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MG MGF Technical - HGF Early Warning
| Hi All ok so still new to the MGF and loving every min of it Had the car the 3 months now so .... Been reading a lot about the HGF and the problems that the MGF has had with this fault. On discussing with my Dad the other night about the car and all the checking that i do on the collant and not driving above 3000rpm till warm etc etc he asked "cant we make an early warning system ?" well has this been discussed before ? anyone ever tried this ? and now to my limited knowlegde the HGF is generally found not because the gasket is at fault, but because it fails normally sue to some other failure and this in turn is normally the coling system so Its a pressurised system right ? that runs at a set pressure once up to temp and engine functioning correctly right ? Does that mean that through some sort of pressure device inserted in to the coling system and a bit of electronics with lights on the dash then a system could be made that will tell the driver if there is a major pressure change in the colling system and thus a fault ?? then the driver would be aware, stop and hopefully not have to go the whole hog and replace the HG, just find the fault with the cooling system and fix, no HGF !! I do appreciate that i know next to little about the car, im a computer engineer by trade !, so please feel free to correct me on anything here :) Also anyone got a copy of the workshop manual on CD, ftp site or the like :) Cheers Slayer |
| EvAl Slayer |
| >>>>Also anyone got a copy of the workshop manual on CD ==these are frequently for sale on eBay for a couple of quid |
| David S |
| Not that simple I'm afraid. The pressure varies a little, but a pressure gauge will only warn you if the system has excess pressure, and this is usually a teltale that something has gone wrong already. A water level meter would be more sensible - as a lot of the overheating problems come from low coolant. 4Life coolant may be a way forward, it does not expand with heat, so should be less stressful on the gasket. The most common failure point is above the alternator, it looks like the gasket rubber seal gets freed from the gasket and pushed out by the water pressure - but this might not be what is actually happening. |
| Will Munns |
| My "early warning" for my HGF was that it absolutely stank when I pulled up at traffic lights... of coolant... that was for an external coolant leak through the gasket... I caught it before the big full-on smoke and steam show from the bootlid... Chris. |
| Chris Tromans |
| Another cause which has been put forward as a cause for the gasket failure is localised boiling in the head after the car is stopped when very hot, so leading to thoughts of a water pump circulating coolant for awhile after the engine turned off. Mike |
| Mike (Mersea Office) |
| Slayer. Have copy of CD kindly gifted by JP, if you can get to Warrington area, you are welcome to a copy!. Mark. |
| Mark |
| Mark that would be brill ta I actually work in warrington so thats no trouble :-) send me a mail at evalslayer at dsl dot pipex dot com ta Slayer |
| EvAl Slayer |
| As most owners have an opinion on HGF, heres my 2 cents Worth!. Im no mechanic but........... Mikes localised boiling Idea sounds about right!. I base this on my own line of work (heating engineer),A cars cooling system and a boiler heating system work in a very similar way. Most modern boilers have a low water content aluminium heat exchanger, which can be damaged by excess heat, to overcome this, the boiler has a "pump over run", as soon as the boiler shuts down the heating pump will run on, for a few minutes to disperse heat from exchanger and return cooler water from other parts of the system. Also, sealed heating systems(no open vent)have a expansion vessel fitted, this is a cylinder split into two halves by a diaphram, with air pressure acting on one side, and the heated system water acting on the other, as the temp in the system rises and so with it the pressure, the diaphram expands into the air space thus increasing the volume of the system!. Toyed with the Idea of fitting one to my f, as they are not much bigger than a tennis ball. But if it was so simple why didnt Rover do it!. Oh well just an idea!. |
| Mark. |
| mike chester do you live in warrington i might av seen u about in your mgf.... |
| m e johnson |
| Mark, I think the car *heating* _is_ similar to house heating ;) >sealed heating systems (no open vent) have a expansion vessel fitted, Lots of rubber hoses expand under pressure and app 1.5 liters of air in the expansion tank do the remaining balance. :) >"pump over run" Agree. This add-on has a known application in the Lotus Elise and if you look up in the archives you'll find lots of hints about it. However, the K-Engine has a well working coolant system for usual driving style. As long as nothing fails. (waterpump, split hose, problems with cylinder liner sealing against the metal ring of the headgasket etc) AND as long as the front fan does his job when the car doesn't roll in a traffic jam or similar. Heating failure comparison: Try closing all attached heaters in a house and fire up the heating boiler to maximum until the water boils. I daubt the expansion vessel will carry all the over pressure. The heating security over pressure valve will blow off the water :) At the K-Engine this security pressure valve is included in the expansion tank cap. And if this doesn't blow off enough then a second _security_ function is _provided_ by the silicon ring around the head gasket. :o) Cheers Dieter |
| Dieter K. |
| HI Dieter. Like i Said just an idea( just not a very good one):o( On the right lines with the "Over run" at least, not checked archives but assume must be electrical pump, linked to some form of Stat, with timed run like a rad fan. Seen many boilers damaged due to the systems failure to remove "latent" heat from the exchanger, on shut down, so may be the same on the "K". Having said all of that 70k miles and no HGF!.(touch wood)!. |
| Mark. |
| >Seen many boilers damaged due to the systems failure to remove "latent" heat from the exchanger, on shut down, so may be the same on the "K". :) Quite similar to the K-Engine. (... any engine IMO) Known as _soak mode_ (German-English, dunno the right english name). Missing heat flow with the shut down engine (heating boiler)allow strong temperature gradients special at thin parts of the engine block or head. Different materials like steel and aluminum have different gradients of length change under temperature. Not to worry about unless this happens within the natural flexibility of materials. BUT, strong temperature gradients let the weaker material get warped and bent by pressore from the stronger, resulting in gaps between both finally. Gap means bad seal, resulting in blown of gasket. So the idea was to prevent from huge temperatur gradients with an additional electric water pump. Cut in with engine shut off. Cut out under a decent low temperature. However, another electric add-on which could fail. ;) @Will, please apology !! First step is IMO still to keeping a sensitive eye on fuse No. 2. I fitted a 12V buzzer parallel to this fuse. When the front fan fuse whyever blows again, the buzzer will tell me: Meeeeeaaaap !! Dieter, we got a problem, stop immidiately and have a look to the radiator fan. :))) Cheers Dieter |
| Dieter K. |
| I have a copy of the workshop manual on CD send email with details. |
| Jim Kenny |
| There is a solution to the localised overheat issue - a pump that'll run on after switch off - although you can achieve the same effect by not switching the engine off immediately after a 'hot run'. Dave and I were working on this, but due to problems the project has stalled (it was proving to be very expensive if we had to employ a timer) - but I'll see if I can get one of these pumps fitted to my car and I'll figure out a way of getting it to work... :o) |
| Rob Bell |
| Rob. Dont know if its any help but.......... have some old extract fans, the type you get in bathrooms with no windows!. After you turn the light off, the fan runs on to remove smells etc!. There is a small PCB inside, with an timer which can be set for a 2-10 minute over run!. Ok PCB is 240v, but may take a step down?. Will send if any help. |
| Mark |
| It's a thought Mark - that would indeed provide a cheap source of timers! But what I was thinking of doing was ultilising MEMS's own power down delay signal (the one that Carl utilised for the window circuit delay). Keep that PCB handy though - might still need it! |
| Rob Bell |
| If you only care about a timer then a simple 555 circuit would do, and cost pence, the difficulty comes with making it 'tempeture dependant' |
| Will Munns |
| There is no need to make it temperature dependent Will - just run the pump for 60 or so seconds after switch off - it will do its job. A 555 circuit? I'm not an electronics expert Will - as you know :o) |
| Rob Bell |
| What do you class as normal driving though !! I mean i do like putting my foot down even once in a while !!! |
| Chris Gray |
| Rob If you want a ready to go timer (based on 555 chip) with 12v dc in (car supply), 5 amp switched relay out, but could swich 30amps with auto relay. Visit your local Maplin store in Wood Green, N London and ask for a MK111- order code VT27E. Used to be approx £5. What sort of pump are you using? Davies-Craig, Ozzy ones? There are now some really neat (small) very high temp liquid ciculators I have designed into various processors. I understand they originate from the heating and ventilating industry. I run a B with a V8. Under bonnet temps are a major issue! I have designed a digital display which automatically monitors 5 switchable thermocouple inputs, top hose (thermostat housing), bottom hose, rear of block, oil temp in sump and oil temp by its cooler. If any temp starts to go critical it will initiate a cooling fan, either rad (blower) or one low down (sucker), horizontally mounted between rad and engine. This is designed to draw are through louves in bonnet and then across sump. This cooling cycle will also remain running after switch off, and will of course control block heat soak. Anything I design is pretty simple and all bits are easily availible through RS, Farnell, Rapid or of course Maplin stores. |
| Richard E |
| Rob, 555 timer circuits are GCSE level electronics: I can knock one up when I have a little time, or you can wait 15 years for your prodigy (which looks like it may be faster looking at my current tasks!) |
| Will Munns |
| book http://www.amazon.co.uk/exec/obidos/ASIN/0859340473/qid%3D1096396920/202-0926215-9160664 part http://www.maplin.co.uk/products/module.asp?CartID=040928195000142&moduleno=2704 Just do it :) |
| Dieter K. |
| Will, I look forward to your, usually intentional, palapropisms with almost uncontained excitement. This time you forced me to consult Dr Johnson for elucidation: prodigy: an unusually gifted or intelligent (young) person; someone whose talents excite wonder and admiration progeny: one born of, begotten by, or derived from another; an offspring or a descendant. Do Yimmy and Rob know what they have let themselves in for? |
| JohnP |
| Richard, Rob's obviously offline at present. Your knowledge and experience with the pumps, thermocouples and timer is exactly what we've been looking for. Rob and I started this project over a year ago and have made little headway because of the lack of cheap control circuits to do what we want. We are using the Davies Craig pump based on a similar sized (albeit Bosch) pump used in the Lotus Exige to run-on after engine shutdown and keep the coolant moving to avoid heatsoak and localised boiling of coolant in the K series cylinder head. Perhaps we can get you and Rob together sometime (he's in London N10) and make some progress :-) Dave |
| Dave Livingstone |
| >prodigy () Is what I intended, I mean, child of two Dr's, inspiration of the octogon - what else is required on the road to success? |
| Will Munns |
| LOL Will |
| JohnP |
| If you are looking for timer circuits, using the 555 timer chip is simple. Look here http://www.circuit-innovations.co.uk/555.html |
| Jim Kenny |
| Just been at the local Dealers who told me that all new MGR's are now fitted with a water level sensor/warning light. Regards. |
| H.R. Bridge |
| Oh Will! ... LOL Jim, thanks! I'll check out that link. :o) Roy, a level sensor fitted? Really? I'll check out the in-laws' '04 ZS120... But I don't think that a level sensor is fitted? |
| Rob Bell |
| Jim, Will, silly question - on that 555 site, the time delay is given by a simple equation: t = 1.1 RC - where R is in ohms and C is in Farads Is that seconds or minutes? Richard - just spotted your post - thanks very much - Wood Green is indeed 'just around the corner' from me :o) And, yes, as Dave says, we're using a Davis Craig [best said in the style of Bo Selecta, the wrong way round ;o)] pump :o) Drop me an email if you like - robert dot m dot bell at kcl dot ac dot uk Cheers all! :o) |
| Rob Bell |
| Rob, I had quick look in a ZS catalogue, included, on the spec' page, "Water level warning light". Mechanic said he noticed an extra warning light on a new Rover 25, when he switched on the ignition. Seems MGR don't inform dealers of mods/additions, they just start to appear. Would be nice if we had a BBS regular who worked for MGR or a dealer, to keep us all informed, as things were added/altered. Regards. |
| H.R. Bridge |
| My thanks to Chris Tromans for your comment on the stench of burnt coolant. I turned a corner the other day and experienced the same horrible smell. I recalled Chris's comment and checked the coolant level. It was only down about 200 mls so into the garage to discover a loose coolant pipe hose clip. Thanks Chris :o) Roger |
| Roger |
| t is in seconds, note capacitors are usually rather as microfarads or pecofarads - these are very small numbers! fear not, you use very large numbers for the resistors! |
| Will Munns |
| Also - is it all MGs? Looks like a aftermarket add on for a new water tank! |
| Will Munns |
| >> Rob, I had quick look in a ZS catalogue, included, on the spec' page, "Water level warning light". << That's interesting... I'll get a piccie if I can... Thanks Roy :o) >> t is in seconds << Cool - thought it would be, but never make assumptions! ;o) |
| Rob Bell |
| Would the system require a presence/absence type sensor in the header tank? Sorry don't know Fs do they have header tanks? A simple horizontal or vertical float switch made by Crydom would work for about 10-15 quid, needs a 16 dia to mount. Or does it require a submerged flow type? (for quite a bit more cash) A company called Radiatron produce some really cheap £2-3, bi-matallic auto-reset switches. Could be mounted directly to all your important little bits that start to become hot! (now there's a visual) They oprerate at control temp + -3deg. One could be fitted to rad cap. The thing that confuses me is if a dramatic temp change/water loss is detected what can you do? |
| Richard E |
| Ideally the system should detect over filling (sign of a failed pressure cap) or under level (sign of a leak or weap) >Sorry don't know Fs do they have header tanks? Expansion tanks, there is some water flow thru the tank, and the level will chanage a little whilst on the go >A simple horizontal or vertical float switch made by >Crydom would work for about 10-15 quid, needs a 16 dia to mount. Mounting is a problem in the plastic tank, especially as it has to be water air, alchol (SP?) tight at pressure and temps upto 120 degrees. Doable, but easier if someone else has done it for you! > bi-matallic auto-reset switches. The sort you find in power showers?. Yes I have come across these, but they will only tell you when you are already overheating - and the damage has started. >The thing that confuses me is if a dramatic temp change/water loss is detected what can you do? Nothing to do with sudden loss, but if it is a slow weep (like from a pinholed radiator, leaky underbody pipes, hoseclips not tight enough, perished rubber, faulty gasket on water pump) then it will tell you before and heat related damage occurs. |
| Will Munns |
| >>a slow weep (like from a pinholed radiator, leaky underbody pipes, hoseclips not tight enough, perished rubber, faulty gasket on water pump) then it will tell you before and heat related damage occurs. Will's spot one here - this sort of early warning is what we all need. It's one thing to be reasonably vigilant about the levels in your expansion tank, but sod's law says that the one time you don't check will be the time the hose splits and starts spilling coolant. I'd be interested to know more about any such standard MGR item and whether they are appearing on K series engines. |
| Dave Livingstone |
| Roger in NZ, Glad you managed to smell the stench before anything drastic happened! Glad I could help :-) ChrisT |
| Chris Tromans |
This thread was discussed between 23/09/2004 and 30/09/2004
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