack" noise if you blow down the spout. (025 121 321 B)
If you are in any doubt, replace it.
The only 100% reliable way to test a cap is with a pressure tester.

Expansion tank, the one behind the flap (heh, he said flap) the level of this goes up and down with engine temp, only time to set the level of this is when the engine is clap cold as it is the only constant you can get, run it for 5 minutes and the level may have risen.

Thermostat, usually open about 87°c, it stops coolant flowing to the radiator when the engine is cold to let the engine warm up quicker, once it reaches a preset temp it gradually starts to open and lets coolant flow to the radiator to cool it down.

Fan switch, turns the dirty great fan behind the radiator on at a set temperature, usually comes on at 87°c and goes off around 76°c the thermostat and fan switch do a really good job of keeping the temperature of the engine regulated, thermostat opens, coolant goes to the front, rad temp reaches 87°c, fan comes on, cools coolant, temp goes down, , thermostat closes a bit, fan goes off, engine warms, thermostat opens more,fan comes on, la di da etc, you get the picture.

Heater circuit, is like a minature cooling system, it has pipes, a radiator (heater matrix) and temperature for the heater is controlled by a remotley controlled valve (much like a tap)


Bleeding the system.


Lets presume you have a totally empty cooling system, say, you have changed the front to rear coolant pipes.
The T3 cooling system takes somewhere in the region of 16 litres of coolant, so for a 50/50 mix you need 8 litres of antifreeze.

First off, if you are filling a completely empty system, undo the bleed screw on the radiator, like we said earlier water finds it's own level, if you don't the job will take longer and you will use more fuel!
make sure heater controls for front and rear heater if fitted are in the hot position.
So, pour in neat antifreeze first until you can't get anymore in.
Close the bleed screw.
Fit header tank cap.
Start engine.
Remove cap, now pour as much coolant in as you can.
Once you can't get anymore in, rev the engine to 2000rpm ish.
The coolant level will drop, add more coolant till you can't get anymore in.
Keep revving, screw the cap back on, if you let go of the revs without the cap on and the level will swiftly rise and you will have just wasted a "pooh" load of new antifreeze onto the floor, well done!
Okay, Got all your antifreeze in yet? You need to get that in first before you put any water in.
Go to the cab and give it a right good rev!, like a right good up to the redline rev!
Go to the radiator, undo the bleed screw and let some air out.
Go to the back, undo the header tank cap and add some more coolant, if the level has dropped a load, rev it to 2000 rpm again and get a load in till no more will go, cap on.
Go to cab, give it a rev, go to rad, let some air out.
Once you get to a piont where it feels like you can't get much more coolant in, then go to the cab and have a break, sit down for a minute and keep it revving at 2000 rpm to get it to warm up quicker.
To make it look like you really know what you are doing, flick the heater on and see if the heaters are starting to blow warm, for a real manly "I'm a mechanic me" look, set the heaters to demist and hold your hand above the vents, works great and if the missus is watching you may even get a brew out of that one.
If the heaters aren't even tepid yet, rev the nads off it again.
The heater circuit isn't controlled by the thermostat, so the heaters work regardless of thermostat position.
Once the temp gauge starts getting towards 1/2 way best let some more air out so let it idle.
Go check water level.
Top up as needed.
About this time I like to fill the expansion tank up right to the brim and attach the pipe from the header tank to the expansion tank cap.
Give it a rev, let some air out.

Now, listen to this bit, it's kinda fundamental as to how the system works.
The cooling system is meant to run at about 1 bar of pressure, thats about 15PSI in old money, that means that the coolant won't boil until about 115°c
So, the header tank is full to the brim, the cooling system reaches 1 bar and a valve opens in the cap and lets the excess pressurised coolant out into the expansion tank, the level in the one behind the flap rises.
once the engine cools, the coolant cools and contracts, if the system were to be totally sealed you would get rubber hoses collapsing, so inside the header tank cap is a second valve, a vacuum valve, this opens at some pressure or other (dunno that) and lets coolant from the expansion tank back into the header tank.
This keeps the header tank constantly topped up with coolant and no air in the system.
Right...
back to bleeding..

What we are doing here is warming the cooling system to increase it's pressure, we are using this pressure to expell the air trapped at the highest point by letting it out of the bleed screw.
easy really when you think about it.
When did you ever see your plumber with a acro prop under your house jacking it up so he could bleed the radiators?
You didn't thats why, so why should you do it on your van?

Right.
Where is the temp gauge? as we mentioned before, the thermostat and fan do a really good job of keeping the engine temps stable, from new the gauge should come up to half and stay there more or less, just over half fan should come on, just below half and the thermostat will start to close and bring the temp back up.
If at any point the needle goes over 3/4's you may have a problem.

Always run the engine up to test the cooling fan works.

With the engine running, cap on and pip to the expansion tank connected, i find it helpful to unscrew the cap with the pipe connected to let the last bits of air out.

Go for a good run

Come back.

Let some more air out of the rad, once it runs warm water with no bubbles it's done.

let it cool, check level when clap cold in the expansion tank.

If this doesn't work you are either stupid and havn't listened to the above or you have problems, possibly head gasket problems.

Thank God mines Aircooled

OBG, I have read the above and I thank you! very comprehensive.
I will do this once I get time probably tomorrow after work.
I will report back sir!

I humbly bow down before the might of knowledge that emanated from OBG!
Suffice to say I had a nice drive today, a little uphill, then a little downhill.

Uphill was as before, she does get slightly hot, enough for the fan to kick in but didn't reach 3/4 on the gauge, hills are fairly steep and twisty so no decent airflow.
Downhill slighty more rapid and temp gauge drops nicely to just under 1/2.

Have yet to take on the motorway, maybe a bit later on after it cools down here, currently 27, and thats up here in the mountains 900m high!

Only thing I have noticed is a lot of black smoke under acceleration. Now she didn't do that before..... I had a leak from the LDA shaft so I replaced the seal, when I removed the old seal there were two washers on top of it, just wondering if that was restricting the shaft movement. I'll have to have a read up on the LDA and see exactly how it does what it does. I must say there does seem to be more oooomph since changing that seal.

Once again, eternally gratefull to OBG for helping me out with this.

Jon

....and dont forget clogged up hoses feeding into the bleed rail thanks to P.O. using "Barrs Leaks" and other vile stuff! They are not your friend and can cause endless frustration... the one coming off the top of the thermostat cover (late petrol system) seems to be a favourite for sludging up.

Sent by Morse code from the bunker

Oh, I think any sludge would have been well 'steam' cleaned internally , but yes, I think I will do a complete change of coolant in the near future, after all, I can't get any blue coolant out here easily.

Jon

Today was a good day!
First long run since the *coughs* episode *coughs*
It may not sound much but 110 km to a place called Turre, 90% motorway and she was quite happy sitting at just below 3000 rpm, on the speedo 90kmh.
Temp gauge rose and fell as expected but no more than 2mm movement from the bottom of the LED to the top mimicing the relatively easy ups and downs. On the ups it felt that there was always a little bit more power should I have needed it, in fact the only time I had to change down was caused by 2 'knights of the road'duelling it out on the steepest uphill section on the way back

The only slightly grey cloud on the horizon is the tendancy to get hot on the way back up our mountain, the bottom of the needle is past the LED and after every swinging uphill righthander (down to 35kmh and under 2000 rpm) the BOD chirps until I can get the revs back.
Before, I used to just put the heating on and carry on, now, I pull over and give her a chance to cool down before the really steep twisty bit..... besides you get nice views (must remember the camera tomorrow!) and the weather is not too shabby!
All in all I am very pleased with the way she conducted herself.

Jon