Pressure in coolant system

[Sean1989]

I have fitted a new radiator, water pump a couple of hoses and a thermostat to my 95 bongo,
I have followed the bleed up process as shown in the video until the thermostat opens and fans kick in fine,
However when I run the van out there seems to be pressure in the pipes and the thermostat struggles to open, all the heaters work ok and I have done a sniff test is ok , the thermostat does open if I give it some while stationary ??

[Sean1989]

Should there be a fair bit of pressure in the pipes?

[Northern Bongolow]

during normal running when up to temp the internal pressure is about 10 pounds, the fans first stage come on at around 12-13 pounds, full fans a tad higher. the system safety valve (the expansion tank cap) is set at 1.1 bar =15.95 pounds.

in a normal healthy system you will struggle to get above 12-13 pounds, this is when the fans kick in so the temp will then fall along with the pressure.

i use pressure gauges to monitor my system and ignore temperature altogether, this ive found more reliable as temps are only measured at the sensor, but pressure is measured on the whole system, an increase is temp anywhere can be detected via pressure
hope this helps.

[mikeonb4c]

Rubber hoses should be firm, but squeezable. One thing you can check is if they make a crunching sound when squeezed (from cold when its easier to squeeze and distort them). If they do, it suggests deposits/clogging associated with a clogged system that has not had its corrosion inhibiting anti-freeze changed often enough. In that case the system (radiators especially) is likely to be obstructed leading to risk of overheating and back pressure in the system (causing affected hoses to feel rigid with pressure). I think I've got that right but no doubt the techies will correct me if not. The firmness/crunch test advice though comes from Adrian at JapanDirect in Bury, who services mine and who knows his stuff.