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MG MGF Technical - Steam coming from engine...HELP

On a recent journey on m'way, I stopped for petrol and noticed steam rising from the the boot lid. Opening the boot, the steam was coming form the coolant reservoir. It looks to have been forced out at some pressure as there was splattering on the paintwork.

I immediatley panicked and thought HGF however, on further inspection (roadside at night) I could see no mayo. I had been driving the car at about 4-4200 rpm for about an hour, but due to a very silly error, had redline the car in reverse (please, don't ask!!!)

I refilled the reservoir, took it easy for the next twenty miles or so and then stoppped to check....no water had been used as levels had not dropped. I continued my journey for the remaining 100 or so miles, watching all my guages like a hawk with no problems.

I think that my sudden high reves, coupled with a long journey as (resaonabley) high revvs may have caused a sudden build up of pressure, evacuating the coolant in a one-off spurt.

Can anyone give advice on checking/next best course of action. (please don't suggest I don't redline in reverse, I already know!)

Cheers

Nick
N Platt

Hi Nick,

had a similar experience (without that red line moment!) - fluid boiled off. Problem turned out to be the coolant expansion cap.

I'm told that a number of MGR service agents now regard this cap as a regular service item, and replace them when ever a car comes in. I'd recommend the same.

But do keep an eye on the fluid levels for the time being.

Nick, you didn't say which model you've got and how old it is? What's the mileage?

For more see http://www.mgf.ultimatemg.com/hgf_pages/HGF.htm and also follow links to Dieter's web pages.
Rob Bell

agree, it happens when you stop because the engine is hot and you turn off the pump (by stopping the engine) and without pressure in the system you will get localised boiling in the engine, this will force coolant up as the bubbles cannot easily escape and then it comes out of the cap, when the engine cools a bit the steam will condense and suck back coolant, but not the coolant which has escaped!

Will
Will Munns

Isn't the cap specifically designed to function like this, to prevent damage elsewhere?

much easier to replace a cap, than a burst hose.
paul weatherill


Thought the cap only 'let go' when the pressure way *way* to large. If the cap let's go (when it's working correctly!!) then you have problems.
The problem here is that often the caps are mildly faulty.

P.
Paul Nothard

Pauls, yes The cap is disigned to do this (as are all caps, even the midget one), but the F cap has a habit of dieing over time and letting go at much lower pressures, I would guess it's thermosoftening plastic and a hot engine bay that does it.
Will Munns

I remember when two regular contributors to this board had the very same problem after a 14 mile drive around the Nurgburgring on a Treffen 3 (?) years ago.

Both pulled into the car park feeling both shaken and stirred after the drive only to see that their cars appeared to be puking green vomit out of their rear ends.

Both had a nicely boiling cooling system gushing liquid from the filler cap. Once both engines had settled, the expansion tanks were topped up and the Treffen continued for another 1,000 miles plus with no hint of HGF. Neither (I think!) has subsequently had an HGF. One of these has however recently explored the effects of driving an F at high speed into Armco. From this experimentation, it would appear that driving your F into Armco is far more damaging than boiling the coolant!

More seriously, never forget that the engine in the F was originally designed to power the dear old Metro. Don't thrash it until it is warmed up and don't switch the engine off unless it is at normal temperature!

Cheers

Patrick
Patrick Beet

>don't switch the engine off unless it is at normal temperature<

Being the other Treffener mentioned with a puking engine I can only emphasise what Patrick says.

Besides puking green stuff it also upsets German Officials!

Ted
Ted Newman

Thanks all...panic over I think! I am going to monitor it closely and if there are any further developments, I will let you know!

Oh, it's a 1998 Abingdon MPi. Had it two months, best car I've ever bought...well chuffed!

Nick
N Platt

Thought Scarlet had been touched by the HGF curse once (fairly recently too)?
L Reid

Sorry Nick, but I *have* to ask:

>>had redline the car in reverse (please, don't ask!!!)

How the f*** did you REDLINE the car in REVERSE by ACCIDENT? :-)

How fast does the F go backwards when you do that? I'd love to know. And what does the gearbox sound like?
David Bainbridge

Not just the MGF, but after a sustained hot motorway run the very hot engine of almost any car can build coolant pressure way above normal immediately after switch off. One of the reasons why there are warnings to remove the hot pressure cap with extreme care. Turn the ignition on again without starting the very hot engine and observe the coolant gauge reading. It will usually climb way above normal on most cars after a hot high speed run. This is due to localised heat transfer to the non-circulating coolant from the very hot engine parts.

I learned this first hand many years ago with my first MGB following a sustained 100mph plus run down the M1 (perfectly legal and safe back then - motorways designed for high speed transit). The force of pressure took me by surprise and the resultant rush of coolant knocked the bonnet off its stay.

Back in 1983, following some warranty work on the gearbox, the lower coolant hose clip on my then new MG Metro was not secured correctly after reassembly by the Dealership. Just a push on fit. Soon after switch off on a hundered mile summer trip, I discovered a large pool of clear yellow liquid under the front of the car. On closer inspection, found the increased pressure after hot engine switch off had eased the push fit hose off the radiator pipe completely!!! I tightened it, refilled and no further problem.

Drivers of turbocharged cars are also aware of premature switch off potential damage to turbos and engines. Indeed, some cars have devices to delay engine switch off for a minute or two even after key removal. This allows time for the coolant and lubricant to "warm down" vital engine and turbo components. So if you see someone lock their car and walk away with the engine still running, thats probably why ..... :o)
J McFeely

>So if you see someone lock their car and walk away with the engine still running, thats probably why ..... :o) <

I thought that was actually illegal - to leave the car unattended with the engine running!

Ted
Ted Newman

It is Ted (unless off road on private premises protected from the public) but so is exceeding the NSL but I understand some people do that as well.
JohnP

John

People dont break the law do they?

Ted
Ted Newman

>People dont break the law do they?

Shops which open at 11 and close at 5 on a sunday, rather than 10 till 4. Either you're a criminal or your not - there is no middle ground!

Will
Will Munns

Will

Are you telling me you do not understand the distinction between theft and contravening some silly rule?

Do they teach nothing about morality to the youth today?

Cheers

Patrick
Patrick Beet

Actually Will the law is 'six hours' trading on a Sunday so 10 t0 4 and 11 to 5 are both legal as is 12 to 6 or 9 to 3.

Ted
Ted Newman

>do not understand the distinction between theft and contravening some silly rule?
like speeding? yes the silly rule is 70, the theft is called a NIP

>Do they teach nothing about morality to the youth today?

nope, duty of the church apparently, so either you can go shopping or go to hell, there is no middle ground
Will Munns

To go back to where this started:

Theft:
The act of stealing; specifically, the felonious taking and removing of personal property, with an intent to deprive the rightful owner of the same; larceny.

Americanized, but the English description is very simmiler.

>Actually Will the law is 'six hours'
I thought as much, but I was trying to come up with a suitable 'silly rule', I supose I could have talked about breaking into your own house...
Will Munns

>> Neither (I think!) has subsequently had an HGF. One of these has however recently explored the effects of driving an F at high speed into Armco. From this experimentation, it would appear that driving your F into Armco is far more damaging than boiling the coolant! <<

Harrumph, well, thanks for reminding me Patrick. ;-)

Incedentally, Scarlet had a HGF at 91,000 miles, late last year. Happened in a traffic queue and i was able to pull over and stop with little or no damage. Still, Scarlet being a 7 year old F i thought it wise to take the opportunity of replacing the rad and underbody coolant pipes whilst the system was drained with aluminium ones and this, along with the Stage 1 gas flowed head made the repair bill somewhat more than the £500.00 i had stashed away in my 'anti-HGF fund'... ;-)

I think, given the time between the 'green vomit at the Nurburgring' incedent and the eventual HGF, they were unrelated. Especially given the subsequent 2 trips to the Nurburgring in between!

SF
N926 FEV - MGF (wreck) :-(
EF52 DXY - ZS 180 (new) :-)

View the rebuild of Scarlet at >> http://www.sfforever.co.uk <<
Scarlet Fever

>>Sorry Nick, but I *have* to ask:

>>had redline the car in reverse (please, don't ask!!!)

How the f*** did you REDLINE the car in REVERSE by ACCIDENT? :-)<<

Seeing as you've asked so nicely, I was pulling into Warwick services for petrol and overshot the petrol station entrance (they have changed the access and not the signs...I was about the 5th person to do this in about a minute, so I wasn't being totally crap!). Anyway, I found myself stuuk at the HGV pumps, which had been blocked off from the M'way and the other side of the petrol station. I put the car into reverse and in my frustration and desire to get out the the way as quickly as possible, nailed the carpet, spun on what I think was probably deisel and carried onto the correct pumps (it was at this point that I noticed the steam).

FYI, the engine sounded great, if a little strained! The K&N was in full flight so that sort of masked the sound of the gearbox.

Please don't be too harsh on me! I'm young, having fun, making lots of mistakes and ocasionally learning from them....castigation not required!!!

An ever-so-slightly-less-hasty...

Nick
N Platt

Will,

You do seem intent on proving my worst fears about the papacy of modern education and the lack of understanding of morality that is being instilled.

Your statement "so either you can go shopping or go to hell, there is no middle ground" completely misses the mark. The message is surely if you shop on Sunday, then you will go to Hell!

Cheers

Patrick
Patrick Beet

Ted, WROTE:

>>I thought that was actually illegal - to leave the car unattended with the engine running!<<

Under normal circumstances I believe it is. But, with the car locked and the key removed from the ignition switch, it would be an interesting one for the courts ...:O)))

Actually, I believe they're called "Turbo Timers" or something similar and allow the engine to idle for a minute or so after key removal and locking the car. Probably works just as well on a normally aspirated car thus could be an engine "safety" device for still hot MGFs on switch off.... :O)

I guess the device is something simple like the interior lights on my old Montego turbos. They stay on for a period after I've locked the car up and walked away .....
J McFeely

This thread was discussed between 25/03/2003 and 26/03/2003

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