Technical Help with infuriating gurgling sound!!

[gadge]

My MK2 Punto has developed this gurgling sound every time I start it up. Despite several attempts to bleed the air out I’m still getting what sounds like a a trickling noise coming from behind the heater when starting it up from cold. Now I’ve read several threads on this and have done the usual procedures like undoing the bleed screw on the rad and filling it until it comes out, I’ve also undone the the screw behind the engine and got that to dribble out until it was bubble free. I’ve undone both screws when hot, Luke warm and stone cold and still I get the sound. Yesterday I thought I had a break through as I managed to find a very small funnel with a spout that just fitted in the hole of the bleed valve behind the engine and poured coolant down there squeezing and massaging the heater hoses and managed to expel some air out of the contents of the funnel which in turn emptied into the system so full of confidence I started the car this morning and ..... GURRGGLLEE-GLUMMMMPP-GURRGGLEEEEEEE.....

So is there any definitive way of curing this? As per other cases the car heats up fine, blows hot air, temp needle stays where it should and the fan cuts in but still seems to be hiding an air lock when it cools down.

 

[Brendan W]

The bleed screw on the heater pipe can run bubble free for quite a bit and still have air in the system. Try filling the rad to the top, upend a 500ml drinks bottle of coolant on the rad filler, get a good seal and with the heater bleeder open give a good long squeeze or three. That should put manners on it

 

[judderbar]

My MK2 Punto has developed this gurgling sound every time I start it up. Despite several attempts to bleed the air out I’m still getting what sounds like a a trickling noise coming from behind the heater when starting it up from cold. Now I’ve read several threads on this and have done the usual procedures like undoing the bleed screw on the rad and filling it until it comes out, I’ve also undone the the screw behind the engine and got that to dribble out until it was bubble free. I’ve undone both screws when hot, Luke warm and stone cold and still I get the sound. Yesterday I thought I had a break through as I managed to find a very small funnel with a spout that just fitted in the hole of the bleed valve behind the engine and poured coolant down there squeezing and massaging the heater hoses and managed to expel some air out of the contents of the funnel which in turn emptied into the system so full of confidence I started the car this morning and ..... GURRGGLLEE-GLUMMMMPP-GURRGGLEEEEEEE.....

So is there any definitive way of curing this? As per other cases the car heats up fine, blows hot air, temp needle stays where it should and the fan cuts in but still seems to be hiding an air lock when it cools down.

The car has a design fault because the bleed screw at the back of the engine is higher than the level line on the radiator filler pipe.

If you run the car up to temperature with the radiator cap off without revving the engine all of the air will definitely be removed in a few minutes. I tested that idea by putting a clear plastic pipe in my system to see what happens. Once hot and unpressurised the entire system is full of a relatively frothy steam water mixture. All gases are continually brought to the radiator filler. There is no way any air could remain in the system without being brought by the gas of water to the filler.



However I am convinced myself that if you have absolutely no air leaks in the system the air will eventually all be purged from the car sufficient for you to not notice a problem.

The problem is because air easily travels into a system but water find it much much harder to travel out of the system. With the filler too low air is easily forced into a system via tiny leaks when the engine cools down.

The later grande punto uses a separate pressurised filling container that sits above the radiator so this problem is avoided. Small water leaks out of the system cause no problems if the filling level is above all other connections, and all connections are pressurised by the height of the water above them.

Anyway there is a bit of an argument here in the forum about what to do in your situation. Personally I just fill the thing up and let the air come out naturally - and yet that will never happen if your system has leaks.

 

[gadge]

Excellent stuff guys judderbar that definitely makes sense about the different heights - I thought it was strange how when I had coolant dribbling out of the heater valve the coolant bottle was under the max mark. I’m wondering if by undoing the heater valve has inadvertently let more air in rather than helping to get air out. I will try just running the car up to temp with the cap off and see what happens.

 

[Geocalico]

Common problem. In my car it appeared to stop after I'd given it a flush and replaced with some decent coolant. However it still happens occasionally.

 

[gadge]

Well after many attempts mine is still gurgling. I ran it up to temp with the cap off and expelled all the bubbles until I was satisfied I had bled all the air out and still the next day it gurgled. The symptoms are baffling. I'm not loosing coolant as the level stays at the maximum and there's no sign of water on the ground. The car starts and runs up to temp and doesn't overheat yet I'm convinced I have a very small hole somewhere that's letting air in as it cools down I have some RadWeld in my garage so I'll bung some of that in at some point but seen as though it seemingly doesn't effect the running of the engine I'll just have to put up with it until I can get around to looking at it properly even if it means whipping the head off and starting from scratch

 

[gadge]

UPDATE! I've finally sorted it out. In the end despite running ok with no overheating issues I decided that maybe the head gasket was to blame and sure enough it was - I think..... I say "I think" as it may have been a dickie seal on the inlet manifold (see bottom photo) but given the oily residue on the two end cylinders it looks like the gasket needed changing anyway. So after a skim and a rebuild the head was refitted and since then no gurgling and no loss of coolant







Could this be the source of the leak?

 

[varesecrazy]

Obviously youve drained and refilled since.. so hard to say conclusively

But that does appear to show the gasket wasnt sealing the various paths..

Im sure I will get to see this car.. one day

On a side note..
That pic of the head.. on the inlet end.. bottom of pic..
It looks like silvery gold buttons around cyl 2/3
trick of the light.. or proper features?

 

[gadge]

Obviously youve drained and refilled since.. so hard to say conclusively

But that does appear to show the gasket wasnt sealing the various paths..

Im sure I will get to see this car.. one day

On a side note..
That pic of the head.. on the inlet end.. bottom of pic..
It looks like silvery gold buttons around cyl 2/3
trick of the light.. or proper features?

Drained and refilled? Not sure what those were between 2 and 3 cylinder - slight indentations I think? Heres a pic after it was skimmed (home skim job ) what ever they were they cleaned up.

 

[varesecrazy]

Shiny..!!
What did you 'skim' it with ?

Shifted the rusty marks from those pockets whatever you did

 

[gadge]

I built a gig to mount the head in which was bolted to my work bench then I used a surface plate upside down with different grades of wet and dry on it starting on 240 grit right the way up to 2000 grit. Using plenty of WD40 I simply rubbed the plate up and down the head with even strokes until I achieved the result I was looking for. It's not exactly precision engineering but after using the first grit at 240 the finish was so even I decided that there was little to no warping on the face so I just carried on up the grades. I did both the inlet and the exhaust side like this too then gave the head a bath in degreaser

 

[varesecrazy]

Spot on.. !!

It didnt look any worse than the dozen or so that I've done..
Like you .. Ive 'caught it early'
So not cooked anything

Should be spot on now

 

[gadge]

Spot on.. !!

It didnt look any worse than the dozen or so that I've done..
Like you .. Ive 'caught it early'
So not cooked anything

Should be spot on now

Done a few runs in it now including a 15 minute blast at 60 up the M6 and it didn't miss a beat. Only time will tell but I'm confident it'll be ok

 

[gadge]

Here you go varesecrazy. I ended up giving it a lick with some satin black engine paint and then gave it one last rub over to get the over painted bits off. It was ashame to cover it up again by refuting.