John F - I'd rather not attempt to repair the leak. I'd imagine the pressure it is under will cause the repair to split in no time. Cam-belts I think are due around the 70-80k mileage mark. Having mine done at 90k I think was more than late enough. You are often advised online to have the water pump replaced at the same time to save on labour costs down the line.

elekie&a/a doctor - I've seen lots of second-hand original Ford expansion tanks on ebay for as little as £13. My concern is how do I know these are sound?? I guess I don't.

If someone can pin-point a cheap but reliable/robust part then I'd be grateful. Would prefer not to pay silly prices.

Thanks.

Edited by dac1 on 23/06/2019 at 12:02

So with that said... I was correct to have my water pump replaced at the same time as the cam-belt (or to put it another way, I didn't have a choice if a cam-belt pulley is built into the water pump).

I've seen a good few Ford original second-hand expansion tanks on Ebay but they could be brittle and crack as I install it. I'm going to purchase a Hella expansion tank as I've heard these are good quality.

Edited by dac1 on 23/06/2019 at 20:29

There's hardly any pressure - 15psi max - unless you've got a serious CHG failure which blows it out all over the place!

JohnF. Why not take your car for a good long drive and get it really hot. When you get home remove the cap off the expansion bottle and then you will see how little pressure there is in there.

You say somewhere that it does not leak if not driven, are you sure that the pressure release cap is OK given the age?

I have read your post again. You either have an air lock from the original water pump job, cracked bottle, or faulty cap. The problem started after the water pump change so my money is on an air lock causing over pressure and this is released by the filler cap and coolant would run down from the top. Unless you can see a crack which you can't I would not go with this or the cap. If you google Focus expansion tank problems it may change your outlook and you should try to clear possible airlock. As you say there was no coolant problem before the water pump go back to root cause and NOT somewhere else.

If all you are doing is replacing the expansion tank with a new one, empty all the contents into a jug or something similar, detach all hoses (hopefully they will separate easily) and tie them up as high as is convenient to prevent entry of air. Hose off the engine mounts etc. with water and let dry. Connect hoses to new tank, refit and replace removed coolant. Old cap should fit new tank and be serviceable. There should be no airlocks to worry about. Run engine and check hose connections. No worries .....

I don't buy the tale of airlocks lasting for three months. Repeated use of an engine sends locked air into the expansion tank quicker than that.

Edited by Andrew-T on 25/06/2019 at 00:07

If a cracked tank is the root of your problem I don't think you should have any airlocks left in the system - your coolant losses are caused by increased pressure in a working engine. The problem follows the waterpump operation, so if that new pump is leak-free, the most likely other cause seems to be damage to the old tank, which may be brittle with age. It's possible that the pressure-relief cap has become faulty, but that would be an unlikely coincidence, unless it was also damaged during the work.

Cooling systems I am used to have other bleed points for releasing trapped air, and your garage should have used them after refilling your system. Some air probably remained, but should have migrated to the top tank after three months. See what happens after your new tank has settled down.

You could refine your check for leaks by wrapping the tank-cap with paper-towel while the engine runs, just to be sure the leak is at the base of the tank.

Edited by Andrew-T on 25/06/2019 at 10:39

I'm reading elsewhere that t could be a faulty water pump or a damaged head gasket.

Unlikely. I thought you said the pump had been (probably unnecessarily) replaced.

How do I test for these things?

A faulty water pump could leak, make a noise from a failed bearing, or just not circulate the water properly if its impellor blades had disintegrated (some cheapskate ones are made of plastic). They can usually do huge mileages these days. A failing CHG will contaminate the oil and mysteriously lose coolant long before a pressure test will reveal a fault.

Would running the heater test it in some way ...?

No. But sometimes those who don't keep an eye on their coolant level only know that much of it has disappeared when the heater runs cold.

And should the expansion tank become hot whilst the car is ticking over ..

Yes - eventually

or should the coolant keep the expansion tank cool?

No. It keeps the engine cool. Even after driving up an alp on a hot day it will never get hotter than boiling point - circa 120degC at around 20psi

I'm reading elsewhere that t could be a faulty water pump or a damaged head gasket. How do I test for these things? Would running the heater test it in some way and how?

You are worrying unnecessarily. Before your cambelt change the car apparently had a stable and working cooling system. Nothing has happened since except this garage work, so do not start suspecting other causes without good reason. A very remote possibility is that the replacement pump was itself faulty. Given the method shown on your video, accidental damage to the top-tank or its relief-cap seems the most likely cause, so deal with that first.

Some final questions:.......

...and answers...

1) Yes. Coolant lasts the life of the car. (ours is 18yrs old....even older in my TR7). I have argued why elsewhere.

2) No need.

3) No

4)A combination of old age and rough handling by your mechanic. Nothing to do with the coolant.

5)Just use an old slightly oily rag.

6) Can't answer this. You almost certainly have a tiny hairline split which only leaks when a bit of pressure develops in the tank. This pressure never gets higher than about 15-20psi (the reservoir cap is a pressure release valve) which is hardly anything - half car tyre pressure and a quarter of bicycle tyre pressure. You will probably only locate the crack after taking the tank off, cleaning it and inspecting with a magnifying glass. If you can't afford to spend money on it just use a bit of glue as I previously suggested.

There's hardly any pressure - 15psi max - unless you've got a serious CHG failure which blows it out all over the place!

JohnF. Why not take your car for a good long drive and get it really hot. When you get home remove the cap off the expansion bottle and then you will see how little pressure there is in there.

'Really hot' ?? Basic physics should tell you that no matter how long the drive it can't get hotter than around 120degC thanks to the cap which is designed to release gas at a pressure of around 15 - 20 psi. - which is hardly anything. In practice this never happens as the fans keep the coolant at around 90 deg C.

The stat on a Zetec is designed to keep the engine at 92 degrees (on early Escort and Mondeo ones it was 88 degrees). The fan is 2 stage, the first comes on at about 100 degrees, the 2nd at about 110.

By "really hot" I actually meant "normal" ie 92 but since a modern temp gauge lies its not a simple matter of driving until it shows normal since the gauge shows "normal" from about 60 to 120 degrees. It only deflects to the right just before meltdown occurs, its little more than a warning light in reality.

So are you going to try my suggestion and take off the cap when the car is full up to temp and report back about what happens? Since you are are so certain there is hardly any pressure you will be fine.

Warning to less knowledgeable forum users. Taking off the filler cap when the engine is at normal operating temperature will result in severe burns due to the coolant escaping so please do not try it.

<< Do not use water straight from the tap. It contains air and as that is released the coolant level drops. I always use water that has been in a container for a few days prior to use and never have an issue with the level dropping. >>

Just to be clear: if you want to use air-free water, boil any gas out of it briefly before use. Gases dissolve best in cold liquids, and are removed by a quick boil. They tend to redissolve gradually on standing. And if you live in a hard-water district (most of south-east England) get distiiled or deionised water for the cooling system - or use Highland Spring :-)

Edited by Andrew-T on 25/06/2019 at 16:12

<< But if you really want mineral-free water, use rainwater from the butt. >>

Now that really is a daft suggestion. At least tap water will be clean, even if it does contain some dissolved air. Water from a butt (at least from my butt) contains anything the passing birds choose to drop on my roof, plus algae or fallout from local trees. If you don't mind that in your cooling system, go ahead. Or filter it first.

And (following your earlier point, John) coolant does not necessarily 'last the life of the car'. I have seen the top-tank of my daughter's Mk-1 Clio full of what can only be described as something between gravy and Windsor soup. That would be because of a cast-iron block and the fact that Renault didn't bother to suggest regular changes of coolant, so no-one bothered. And perhaps previous owners had topped up with water from their butt.

Edited by Andrew-T on 26/06/2019 at 10:44

<< The contaminants you mention sink or float. After settling, the water emerges clear. >>

I still wouldn't use it in a cooling system. All kinds of solutions are 'clear' including sea water (if you let it settle).

<< Does it need regular topping up? >>

I'm talking many years ago now, John. The Clio was probably about 7 years old and otherwise in decent running order. Cars of that era - perhaps not so much now - needed their coolant changed every few years because the antioxidant degraded, especially if the pH was affected by careless additions.

<< Your point is...? >>

I hoped I had implied that a clear liquid is not necessarily free of nasties, impurity if you prefer.

<< The Clio was introduced here in 1992. My friend's mother had a Renault in the early 1970s. It had a sealed for life cooling system. >>

That may well be true. The service schedule with my daughter's Clio made no mention of changing coolant, suggesting that was still their attitude. Even though the engine didn't overheat, I decided that thick brown liquid was not the ideal coolant, so I changed it. Other makers at the time (Peugeot for one) thought that was a good idea every 2 or 3 years.

Maybe you should stick to physics and leave chemistry to others ? :-))

So are you going to try my suggestion and take off the cap when the car is full up to temp and report back about what happens?

SWMBO just back from 26 mile round trip, so nicely 'full up to temp'. And oil near minimum, soon due for top up. Cap cautiously removed. Very slight transient hiss of air. Coolant well below boiling point according to the tip of my finger which remains unscalded, let alone a 'severe burn' !

Looking forward to a follow-up post from the OP re what he has done.

As this seems to be the most interesting and also non sensible thread on here at the moment, I will add my two pennies worth. When you add any fluid to a cooling system regardless of the air content of the fluid, there will be beads of air trapped in the rad, hoses engine water jacket and filler tank. You do NOT remove the filler cap of any HOT closed cooling system unless you are very foolish.

I had a Ford fiesta and it took me hours of messing around with the thing to get rid of an airlock

Dac1, in reply to your latest, I can't think of any way a very heavy-handed mechanic might cause a head gasket to fail, at least soon afterwards.

Re your experiment with the header tank: let's assume it has a small crack. You run the engine for a while and some coolant gets expelled. Engine then cools, causing a slight partial vacuum in the system, which therefore stops leaking, at least until you take the cap off. That may explain what you have just described. Normally a cooling system will be filled cold, so will be under some pressure when the engine has warmed up. If an engine overheats, excess pressure may relieve via the tank-cap. This safety-valve allows the system to get a few degrees hotter before the water actually boils.

The cambelt in my car (a diesel) was changed a few months ago, and next day I found no visible coolant in the header tank. The 'mechanic' had not run the engine long enough for the thermostat to open and clear the airlocks. It didn't cause the engine to overheat, which just shows that the tank doesn't have to be full; but the translucent plastic makes it easy to check for losses.

Edited by Andrew-T on 26/06/2019 at 19:38

The Ford Zetec also has a cast iron block and my nearly 19yr old 140,000m coolant is pink and clear.

JohnF. I thought your Focus was a 1.6. If it is you will find its has an alloy block. The 1.6 used the Yamaha designed engine that has been used in 1.25, 1.4, 1.6 and 1.7 versions in the Fiesta, Focus, Mondeo etc.

If your car is a 1.8 or 2.0 it will have a cast iron block since its the Ford designed Zetec taht was introduced in the Mk1 Mondeo and was slightly modified for the later Mondeo and Mk 1 Focus. The Mk 1 Mondeo did have a 1.6 cast iron Zetec engine but this was never fitted in a Mk 1 Focus.

Avant. You deleted my earlier comment which you say was offensive but you continue to allow JohnF to post his dangerous d*****. Its Honest John and possibly yourself that will ened up in court should a Forum user get injured following his crazy advice. You warned him to stop some time ago and personally thanked me for alerting you to his potentially dangerous advice but you now appear to have given up. Perhaps I should alert Honest John himself since its him that would ahve to defend the site.

Right folks.

I have changed the expansion tank over to the new Behr Hella replacement. Pretty simple process and feel pleased for doing it myself.

One thing I messed up was watching for the Antifreeze/Coolant coming out of the hoses. I was too focused on draining the Antifreeze/Coolant from the tank. As a result one hose dripped all over the belts and the other hose dripped all over the oil cap/spark plugs area. I dabbed up what I could but couldn't reach down the belt area. I would say about three table spoons of Antifreeze/Coolant spilled on both the belts and the oil cap/spark plugs area. In an attempt to draw out any Antifreeze/Coolant, I sprayed a good helping of WD40 in those areas. The oil cap/spark plus area is closed off so the Antifreeze/Coolant and WD40 will evaporate in the that area (especially in this heat). The belts aren't closed off so I just hope the WD40 draws out the spilt stuff and then evaporates too.
Is the Antifreeze/Coolant (and WD40) likely to corrode those areas, especially the belts?

Where the engine mount is, and where the Antifreeze/Coolant had been dripping, there is this black thing with a little rubber top (or what looks like rubber). Well it seems the hot leaking fluid has melted the rubber a bit. Not badly so its gone straight through but just disfigured it slightly on one side. Is this a problem?
(EDIT: I've just watched a clip and the rubber thing is actually the top of the hydraulic engine mount. I thought the engine mount was just that big metal thing surrounding the hydraulic engine mount -- the question still applies, has the hot Antifreeze/Coolant leaking onto the hydraulic engine mount and disfiguring it damaged it or likely to cause harm to my car??)

Having connection everything belt up I clipped the tank back in place. To clip it in you need to push fairly hard and then it goes thud. So I can definitely see a brittle tank cracking with the force of the thud. Having view the underneath of the old expansion tank I could see two areas that looked suspicious. One of which was a prime suspect. It looked like a stretch mark area.

Once all was ready, I filled the Antifreeze/Coolant up to 4mm above the maximum line. This was to align it with the middle part of the X (in Max). Still 2 inches below the top of the tank. It was filled with fresh Antifreeze/Coolant mixed with cold tap water. I mixed it two days ago so it had time to air (one tip mentioned in these posts). The drained stuff had a few little bugs in.

Having the expansion tank cap off, I then put the fan on full temperature and at full blast and let the car tick over for 22 minutes. I gave it the odd 3,000rpm rev. To be precise -
1 - 15 mins - heater and revs.
16 - 20 - just ticking over.
21-22 - just ticking over with the expansion tank cap placed back on.

All seemed fine. No dripping.
I will take it for a half hour drive this evening and park it up over night on a fresh bit of driveway to see if there is leakage on the drive over night.

In the morning I shall let it run for 15 minutes but this time placing tissue in certain places to see if it leaks. If it doesn't then I reckon all is resolved. Of course, I'll still keep my eye on it.

Thanks again all. Really helpful for me.

Edited by dac1 on 29/06/2019 at 13:26

Even though the plug area appears sealed its not 100% and liquid can get down there. It should evaporate but I would check and dry it out if necessary, but don't remove the plugs.

If spark plugs are gas tight how on earth can liquid pass the plugs?

Reading dac1 last comments I am beginning to wonder if the whole posting is a wind up!

If spark plugs are gas tight how on earth can liquid pass the plugs?

Its the plug lead ends that are designed to seal onto the cam cover and prevent water (and other containments) getting where they shouldn't. I can assure you that they are not 100% water tight and Ford are aware of this. There is a hole in the cam cover at the coil end that acts as a drain to prevent water collecting and eventually getting past the plug lead ends.

Is there anything I should do to undo the WD40

Not really. Once its on the rubber the solvent will probably evaporate quickly and the oil will soak in. There are plenty of old wives tales but none are a cure, they just disguise the problem whilst you sell the car.

What is the belt that is directly under the engine mount?

There are 2 belts, the cam belt and the auxiliary belt. The auxiliary belt is exposed, the cam belt should be under covers.

Easy way to spot the difference. The cam belt is toothed, the auxiliary belt is ribbed.

If its the auxiliary belt it will probably make one heck of a squealing noise due to the containments. It may possibly slip as well which will lead to the charge light coming on. Probably best to have a garage change it if either of these happen.

If you have sprayed the cam belt how lucky are you feeling?

Well, I can't do anything about it now.

Just be nice to hear some reassuring comments like I haven't damaged my car in any way (but only if that is true), like sammy1 has.

Just had a good inspection of the engine area. No liquid or grease anyway. Everywhere is dry. Just taken it for a 15 minute drive (gear changes and top gear) and all sounds and feels fine. Had a look afterwards and all looks good. The expansion tank was very hot - so definitely don't take the cap off when hot - don't even touch the tank when hot.

I will give up now, but if there is anything else I should do then let me know.

Thanks all, again.

This is not a wind up. I'm no mechanic.

You don't need to be a 'mechanic' to DiY, but I suggest that you do need to be able to identify any parts you are dealing with. Getting a Haynes manual, or perhaps borrowing a library copy, might be a good idea.

And you seem to be rather liberal with the WD40, as if it were a magical cure-all. It's a light penetrating oil (actually a water dispersant, hence the WD), not a lubricant or a cleanser. It's great for releasing tight nuts or removing grease from awkward places.

Edited by Andrew-T on 29/06/2019 at 22:54

I remain puzzled why you think the use of rainwater is either dangerous or crazy.

John F. Check your facts again, I have never commented about your crazy use of rainwater. However, I have commented on your dangerous advice to remove the water filler cap whilst the engine is hot.

Skidpan - please check your facts. It was you who advised the removal of the cap to see how much pressure there is, not me. Here is your post.....

JohnF. Why not take your car for a good long drive and get it really hot. When you get home remove the cap off the expansion bottle and then you will see how little pressure there is in there.

I actually posted that thanks to the ability to see the coolant level from the outside there was no reason to ever remove the cap apart from topping it up, which I have done once in 15yrs as, thanks to modern design, it is virtually a sealed system.

No more to say.

Thank goodness for that!

Just as a matter of interest, and possibly for the amusement of our readers, I performed the same experiment on the TR7 today. It was a warm day, and I drove briskly back from lunch in a village ten miles away. The TR7 has a bigger less efficient engine than the Focus, so it generates much more wasted heat. However, on cautiously opening the reservoir cap there was again nothing more than a transient hiss of escaping gas. However, the metal reservoir was much hotter than the plastic Focus tank, which gets merely warm. I could only hold my hand against it for about five seconds, so I guess it was about 60 - 80C. Anyway, it was nowhere near boiling and I thought the experiment far less hazardous than cooking Sunday lunch! I also syphoned off a glassful of coolant and was gratified to note that it was a clear turquoise colour - untouched since I had to renew the water pump in 2003. No sign of 'Windsor soup' (I bet that Clio didn't last much longer) - and the Triumph slant 4 engine really does have a cast iron block. If the OP's reservoir is 'very hot' as he says, I would be keeping a very close eye on it.