Rust in radiator - Overheating

[worm]

Hey guys/gals

My mk1 has got a MAJOR rust problem within the coolant system. The water was brown and the insides of the hoses i checked all had brown goo in them.
So I flushed the system out in the hope to fix the problem.

First I disconected the lower radiator hose which goes from the radiator to the waterpump/thermostat. As below.



Once the hose was disconnected and ALL the water had ran out i took out the thermostat which is located in a plastic houseing of the water pump. See below. Undo the 2 screws and ake off.



Next I reconnected the housing and hose (without the thermostat) and removed the top radiator house which connects from the block to the radiator. Stuck a hose into the radiator, turned on the hose, and flushed it out. I also has the car running for about a min until no more brown muck was running out.



Once I had the thermostat out (see below) I had to see if it worked.



To test, I put it into a cup and heated until almost 100 degrees. It should be fully open at 94 degrees. As u can see below, it opened fully.



I put everything back the way it was and filled her up with coolent. Made sure there where no leaks and started the car. Once running for a few minutes I re-checked for leaks.

Mine still overheats. Because it was so badly rusted I think it may need new radiator, water pump, hoses. I also NEVER noticed the fan come on, so this my me broken also.

[Golf Loon]

Check the fan wires first. Notoriously dodgy. Have you got coolant in the syetem, as well as water? Fix the fan, then see if she still overheats.

Then I`d do radiator and then waterpump.

People on here can help if you need bits.

[worm]

Could it be the fan cut in thermo? Im not sure exactly what it looks like, but im guessing its the round thing thats in the radiator with 2 wires hangin out of it?

I only have coolant, is this bad?

One other thing... where abouts would the needle be on the temp guage in the car when the fans cut in... It got just over half way, maybe a tad more, when I freaked out and turned the car off.... I might add, it got to that temp rather quickly also.

[imported_brackie]

Hot wire

Hot wire the fan by supplying 12V continuously to it. If the fan works then the problem will be the fan switch. While it's hot wired, keep the motor running at just above idle. Observe the temp gauge. It shouldn't go past 2/3. If it does, and you're sure the thermostat is OK, you have a blocked radiator core. No drama. It can be cleaned by a radiator specialist. (In truth you can do it yourself if you know how!)

[Golf Loon]

Gague should be at middle or slightly after when fan cuts in.

You have until the red mark and a red warning light also before you need to turn off engine instantly.

[worm]

Just for future reference, if anyone does a search for similar problem.

Fan didnt come on, so I hot wired it on, and the temp didnt reach above 3/4. So this means there is a problem with the fan switch.

I also found a slight kink in one hose, although i doubt this wold cause it to run hot. I removed EVERY cooling system hose, and removed as much "rust gunk" (for lack of a better term) from them as possible. Problem must lie within the radiator or water pump. Will get the system flushed.