Outer Limits 4x4 Board

G'day,

I have a water to air intercooler, PWR barrel, heat exchanger and radiator connection with a bosch 0392022002 pump, fed 12V.

The pump flows about 20L/min. I am having problems with cavitation, I can bleed all the air out of the system, no leaks or anything. Have the car running and can barely see any bubbles in the water. Drive for a few days and there are heaps of bubbles in the water.

Is this a common thing for W2A systems that I just have to live with and bleed out reguarly? Or is it something else? ie faulty pump impeller ?

I have tried numerous combinations of having the pump before or after the barrel and before or after the heat exchanger.

Any help appreciated.

check the pump seals. could be sucking air in past the seals.
the other thing are you sure you have gotten all the air out of it. wheres the hose connections on the IC, on the top or side ?

Hose connection is on the side of the barrel when installed, during bleeding I remove it from the intake and drop it down low with the connections straight up. So the bubbles are more likely air being sucked in rather than cavitation? On another forum someone mentioned cavitation bubbles collapse straight away and wont build up in the system like mine do.

i'm a bit rusty on it but i don't think cavitation makes more air into the system. it may pull air out of the water but it will dissolve back in.

i forgot to ask, when you undo the cap is it under pressure?
if so its likely air being sucked in by the pump. if not you could simply be leaking water out and sucking air back in.

the pump should ALWAYS be on the outlet (cold) side of the heat exchanger as the pumps dont like heat for to long.This info is on the Bosch web site.
The seals in the pump could be stuffed if it has been on the hot side.
also might not hurt to have the barrel pressure tested to make shaw its not leaking.The boost pressure could be creating your bubbles if the barrel is leaking or even worse you could get water pumped into your engine @ 20ltrs a min if it gets to bad.
are you bleeding the air out from the highest point?

my 2 cents

Pump was originally on the outlet of the heat exchanger. Only been on the hot side a week, doesnt get that hot anyway unless I hold it on 18psi.

I have not checked the barrel that well, I pumped some air into it and held outlet closed, didnt notice any leaks. Its been on the car a few weeks now with water.

I raise the filler up to be the highest point when bleeding then put it back down when running.

Mine had always had foamy bubbles in it (has some corrosion inhibitor in there). Could never get rid of them, gave up in the end.

Does your system ever build enough pressure to overflow?

hulsty wrote:Hose connection is on the side of the barrel when installed, during bleeding I remove it from the intake and drop it down low with the connections straight up. So the bubbles are more likely air being sucked in rather than cavitation? On another forum someone mentioned cavitation bubbles collapse straight away and wont build up in the system like mine do.

Your terminology is most likely incorrect by describing your problem as cavitation.

Cavitation occurs when the suction pressure drops below the vapour pressure of the fluid. This allows the fluid to vaporise in small bubbles that collapse when the fluid moves to a region at higher pressure where the vapour condenses. The rapid collapse of the vapour bubbles causes damage to the pump components they are in contact with.

As others have said, you may be sucking air from somewhere, may not have bled all air out, or are getting vapour at hot surfaces in the intercooler particularly if you have the pump after the intercooler.

I haven't had anything to do with those barrel types or seen their instructions. If vapour can occur in the intercooler you could use a header tank after the intercooler where it can escape from the coolant. Incline the intercooler up in the direction of water flow with the outlet at the top so the vapour bubbles are carried to the header tank.

Any cooling system needs a header tank to allow the air in the system to escape and be replaced by coolant.

I run a W2A system and never need to add coolant if you don't run a header tank you'll never get rid of the water nor ensure the system is always full of coolant.

zuffen wrote:Any cooling system needs a header tank to allow the air in the system to escape and be replaced by coolant.

I run a W2A system and never need to add coolant if you don't run a header tank you'll never get rid of the water nor ensure the system is always full of coolant.

What he said ^^.

IIRC the bosch pumps are magnetically driven ( i.e. no seal... ) so i think you can cross that one out.

I didn't read the entire thread so if this has been said ignore me. The issue is due to PWR not having a header tank. Get a header tank made the size of a coke can with the outlet at the bottom and the return 3/4 of the way to the top. This allows air to escape and for you to bleed the thing without the water gong down both pipes from the filler neck and causing an air lock. The tank needs the radiator cap fitted on the top of it. We have modified dozens of these due to bleeding and air locking issues.

I'm having the exact same issue with my PWR barrel/intercooler system. I'm really keen to solve the issue as well...

I have the newest Bosch pump so as mentioned not worried about the seals.

I have given up bleeding the system because it will always require re-bleeding, generally within a week there is air back in the setup.

I'm interested in the header tank idea as this seems the most logical solution.

If the barrel is leaking, I assume +ve boost pressure would stop water entering cylinders? (ie air is added to the cooler circuit and water levels drop out the breather hose).

It would be good to sort this before I increase the radiator size (which I believe to be too small).

Any advice from those who have done this? Is it as simple as fitting a header style radiator return tank from a small vehicle to the outlet hose of the filler cap?

Cheers for the info so far.

Do you have a over flow in the system?

My dad had the same problem in his set up, we put a 600ml coke bottle in as a over flow, so when the system heats up and cools down it would it would suck the coolent back and stay full. I think thats what is happing, I would give it a go just drill a whole in the top of the lid the same size as so small hose push it in and put on tho the barb of the over flow.


And like i said my old man had the same problem and this fixed it, never had any isues after we did this.


Red Dog