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MG MGF Technical - Recipes for broiled head gasket: delicious

@&%&!

On Friday night, a coolant hose split - dumping the contents of the coolant system over the A303 at 10.30 at night. :o(

Managed to effect a road side repair by cutting the hose a little shorter to enable me to push the split section of hose over the engine outlet stub. Leak cured. Re-filled the coolant system with water, and completed my journey...

Unfortunately, on driving to Castle Combe the next day, more coolant was lost - this time past the expansion tank cap. Topped up, and re-bleed the coolant system.

Did a single session on track (brilliant) - but returned to discover no coolant in the expansion tank - again, blown past the expansion tank.

I may be being oversenstive, and feeling differences that aren't there, but it feels as though the engine idle is not as smooth as usual, and seems just 2-3 bhp down on power...

I fear that the coolant loss has boiled the head gasket. :o( 82k miles and to fail now! Argh!

Haven't been able to confirm HGF (no oil in coolant or vice versa) - but suspect that the coolant system is being pressurised by a failure past a fire-ring.

Would a compression test be helpful with the diagnosis? I guess an exhaust gas sniffer would be helpful too.

Unfortunately, the car is in Wiltshire and I am now back in London, so will get the car relayed up to Tech-speed for further investigation.

If the gasket has failed (I hope that the liner heights are still within tolerance!), then I'll probably fit a TF135 head and cams (and will see whether DVA can do a quick and dirty port on it first!)

A bit of a downer on an other wise brilliant Castle Combe track day! I want to make a big thanks to Tim for him bravely allowing me to drive his precious MGF - it's a brilliant car you've got there Tim! :o)
Rob Bell

Sorry to hear about this Rob, I hope that the damage is not too great and that you are back on the road again soon !

If the worst comes to the worst and it means a new head, then looking on the bright side - a ported 135 version will soon bring back the smiles !!

All the best
Steve
Steve Owen

Rob. Now with the head comming off don't let the dark side take over to much. LOL.
Andrew.
Andrew Regens

Bad luck, Rob! Hopefully, there won't be too much damage.

Might be worth replacing the water pump whilst your at it. Within a month of losing coolant due to corroded under body pipes my pump failed. I've also heard of several other failing around the 80k mark.

Ralph
Ralph

Hi Rob,

Sorry to hear this...

I too suffered HGF as a result of a split coolant pipe (at 72k) on my 97F...

Luckily, as a direct result of info from this BBS, i had taken out AA's parts and labour super-cover (no longer available it seems?), and they paid-up in full for my repairs at B&G - so thanks to all!!

I also took the chance to fit their water-level alarm system at the same time, to hopefully give me enough warning if and when the same thing happens again (oh, plus a K&N 57i kit for the fun-factor)...

Agree with Steve - take the chance to upgrade the head - smiles will return, i'm sure...

Mike

Mike Chase

bad luck mate - so you think that maybe the pipe bursting was a symptom of pressurisation rather than the cause of the head trouble? Me thinks a beast of an engine is now waiting in the wings!
Tony

Rob sorry to hear this,
but that poor old car has had a major thrashing for nearly 10 years!

SO NOW is the time to fully embrace the DARKSIDE!
get your wallet out!
GO LARGE with the gas flowing, do it to everything ports airbox etc etc, get the bad cams in, 4,2,1

watch the difference!

Neil

Tony, I think that the split hose came first :o( I felt the heater go cold before I could find somewhere safe to stop - so although the temperature gauge at no stage showed signs of overheating, I am not sure that this is a reliable indicator. :o(

Neil - already got the 4-2-1 ;o) The TF135 used quite warm cams as standard - it is the perfect stealth mod that was I going to perform on my standard MPi head anyway! ;o)

I think that plan B will be a Q&D port on the TF head - will depend on DVA's schedules though.

Secretly I am hoping that the gasket is actually okay, and that the coolant dumps that I've seen are a combination of air locks and a dodgy expansion cap... but how likely is that?

Thanks for the words of encouragement guys - I'll let you know how this all works out.
Rob Bell

I work for a MGRover dealership and whenever we have a k series head gasket problem(often) we now always replace the water pump, thermostat, rad cap and have the radiator overhauled as well as the head gasket itself. Too often you replace on and the other fails soon afterwards.
tony pearce

Rob, you did bleed the radiator after filling up didn't you - It has no auto bleed function
Will Munns

Thanks Tony. The rad etc were replaced at the last service.

I plan to get the water pump, cam belt and tensioner all changed at the same time - would be mad not too.

Will, yes I attempted to bleed the rad - didn't appear to be much air in there to be honest, but there was plenty behind the other bleed screws (coolant rail and heater box).

Not impossible that there is more air trapped in there though...?
Rob Bell

I am sorry to hear this story of bad luck Rob. I guess it takes some courage to enter a track day with the knowledge of what happened a day before.

Maybe you want to invest in a "coolant low level alarm".

Let the darkside rule your decissions. ;o)


Erik,
RT 165 Sport after 2nd HGF
Erik

Rob it would be very intresting to find out what DVA calls a quick & dirty and does he remove thee valves etc?

c.f. The RaceSpeed/Janspeed head: The inlet and exhaust valve ports have been reworked to increase the power it can develop - whilst maintaining maximum torque. Work has also been done on the inlet valve seats. The head retains standard valves (27.5mm inlet, 24mm exhaust), stems, springs, and cams.

Steve
Steve Ratledge

Erik, you'll not be surprised to hear that the B&G kit has now rocketed to the top of my shopping list!!!

The track session was a "kill it or cure it" outing. It didn't exactly die, but the problem persisted - so that was that. Could be expanding air dumping coolant everywhere, coupled with a boiled/ failed expansion cap - but that's clutching at straws I fear. :o(

Steve, the valves are removed, and the ports are worked on - as indeed are the valve seats. Dave recommends a light skim to retain the CR - but it is nothing like as involved as the porting that Tim had done on his cylinder head... Probably OTT for the spec that I want to run this engine anyway.

The SC engine will get a fully ported, big exhaust valuve head (probably VVC - or possibly VHPD - we'll see!)
Rob Bell

Just to add our commiserations! Which hose was it? Ted had a hose problem a couple of years ago, wonder if it is the same one and if so, is their a component in the F that should be changed after 7 or 8 years?

Cheers

Patrick

PA Beet

Same hose Patrick - but in a slightly different location. Probably is worth considering as a service item from this experience!
Rob Bell

Rob,
Mine has now covered over 2000 miles without a squeek, so thrashing it around the track should not set off the sensor, the anti splash guard seems to work OK, I have thrown it around a few corners to test it.

One item of thought though, B&G offer a buzzer (loud) and a light, if you are wearing a crash helmet will you hear the buzzer.

I have both on my car.

Adrian
Adrian Clifford

Hi Rob,

sorry to seeing you off the road :(
Special, .. how will you get to Silverstone ?

I recall it was the split Y-hose to heater at Ted's , but anyway, go for all new hoses behind the engine and the alloy interconnection pcs from Mike.
Coolant sensor and other easy bits can be made later DIY.

And at last, the old Battery discharge troubles need to be done.

Regards
Dieter


Dieter

Rob - I had a similar problem myself last month, the thermostat on my '97 VVC stuck partially closed and the engine warmed up a bit too much (2 notches on the guage), of course by the time I got it to the dealer the thermostat had opened ok and the temp was normal again. Happened three times again in three weeks, thermostat eventually replaced, but it just stressed the HG enough to blow it. No coolant loss, no sign of mayo in the oil, all levels ok, but just felt a bit down on power as you mentioned. Luckily there was no damage at all to the head, block or liners but the water pump was found to be on the way out. With the new HG fitted it feels much smoother and perkier. Seems not all HG's fail in a cloud of steam, some are more subtle!
Mike

Dieter, will be going to Silverstone in the airconditioned comfort of a MG ZTT ;o) Not quite the same as a MGF though :o(

Mike - you're right about that - a subtle failure. It's just so frustrating that it should go like that... aarrrgghh!

Oh well. Hopefully DVA can fit me in during the next couple of weeks to get the spare cylinder head ported... The Silver lining!
Rob Bell

Rob - be sure to get some before & after photos of the head. To help us understand how far a Q&D goes etc.
Steve Ratledge

Okay, will try to Steve! May well try and drop the head off to Dave tomorrow evening on the way back from Silverstone...
Rob Bell

Rob,

As you already mentioned: The Silver lining!
It's THE most important thing now!

Good luck and have it on the track soon!

Valter.
Valter

Thanks Valter. :o)

Head was delivered to Dave's metal miracle heaven on Friday night! :o) Fingers crossed we can get the timings worked out!
Rob Bell

This thread was discussed between 18/07/2005 and 25/07/2005

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