Bleeding help. Non standard engine change

Bleeding help. Non standard engine change

Author
Discussion

GreenV8S

30,149 posts

283 months

Sunday 18th October 2020
quotequote all
tommobot said:
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.
How small?

I can't visualise what it is connecting to what, but it's quite common to have a 1/8" or so leak through the stat just to let the stat housing bleed. It doesn't flow enough coolant to affect the operation of the cooling system. You need some way to get a significant flow through the stat housing so that the stat is immersed in coolant at the engine temperature, and not stagnant cold coolant. Normally, that flow comes through a bypass hose. Any flow coming in from the radiator is no help at all and actually makes things worse since it is dead cold if the stat is closed.

tommobot

Original Poster:

641 posts

206 months

Sunday 18th October 2020
quotequote all


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?

GreenV8S

30,149 posts

283 months

Sunday 18th October 2020
quotequote all
That looks about the right size to be a bleed hole. I take it the stat sits in the circular opening. Is the hole at the top of that space when installed? That would fit it being a bleed hole. Is the pipe entering the housing from that side connected to the top hose? That is where I'd expect a bypass to connect.

tommobot

Original Poster:

641 posts

206 months

Sunday 18th October 2020
quotequote all
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..

GreenV8S

30,149 posts

283 months

Monday 19th October 2020
quotequote all
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?

tommobot

Original Poster:

641 posts

206 months

Monday 19th October 2020
quotequote all
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

Original Poster:

641 posts

206 months

Monday 19th October 2020
quotequote all
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..


buggalugs

9,243 posts

236 months

Tuesday 20th October 2020
quotequote all
How frustrating

Definitely worth taking the water pump off and checking the impeller is attached properly etc. I know it's new but still. Problem must be somewhere. Could you rotate the outlet hose by 90 degrees so it sticks in the air and confirm that the pump fires water out of it with decent oomph?

tommobot

Original Poster:

641 posts

206 months

Tuesday 20th October 2020
quotequote all
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?