Overheating Question

[h00per]

Overheating question. I posted a while back about my bus getting hot with WOT in 5th at 45mph. I thought that was an isolated incident, but the last couple of outings with normal driving I have seen the gauge climbing again. Today I thought I would investigate.

1. Checked temp sender voltage on Y/R wire 10v.
   
2. Checked resistances of expected gauge readings e.g. 66 Ohm for normal running, 33 Ohm for top of gauge etc.
   
3. Thought I might have an airlock, so tried to bleed system.*
   
4. Suspected stuck thermostat so pulled that out and tested it - OK.
   

*Saw the gauge rising well past normal whilst revving with the bus with the cap off the header tank and watering can in hand. Top pipe to rad was cool/cold bottom one was warm. A little background. its a 1.9WBX early cooling system. Replaced the water pump (Meyle) earlier this year as it was noisy and failing. Did the thermostat (Wahler) at the same time. What should I try next?

[Aidan]

I think I'd check the radiator out, bleed screw open first to check that it does open, sometimes they just turn in the casing because the insert is turning and the screw is staying put in which case rad is probably scrap; then pipes clamped and take lower one off and see what comes out, then both off and give it a flush with a hose both ways, then check by filling with warm water to ensure it fills properly. 

[syncroandy]

As AT says, don't rule out the rad. I've had my 1990 kombi off the road for a bit. Prior to this I'd had overheating issues. When I had the rad out, it was corroded to *&^%!