Engine overheating when driving/idling - What to check?

[PeterS]

Jonas - if you can unbolt the hydraulic pump and lift it slightly you may be able to get access to the thermostat cover mounting bolts from the front of the engine

[Jonas_R]

And if I can't then I suppose the main rad needs to go out?

[Jonas_R]

Ohh yeah I checked the flow through the main rad and it is fine.

[PeterS]

what it comes to is how much of the stock radiator ducting in place, and whether you have the secondary radiator in place - that's what limit your access

[Jonas_R]

I have all of it

[quattro-nick]

have you checked that water comes out the little hose above the water reservoir when engine is running?
if there is no flow at all on the little tube,maybe the connection on radiator side is blockked

[sjw185]

I had similar issues recently on track car build.
Bottom of radiator not warming up, fan not coming on?
After warm up stopped engine and opened expansion tank but no pressure.
Replaced expansion tank cap and all was well.

[Jonas_R]

have you checked that water comes out the little hose above the water reservoir when engine is running?
if there is no flow at all on the little tube,maybe the connection on radiator side is blockked

Water is running through the little hose.

[Jonas_R]

I had similar issues recently on track car build.
Bottom of radiator not warming up, fan not coming on?
After warm up stopped engine and opened expansion tank but no pressure.
Replaced expansion tank cap and all was well.

Same symptoms, but there is pressure when you remove the cap.

[mike74]

try bleeding it again....these things are a pain to bleed right

[Jonas_R]

Yeah I need to bleed again anyways since I checked the flow through the main rad yesterday.

I will try and use rusty's method as described here:

http://www.s2forum.com/forum/showthread.php?t=46952

[Jonas_R]

Just reading that method a bit more and I don't understand how you can bleed a system with having the engine running?

I would think that I need to do the following:

Run engine up in temp and have heater on Max

then open the two bleed nipples

Close them when water comes out.

Or should I do it another way?

[mike74]

The way I did mine was to have engine running with bleed screw on radiator open. Undo screws holding expansion tank in place and lift this tank up as high as you can get it (probably only a few inches). When water starts to come out of the bleed screw then re-install bleed screw. It helps if you can squeeze some of the hoses while doing this.
That method only got me so far and there was STILL air in the system, no matter what I did. I then resorted to opening up the little plastic bleed point at the bulkhead, on one of the heater matrix hoses with engine running. Using a small funnel I then dribbled some coolant in there until it started to come out of the bleed point. After that it was fine and temperatures returned to normal.
Note I only employed this second part of the process after trying for a couple of months to bleed it using the first part. I discovered this method out of pure desperation and frustration!
There's no harm in trying this and might save you having to pull the radiator out

[quattro-nick]

i have worked many times on the cooling system from a b3-b4 cars and this is how i bleed it:
-loose the screw on radiator and fill water in the reservoir until it's full
-if there comes no water out the radiator,take a little funnel and put it on the radiator and fill water with it untill it's comming out
-for last i remove the 2 heater hoses and full the 2 also with water untill i see water rises in the reservoir(without sealing cap) or you can remeove the bleedscrew and put the little funnel on it and fill it with water untill the water rises in the reservoir

[Jonas_R]

How can you bleed the system without running the engine up in temp and getting flow in the water?