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MG Midget and Sprite Technical - 1500 Piston Rings

Looks like my running rough problem is cylinder not fuel related. Not unsurprising when remembering that cylinder 2 was stuck after nearly 10 years of lay up. Compression tester on its way by late afternoon to verify but I am convinced by the generation of smoke which is coming out through the rocker cover vents and then out of the air intake of the carbs. Its very noticeably from the front carb.

As per my usual keep the work down and the use of the car up I am thinking of doing this with the engine in. Also as usual I have never done this before. I know that Malcolm and a few of you have / have been rebuilding your 1500 engines so must have done this recently. Any advice apart from 'don't do it' would be gratefully received. I am confident I can do it and am happy enough to take off the head and carbs (again) and get on with taking off the sump etc. as necessary.

I was half expecting to be at this point earlier anyway so was expecting the work. Just a matter of coming up with the quickest successful way of doing it.

(and pushing it 400m to the garage if I cock up).

As always, thanks in advance, Dave
Dave Squire (1500)

Having just finished rebuilding a 1500 engine (Spitfire, but essentially the same unit), yes... you can do this with the engine in place. At the very least, you can drop the sump, pull the pistons, and inspect the bores and rings for damage and wear.

-:G:-
Gryf Ketcherside

Nothing really that can disastrously wrong on a 1500 re-build. That said... I did mine 12 months ago but engine has not gone back in yet so don't know if it actually works! :-D

Uprated con-rod bolts are oft recommended for reliability sake. I used Ford Cosworth bolts, they are a direct replacement, cheaper than ARP and used safe up to 200 hp+ in their native engines. I got mine from Burton Power.

(Just checking BP website, ARP bolts are looking excellently priced and cheaper than standard bolts!)

Thrust washers are, as ever, a good shout if you want to go that far too.

Have plenty of pictures if you get stuck.

Malcolm

Malcolm Le Chevalier

Thanks fella's, excellent.

So I plan to get the oil drained, the car up, take off the sump and drop the number 2 piston from there. Having just done the HG I am hoping not to do it again and your advice is backing that up. I know I can't assume anything but hoping this is a ring that is gone. From the way that the engine has sounded from day 1 and sounds now I am hoping that is a good bet.

Anyway unless anyone can think of anything else I will start taking apart tomorrow pm and find out the parts I need to get. Anything else apart from the aforementioned you can think of while keeping the amount of work down would help.

And yes please Malcolm, pics very welcome, e-mail enabled if its easier to send that way.

Cheers, Dave
Dave Squire (1500)

Dave,

It sounds like you are thinking the piston is going to come out the bottom. They don't (at least as a general rule, I never did a 1500). You have to pull the rod cap from the bottom, but the piston and rod go out the top.

Because of the cost of another head gasket set and a pan set, I think it may be false economy to replace the rings on only #2. I would be inclined to do them all.

I would also be inclined to replace all the rod bearings and, as Malcolm said, the thrust bearing (especially the thrust on a 1500)

Remember that if you have a significant ridge on the top of the cylinder wall, you need to cut that out or try to find ridge dodger rings. Otherwise the top ring may break as soon as you start the engine.

Remember that the pistons may not be good for several reasons, and the bore may be worn as well. If you don't know how to check, find someone who can.

Also, you need to consider measures to minimize the grit you get in the engine when you run the glaze breaker through the bores. Oily rags over the crank can help, and lots of solvent spray.

When you slide the rods and pistons back down the bores, put rubber fuel line or something like that on the rod bolts to keep from damaging the crank.

Charley
C R Huff

Yeah, as Charley says actually. Pistons tend to come out the top, not the bottom as the crank gets in the way. Also I imagine it would be a huuuuge PITA to try to re-install them from the bottom. Probably not what you want to hear Dave! Sorry!

It is still a fairly easy job but one that will take a bit of time and patience. Once you start digging you are probably best doing all four at once (as Charley says) especially as rings only come in packets of four!

As a thought, I found the green scotchbrite pads useful for scrubbing and decoking things and they would probably work well for cleaning up the bores (I stripped my block and had the bores honed by a shop). But again, as Charley says, watch out for muck! And reassemble with some assembly lube to protecct things for those few seconds before oil circulates properly!

Drop me a mail at mlechevalier (at) o2 (dot) co (dot) uk if you want some pictures or just need a chat.

Malcolm
Malcolm Le Chevalier

Wow, I can't believe I suggested removing the pistons from the bottom. Ignore me and carry on. Apparently my medication is wearing off.

;-)

-:G:-
Gryf Ketcherside

Hey Gryf, have you taken the pistons out the bottom then? Wouldn't have thought it possible, but if you have actually done it then there is no arguing with that!

Or have I lost something in translation? Damn words, why are they so difficult to interprit?! :-D

Malc.
Malcolm Le Chevalier

Cylinder test just changed this to a take the head off and look.
Cyl 1 250psi
Cyl 2 175psi
Cyl 3 0psi
Cyl 4 0psi

Have put tester on first two cylinders and got same results again for 1 and 2 so tester working.
Have put tester on Cyl 3 still 0
Have put tester on Cyl 4 still 0

Looks like HGF again (unless anyone disagrees and can give some ideas) so when I take the head off I will check the torque of the head bolts to see if they have changed. Then inspect my previous handiwork.

Back in a bit after head off.
Dave Squire (1500)

Malcolm...

They can certainly be removed from the bottom, but not with the engine... and therefore, the crankshaft... in place.

Cheers,

-:G:-
Gryf Ketcherside

Its the cyly head gasket. Failed between 3 and 4 so hence no other signs of a problem. (muted yippee).

Used a standard one last time. Some of you have mentioned a super duper branded one from time to time and I can't remember the name of them. Can anyone give me a heads up on brand please?

Thanks in advance,

A thinking about it, Dave.
Dave Squire (1500)

Found it, its a Payen and Rimmers have them (not far from me). So will check if in stock on Mondey and fetch one. Can anyone make suggestions why it failed and any other parts I should change as well?

The head bolts were still up to torque, the spanner is new, nothing else seems amis. If anything I would have expected a fail between 1 and 2 as its 2 that was stuck when I re commissioned the car.
Dave Squire (1500)

Have you checked the head face ( the face that bolts to the block) is flat. You can check this if you hold the edge of a steel ruler across the face and see if you can see daylight between the two edges. If you can see daylight the face may want a skim at an engineering shop.

If that is ok you can clean the face by putting some 120grit paper on a flat surface and rubbing the head over it. Don't go too hard, just enough to remove any crud etc and leave a clean face. Make sure the block face is also clean
Bob Beaumont

Dave,

When you check the head bolts to see if the torque has changed, you need to mark the location of the nut or bolt, then back it off about a half turn, then pull it back to torque and see if it went farther than its original position. Just pulling on the torque wrench won't tell you that it was too loose unless it was very loose. It's the same technique as used to re-torque the head (one bolt at a time).

When you do the straight edge check, you need to check it in a bunch of places. Like, several places end-to-end, several across the width, and corner-to-corner. If you see daylight and want to be more scientific, you can try slipping a feeler gauge under it. Also, use the straight edge on the block.

When you get it back together and have run it a bit, check the compression again so you will have a baseline.

I don't remember whether you fell into the camp of believer or non-believer for re-torquing a new head gasket, but if you were a non-believer perhaps you should consider changing camps.

Charley
C R Huff

you've guessed it there's a JT vid that details the re-torquing Charley's put

I'm glad it been put to check the surfaces of the head and block and to check by doing so at different angles and places across the faces

daft as it sounds I'd look for small pieces of crud or metal debris that could have been picked up by the gasket by putting it on to another surface but even if by a remote chance that happened they might be gone with the pieces of gasket

if the head was to go away for skimming they check for cracks too

I was surprised no one commented on the 250 on number 1
Nigel Atkins

All re torqued etc. as you all say and checked as per steel edge ruler before and now.

Failure was between 3 and 4 in the recess part so starting new thread re recessed heads.
Dave Squire (1500)

This thread was discussed between 02/06/2013 and 09/06/2013

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