Hello dears,

I am chasing the problems one by one and no success, I fixed the upper coolant hose and bleed the coolant with cap off and ac heater on, anyway if I start the car for 15 mins with cap off, coolant keeps raising until boiling and after this fans will kick in.
I found the inside of the cap as you see in the picture, and I ask if there is a cross reference for VW cap.

 

I wouldn't be surprised if the reservoir cap for a VW phaeton wouldn't be the same or fit/work. They look the same from the pictures I have seen, but I do not believe the actual reservoirs do not cross since I believe the Bentley has a extra hose going to it. The cap might be it below or the equivalent. I would buy it if I needed one since it would probably work. If you have a VW near you, try bringing your cap there if they have one to compare. For many of the parts to find potential crosses, change the 3W0 to 3D0 (VW) or potentially an 8E0 for Audi.
For a Phaeton Cap which appears to be blue.
https://www.jimellisvwparts.com/prod...3d0121321.html

Here is a knockoff I saw on Amazon might be worth $7 to see if it work, but I can't vouch for the quality. I try and stick with OEM.
Here is a link to a website explaining how the numbering works.
https://www.shopdap.com/blog/post/ho...bers-work.html
Best of Luck,

 

Be certain that the coolant pump is actually activated. Heat should come out the vents when set to highest settings. A new cap may be inorder although this isn't the cause. When I drained and flushed the system there were no issues refilling as in airlock..etc.

 

Im trying to get my head around what you call a problem.
The caps primary purpose is to allow the pressure to build in the exspansion tank. Probably at a guess around 10 to 15 psi.
Without the cap on the coolant will keep rising up the tank and either boil or overflow the top.
Have you simply tried to run the engine with the cap on,keeping an eye on the engine temps. Take for a small run. Come back allow to cool and check the coolant level??

 

ditto Frank!

@Shaqovic - your test if wrong if I understood you clearly - you take cap off an you are surprised the coolant go out? This is normal.

Other story would be if you have all on, cap on, start engine, get temp up and you got the temperature raising and coolant will start going out - fans wont start earlier enough to cool it.

But in this scenario you must have the cap on.

 

Hello All,
I think what is missing here is the detailed information as to the issue, I believe that the cap it broken as shown in @Shaqovic 's photo, but the real issue may lie elsewhere, as his comment as to the coolant rising and boiling, well, that really shouldn't happen when starting a cold engine with the cap off, not at idle in only 15 minutes, I think a compression test is in order for all cylinders, but now as I type this, I just received an email notification that Shaqovic responded in his other thread about the suspension, and I just noticed that there is a video attached to that post, and the comment is that white smoke is only coming out of one tailpipe, not a good sign, I also believe that Shaqovic resides in Malta, which today is about 77°F, if in fact that video was taken today, I wouldn't expect to see any white smoke with the warm weather, and only one side is not good, so a compression test on the offending side is definitely in order, as the coolant coming out of the reservoir now looks like a head gasket, or cracked head issue.

Shaqovic,
Tell us if the exhaust with the white smoke smells sweet, that is if you have actual coolant/antifreeze in the system, and not just plain water.

Give us some history, any overheating issues ever, as I recall you using RTV on the upper radiator hose at the thermostat housing, instead of replacing it with a new o-ring...

Johnny

 

IT might be worth buying a head leakage tester. Cheep tool that sucks coolant gas out of the expansion bottle and turns the blue chemical yellow if in contact with hydrocarbons. Over here they are about £10.

 

thanks for the detailed reply Johnny, after I raised the front of the car and burped the coolant, many air came out and never had overheating again with cap closed, every 2-3 days I start the car for 20 mins max idle and turn off and never checked coolant or touched the cap at all 😅
I don’t know if it’s sweet or not, tomorrow will start the car and smell it, but any quick diagnosis I can do to minimize the circle.

 

@Shaqovic ,
Well that is good to hear, BUT, as Frank stated, get yourself a tester for the coolant reservoir, it detects exhaust gases in the coolant.

Also, when the engine is cold, check the coolant level from day to day after letting the engine idle as you have been doing, this way each morning on the cold engine, you can see in the reservoir if the level is dropping over engine starts.

Did you do any work on the left side that would have gotten coolant into the exhaust manifold or pipes, if so, it should burn off, how long does the white smoke last, is it all the time through the 20 minutes of running, when did it start ?

Regardless of the weather you have, the one side only is of concern, if it was colder climate, one would expect both exhaust tips to blow condensation for the first few minutes of startup, not just one side on a true dual exhaust system.

Johnny

 

I did not touch the engine or opened anything except the cap to burp the air, this was a month ago.
today when I took started the car only to take the video and turned it off.

I will watch the coolant level for the coming days after each warm up as you instructed.
I can’t find a tester locally like those I watched on YouTube.
thanks a million for your help

 

EBAY have plenty of them starting at £6 going up to £40. They are real easy to use.
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I have something like this.