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MG MGF Technical - HGF caused major engine blow up

HGF caused major engine blow up the results of which leads me to ask a couple of questions of the more technically minded members who post here.

Well after 2 years of mgf motoring I’ve finally been hit by the dreaded hgf bug and in a big way…

Yesterday morning I started her up only to hear a big bang, pop and splutter quickly switched off and looked under the hood to find water everywhere.

This morning I stripped off the head to find the liner on cylinder 4 was smashed to pieces, piston broke ( not me, the engine ) and damage to all four valves in that cylinder as you would expect. And no doubt damage to the con rod etc. So I think it maybe more cost effective and easer to fit a replacement engine, either second hand or new.

I trained as a motor mechanic many years ago but this is my first mgf engine strip so can I remove the rest of the engine through the top or will I have to take it out the bottom and am I likely to have any problems with things like the suspension etc ?

Question 2. How much will a new engine cost ?

Question 3. Can anyone point me in the direction of a good breakers yard in the east midlands where I could get a replacement second hand engine ? and any ideas on cost ?
Rob Bristow

Sorry about the blown engine. I'd go as well for another engine instead of a probable high risk DIY repair.
Not sure, other may correct me, but in your case there might be as well have happened pre-damages to the crank shaft or crank shaft bearings.
Anyway, the engine must get out below. Thus is not so difficult if you have the right car jack equipment.
In principals straight forward disconnect electrical connections, coolant hose connections, gear box cables, hydragas suspension connections (depressurise at first), brake line connections, hand brake cables.... hmmm ... did I forget anything ???

Then lift the car, place 'applicable' second jack below the engine and unbolt the whole sunframe at it's four bearings.
Lower the whole frame with axles, engine etc. Done ready.
(dismantled one from a wreck)

re 2)
Dunno about prices in the UK. I think 2.000 quid will end up in a low mileage one.

re 3)
see for next recommendations from other friends..

If you like do do the difficult way of repair. Try getting hands on a workshop manual RCL0051ENG and/or a K-Engine overhaul manual.

At last I'm always curious about the true reasons which led to this blow up. Did you see any damages to the cam belt or cam wheels ?
Was the cam belt changed at recommended sequence ?

Good luck in any.

PS.. any pics of the gone parts availiasble ?
Dieter K.


Sorry to hear of your rather expensive sounding HGF but you could try

For a possible replacement. HTH.
Paul Lathwell

Following on from Dieter's post you can find the part number for the various other MGF related manuals including the engine in the MGF/TF FAQ...
Paul Lathwell


Following on from what I said first... :)

Midland MGF can be contacted on...

0121 585 8734 or 07866 476705
Paul Lathwell

Thanks Dieter and Paul for advice, I think what happened was the HG was leaking into the fourth cylinder and while the car was stood in the garage ( one week since I last ran it ) the cylinder must have filled up and when I started the engine the water was compressed causing the liner to crack up and damage the piston etc.

There are no other signs of another cause and I realise the damage could be extensive and costly so I think it will have to be a second hand engine.

Which other Rover cars models was the K series engine installed in ??

I'll take some pics of it tomorrow and post them here.

Rob Bristow

MGF Centre can source low mileage engines.

Give Victoria a call on 01902 403045 (Wolverhampton)

Neil Stothert


can you ensure the water didn't leak through the inlet manifold ?
Might be an option if the car is a 120bhp engine and hstill ad installed the old black inlet manifold gasket. Newer gasket is green (Viton)

Haven't got all the other Rover K-Engine applications to hands. Please check the archives if nobody else just puts them here.


Dieter K.

>Which other Rover cars models was the K series engine installed in ??

Pretty much all the recent models I believe. Certainly the MGR and Rover 25 models have used the K series, although whether there are any techinical differences due to application I really have no idea.
Paul Lathwell

And the 75 in 1.8 guise. And the Freelander.
Anthony Braham

Rover 200 as well, I think.

btw, why not just going for a conversion to a Honda Civic Type-R K20A engine. ;)
Up to 240bhp .. .. ..
Dieter K.

Is this a HGF or the cambelt breaking?

It sounds to me like the valves and piston have met and this is likely to be caused by the broken cambelt. The effect of the piston and valves meeting is likely to have also caused the head gasket to fail. This HGF is effect therefore, not cause.

How old is the car, has it had the 5 year cambelt change - if so when?

Replacment engine sounds like the safest solution.

My sympathies to you.


Patrick Beet

Or may be have a word with Dave Andrews or Mike Satur and take the opportunity to have some fettling done at the same time.

As Neil said MGFCentre can sell you a VERY nice engine for a Very reasonable price and fit it and will almost certainly beat even MidlandsMGF :0)
tim woolcott

The cam belt was changed at 60k (the car has now done 71k ) and its still in very good condition the problem was caused by the volume of water in the cylinder being compressed and not being able to escape fast enough.
This often happens to diesel engines that suck a large amount of water through the air filter i.e. while driving in floods or fords ( crossing water type ) .

Rob Bristow

Rob sounds nasty, but you sound like you're sorted technicly so hopefully this won't cost you the earth. The guys in the k-series midget page recon you can grab a second hand engine with low miles for about 700, obviously this will be bare, but you have all the other bits from your current engine. Be careful that you get an engine of about the same age, there were some changes with the ECU and wireing loom, so you have to make sure you get the right one or you'll end up changing these bits too. (dieter- any idea's on the age of the change?)

Will Munns

I reckon that Will is in the right ball-park on the likely cost of a new engine - 6-700 quid for an MPi lump. The MGF Centre will probably be your best bet.

The destroyed piston certainly sounds to me like a hydraulic lock, so I complete agree with that diagnosis.

However, as Dieter says, HGF may not have been the cause of this (not as if that matters now) - an inlet manifold leak could equally flood cylinder 4 with coolant. :o( In fact, assuming that you have the MPi, I'd say this was the most probably cause.

Based on costs involved, definitely cheaper to buy a new engine.

Best way to work on the engine (based on observation of the way that all the 'experts' do it is to drop the subframe - which means you'll need to gain access to a car lift...
Rob Bell


I tend to have the same suspicions as Patrick.
The impact between pistons and valves can really only occur if the camshaft timing is completely adrift. Even if there was water in the cylinder it could cause a bent conrod, broken piston, and broken liner, but still the piston cannot hit the valves (unless the top has come off the piston).

Even if the belt is OK, what about the belt pulley to camshaft securing bolt?
This bolt is a well known MGF weak spot, there are many examples of this problem causing bent valves.

M F Anderson

Hi all,

when the water in the liner is up to the brim it does "lock the valves "The force to open the valve via the cambelt is not enough when the piston+water is going further up the liner and usually the belt cogs over or does shave off a few tooths.... Some diesels (VAG) were famous for this and the result was usually a need for a clean exchange engine where all the auxillaries were shifted over .

Best of luck with finding and fitting a new / used good engine ! At least you over there have a few to choose from ;)

BR, Carl
Carl Blom


an update.
Thanks Rob for sending the picture.

May be it can be repaired ? *change the liner* and piston, valves ?
Any better recommendation possible now ?

PS. Rob B., see your inbox, you have mail.
Dieter K.

Rob, as Dieter,MOD;¬) has said it is possible to just change the damaged parts with engine insitu, we recently did this exact type of damage repair to an engine that had gone through a flooded road, this bent a rod and damaged the piston/liner and some valves. As the head has to be removed to check the damage it might be worthwhile to do this first and assess the extent of repair. If the block is damaged, sometimes the liner splits and damages the block ,then a replacement engine is required. If not then a new piston/liner and a few valves are quite easy to fit,well easier than a complete engine swap.

> If the block is damaged

Mike, <-- the true MoD* :oP
can't be seen on that pic, is it ?

Just curious. I'd be pleased never having that problem myself.
Dieter K.

This thread was discussed between 09/03/2003 and 10/03/2003

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