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MG MGF Technical Loosing Coolant (not HGF or expansion cap) BBS discussion at MG-Cars.info
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MG MGF Technical - Loosing Coolant (not HGF or expansion cap)
| I'm loosing lots of coolant on my MGF trophy 160 but don't know why. I suspected HGF so took the car to the MG dealer who pressure tested the system and said it was all ok. They suspected the coolant cap so replaced that. Unfortunately after picking up the car last night, it still seems to be loosing lots of coolant (1/4 of expansion tank). Anyone have any ideas? I've checked the pipes around the expansion tank and they look ok. Steve |
| steven mancey |
| Any external signs of loss,i.e. puddles?? Mike. |
| mike |
| I haven't noticed any puddles etc, but will have a closer check. |
| steven mancey |
| Mmm, If you're loosing coolant then a pressure test WILL show up the leak unless the cap is at fault. It has been know for a batch of caps to be defective. Is there any sign of coolant around the rim of the expansion tank....? Also look at the underside of the black plastic flip cover to see if there is any sign of hot steam on the underside. Also how full are you filling the coolant tank....? it should be only half full maximum (but i'm sure you know this) What are the symptoms of the coolant loss. Does the coolant level go down when the car is cold or is the coolant loss only when the car is hot and under pressure. Can you see any coolant under the car (I suspect not) If the car is loosing coolant which is not manifesting itself then it is either interal or is spraying onto something hot and so evapourating. It is worth removing the engine instection cover and running the engine until hot and see if there is a small jet of water just over the alternator a favourite place for HGF. Coolant leaking here will evaporate ont the exhaust manifold but will not show mayo in the oil. |
| tim woolcott |
| <<If you're loosing coolant then a pressure test WILL show up the leak unless the cap is at fault>> sorry m8, got to disagree. MG Rover pressure tested my coolant system, and couldn't find fault. Ended up being rear hose clip, but only showed up under after long journeys. (think heat can be a valid factor as well as pressure, considering things do expand/contract) Think rather than a pressure test, get a competent mechanic to check all hoses and fixtures for anything loose. |
| paul weatherill |
| Paul, Yep, Heat is an issue, I thought about that after posting. |
| tim woolcott |
| Could be a long shot in the dark, but hot coolant vapor does have a typical smell. So maybe after a run you could identify if the problem is situated at the front or at the rear of the car. |
| Erik |
| Steven, I also had a problem with coolant loss. The car was pressure tested and while the system passed, the cap failed. A new cap was tested and duly fitted. However, I continued to lose coolant. I noticed that the expansion tank was loose and the clip on the hose into the top of the tank was finger tight. My thoughts are that the the tank was moving and the seal in the hose was being broken periodically allowing coolant to drip out. I was a bit worried that this wasn't the answer after filling it up above the seam - I still lost liquid. I didn't top it up and it seems to have found it's own level just below the seam. I did 750 miles last Saturday (mostly motorway) and it didn't move at all. Hopefully I've found the solution to my problem. |
| David Clelland |
| pressure testing does not exclude the possibility that it is HGF. putting an (MoT) exhaust analyser into the expansion bottle is another test, but I still don't think you can rule out HGF just yet. HGF here could be a small leak from coolant circuit into a combustion chamber - and it may only be under some circumstances. If it is HGF then it will rapidly get worse, so you need to keep a very watchful eye on your coolant (and keep checking your oil). Is there any sign on the coolant bottle that coolant is escaping here ? - keep it clean so that it's easy to check for leaks. I hope I'm wrong, but if you can't find signs of a leak, or coolant escaping under pressure, then it's likely to be going out through the engine. |
| Steve |
| Thanks for all the comments guys. There are no signs that the coolant is escaping from the expansion tank or cap and I can't find any puddles under the car (running or not running). There are however some light build ups of yellow gunge most of the way up the oil dipstick, although no build up in the oil cap itself. Maybe a small crack in the head gasket? |
| steven mancey |
| <<There are however some light build ups of yellow gunge most of the way up the oil dipstick>> :-( |
| paul weatherill |
| >>There are however some light build ups of yellow gunge most of the way up the oil dipstick,<< The dealer that did the pressure test had no comment on this ? They considered a head gasket failure and didn't check the oil ? At this point, I expect there's no damage to the engine, but you do need advice from a trained mechanic. Good Luck ! Is the car still under warranty ? |
| Steve |
| Steven, be careful here as although there is no apparant water loss externally and you seem to be certain that water(coolant) is being used it IS going somewhere. I suspect into the sump and any further driving the car could do irrepairable damage. A recent customer of ours had a similar problem and thought as long as the coolant was replenished it would be OK to drive. Well it spun the bearing on number 1 main(lack of lube due to oil being lighter than water in the sump) and put a 5 thou distortion in the bearing ladder, result block scrap and a big bill.Return the car for a proper diagnosis,quickly. Good luck. Mike. |
| mike |
| mayo on dipstick=HGF. no doubt about it! the only other thing it could be is a problem with your liners, but i doubt that. |
| colin |
| Steven Don't know where in Herts you are but, assuming the car is not under warranty, Brown & Gammon in Baldock are reputable 'specialists' not MGR dealers. If the car is under an AA Used Car Warranty then B&G are still a good option. Mike Satur is a bit far away from Herts but his advice above is based on being one of the most well respected specialists in the country. |
| John Ponting |
| Ok, have taken car back to MGR in Chesham (Priests) - is still under warranty. After complaining yesterday, I think they are going to have a closer look and possibly change the head gasket. I'll let you know what happens. Steve |
| steven mancey |
| Head gasket changed. Problem seems to have gone away, although Priests (MGR) said there were no obvious problems with the original gasket. Fingers crossed all will be well. Just got to fix the alarm now... Steve |
| steven mancey |
| Same thing has just happenend to me. HGF repaired on the 15th September, and car only done a few miles since. Wife noticed "ticky yellow leak" on the driveway this weekend when she put it back in the garage. No sign of any leak on the garage floor. Checked it out this morning - oil level OK, but coolant expansion tank completely empty. Topped it up with a couple of pints of water and drove it straight to the dealer. Oil and water temp both OK during 15 minute journey. They think it was an air lock - but what about the yellow stuff! Have left it with them to investigate. Sam |
| Sam Murray |
| steven :- >>Head gasket changed. Problem seems to have gone away, << Even if it wasn't the head gasket, then the work involved in changing the head gasket has probably fixed the problem. Looks like a good result. Sam :- >>They think it was an air lock - but what about the yellow stuff!<< very probably was an air lock. Was the coolant yellow ? Temp. gauge is near useless - coolant level is a much better indicator. |
| Steve |
| >>Temp. gauge is near useless - coolant level is a much better indicator.<< Completely agree with you Steve. By the time that the water temperature rises after loosing significant amounts of coolant then the chances are that the cylinder head will be warped by the time you stop... :o( Coolant level is really the only way to keep tabs on things. |
| Rob Bell |
| Steve, No - the coolant is pink. Hence my concerns. Sam |
| Sam Murray |
| Well if my F ever goes HGF (fingers crossed) 47k up and no sign of one I'll be getting a replacement head from Dave Andrews with his K13A improvements N |
| Neil |
| Just spoken to my MGR dealer. It would appear that my coolant loss is being caused by something not affected by the work they did in repairing the recent HGF. Is it just me, or could this have been the cause of the HGF in the first place?!!! I'll wait until I get a final diagnosis before mentioning this to them. Sam |
| Sam Murray |
| >Completely agree with you Steve. By the time that the water temperature rises after loosing significant amounts of coolant The reason for this is because Alloy doesn't conduct very well, and the 'only' link between the metal on the head and the temp sensor is two bolts (and a cardboard insulator, i mean gasket). So if the engine runs very low on coolant then the gauge is not in the water and reads low, then the coolant turns to steam and steam rushes thru the pipes rising the temp of the temp sensor right up very suddenly. >Is it just me, or could this have been the cause of the HGF in the first place?!!! quite possible, although find out what it is, because almost everything water related in the engine bay is disturbed by a HG change. |
| Will Munns |
| One possible source of coolant loss (I have just experienced it) is via the expansion tank cap. It is possible to cross thread the cap and although it feels tight it does not fully seal. The coolant expands as it heats and finds its way out of the cap whilst the car is being driven (ergo none or little evidence on garage floor as the coolant level is so low when you get home that it will expand within the system without overflowing) My MG service shop pressure tested my car to well over the required test pressure....no leaks, recent HGF repair meant no HG leaks. Care in screwing on the cap has meant a big reduction in collant loss and I now add about a cupful pre week to maintain it at about the seam level in the tank. |
| Phil Stafford |
| Just got a call from the garage. My coolant loss was due to a problem with the heater hoses within the cabin of the car. They say this has nothin gto do with the HGF I suffered recently, nor was it caused by them when they carried out the necessary repair. ARE THEY HAVING ME ON! I'll probably be able to claim the £355 charge back through my AA extended warranty, but that's not the point. Any comments folks? Sam |
| Sam Murray |
| Sam, You certainly don't need to do anything to the heater pipework to change the HG (other than open the bleed point under the front bonnet), but if this has been leaking for some time then it is possible air could have got into the system here and CAUSED your HGF (hot spots on the gaskets caused by air bubbles). Not sure if this will help you or not, you may be able to get them to include the work as part of the HGF rectification costs (an 'add on' to the bill), but this is only if the go for the above theory. I don't think it could be something they might have done accidentally during the HG change though. SF |
| Scarlet Fever |
| The HGF costs have already been settled by the AA. I don't think they damaged to pipework either, but I do suspect that the coolant leak contributed to the HGF, and perhaps they should have investigted this during the first repair. Anyway, I'll pick it up later this afternoon and see what they, and the AA, say about it. I just hope they've made a good job of re-fitting the interior after having stripped it out to dry out the car! Thanks for the moral support. Sam |
| Sam Murray |
| Well, collected the motor yesteday from the garage. One of the metal heater pipes which runs along the tunnel inside the car had fractured slightly, and was leaking coolant when hot. Mechanic reckons that the slight loss of coolant was enough to cause HGF, but not serious enought o show up on pressure test after repair. Said it was the first time he had seen a leak like this. Interior of car had to be stripped out to get access to pipework and to allow the carpets to dry out. They seem to have made a good job. AA have agreed to pay for repair under extended warranty. PHEW! Sam |
| Sam Murray |
This thread was discussed between 25/09/2003 and 03/10/2003
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