|
||
|
23rd March 2021, 13:40 | #1 |
Still learning...
Gold 04 75 Connie SE 2.5 V6 Petrol, Silver 52 Connie SE 2.5 V6 Petrol, 04 BRG Connie 2.5 V6 Petrol Join Date: Sep 2009
Location: MANCHESTER
Posts: 231
Thanks: 129
Thanked 40 Times in 27 Posts
|
Coolant Bleeding problem on KV6
Guys
Following on from my post about overheating I've now bled my coolant three times and yet again, after cooling overnight I still get a hiss when removing the header tank cap, or just loosening the bleed screw. So If i explain exactly what I'm doing and the results of my actions maybe someone can tell me if I'm going wrong somewhere 1. Remove bleed tube from clip on top hose 2. Undo 8m bolt holding header talk to slam panel and bumper 3. Undo bleed screw from bottom hose, at this point there is no flow from the bleed screw hole 4, Unscrew header talk cap, At this point coolant starts gushing out of the bleed screw, no gurgle, no stop start just a constant flow. 5 Raise header talk and start filing with coolant. The coolant is flowing out of the bleed screw hole almost as quickly as I can fill the header tank. 6 At this point I have to lower the talk slightly as I need two hands to manoeuvre the bleed screw into its tight blind spot by which time the flow has stopped. 7. Refit the header tank and fill to the neck 8. Refit header bleed hose to clip on top hose 9. Make sure aircon and heating is off and rev engine at 2000 rpm 10. The coolant almost immediately goes to the top of the header tank spilling even more all over the place. 11 refit the header tank cap 12. Drive for a short time until fan kick in at 100 degrees. I've even change over the header tank cap but still getting air out As I said despite following this procedure three times there is still air coming out of the tank when cold suggesting I've not moved the airlock so what if anything am I doing wrong? Cheers Paul Last edited by paulh260260; 23rd March 2021 at 16:39.. Reason: coerrection |
23rd March 2021, 14:41 | #2 |
Doesn't do things by halves
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,344
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
|
Hello Paul,
Here is the official MG Rover method for reference but it sounds as if you have already been following it. When undoing the expansion tank cap on a cold engine a slight hiss, akin to opening a beer, is nothing to worry about. If I were you Paul I would drain your cooling system fully, i.e. using the LH bank cylinder block drain plug as well as removing the radiator bottom hose and start from scratch. If you can, rig something to support your expansion tank leaving both hands free. Note from the official method that as soon as coolant starts flowing steadily from the bleeding orifice, the screw should be refitted. This shouldn't occur until you've poured quite a lot of coolant into the system. If it happens immediately, something's amiss. By the way, the bleed screw is in the bottom radiator hose on its way to the thermostat. Any comments? Simon
__________________
"Whatever is rightly done, however humble, is noble." Sir Henry Royce. |
23rd March 2021, 14:43 | #3 |
Premium Trader
Rover 75 Join Date: Nov 2010
Location: Devon
Posts: 33,763
Thanks: 8,837
Thanked 14,831 Times in 8,030 Posts
|
Normally when you are getting a constant flow from the bleed screw that’s all you need?
__________________
Lest we forget..
|
23rd March 2021, 15:01 | #4 | |
Still learning...
Gold 04 75 Connie SE 2.5 V6 Petrol, Silver 52 Connie SE 2.5 V6 Petrol, 04 BRG Connie 2.5 V6 Petrol Join Date: Sep 2009
Location: MANCHESTER
Posts: 231
Thanks: 129
Thanked 40 Times in 27 Posts
|
Quote:
It's the IMMEDIATE flowing of the coolant that concerns me,, that doesn't sound right but I suspect that a complete drain flush and refill looks sensible whilst I'm under her changing the oil as well Paul Last edited by paulh260260; 23rd March 2021 at 16:39.. |
|
23rd March 2021, 15:07 | #5 |
Still learning...
Gold 04 75 Connie SE 2.5 V6 Petrol, Silver 52 Connie SE 2.5 V6 Petrol, 04 BRG Connie 2.5 V6 Petrol Join Date: Sep 2009
Location: MANCHESTER
Posts: 231
Thanks: 129
Thanked 40 Times in 27 Posts
|
|
23rd March 2021, 18:18 | #6 | |
Doesn't do things by halves
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,344
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
|
Quote:
Simon
__________________
"Whatever is rightly done, however humble, is noble." Sir Henry Royce. |
|
23rd March 2021, 20:28 | #7 |
Loves to post
Rover75 tourer Join Date: Jun 2018
Location: Ashton
Posts: 428
Thanks: 121
Thanked 206 Times in 145 Posts
|
Might sound silly but is the hiss from pressure escaping, or a vacuum being released.
__________________
Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it. |
23rd March 2021, 21:25 | #8 |
This is my second home
Rover 75 cdt club + Rover 2.5 KV6 Conni SE Join Date: May 2008
Location: Birmingham
Posts: 11,387
Thanks: 6,587
Thanked 2,262 Times in 1,729 Posts
|
It should be the air being sucked into the system. With the header tank normally full to the top when the engine is at operating temperature, when it cools down, there is a ‘shrinkage’ of water, therefore there is a space in the header tank for a vacuum to form. When you undo the cap, this allows air to get into the tank..... the noise that you hear. If there is pressure, not a vacuum when you take the cap off, there is a different noise and you can feel it being ‘pushed’ away from the tank.
__________________
Great Barr, Birmingham. |
24th March 2021, 11:08 | #9 |
This is my second home
Rover75 and Mreg Corsa. Join Date: Nov 2006
Location: Sumweer onat mote o'dust (Sagin)
Posts: 21,752
Thanks: 341
Thanked 3,660 Times in 2,924 Posts
|
Apart from a 22psi-plus pressure relief valve, the header tank cap also has a hair spring valve to allow air in (if necessary) as the system cools down. Without a vacuum relief valve, the radiator would collapse following an overheat situation. So, there should be no hiss of air being sucked in when the cap is slackened. Similarly, there should be no significant hiss of air being released. If there is, you have to ask where does this excess pressure come from? The pressure when cold should be the same as it was the last time it was cold.
TC |
24th March 2021, 11:46 | #10 | |
Still learning...
Gold 04 75 Connie SE 2.5 V6 Petrol, Silver 52 Connie SE 2.5 V6 Petrol, 04 BRG Connie 2.5 V6 Petrol Join Date: Sep 2009
Location: MANCHESTER
Posts: 231
Thanks: 129
Thanked 40 Times in 27 Posts
|
Quote:
|
|
|
|