Bleeding under bus radiator

helbus Administrator Mad fabricator, paint and body

7,386 posts · joined Sep 2002 · 21 Mar 2009, 12:34 pm

#702241

Got a small pinhole fixed in the radiator under the bus. Had to drop the water of course. Now this pinhole repair is the only thing that has been done. Everything else is the same, and it all worked before.

Now I am having trouble bleeding the air out.

The back of the bus has a header/ bleed tank. This is also the fill point.

I undid the hose on the actual radiator and held it so it hissed air until it started dripping water.

I am thinking maybe jack the back of the bus up.

I checked the thermostat and it is a standard genuine Subaru 78C, and checked it opens at the right time and right open. I checked the heater bypass circuit and it is looped as we have no heater yet.

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modulus Veteran Volks Folk

2,009 posts · joined Jul 2003 · 21 Mar 2009, 12:59 pm

#702243

Can you get it so the back end is on car ramps and the front end in the gutter of your drive? i.e. as nose-down as possible - then bleed air, run engine for 20 seconds, repeat....

hth

Peter Hill
1975 Type 2 Double Cab
modulus.com.au

ElusiveStranger Officially Full-On Dubber

330 posts · joined May 2006 · 22 Mar 2009, 4:53 am

#702345

Get as much air out as you can & get her up to temp (stat open). Hoof it from a standstill a few times. Works for me.

Getting those last few bubbles out is a PITA. Mine has high spots in low places - hope you understand what I mean.

helbus Administrator Mad fabricator, paint and body

7,386 posts · joined Sep 2002 · 22 Mar 2009, 11:13 am

#702380

I did it. I put the back up on wheel ramps, then undid the long hose on the drivers side that comes off the thermostat housing and comes from the radiator underneath. I cupped my hand hard over the end of the hose to seal as I fed the garden hose on full pressure down the couple metres of hose until the garden hose stopped at the radiator under the bus. All the time, the water that the garden hose was putting in was force feeding through the system backwards and water shooting out the header tank. Then I unfed the garden hose and quick as lightening put the radiator hose back on the thermostat housing.

Ran it for 20-25 minutes. The first ten or so minutes the temp sat exactly on 80C on the temp gauge. Then it crept to 90 over the next few minutes, then the thermo fan come on and it dropped back to 80. Over the next 5 minutes it did this twice. Seemed pretty normal. The water level dropped in the header tank afetr a few small burps requiring about 200ml topup

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helbus Administrator Mad fabricator, paint and body

7,386 posts · joined Sep 2002 · 22 Mar 2009, 5:46 pm

#702433

Had to go to do a few things and see a few people today. Did about 100km test driving in all conditions. Traffic, hill climbing, freeway etc. The temp never went below 80, and stayed there when cruising. It never got higher than 90, even after a labouring 4km climb up a constant gradient and then stopping at a traffic light idling.

Seems like a success. Now to add some coolant.

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20bkombi Wolfsburg Wizard

597 posts · joined Mar 2009 · 22 Mar 2009, 8:07 pm

#702475

hi, glad to see you got it sorted, thats the same way i fill my fathers ej22 up, and will stick to it!!! plus a steep driveway helps.
As for mine, i have an electric water pump, so the engine doesn't have to be on which helps a lot.🙂

AARON'S SPEED SHIFT AUTOS
Specialising in Vw automatic transmissions, differentials and torque converters
Stock or modified to suit your application (street, drag, off road)
Ph 0402 233 027

GeorgeL Officially Full-On Dubber

231 posts · joined Feb 2006 · 23 Mar 2009, 2:37 pm

#702582

helbus wrote:Had to go to do a few things and see a few people today. Did about 100km test driving in all conditions. Traffic, hill climbing, freeway etc. The temp never went below 80, and stayed there when cruising. It never got higher than 90, even after a labouring 4km climb up a constant gradient and then stopping at a traffic light idling.

Seems like a success. Now to add some coolant.

The geometry of your system makes it seem that a healthy nose-down attitude would make bleeding fairly easy. The big issues are with high spots along the hose runs. If you can tilt it enough so that the air gets out of those you probably have the problem solved.

I don't know about the quality of your water, but we don't run anything but distilled water and coolant here. The minerals in our water do bad things to cooling systems.

helbus Administrator Mad fabricator, paint and body

7,386 posts · joined Sep 2002 · 23 Mar 2009, 6:37 pm

#702641

Yeah it is the high spots in the hose runs that cause the air bleed issues when first charging the system. I have dropped the water from the engine side and it has not had this effect.

Water quality is fine, it is not hard, and not mineral ridden. I will drop about 5 litres from the motor/ header tank side, and 5 litres of coolant will give me about a 33% mix. Whilst not creating any air locks. It seems only a radiator removal will do that.

Next time I want to change water/ coolant, I will go to my mates mechanical workshop, get the bus one end up on his hoist to about 1 metre up on the rear, and it will easily bleed past any high spots in the 2 metre long radiator hoses

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GTMac Fahrvergnugen

976 posts · joined Nov 2004 · 23 Mar 2009, 9:02 pm

#702680

had big issues with my EJ20 in the Fasty. Fixed it doing similar process but actually made up plugs for the process. Machined up 2 x 10cm lengths of timber on the lathe that would fit snuggly into the rad hoses. One of these pieces had a hole drilled through the middle that took the bare hose. This way you can take bottom rad hose off and blast water back through engine and leave the header tank open, all air will bleed out. Put header tank cap back on, put bottom rad hose back on (rad tank will now be empty). Put plug with hole in it into the top rad hose, take header tank cap off and blast water, should only be small amount of air caught in that rad hose. Continue water but put header tank cap back on and then the rad will fill up taking any air in the rad to the top.

Trust my memory serves me right on how I did it but this method was fool prooth and too about 20 min.😊

Saves using the cupped hand method. May be slight different process in the under mount bus version but similar and you get what I mean!

1971 Type 3 Fasty - EJ20T

I love 242HP sleepers. 🤪

How many sets of lights does it take a $229k Carrera S to learn? 😂 UPDATE: Cayman S, M3, B4 now added to the list.

GeorgeL Officially Full-On Dubber

231 posts · joined Feb 2006 · 24 Mar 2009, 4:52 am

#702724

The watercooled vanagon folks use the "tilt nose down" method along with a bleed valve at the top of the radiator to get air out of that pocket. The under-bus radiator should be able to avoid that issue as it doesn't have the "high point".

I'm rather leery of the Vanagon design since it just about guarantees an airlock if an air leak develops in the system. The under-bus radiator with a good swirl pot is much better in this regard as regular vehicle motion and flow will flush out just about every bubble.