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MG Midget and Sprite Technical - Grey clay sludge

At last I got to hear a different 1500 last night and now know mine is definitely not right.

After the 'grey clay sludge' of last weekend, its take the bearing shells out time this week end, as per advice last weekend. I have looked up the diagrams and descriptions and it all seems straight forward to me. Just a matter of keeping the lock washers, bolts etc all in order.

So should I inspect and replace one at a time (engine in car) and if so big ends first? thrust washers? or main shaft?
I suppose I am asking what order is best? and any practical advice re inspecting and if necessary refitting / fitting replacements.

Have the tools, gaskets, and a set of standard shells ready. Sump removed last weekend so will be a doddle and I have a quick way of raising the car to be safely high enough to get under OK.

Thanks in advance, Dave
Dave Squire (1500)

Big ends first - rotate the crank so 2 are down and remove the caps - put them somewhere where you can identify where the came from - a sheet of card with the cyl numbers written on is a good idea.

The bottom half of the shell will stick in the cap.

Turn the crank to bring the other two down and remove them.

Turn the crank 90 degrees and pull the rods down to flip out the top half of the shells - pressing sideways on the shell with your fingers will dislodge them

Put the top shells with their mates on the card.

Now release the main bearing caps and put them on the card in their order.

The crank will drop a little bit which will allow you to push the top half of the shells round the journal - note one side has a locating lug - you need to push on the OTHER side of the shell!

The trusts may well fall in your face as you remove the rear cap - if not then poke them round - they are only retained by the rear cap - inspect the cap for wear - if excessive the thrusts can spin round and drop out - not good news!

Reassembly with new shells is a direct reverse of this - note the lugs and may sure they fit in their recesses. Do up each main cap in turn and test rotating the crank to make sure it is not binding.

When all the mains are in and torqued up the crank should spin freely. The do the big end caps and test the same way but obviously now you will have the drag of the pistons - this will be minimum at TDC so you can still get a good feel for the freedom of the BE bearings.
Chris at Octarine Services

Dave, if you have bought standard shells, I presume that you took one off last week to check as I suggested?
When you take the caps off, check for damage on the crank pins, especially if the old shells have worn through to the backing.

If the top half mains shells won't budge, use a new oiled shell to feed around and push the old one out as you turn the crank.

You cannot replace the rear main on a 1500 with the crank in situ, so you just have to leave that one.
Guy W

If you need more pictures or anything Dave, just drop me a mail.

Good luck!

Malc.
Malcolm Le Chevalier

Dave,
To get at the front main cap you need to remove the alloy "bridge" piece. Held with 2 screws IIRC. The manual assumes you are doing a full strip down and says to remove the timing chain cover first. No need, remove the bottom most 3 bolts and carefully separate the bridge from the timing chain cover gasket with a Stanley blade so it isn't damaged. If it does tear, repair with silicone gasket when you reassembled

. Don't lose the 2 little wooden wedges (yes, wood !). When resembling be carefully not to overtighten the sump bolts and the 3 chain cover bolts that go in to the alloy. All the others go into steel and can be tightened up much more without fear of damage, but those alloy fastenings are vulnerable. I think they are also a different thread - UNC probably

Guy W

Ah, to be honest I think it was a bit premature to buy a set of standard shells.

The first job is to drop the sump... and then wiggle the conrods in turn... if any one of them has obvious movement in it.. you are in trouble... take that big end off first.

If none wiggle... then just take off which ever is most easily accesible... check the bearing... if its down to the copper then its also likely the crank is scratched... rub your fingernail gently over the crank bearing surface and see if you can feel any grooves... if you can then you won't be able to use your standard shells... and the next job is to get the engine out.

Incidentally... if there is no wear on the crankshaft... beware that your crank may not necessarily be a std crank anyway... it could have been reqround before... so check the shells which come off for markings (STD, -10, -20 etc)

Good luck
C
C L Carter

Chris, I think Dave checked the shell sizes last weekend, when he dropped the sump.

Another thing needed for doing this job in situ is a pair of safety goggles. And also a face mask. Without these oil WILL drip in your eyes.
Guy W

Guy,

Excellant tip about glasses- I'd forgotten about the dreaded drip - always gets you !!

If a shell is only just showing copper often a new set of shells will last quite a while - especially if not driven too hard - well it has for me on quite a few occasions when cash was short.

As has been said do not mix up / rotate caps.

Get pressure up before starting and treat it gently for a few hundred miles + change oil and filter again.

R.
richard boobier

To see or not to see; Colour dyed or phospahated is the question?

Sorry its a crap pic, can't get the light on it right. Its basically a big end cap bolt that's black and where the socket drive has been in contact with the shoulders of the head the black is worn away slightly showing steel through.

In the mean time I will get the socket in the torque wrench and see if the lower value will shift the other bolts.

BTW no lock washers or anything, just bolts.

Dave Squire (1500)

Two things:

The lower value moves the bolts so that's a guide unless the PO erred on the side of caution and that has caused more wear than there should be.
And the guide I have downloaded says to put the tangs on the same side on each rod bearing on reassembly and yes you guessed it one of mine is the opposite and its number 4.
Dave Squire (1500)

Breathe bearing caps marked with anything on the backs? They may say something like +10, +20, or std. Sometimes there's no size, in which case that are standard.

For the crank, if you do the centre main first, and it turns out to be in good condition, I would then leave well alone for the front main as although it isn't difficult, it is quite a lot more hassle.

But do replace the C shaped thrust washers when you do the centre main.
Guy W

Guy - have you ever actually taken apart a 1500 engine?

The thrusts are on the rear main, not the centre....
Chris at Octarine Services

Yes Chris. I had two 1500s over a period of 12 years. On one of them I used to change mains and big end shells as a service item every 25,000 miles - did them 3 times, and on the other I fully rebuilt the engine. But as regards the thrust shims I must be confusing with the A series. It is 13 years or so since I sold the last 1500 so memory may well be failing me on that ! Apologies to Dave for that.
Guy W

No problem's gentlemen, dare I say it - its all going swimmingly, shells standard so no worries, crank turning OK with shells changed on one and four. Just needing a rest to remove last cap bolts from 2 and 3.

Main problem is as previous could do with confirmation re big end cap bolt type. I think its a coloured dyed, can anyone confirm? All cap bolts coming off with torque wrench set to colour dyed settings so assume so. (phosphor is a higher torque).

Anyone got younger or fitter arms and shoulders they can lend me let me know asap.

Thanks for all your advice so far its really helpful as written instructions are not like interactions at all.
Dave Squire (1500)

Spoke to soon, some idiot PO knackered the shoulders on the bolts on 2. Any suggestions other than grip the heads and knacker them with stilsons (as I don't have any spares at the moment) much appreciated. If all else fails I will fetch some tomorrow from Rimmers.
Dave Squire (1500)

Found hex mm drive that fits and long extension so removed. Just need new shoulders now to replace these aging bones.
Dave Squire (1500)

This thread was discussed between 08/08/2013 and 11/08/2013

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