Frostplug change

[Burtie1]

Advice needed on mk6 2.4di put frost plug back in top of cylinder head as water froze up but before changing plug I filled header tank up with water as there was none in there it took a while then I noticed water coming out where dipstick is I then removed oil cap and noticed water coming up in the rocker area so I removed the sump plug and drained everything out but would any water have gone in the pots where the pistons are whilst it was coming up into the rocker cover area

[jumbo 57]

No Bertie, plugs only cap the coolant galleries so you should be fine on that count.

Always clean the core plug seat and apply the thinnest smear of general gasket sealant on the edge of the new plug, then bash the centre until it just reaches a flat state, not beyond.

You did fit them lip edges facing out I hope.

[Burtie1]

No Bertie, plugs only cap the coolant galleries so you should be fine on that count.

Always clean the core plug seat and apply the thinnest smear of general gasket sealant on the edge of the new plug, then bash the centre until it just reaches a flat state, not beyond.

You did fit them lip edges facing out I hope.

Yh I’ve already done that but it’s not turning over it just turns about a few mil and like bounces back to same place it’s as though it’s hydrolocked I thought that whilst I was filling the header tank and noticed the water coming up in the rocker cover that some may have gone down an open valve into the pots I forgot to mention that I was filling the water up before I knew there was a frost plug pushed out that’s why the water was filling up in the rocker cover

[knobby1]

No Bertie, plugs only cap the coolant galleries so you should be fine on that count.

Always clean the core plug seat and apply the thinnest smear of general gasket sealant on the edge of the new plug, then bash the centre until it just reaches a flat state, not beyond.

You did fit them lip edges facing out I hope.

Yh I’ve already done that but it’s not turning over it just turns about a few mil and like bounces back to same place it’s as though it’s hydrolocked I thought that whilst I was filling the header tank and noticed the water coming up in the rocker cover that some may have gone down an open valve into the pots I forgot to mention that I was filling the water up before I knew there was a frost plug pushed out that’s why the water was filling up in the rocker cover

If you're worried about coolant/water in the bores, pop the injectors or glow plugs out and wind her over, you'll soon find out..!

Lord Knobrot

[jumbo 57]

No way for water to enter bores from the top, apart from maybe a fubard egr cooler, Head gasket fail or cracked head.
If you keep pouring water into an engine with a blown core plug then it may pass the piston rings from below, but you'd have to put a fair few gallons of water in I'd think.

As Knobby suggest, remove the injectors to see if you have water in the bores.

[Burtie1]

No way for water to enter bores from the top, apart from maybe a fubard egr cooler.
But if you keep poring water into an engine with a blown core plug then it may pass the piston rings from below, but you'd have to put a fair few gallons of water in I'd think.

I did put a fair bit in untill I noticed water coming out from the dipstick tube then I took the oil cap off and noticed the water and oil coming up inside the rocker cover so I’m now thinking that a valve or two may have been in the open position letting the water go in

[jumbo 57]

An open valve won't let water into a bore ordinarily, even by doing what you did, but if the egr cooler is bust maybe from freezing or internal perforation then it can get in via a flooded inlet manifold.

I don't know these engines intimately, but that's my guess.

If your lucky, the starter motor might not have enough oomph to bend the rods.

[Burtie1]

An open valve won't let water into a bore ordinarily, even by doing what you did, but if the egr cooler is bust maybe from freezing or internal perforation then it can get in via a flooded inlet manifold.

I don't know these engines intimately, but that's my guess.

If your lucky, the starter motor might not have enough oomph to bend the rods.

Sorry jumbo I can’t work that out since I have not started the van since it froze when I did manage to get the ice out of the top hose and started to fill with water and it ended up coming up to the top of the valves so how can an open valve not let water through when the top of the head was flooded obviously as I’ve been filling with water it’s been coming up through the pushed out core plug and filling up in the top of the head covering the valves so how can an open valve not let water through into the pots

[jumbo 57]

Hi Bertie,

The reason that water/coolant cannot get into the bores when a valve is open is this....

The valves run in guides with seals at the top of the stems, under the springs. When a valve is opened by the camshaft lobe only air can get into the bore through the inlets ports via the manifold, and then out via the exhaust ports and exhaust system after the usual compression and ignition takes place.

Water/coolant in an operational engine can only circulate through the waterways cast into the head, these run close to the valve ports but they are isolated from each other by a designed thickness of metal.

This is how all water cooled engines are made. Water can't meet oil.
Simplistically, the rockers area operates in an environment of oil, not coolant. The frost plugs are an interface/barrier between the coolant areas and the oil areas.


I must of misread that you'd been trying to fire it up, if you haven't that's good.
I presume you are feeling resistance turning the crank by hand then, ok, don't force it.
My advice is remove the injectors in the first instance, then suck out any water from each bore.
Replace injectors, turn over by hand and if it rotates freely you can move onto the task of reinstating the the injector pipes and bleeding the fuel, at this point it will be fine to use the starter motor. (remember to put the oil in).

One little concern I have is that other frost plugs may be compromised after the freeze, only you can make that call really.

[Burtie1]

Hi Bertie,

The reason that water/coolant cannot get into the bores when a valve is open is this....

The valves run in guides with seals at the top of the stems, under the springs. When a valve is opened by the camshaft lobe only air can get into the bore through the inlets ports via the manifold, and then out via the exhaust ports and exhaust system after the usual compression and ignition takes place.

Water/coolant in an operational engine can only circulate through the waterways cast into the head, these run close to the valve ports but they are isolated from each other by a designed thickness of metal.


I must of misread that you'd been trying to fire it up, if you haven't that's good.
I presume you are feeling resistance turning the crank by hand then, ok, don't force it.
My advice is remove the injectors in the first instance, then suck out any water from each bore.
Replace injectors, turn over by hand and if it rotates freely you can move onto the task of reinstating the the injector pipes and bleeding the fuel, at this point it will be fine to use the starter motor. (remember to put the oil in).

One little concern I have is that other frost plugs may be compromised after the freeze, only you can make that call really.

Jumbo after it froze up I noticed that the top hose was froze I managed to get the ice out of it and by tipping lookwarm water in to melt the ice then I noticed the expansion tank was empty so I filled with water untill I noticed it filling up in the top of the head into the rocker cover area at this stage I’ve never tried to start I immediately drained the sump to get a lot of water out then oil after the water I then removed the rocker cover to see the core plug sitting there by the injector I put it back in after cleaning using lecture on it and checked the rest of them which were fine I then cleaned all pipes and hoses out and checked the oil cooler which is also fine I only put it back on the other day and put fresh oil in but when I tried it on the key it only turned a fraction and sort of bounced back I’ve even had the battery on charge and its the same that’s why I thought it may be hydrolocked so it looks like injectors out then

[jumbo 57]

Ok Bertie, first you say you never tried to start it, now you say you did try?

Don't be concerned about the idea of water falling into the bores through an open valve inside the rocker cover, it can't do that.

The water that got into the rocker area got there because of the popped frost plug, when you continued to fill the engine with water it would of drained down the oil drains and land on top of the oil in the sump, then as the sump volume increased with the water it's possible that some water was forced up into possibly 2 bores (the two that would of been lowest in the bore), but maybe all 4.
As oil is lighter than water is wouldn't even be as basic as that.

Back to basics, you need to remove any water/oil from the bores, either injectors off or glow plugs out.


All else is as my last post. Good luck and keep us updated.

[bambi mk 1]

Take out the injectors and see will it turn.How much water did you put in before you realised the plug had popped The water will run out the breather pipe and down through the turbo into the intercooler ect ect if you fill it for long enough

[Burtie1]

Take out the injectors and see will it turn.How much water did you put in before you realised the plug had popped The water will run out the breather pipe and down through the turbo into the intercooler ect ect if you fill it for long enough

Hello bambi mk 1
Here is the story I came out of the house one day and thought I’d start the van up as I hadn’t started it for a couple of weeks but first I checked the oil it looked a bit funny on the dipstick then I noticed the top hose was froze it could be squashed so I undid the top hose and got most of the soft ice out and tipped a touch of warm water in and left it the next day I went out and started to fill the header tank as it was empty I was filling it for ages then noticed water homing through the dipstick tube then upon removing the oil filler cap I noticed it was filling up in there so I immediately let all the water out by removing the hoses it was at that time I came on this forum and asked questions as I never knew there were frost plugs in the top of the head so when I was told this I drained the sump and took of the oil cooler then I took of the rocker cover and saw the frostplug sitting there I’ve since put it back in and tested the oil cooler and put that back on cleaned all hoses and put fresh oil in then come to try start and it just turns a fraction

[bambi mk 1]

Remove the intercooler hoses and see if there is water in them

[knobby1]

Hello bambi mk 1
Here is the story I came out of the house one day and thought I’d start the van up as I hadn’t started it for a couple of weeks but first I checked the oil it looked a bit funny on the dipstick then I noticed the top hose was froze it could be squashed so I undid the top hose and got most of the soft ice out and tipped a touch of warm water in and left it the next day I went out and started to fill the header tank as it was empty I was filling it for ages then noticed water homing through the dipstick tube then upon removing the oil filler cap I noticed it was filling up in there so I immediately let all the water out by removing the hoses it was at that time I came on this forum and asked questions as I never knew there were frost plugs in the top of the head so when I was told this I drained the sump and took of the oil cooler then I took of the rocker cover and saw the frostplug sitting there I’ve since put it back in and tested the oil cooler and put that back on cleaned all hoses and put fresh oil in then come to try start and it just turns a fraction

Geezus...That's a long sentence right there..!

If she won't turn over, (and we'll have to assume the battery and starter are ok).... I'm guessing the water may have gone up past the piston rings or via the turbo/inlet manifold and into the cylinders, time to get the injectors out and see for sure.

Lord Knobrot