Coolant blowing out of rad cap.

[Farmer_Terry]

When we first had the car last year, the temperature gauge would rise steadily to about 90, where the fan would cut in, and there it would stay. No thermostat fitted, but no problem.

 

However, the car has recently started to blow coolant out of the radiator cap. (We thought is was a rotten hose, but Andy at McMillan says it is coming out of the radiator cap). At the same time, the coolant temperature is much lower. On a track on a hot day it might get up to 90 as you pull into the pits and stop, but it runs at about 60 ish. It has been doing this for some time now, although we have not had to top the levels up as the quantities are relatively small. 🙆🏻

 

The only thing that I can think of is that we changed the coolant over the winter. It now has Comma X Steam Red Longlife in mixed with 50% water (I assume this is what we did – its what it recommends on the can). But why would this cause the problem?

 

Other than that, it might be the radiator cap? The only marking I can find on the current cap is “1.1” – what might that mean?

 

Thanks for any suggestions.

 

 

Farmer Terry (and his car)

[John Howe]

Working back from your web pics... so the engine is a Zetec. Thus we can ignore all the usual K-series suggestions.

 

Can't see changing the anti-freeze is going to have any effect on the temperature and a suspect temperature sender can't be the cause, as that would not make it blow out the header cap, just head higher values.

 

If the header cap is anything like the one used on the K series engine, they are known to fail. Since they are only pennies, why not try replacing the cap in the short term and see if the problem goes away.

 

Failing that, have the cooling system checked for engine fumes. Your problem could be coming from either a possible HG failure on the way or perhaps the water pump not moving the coolant around fast enough.

 

Why no thermostat?

 

JH

Deliveries by Saffron, the yellow 230bhp Sausage delivery machine

[I.Mupferit]

Out of interest, do you know what water pump you have fitted to your engine?

 

2L Zetecs in a 7 installation, generally have a belt drive layout that reverses the rotation of the water pump impellor. Now some people leave the standard Mondeo pump in place which will work but will not flow as much coolant around the cooling system. I believe it reduces the coolant flow rate by something like 15-20%. I think it has something to do with the drive belt configuration being different on the Mondeo because of operating the A/C compressor, but could be wrong on that particular info.

 

The standard fix is to fit a water pump from an 1800 Zetec Escort which utilises impellor vanes in the opposite plane thus restoring the cooling system to its full efficiency.

 

And as John asks, do you know why there is no thermostat fitted? Could it be because the original owner hadn't fitted an Escort water pump, was experiencing some overheating as a result and thus decided it was easier to mask the problem somewhat by removing the 'stat?

 

Personally, I don't like leaving the thermostat out, it is there for a reason ie, it controls the engine operating temperature within acceptable working parameters, allowing it to warm up quickly and keep it within that acceptable range. Leaving it out is often a 'quick-fix' that is treating the symptoms of a problem rather than the cause.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

 

 

 

 

 

 

 

Edited by - Brent Chiswick on 19 Jun 2006 23:47:35

[Farmer_Terry]

Thanks for the replies.

 

John

 

why not try replacing the cap in the short term and see if the problem goes away.

 

I wanted to try that before I posted here, so I went to Halfords, but couldn’t find any caps that were even close to one marked “1.1” They were marked things like “7lbs” or “11lbs”. What should I be looking for?

 

 

 

Brent

 

An interesting set of questions to which, at the moment, I have no answers. I have contacted the previous owner to see if I can get any answers there, but the fact remains that it was fine for the six months of last year after I first bought it, so it doesn’t seem to be anything systematic like an inappropriate water pump. Something seems to have changed.

 

I will see if I can get any joy on the rad cap, and take things from there.

 

 

Farmer Terry (and his car)

[I.Mupferit]

Yes sorry, I should have said last night but it was getting late. I would replace the cap as if it is leaking, it wouldn't allow the system to pressurise thus lowering the boiling point and losing water. It may be just a simple problem like a knackered seal under the cap.

 

Onve you have that sorted though, I would still be inclined to investigate why it has no thermostat.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Farmer_Terry]

Brent

 

Sorry to be a pain but where could I go for a cap and what am I looking for? No help in Halfords, and none that I can see in Low Flying. Total numpty I am afraid. 😳

 

Farmer Terry (and his car)

[I.Mupferit]

I can't recall the pressure rating I had on the cap of my Zetec but why not call Raceline on 01483-811978 and ask them. They specialised in Zetec installations in 7's so will be able to help on this or alternatively call James Whiting.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Farmer_Terry]

Thanks Brent - I am on it

 

Farmer Terry (and his car)

[Farmer_Terry]

Brent

 

I have heard from the previous owner and his reply is:-

 

"The car has a Raceline water rail which will answer the question Brent is raising. The water rail is a nice add on but the thermostat often caused a problem with regard to open and closing giving fluctuating temperature readings. As the car has no heater and I used to bring the temperature up before 'giving'' it some' so never had a problem.

 

I would check you have not got air lock in the tubes going to the header tank as it only just sits in line with the rad cap could be susceptible to an airlock)."

 

I don't know enough to understand it all ( ) but hopefully that will eliminate most of the potential problems you raised, and I will check out the airlock idea as well.

 

Farmer Terry (and his car)

[I.Mupferit]

Ok, I know of the Raceline water rail giving fluctuating readings but there is a simple fix to this. The problem is because the water rail resites the thermostat away from the back of the cylinder head where it sits in the OEM application, it doesn't immediately 'read' the temperature in the head where the water exits. The result is that the engine temp rises until, by convection, the thermostat eventually gets the message and opens, allowing a sudden surge of cool water into the engine which then circulates, gets to the 'stat and immediately closes it again. You would see this constant cycling of hot/cold until eventually it all evens out as the engine and radiator become sufficiently warm to prevent it happening.

 

The simple, and now acknowledged by Raceline, fix is to drill a 2.5mm hole in the thermostat top plate thus ensuring there is a constant stream of gradually warming coolant passing over the bulb. This will completely solve the temperature cycling which can't be good for any engine although it has to be said the Zetecs are fairly tolerant of temperature swings (unlike some other engines we know of )

 

Two questions remain though:-

Have you spoken to Raceline about the rad cap rating (speak to Peter McEwen there who is a top bloke) as your current problem could just be a knackered seal.

Was the previous owner able to confirm if the engine has the Escort 1800 Zetec water pump?

 

 

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

 

 

 

Edited by - Brent Chiswick on 21 Jun 2006 09:37:46

[Farmer_Terry]

Have you spoken to Raceline about the rad cap rating

 

I ordered one from them yesterday, but, at the time I didn't know about the Raceline water rail, so when it gets here, I will phone them back and chat through it as you suggest.

 

Thanks

 

Farmer Terry (and his car)

 

Edited by - Farmer_Terry on 21 Jun 2006 11:13:29

[I.Mupferit]

It's a very simple mod to carry out on the thermostat just with a 2.5mm drill bit but if you are buying direct from Raceline, they will often come ready drilled but chat it over with them anyhow, they are really nice guys.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Farmer_Terry]

Just to finish this thread off. We fitted the new radiator cap for the club track day at Oulton yesterday and had no coolant leakage at all. So it looks as if it was that simple.

 

The coolant temperature was better, but still not where we would like it, but I have ordered the modified thermostat from Raceline and we will get that fitted.

 

Thanks Brent (and John) for all your help. *thumbup*

 

 

Farmer Terry (and his car)