BMc 1.5 diesel piston rings.

[pete.i]

I just want to post this to say how impressed I am with F.W. Thorntons. I ordered a couple of piston rings from them mid Tuesday afternoon and they arrived first post Wednesday. They are exactly what I wanted and the price was excellent. I have emailed them to tell them how impressed I am with their service, the chap I spoke to was extremely helpful. I think it was Alan. He knew exactly what I wanted from my very poor description and a couple of measurements. I will, most certainly, be using them again. Thanks also to p6rob for suggesting them.

[bizzard]

I just want to post this to say how impressed I am with F.W. Thorntons. I ordered a couple of piston rings from them mid Tuesday afternoon and they arrived first post Wednesday. They are exactly what I wanted and the price was excellent. I have emailed them to tell them how impressed I am with their service, the chap I spoke to was extremely helpful. I think it was Alan. He knew exactly what I wanted from my very poor description and a couple of measurements. I will, most certainly, be using them again. Thanks also to p6rob for suggesting them.

And scrape those ring grooves out scrupulously with a bit of old snapped off piston ring. There is a knack with fitting piston rings without them breaking, it's difficult to describe though. its' a sort of gentle curling motion.

 

And when reinstalling the pistons in the bores put the ring compressor squarely on the piston, insert it in the cylinder and then stop and inspect to make sure the clamp is firmly resting fair and square on the block face and that not rings have been caught and sticking out, you'll be making minor adjustments to the ring clamp to get it just right before tapping the piston down very gently with a bit of wood, a hammer shaft is good. Again there is a knack doing this without breaking rings.

Edited December 4, 2014 by bizzard

[pete.i]

Thank you for that Bizzard.. I do appreciate the advice but being a novice, this is only the second engine that I have ever worked on to this extent, it is all to easy to break these rings. In my defence (sort of) I broke it because I pushed the piston down into the cylinder too far and the ring came out of the bottom of the cylinder. I tried to compress the ring to get it back into the cylinder but couldn't so I then tried to get the ring off and that is when I broke it. It wasn't in the most accessible of positions at that point. Having said all that your advice is valid and much appreciated, as is everyone's advice on this forum. Hopefully it will all go back together and all will be well.

[RLWP]

And scrape those ring grooves out scrupulously with a bit of old snapped off piston ring. There is a knack with fitting piston rings without them breaking, it's difficult to describe though. its' a sort of gentle curling motion.

 

 

 

I find it easiest to put them in a vice with the ring pointing upwards and give them a sharp tap with a hammer

 

Curiously, I have been doing some cleaning this week and on this set of pistons, the second ring is brittle as I expected, the top ring is softer and would bend

 

Richard

Thank you for that Bizzard.. I do appreciate the advice but being a novice, this is only the second engine that I have ever worked on to this extent, it is all to easy to break these rings. In my defence (sort of) I broke it because I pushed the piston down into the cylinder too far and the ring came out of the bottom of the cylinder. I tried to compress the ring to get it back into the cylinder but couldn't so I then tried to get the ring off and that is when I broke it. It wasn't in the most accessible of positions at that point. Having said all that your advice is valid and much appreciated, as is everyone's advice on this forum. Hopefully it will all go back together and all will be well.

 

That all sounds very familiar - welcome to the club! I'm afraid that is often how experience is gained - by breaking things then working out a solution

 

Richard

[Tony Brooks]

I tend to use feeler gauge to prevent me over stretching a ring and snapping it.

 

Hard to describe but I will try. Select a feeler gauge that's about 15 thou" thick, that one that stiff but not too thick. Gently pus one end of the ring onto the side of the piston with probably about half of it on or above the top. There should be a gap between the ring and piston just where it rises above the piston crown. Push the feller in here and then move the feeler to be parallel with the piston side, handle/case end of the feelers well above the ring.

 

Then apply a downward pressure on the ring in front of the feller between the feeler gauge and the end of the ring that is above the piston crown. Gradually wiggle/slide the feeler towards the end of the ring that is elevated so the feeler lifts it clear of the side of the piston just enough to slide down onto the side of the piston. Then move one end further down the piston and repeat if you can not just slide the ring down without expanding it.

 

If the ring gets into the wrong groove lift one end out and down a little and repeat.

[p6rob]

For this engine I bought a pair of piston ring pliers from Machine Mart, a lot easier than the methods mentioned above (I've used them all at some point on Rover P6 engines, probably broken rings using each method too). The pliers worked well except for the big fat oil control rings. Although, after a lot of effort, I did still manage to break one ring

 

Good luck with the rebuild.

 

Rob

[pete.i]

For this engine I bought a pair of piston ring pliers from Machine Mart, a lot easier than the methods mentioned above (I've used them all at some point on Rover P6 engines, probably broken rings using each method too). The pliers worked well except for the big fat oil control rings. Although, after a lot of effort, I did still manage to break one ring

 

Good luck with the rebuild.

 

Rob

I have ordered a set of those off EBay. They were only a fiver. I think they could still stretch a ring to far though so I will have to be careful. To be honest I haven't broken any rings during "normal" installation or removal. I broke it because it had come out of the bottom of the cylinder so that it was between the bottom of the cylinder and the crankshaft. As you can imagine it was extremely difficult to get at and I couldn't get at it sufficiently to compress it enough to get it back in the cylinder so I thought next best was to remove the ring and that is when I broke it. The other one broke when the engine was running. Those were those fancy rings that the landrover guy made up for me. The engine was running well i.e. starting first time and no misfires but it was smoking like hell after I had put it back together with those fancy rings in. When I pulled the engine apart again I found one of those had snapped. These rings that I got from Thornton are the real MCoy, exactly the same as the old rings so I'm hoping that once these are fitted the smoking will be muchly reduced or even. dare I say it, not smoking at all. Not likely though on an old BMC. Luckily this isn't the engine off my boat this is a spare.