Discussion
Morning friends
I'm currently experiencing cooling issues with my 350i
A bit if back history first: A while back I blew a head gasket - a hose went and by the time I realised I had well and truly cooked it. Anyway head gaskets replaced I had a run out to a car show (around 120 mile round trip) with no apparent issues.
Just before the fest I drained the cooling system and replaced the coolant with a new 50\50 mix of water and antifreeze
On the way to the fest a problem became apparent with the cooling
The temp will hold steady around 90 (pre head gasket Change it was more like 80) for long periods then it will drop to about 80 (takes 2-3 seconds) it will then stay there for a random period of time (a few secs to a mins) then rapidly rise to just under the red 98 degrees ish where it will stay for a random amount of time (a few secs to a few mins) before quickly falling to settle at 90 before repeating the process again.
It seems to be more prevalent at motorway speeds less so at 30
I lost around a pint of water on the run (140miles roung trip)and on a run this morning its apparent its blowing the water out of the expansion tank cap
I've tried several times to burp the system
So what do you think
1 Just a stubborn air lock
2 faulty thermostat
3 faulty expansion tank cap
4 head gasket failed
5 something else ??
As always your help is appreciated
Cheers Ron
Eta
It doesn't actually boil over
The fans work as the should
I'm currently experiencing cooling issues with my 350i
A bit if back history first: A while back I blew a head gasket - a hose went and by the time I realised I had well and truly cooked it. Anyway head gaskets replaced I had a run out to a car show (around 120 mile round trip) with no apparent issues.
Just before the fest I drained the cooling system and replaced the coolant with a new 50\50 mix of water and antifreeze
On the way to the fest a problem became apparent with the cooling
The temp will hold steady around 90 (pre head gasket Change it was more like 80) for long periods then it will drop to about 80 (takes 2-3 seconds) it will then stay there for a random period of time (a few secs to a mins) then rapidly rise to just under the red 98 degrees ish where it will stay for a random amount of time (a few secs to a few mins) before quickly falling to settle at 90 before repeating the process again.
It seems to be more prevalent at motorway speeds less so at 30
I lost around a pint of water on the run (140miles roung trip)and on a run this morning its apparent its blowing the water out of the expansion tank cap
I've tried several times to burp the system
So what do you think
1 Just a stubborn air lock
2 faulty thermostat
3 faulty expansion tank cap
4 head gasket failed
5 something else ??
As always your help is appreciated
Cheers Ron
Eta
It doesn't actually boil over
The fans work as the should
Edited by Rockettvr on Sunday 17th July 12:15
Ron, that header tank is not the usual type, and there doesn't seem to be any auxiliary catch tank. Has the cooling system been modified? Is the tank cap of the correct rating (15 psi IIRC)? They can be difficult to fill properly and remove all the air. I would empty the header tank, and take off the secondary non-pressure cap from the swan neck pipe. What I do is alternately squeeze the top and bottom hoses whilst that second cap is off - you should see / hear the water in the top hose being squeezed up a bit towards that removed cap, and you should also be able to her the jiggle pin rattle in the thermostat (if it has the correct stat). Once you're happy that there is no more air in the rad, slowly pour as much coolant into the swan neck as possible and replace the cap. Then put some coolant in the header tank (about 1/3 full) and run the engine with the cap off. Blip the throttle at the plenum linkage to speed up the flow. As the coolant heats (have the heater open) the level will rise. Once it gets as close to the top as you dare, replace the cap and allow it to get up to temp and check the fans kick in and at what temp. You should also see the temp rise, and as the stat opens, it will drop back again, before coming up to normal temp.Allow the engine to cool, and top up the header to your normal level.
As Paul says...I think its because there is no room for expansion...Bit like my trousers on the BBWF Saturday night....
Do you have a sealing rad cap on the swan neck?...What is your thermostat rated at and at what temp does the fan kick in?...
Do you have a sealing rad cap on the swan neck?...What is your thermostat rated at and at what temp does the fan kick in?...
Edited by mrzigazaga on Sunday 17th July 13:05
Number 7 said:
Ron, that header tank is not the usual type, and there doesn't seem to be any auxiliary catch tank. Has the cooling system been modified? Is the tank cap of the correct rating (15 psi IIRC)?
Hi PaulI was aware that my cooling system differs from other wedges Tha id seen but thought that I was a TVR thing that they'd changed something according to what the had to hand or a cheaper alternative
Its always been reliable till now - I put a 82 degree stat in soon after I got the car and its always run slightly cool (80-85 deg)
The cap on the expansion tank is a motorcraft an on a bit of investigation looks to be a mondeo item. The cap is rated at 21 psi
As for expansion the coolant level just rises and falls inside the resevoir - usually sits on the min level when cold on the max level when up to temp
After the last couple of outings its expelled around a pint of water so once cooled down again the reservoir Is nearly empty
The way the temp goes up and down in cycles makes me think it is just a stubborn airlock going round the system
I'm hoping its not the head gasket again
- surely if it was the head gasket it would just blow all the water out and boil ???I'll try another burping session as you suggested Paul and hope for the best before delving deeper
Cheers Ron
Hi Ron
Agree with Paul's advice plus as mentioned get the front of the car up on ramps when you are doing the burping and do at least 2-3 hot cold cycles do it at the swan neck sealing cap as well as at the tank itself. I have found that the sealing cap is not seating correctly make sure the rubber is good ... I changed the rubber on mine on the old setup (flapper) as it was tired and it cured the problem. Found some rubber in the garage and cut it to shape! Your Mondeo cap should not cause these issues I would have thought.
Agree with Paul's advice plus as mentioned get the front of the car up on ramps when you are doing the burping and do at least 2-3 hot cold cycles do it at the swan neck sealing cap as well as at the tank itself. I have found that the sealing cap is not seating correctly make sure the rubber is good ... I changed the rubber on mine on the old setup (flapper) as it was tired and it cured the problem. Found some rubber in the garage and cut it to shape! Your Mondeo cap should not cause these issues I would have thought.
The thing is if it seems that air is re-entering the system it might be the gaskets again.
When you had them replaced last time, what type did they/you use? Do you have a receipt for them so we can see exactly which type?
By all means try burping it first - but then keep an eye on it. if you notice gas escaping from past the expansion tank cap, bubble it through some lime water, if it goes cloudy then it's CO2 and a sure sign of gasket problems.
When you had them replaced last time, what type did they/you use? Do you have a receipt for them so we can see exactly which type?
By all means try burping it first - but then keep an eye on it. if you notice gas escaping from past the expansion tank cap, bubble it through some lime water, if it goes cloudy then it's CO2 and a sure sign of gasket problems.
Ron, I assume you have the 14 bolt heads. Did you omit the 4 outer row bolts (or set them at a low torque value)? As Adam says, what type and brand of gasket was used (hopefully Elring or similar) composite type rather than tin? Conventional bolts or stretch? What torque value?
Also, having just checked my header tank cap, its rated at 15psi. I'm not quite sure what effect having a higher rated cap would have, other than obviously increasing the threshold at which it vents.
Also, having just checked my header tank cap, its rated at 15psi. I'm not quite sure what effect having a higher rated cap would have, other than obviously increasing the threshold at which it vents.
colin mee said:
Do all wedges have problems with the cooling.
If your rad has been recored and the hoses replaced and your fans kick in when they supposed to then no...If you are re-filling the system then the art is to do it slowly and to have the front lifted up slightly...Always fill from the swan neck first...Run up to temp...Allow to cool and check and top up if needed.Job done!!
Hi all
Not had a chance to burp the cooling system yet but in response to some if your questions
Head gaskets were composite elring I think (came from Island 4x4)
Used new stretch bolts torqued in the correct sequence and to correct torque levels
Outer row of bolts were left out
Hoping to get to burping system tonight -
I shall report back
Not had a chance to burp the cooling system yet but in response to some if your questions
Head gaskets were composite elring I think (came from Island 4x4)
Used new stretch bolts torqued in the correct sequence and to correct torque levels
Outer row of bolts were left out
Hoping to get to burping system tonight -
I shall report back
Hi Ron, sounds like a good combination, your heads should be fine.
I have a slightly different strategy when filling mine from scratch - if you have a small diameter hose going from the swan neck to the expansion tank you can try this.
With my method I never disturb the swan neck cap, which maintains a good seal.
Undo the small hose at the expansion tank end, raise it up and attach a small funnel with an end that can stick into the pipe. Observe the level in the expansion tank. Fill through the funnel, keep the funnel raised at all times. (I have a string hanging from the garage roof.
)
For extra burping squeeze the top/bottom hose occasionally.
Reattach the small pipe when the expansion tank is full - you might have to keep your thumb over the end as you drop it down.
I have a slightly different strategy when filling mine from scratch - if you have a small diameter hose going from the swan neck to the expansion tank you can try this.
With my method I never disturb the swan neck cap, which maintains a good seal.
Undo the small hose at the expansion tank end, raise it up and attach a small funnel with an end that can stick into the pipe. Observe the level in the expansion tank. Fill through the funnel, keep the funnel raised at all times. (I have a string hanging from the garage roof.
)
For extra burping squeeze the top/bottom hose occasionally.
Reattach the small pipe when the expansion tank is full - you might have to keep your thumb over the end as you drop it down.
Hi all
I think I may have stumbled upon the cause of my fluctuating temperature issues
This morning I burped the cooling system as per number 7 instructions
All seemed well - didn't seem to get any air out but the car ran up to temp , the fans cut in at around 90 and temp came down again - cool - fixed it - time for a test drive. A quick run out and the temperature quickly rose and rose and rose b
ks pull over to let it cool quietly swearing under my breath and I realise theres something missing - the sound of the fan running. So it would appear I've got a temperamental fan
I'm guessing its more a faulty otter switch rather than the fan itself so will wire in an override switch as a temporary measure
Id like to replace the otter switch with an adjustable control - any recommendations??
There's one in Car builders solution website which seems to be ideal - the temperature probe goes in the top hose http://www.carbuildersolutions.com/uk/adjustable-f...
Thanks all Ron
I think I may have stumbled upon the cause of my fluctuating temperature issues
This morning I burped the cooling system as per number 7 instructions
All seemed well - didn't seem to get any air out but the car ran up to temp , the fans cut in at around 90 and temp came down again - cool - fixed it - time for a test drive. A quick run out and the temperature quickly rose and rose and rose b
ks pull over to let it cool quietly swearing under my breath and I realise theres something missing - the sound of the fan running. So it would appear I've got a temperamental fanI'm guessing its more a faulty otter switch rather than the fan itself so will wire in an override switch as a temporary measure
Id like to replace the otter switch with an adjustable control - any recommendations??
There's one in Car builders solution website which seems to be ideal - the temperature probe goes in the top hose http://www.carbuildersolutions.com/uk/adjustable-f...
Thanks all Ron
Mine has a Kenlowe controller which has been on there since the year dot. It is quite heavy duty and does what it says on the tin. I think you can buy them separately from the fan kits, they are adjustable and have the same type of temperature bulb which inserts into the cooling hose.
Hope this helps.
Hope this helps.
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