Radiator pressure test procedure 2.0ltr petrol

[Roy748]

Hello all
I appear to have a coolant leak on my 2001 2.0ltr petrol bongo. When driving no loss is evident (coolant alarm fitted) but over night some coolant is lost. I have searched but cannot find any visible leaks, suggesting it's most likely a tiny leak.
My question is therefore can some knowledgeable guru explain how to conduct a radiator pressure test, from start to finish please.
Thanks in advance

[g8dhe]

Not sure what you expect the pressure test to tell you ? Your loosing coolant, hence you have a leak, a pressure test won't tell you where the leak is. You have to visually find it, have you checked the water pump tell-tale holes (two of them) for signs, have you checked the top of the radiator the metal/plastic seal is a common place for a failure, some people have had cracked bases to the de-gassing tank. Have you tried the UV dye approach ?

[Billybongo123]

You put 2 bar pressure in the system using the pump unit, You then carry out another inspection. Any leaks that are hard to normally find tend to show up much more easily.

[Billybongo123]

You want to test the full system though, not just rad.

[Bob]

I'm sure Northernbongolow posted his design for a home made pressure tester.

A search may reveal all.

[Northern Bongolow]

the system has a max pressure of 1.1 bar, the cap is the safety valve on top of the expansion tank, (not the radiator). putting 2 bar in the system may find leaks that you dont have.
on bongos with a bleed pipe i just fit a gauge and tyre valve into the end of the bleed pipe and inflate the system with a pump to 1 bar max, any small leaks usually show quickly on the floor or if your struggling to locate it look at the gauge, if the gauge drops your not looking hard enough. . make sure the gauge is fitted to the correct side of the valve so it reads system pressure not inflation pressure.

if you dont have a bleed pipe like on the 2ltr. get an old cap and remove the bottom seal , but leave the top rubber seal intact, fit this modified cap to the expansion tank, inflate the system through the short vent pipe on the expansion tank fitted again with an old tyre valve and watch the gauge or splash in the puddle on the floor.

most leaks can be detected in the above ways apart from the dreaded cracked head, but can still sometimes show a drop in the pressure. another hard to detect leak which can seal itself with positive internal pressure is the water pump seal, the water pump usually leaks when the system is cooling down and the pressure is dropping or has dropped completely to a neg pressure.

[Roy748]

Hello all.
Thanks for your time and thoughts. Northern Bongolow I will try your method, I have just ordered a uv dye kit too which I will add upon delivery. Hopefully one of these methods will prove successful.
Out of interest if its the head would some uv dye be present in the rear exhaust outlet?
I am hopeful it's not the head as I have been driving around now for 180 miles and no loss is present upon my return just after being parked up over night. The temperature gauge has never gone past 12.o'clock and no water residue is present in the oil filler cap.

[Flanners]

I gather from here the 2.0 is not prone to HGF so given you have not stated there has been any overheating issues all should be good there, more likely a hose, waterpump etc?

[Billybongo123]

If it leaks at 2 bar, the clip is crap and not up to the job.

[Billybongo123]

You are correct though on system pressure etc, I've never had issues testing a tad higher. It's not enough to damage anything and any weak areas are highlighted. The systems have a decent safely factor built in anyway. If something fails it was ready anyway.