Header tank-white"stuff" residue in area. - Page 2

T-Cut · 13th February 2017, 17:51

Quote:

Originally Posted by mileshawk56

Did about 30miles stopped for about 90mins, checked the header tank area, yes more white stuff and as you say looks to have come from the filler cap area.

OK that confirms it's coolant ejecting from the cap and leaving the antifreeze/OATresidue after it evaporates.

Quote:

Did the demist test- - - nothing for a couple of minutes then fan starts big whoosh noise for 5 secs, then stops, then - - - goes again for 5 secs then stops.

Yes the slow speed resistor for the cooling fan has blown. This is essential to avoid the aircon system overheating. When that happens, the emergency high speed trips in to rapidly cool the condenser located at the front of the main radiator. Of course, the overheating repeats and you get the high speed fan cycling every few seconds.

The fix is an uprated resistor which you can get from forum traders, eBay and electronics outlets like RS Components, etc. Fitting requires the front bumper taken off. After that it's reasonably plain sailing.

I think there may still be an issue regarding the coolant ejection, but see how things go when the slow speed fan is reinstated. Remember to update your thread with the results.

TC

mileshawk56 · 15th February 2017, 16:12

So until I get the new resistor fitted is it ok to use the car with setting on "econ"? As I understand it that way the air conditioning is not operating and just normal engine cooling will take place? Thanks for your help. Chris S.

T-Cut · 15th February 2017, 18:36

Quote:

Originally Posted by mileshawk56

So until I get the new resistor fitted is it ok to use the car with setting on "econ"?

Sure, but it won't change the 'chalky residue' thing. That's caused by the engine overheating and coolant being ejected. Please report back on this after the fan's fixed.

TC

mileshawk56 · 16th February 2017, 18:44

Still working (mentally)! and observation on the Chalky residue thing. As a result of reading your excellent stickie on caps and header tanks this morning, I ran the engine from cold with the header tank cap off. After about 8/10minutes I saw drops of fluid dropping down from the underside of the tank neck. At first it was at 2second intervals and and then a longer pause of 5/6 seconds and as time went on the drops increased in frequency and the intervals became shorter until it was nearly a continuous stream of water. This is coming from the lower(furthest) hole in the bottom of the neck. I could see no fluid coming from the upper angled bleed hole, I put my finger over this hole but feel no pressure but it was hot, not boiling but I didn't keep it there. I wanted to check if this hole was blocked but couldn't find a suitable tool, paperclip but will do so tomorrow. A bye the way observation, the space between the inside of outside neck and the outside of the inside neck contained quite an amount semi hard white/pinky deposits, these I have gradually removed and am now wondering if this may be related to the initial problem. Interesting eh. Chris.S.

T-Cut · 16th February 2017, 22:05

Yes the flow of coolant from the head/heads through the bleed hose and into the header tank via the vent hole is an intriguing issue (to me anyway). It really needs some more observations by V6 owners so a better understanding might be gained. Personally, I don't understand how it happens if everything is as it should be. I've tried, but never observed this flow in my 1.8T and other 1.8 owners say the same. It may be something specific to the V6 and if so why? The purpose of this route is simply to vent any air from the heads, the inlet manifold and the radiator top during a coolant refill. The additional purpose is to relieve head pressure during heat soak after shut down.

Your own observation is interesting in that the flow starts after 8-10 minutes from starting up and is initially very slow, but increases to full flow as things warm up. Why should that be? I wish I could find an explanation.

The blocked upper vent hole is mentioned in my write-up and can only be cleared from within the filler neck by probing upwards from below. I believe blockage of this hole is very common and has little effect on the system except during a heat soak event or during over-pressurisation from other causes. The need for the double bleed hole remains a mystery and my proposal (in the write-up) is little more than a guess.

One has to wonder if the residues you've described are related to this bleed flow and/or the bunged up vent?

TC

mileshawk56 · 25th February 2017, 19:15

Since my last post I have been using the ZT, mostly on "econ" setting but occasionally with AC on and I have no more "white stuff" appearing. I think maybe this was partly because the system was overfilled (garage not me)! Another factor maybe the fact that the upper bleed hole in the header tank does in fact produce some coolant flow. I have done the header tank cap off from cold observation and this showed the lower hole showing a dribble of coolant after 3mins which with stops and starts increased to a good flow by 6mins. whilst this was happening I could see a flow of coolant from the upper hole, just visible on the lower edge of the tanks neck. I had poked around in this hole with some soft wire prior to this. The over filling was not too bad but was over the internal fins. I'm intrigued to know what goes on with the filler cap on, I am wondering if when the coolant level closes the bottom of the header tank neck and blocks the lower hole if the coolant is then diverted into the upper hole and thence into one of those slots/apertures in the filler cap? Maybe nonsense but I am puzzled, that cap seems complicated and surely there must be reason for that. The trouble is you never know what previous owners/garages have done. Chris.S

T-Cut · 25th February 2017, 19:32

Quote:

Originally Posted by mileshawk56

I'm intrigued to know what goes on with the filler cap on, I am wondering if when the coolant level closes the bottom of the header tank neck and blocks the lower hole if the coolant is then diverted into the upper hole and thence into one of those slots/apertures in the filler cap?

Me too! http://www.the75andztclub.co.uk/foru...d.php?t=245253

TC

SD1too · 25th February 2017, 23:26

Christopher,

You need to replace the fan resistor urgently. At present, every time the fan starts its cycling routine your coolant temperature is reaching 112°C. That is too hot for comfort and for reliability. It won't make any difference using the 'Econ' setting. All that does is turn off the air con. compressor.

Secondly, on my V6 I get a constant flow of coolant from that breather hose into the expansion tank when the engine is started from cold. It's my understanding that this means that I don't have air in the system,as it's a breather hose. As your car appears to be venting for a few minutes, maybe you do have trapped air. Has a garage been working on the cooling system recently?

Simon

mileshawk56 · 8th March 2017, 20:29

Simon I'm confused(not unusual)! Does not the radiator fan on mine come on when the coolant reaches a preset temperature to cool the engine? independent of the none operating lowspeed fan function. I have understood the low speed fan function is to cool the AC condenser/radiator thing? Or is the engine cooling provided by a combination of both Low/high speed fans regardless of the AC being used or not? I take your advice regarding the replacement of the resistor, hopefully this weekend if weather is kind! Thanks Chris S. P.S. any idea of the gauge/size of the resistor wire if I have to make some tails as per Arctics how to?

mbonwick · 9th March 2017, 06:39

Quote:

Originally Posted by mileshawk56

Simon I'm confused(not unusual)! Does not the radiator fan on mine come on when the coolant reaches a preset temperature to cool the engine? independent of the none operating lowspeed fan function. I have understood the low speed fan function is to cool the AC condenser/radiator thing? Or is the engine cooling provided by a combination of both Low/high speed fans regardless of the AC being used or not? I take your advice regarding the replacement of the resistor, hopefully this weekend if weather is kind! Thanks Chris S. P.S. any idea of the gauge/size of the resistor wire if I have to make some tails as per Arctics how to?

Low speed fan should come on at 104C, or if air con is on. High speed is 112C. Cut out is 96(?)C.

Not sure on the wire gauge, but if you order a new gold resistor from Jules it will come with crimp connectors supplied, so no need for tails.

25th February 2017, 23:26	#18
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,374 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Christopher, You need to replace the fan resistor urgently. At present, every time the fan starts its cycling routine your coolant temperature is reaching 112°C. That is too hot for comfort and for reliability. It won't make any difference using the 'Econ' setting. All that does is turn off the air con. compressor. Secondly, on my V6 I get a constant flow of coolant from that breather hose into the expansion tank when the engine is started from cold. It's my understanding that this means that I don't have air in the system,as it's a breather hose. As your car appears to be venting for a few minutes, maybe you do have trapped air. Has a garage been working on the cooling system recently? Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

15th February 2017, 16:12	#12
mileshawk56 Posted a thing or two MGZT Join Date: Jul 2015 Location: Berkshire Posts: 1,281 Thanks: 1,738 Thanked 299 Times in 216 Posts	So until I get the new resistor fitted is it ok to use the car with setting on "econ"? As I understand it that way the air conditioning is not operating and just normal engine cooling will take place? Thanks for your help. Chris S.

16th February 2017, 18:44	#14
mileshawk56 Posted a thing or two MGZT Join Date: Jul 2015 Location: Berkshire Posts: 1,281 Thanks: 1,738 Thanked 299 Times in 216 Posts	Still working (mentally)! and observation on the Chalky residue thing. As a result of reading your excellent stickie on caps and header tanks this morning, I ran the engine from cold with the header tank cap off. After about 8/10minutes I saw drops of fluid dropping down from the underside of the tank neck. At first it was at 2second intervals and and then a longer pause of 5/6 seconds and as time went on the drops increased in frequency and the intervals became shorter until it was nearly a continuous stream of water. This is coming from the lower(furthest) hole in the bottom of the neck. I could see no fluid coming from the upper angled bleed hole, I put my finger over this hole but feel no pressure but it was hot, not boiling but I didn't keep it there. I wanted to check if this hole was blocked but couldn't find a suitable tool, paperclip but will do so tomorrow. A bye the way observation, the space between the inside of outside neck and the outside of the inside neck contained quite an amount semi hard white/pinky deposits, these I have gradually removed and am now wondering if this may be related to the initial problem. Interesting eh. Chris.S.

16th February 2017, 22:05	#15
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Yes the flow of coolant from the head/heads through the bleed hose and into the header tank via the vent hole is an intriguing issue (to me anyway). It really needs some more observations by V6 owners so a better understanding might be gained. Personally, I don't understand how it happens if everything is as it should be. I've tried, but never observed this flow in my 1.8T and other 1.8 owners say the same. It may be something specific to the V6 and if so why? The purpose of this route is simply to vent any air from the heads, the inlet manifold and the radiator top during a coolant refill. The additional purpose is to relieve head pressure during heat soak after shut down. Your own observation is interesting in that the flow starts after 8-10 minutes from starting up and is initially very slow, but increases to full flow as things warm up. Why should that be? I wish I could find an explanation. The blocked upper vent hole is mentioned in my write-up and can only be cleared from within the filler neck by probing upwards from below. I believe blockage of this hole is very common and has little effect on the system except during a heat soak event or during over-pressurisation from other causes. The need for the double bleed hole remains a mystery and my proposal (in the write-up) is little more than a guess. One has to wonder if the residues you've described are related to this bleed flow and/or the bunged up vent? TC

25th February 2017, 19:15	#16
mileshawk56 Posted a thing or two MGZT Join Date: Jul 2015 Location: Berkshire Posts: 1,281 Thanks: 1,738 Thanked 299 Times in 216 Posts	Since my last post I have been using the ZT, mostly on "econ" setting but occasionally with AC on and I have no more "white stuff" appearing. I think maybe this was partly because the system was overfilled (garage not me)! Another factor maybe the fact that the upper bleed hole in the header tank does in fact produce some coolant flow. I have done the header tank cap off from cold observation and this showed the lower hole showing a dribble of coolant after 3mins which with stops and starts increased to a good flow by 6mins. whilst this was happening I could see a flow of coolant from the upper hole, just visible on the lower edge of the tanks neck. I had poked around in this hole with some soft wire prior to this. The over filling was not too bad but was over the internal fins. I'm intrigued to know what goes on with the filler cap on, I am wondering if when the coolant level closes the bottom of the header tank neck and blocks the lower hole if the coolant is then diverted into the upper hole and thence into one of those slots/apertures in the filler cap? Maybe nonsense but I am puzzled, that cap seems complicated and surely there must be reason for that. The trouble is you never know what previous owners/garages have done. Chris.S

8th March 2017, 20:29	#19
mileshawk56 Posted a thing or two MGZT Join Date: Jul 2015 Location: Berkshire Posts: 1,281 Thanks: 1,738 Thanked 299 Times in 216 Posts	Simon I'm confused(not unusual)! Does not the radiator fan on mine come on when the coolant reaches a preset temperature to cool the engine? independent of the none operating lowspeed fan function. I have understood the low speed fan function is to cool the AC condenser/radiator thing? Or is the engine cooling provided by a combination of both Low/high speed fans regardless of the AC being used or not? I take your advice regarding the replacement of the resistor, hopefully this weekend if weather is kind! Thanks Chris S. P.S. any idea of the gauge/size of the resistor wire if I have to make some tails as per Arctics how to?