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MG Midget and Sprite Technical - Head Gasket woes

Midget new owner! 1976 1500 Midget. Re learning skills I thought I would never use again! Just got Midget back onto road after purchase, had been in garage with prev owner for over 2 yrs before I bought,never used, seems to be issue between 1 - 2 cylinders, how easy/difficult to strip down and change head gasket?
David
D G Boyd

Surely that will depend on your level of competence ?
Alan
Alan Anstead

As David is an ex service engineer he should find it easy!
Compared to modern cars there are no twin OHC gearing/belts/chains to worry about. There are virtually no ancillary extras, engine mounts or head steadies or other stuff in the way to remove. That leaves a straightforward unbolt, remove, clean and replace sequence. I

Other than cleaning the head and block surfaces it then depends on why the gasket blew, if there is anything that needs fixing like getting the head skimmed?

And then it may be a good opportunity to do any other jobs like lapping the valves or replacing the water pump.
GuyW

Trained as electrician, then as service engineer on refrigeration so do know which end of a hammer to hold on to.......would rather try myself than hand over to garage at first problem.
If there is a "guide" out there on how to remove/replace the head would be useful, otherwise will check www and see what comes up.

DB
D G Boyd

All pretty straightforward - the only thing to be aware of is that there is a specified sequence of undoing and doing up the cylinder head nuts.

Get yourself a workshop manual and read !
Chris at Octarine Services

David,
Although as with most things,there are errors in it, the Haynes manual for the MG Midget is pretty detailed in replacing the head gasket. They regularly come up on eBay at very reasonable prices.

Other than your new set of spanners (you will need some sockets too), you will need a torque wrench and a set of feeler gauges. - the valves will need adjusting after fitting a new head gasket.

If you want to do the minimum simple HG replacement it can easily be done in under 2 hours. It's the additional optional tasks which take longer! That said, ISTR that undoing the manifold to head bolts can be very awkward to get at in the 1500. If that joint isn't blowing then you could just undo the exhaust down pipe (3 bolts),release the carb throttle and choke cables, and leave the manifold and carbs attached to the head.
GuyW

Thanks Guys, Haynes manual already ordered on ebay.

David
D G Boyd

(ETA: Guy posted whilst I was typing)

David, hello and welcome.

It depends on how you were trained or if you're too macho to "RTfM" before doing the work (like the electricians I worked with), otherwise there are printed paper copies or PDFs of the factory Workshop Manual (beware all publications have some errors and omissions).

MG Midget 1500 Workshop Manual 1975-1979 - http://brooklandsbooks.co.uk/index.php?route=product/product&path=34_295&product_id=555

I'd also strongly advise that if you actually want to use the car that you invest in a copy of the Driver's Handbook to refresh your memory and perhaps see that everything isn't always as it it should be or standard, it also gives servicing and maintenance instruction but not things like HGF and replacement -
MG Midget Mk 3 [1500] Drivers Handbook - http://brooklandsbooks.co.uk/index.php?route=product/product&path=310_313&product_id=557

I'd also strongly recommend that you give the car a full (rolling whilst you use the car) 36k-mile service and do a thorough coolant clean and flush of the rad, engine block and heater matrix as well as thorough engine oil change (plus gearbox and rear axle).

I've notes on simple but thorough coolant (and oils) changes methods, if you want them email me, my first and last name at bt internet dot com.
Nigel Atkins

When I replaced a HG for a 1500 I replaced all the studs and nuts for mini ones from Minispares as those fitted were like cheese. Also fitted an air bleed on one of the rear water hoses but you wont find that in Nigel's books.
Alan Anstead

Alan,
the books are a good place to start from with standard component cars, yes you will them have to perhaps move away from what's in the books to allow for developments and changes in fuel, oils, ignitions, parts quality (or lack of), use and abuse of car, etc..

For the 1500 I don't have experience but far too many times I've had to drain and refill coolant on my 1275 Spridgets and I've never had any problems just following the instruction in the Driver's Handbook. The very few I know of that have followed the instructions for the 1500 haven't reported any problems from doing so so would they need an add-in valve(?).

(It's a genuine question as I don't know (as you know)).
Nigel Atkins

David,
below gives you an idea of what in the Drivers Handbooks, written over 40 years ago of course but if you read it and use it to refer to you'll know things that many even long term owners don't, possibly including the previous owner and/or owners of your car.

(BTW when did the uploaded photos get so much bigger on screen/monitor)


Nigel Atkins

I also added a shraeder type bleed valve to the upper hose to the heater. Not essential by any means but it makes the job of expelling excess air that bit easier.
GuyW

And!

Incidentally, if just replacing the head gasket there is no need to fully drain the coolant. Just run off enough to get the level down a bit below the top surface of the block.

If removing the head complete with manifold you will also need to disconnect the coolant hose where it goes via the inlet manifold casting at both ends.

And number your plug leads 1 to 4 before disconnecting them!
GuyW

Guys,
Thanks for all of the info and advice, much appreciated and does give me a great starting point. Will read and re-read the manuals, then start the work, fairly confident I can do the work, just did not want to cause further issues by dismantling in wrong sequences.
Been there before on bakery equipment. and looking forward to getting back on the road soon. Let you know how things go.

David
D G Boyd

Nigel
Guy has answered your question with regard to the bleed valve.
Alan
Alan Anstead

Thanks Alan and Guy, I wanted to be sure I hadn't missed anything, a want more than a need then, perhaps more of a want with the 1500.

Having partially drained the coolant on mine yet again recently, down to bottom hose and then later down to top hose, which I'll have to repeat soon (not my fault but Sod's Law) I've refilled just by 'the' book without problems.
Nigel Atkins

First thing is to disconnect the battery. That often gets neglected and it's so easy to have an accident. 6

You can buy a HG alone or a top-end rebuild gasket set. This should include manifold gaskets, thermostat housing gasket and valve stem oil seals if the engine has them (I don't think the 1500 uses them though). Gives you a few options. When buying gaskets bear in mind that cheap gaskets are cheap for a reason. Say no more.

While you have the rocker shaft off take the opportunity to push a few rockers along the shaft against the springs and feel with your thumbnail along the bottom side of the shaft. If you can feel a wear ridge no amount of adjustment will give you quiet tappets. The good news is that complete sets of rocker gear for the triumph engine are not desperately expensive and usually features a better class of rockers than the original. The new ones are usually bushed like the superior A series rockers, if you feel like a change. I'm going to do that when I get round to it because my rocker gear is defo past its best.

Other quick things to check are if the valve springs are about the same length if you have the valves out. I'd defo do that because it's a golden opportunity to check the valves, seats and guides in one go and it's easy. Strictly you don't even need to buy a spring compressor. With your head you can improvise with levers if you're careful.

All the loose valve gear needs to be identified in some way so it goes back in the same place. For example marked sandwich bags or Costa coffee cups or something - put in the pushrods, valves, springs, seat cups, caps and collets from each set (eg: #1 exhaust) so you end up with 8 bags/cups of segregated bits. Also the rockers/adjusters if you take them off the shaft for any reason.
Greybeard

Guys,
Thanks for all of the info, head removal was more just plain laborious rather then technical and much more to remove than I thought before actually taking the head off. Was blown between 1-2 as I thought and clean on both block and head complete, new gaskets in place and just to collect torque wrench on way home to finish off and then start putting all of the bits back on.
Reasonably easy if you just stay methodical and label everything and have lots of small boxes/cups to hand to store all of the bits.
Plan is to spend Sat am putting all together, replace carbs back onto engine, check clearances on valves and hopefully get going by evening time.
Have enjoyed the process, thanks for all of the assistance.

David
D G Boyd

This thread was discussed between 25/07/2018 and 27/07/2018

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