Golf TD cooling issue

[Doug]

When idling, temperature guage climbs into hot range, gets there even faster when driving a very short distance. All fluids are normal, no oil in coolant, no coolant in oil, belt to waterpump okay, thermostat changed, and return line to reservoir has a steady stream of coolant. I dragged this one out of the weeds to get it running a couple of weeks ago. System seems to pressurize okay. Motor runs fine, starts fine, sounds good. A hand on the lower rad hose seems to indicate that the thermostat is not opening as it should be or that there is a blockage in the water pump. Before I start ripping and tearing does anyone have any interesting experiences similar or suggestions.  

I remember Renault used to have a special coolant system bleeding procedure to get air out of the coolant otherwise engine would overheat with an air lock. Possible with the VW?? I have had several NA diesels and there was never an issue. Just fill her up with coolant and go.

I should add that this engine was shoehorned into this car which was originally an NA diesel. I am not sure if the installation was really completed properly before I got it. It remained dormant until a couple of weeks ago. Give me all your ideas.

[irdiver]

the water pump is probably vapor locked, pull the cap off of the fill bottle and start the engine, that should allow the bubble to remove itself, as im sure you know vw's are a sealed coolant sys, if there is no way to let the bubble out it will just sit there.  or you could have a stuck thermo from the car sitting.  im sure some of the other people on here will have other suggestions as well.  good luck!

[jtanguay]

my suggestion, get yourself a nice thermometer, turn on the car take the rad cap off, and wait till it gets up to temp. The coolant will start to boil over out of the rad reservoir too (not good, but it must be done).  You must also let the engine cool with the rad cap off (this is essential).  When the thermostat opens the temp should drop a few degrees instantly.

the air will escape from the long thin hose running to the reservoir tank.  At this point you can verify your rad fan turns on etc.  If it doesn't, turn on your heater motor at full blast and let the engine cool a bit. then turn off.

btw, my problem was the same as yours.  I replaced my thermostat as well.  At first I was affraid some crap got into my rad.  The whole driver side of my rad was cold, but the engine was getting real hot (around 90C) and my fan wasn't coming on (because the sensor is on the driver side of the rad...).  I tried running my engine with the rad cap off for maybe a minute but that didn't release the air.   Flushing the engine was easy because I had the thermostat removed.  With the thermostat installed, only air pockets in the engine bled off.  Only way to bleed the rad is to let the engine get up to temp.   (I was worried about steam from the tank, but it's not much at all)

for your safety and environment, have some towels around the reservoir just in case a lot of fluid comes out (i had a mess... but washed it right away)