Bleeding help. Non standard engine change

[tommobot]

... although, Wil a pressure bleeding test think work? The header tank has an overflow etc.. won't the air just escape via that?

[tommobot]

I think the OEM 5 series header is to the side of the rad.. really wouldn't work in a defender.

This arrangement is how the OEM m52's were, or at least not a million miles away..

[tommobot]

I've lost track of the exact quantity of fluid in the system..

I wouldn't have thought I'd managed to get 10L in, maybe 6L at a guess. Surely that's my point if there's a big airlock which I'm trying to shift.

I've ordered a pressure bleeder so will see how it goes

[tommobot]

As per factory M52... It was the same on my 200tdi..

[tommobot]

So armed with a vacuum refill kit and a pump test kit, I still haven't got this sorted.

I'm fully prepared for being told Ive been stupid.

The vacuum refill, works as it should... Holds a vacuum of about 23 whatever the gauge measures.. all the pipes collapse and refill with coolant. Tried this, still airlock.

So tried again.. drained system somewhat vacuum, refill and then vacuum refill again. Better. Managed to get heat back to heater, and it seemed like bottom hose got warm...

Took it for a spin down the road.. rose up to 120c..

Pump thing doesn't seem to make much difference.

I'm thinking airlock Infront of stat?... water temp Infront of stat was measured at mid 70c...

I've got an aluminium thermostat housing, with 2 extra bleed screws but the chap welded the boss on right Infront of one of the bolts.

Could it be water pump???.

Don't think I'm being catastrophically stupid..

[tommobot]

I ran it without the stat, but couldn't get a decent seal on the stat housing so it was leaking like crazy.. but it was flowing accross the rad with it in..

I'll maybe have another look tomorrow at the stat, but I'm definitely luring towards removing and inspecting water pump..

[tommobot]

GreenV8S said:

Doesn't prove the pump is perfect, but presumably it's doing at least something.

How does hot coolant get in and out of the stat housing when the stat is closed? Is the a bypass from the top of the engine, or does it rely on a heater hose, flow through the header tank and so on?

There a small hole in the stat housing that should allow water Infront of the stat back into the hose leaving the engine towards the top hose.

I can't guarantee that I've got enough coolant, but header is pretty much full, rad is full.. water present at all other hoses but there's either a pocket of air... Or dodgy water pump..

[tommobot]

Generic stat housing image, not mine.. but you can see the tiny bypass hole..

Could there be an air pocket above this, Infront of the stat?

[tommobot]

The stat sits in the circular.. fed from the bottom hose.. the off-rectangular one feeds off to the top hose.

The small link connects the two..

[tommobot]

I take it that this cover attaches to the front of the water pump. As I'm picturing it, the bypass should be taking full engine flow while the stat is closed. You you feel it getting hot when the engine is running?


Almost, the thermostat cover sits above the water pump. I'm guessing that the water pump kicks water up, and out on of the top hose towards the rad.

The plastic thermostat housing is hot, but that's just the general heat from the top hose warming the whole thing up.

The bottom hose for the most part, remains at ambient temp. I thought a few days ago it was getting warm and may be bled, but it turns out it wasn't.

When the system was bled, it was getting hot hoses throughout, and the temp gauge was staying central when driving...

The frustrating part is that following this I replaced the water pump as I thought it was nackered (it was!) and now I can't get it bled at all!



Edit: I'm now wondering whether I used the vacuum tool correctly.

Watched a couple more videos, and 1 of them has actually pointed out to 'prime' the refil hose with coolant before refilling the system - otherwise you'll be just sucking back in air.

Perhaps i'll break out the compressor and at attack it again.

Edited by tommobot on Monday 19th October 08:33

[tommobot]

I've now fitted an aluminium thermostat housing.. this has a non OEM bleed nipple fitted right Infront of the stat.

So, ran it up, and thought the bottom hose was getting warm. However now started noticing odd behaviour that might be associated with my issue.

So header tank off and it seems to behave properly... If I remove new bleed screw or rad top water is circulating.

If I remove either of them with the header on, the water is stationary. Remove/ release header and water visually starts moving again....

See video:
https://photos.app.goo.gl/Kmr2sDMcFJ4chhjt9

Notice water pissing out and then stopping when cap screwed back on..

[tommobot]

So I've spoken to the chap who helped me bleed it a few weeks ago... He reckons this behaviour is normal, as it with cap on it will be creating a vacuum.

That makes sense I think..

It also shows that the water pump is working, as with the header cap open water is clearly circulating...

So on the basis that the water coming from the bleeder infront of the stat was hot (not ultra hot) this would suggest water is circulating, when the water gets a bit hotter the stat would open... I feel like maybe its nearly there?