Kind of a stupid radiator question

[LoneWolf]

the return pipe at the top of the 1600TD rad, the little one to the header bottle, is there a valve INSIDE the spout?

[the caveman]

It just could have or be considered a restriction. I know on some others-Mk2's ? had the restriction in the return hose from the rad to the bottle

[LoneWolf]

i keep getting a MEGA pressure build up in the cooling system, but a compression test has shown the head gaskett is good 

 if i poke a small screwdriver into the outlet of the rad theres a hissing sound and the level in my header tank sinks down again

[rabbitman]

i keep getting a MEGA pressure build up in the cooling system, but a compression test has shown the head gaskett is good 
 if i poke a small screwdriver into the outlet of the rad theres a hissing sound and the level in my header tank sinks down again

A compression test won't tell you much about the head gasket. How long does it take to build pressure?

[LoneWolf]

it tells me that the compression stroke isnt pushing teh gas from the chamber into my cooling system.

 it takes about 10-15 mins to pressurise up, but when its pressurised it feels like the rad pipe could explode at any time, but all it does is blow the pressure out of the header tank.

 i think its air-locked in the rad because of the overflow pipe being unable to vent

 now i notice some of you guys in america/ canada seem to have top rad hoses with the return built into them, what im wondering, is what are your radiators like?

 do you still have the little off-shoot on YOUR passenger side above the top hose?

[burn_your_money]

I believe it is only the AC models that have the return built into them.

[the caveman]

I used to remember this stuff- like which cars had what, which part fit what else, which cat is hanging with which squirrel...

[the caveman]

First of all are you sure the system is completely full? Leave the overflow hose off the rad.  From a cold start after  only a few minutes there should heat from the heater or at least at the heater hoses.  If yes then while slightly revving the engine how are the hoses heating up? Is the top heating before the bottom, indicating the thermostat operation. Does the pressure you are mentioning build before the thermostat opens? Once slightly warm there should be some coolant coming out of the overflow. Also, do you see bubbles coming from the lower hose of the bottle. If so then, if not a headgasket ,then damaged head or block?

[LoneWolf]

maybe im not saying it right, i used to have a gti radiator that didnt give me any problems with overheating even though its half the size of the diesel one.

 if i blow down the return on the gti one its nice and clear, but the gtd one feels a lot more restricted,

 Do you think i should run a drill down the return on the rad to try and clear it out a bit more?

 The end caps of the radiators are hollow arent they?

[Rabbit on Roids]

theres no valve in there, just poke something in there, probably just a chunk of crap caught there keeping it from flowing great.

[LoneWolf]

thats what i thought, ill give it a good poke tomorrow and see what happens, hopefully itll solve the problem