MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - oil rings, need opinions

I have an XPAG rebuild that's been dragging on for over a year... one interuption after another. Around 6 months ago, I installed, what I refer to as the Mowog style pistons (72mm 1466cc, yes, in an XPAG), but was quite disturbed with the oil rings. They required more tightening in the ring compressor than seems normal and now, in my opinion, they're too tight. They're coming out.
One option is to grab some old oil ring springs & spacers and install them with the new oil rings (assuming they are identical) then evaluate their fit.
Another option is the iron oil control ring that goes on the fourth groove at the bottom of the skirt. There's no 4th groove on these pistons, so I wonder if Taiwan sticks the same ring set in for different pistons in spite of machining dimensions. I'd expect the 4 piece oil rings would be more effective at wiping oil away than the iron ones, but what's a little blue smoke among friends.
The day is coming when I'll be installing teflon rings for oil control and an added measure of compression seal, but this isn't the engine to experiment with. Maybe the steam hybrid engine.

Anyone experience oil ring issues???

Anyone go with the iron rings???
JRN JIM

Your problem may not be the same as I had. We rebuilt the XPAG at around 68mm bore and used new JPS pistons with the 3 ring style setup, the engine ran well but burned a lot of oil at idle. Suspected the the valve guides and put in a new set of new seals. Engine still burned oil like a 2 stroke at idle. We then pulled the engine and honed the block taking extra care with the cross hatching at the top of each bore with oversize rings. On the restart same problem only worse, this time blew smoke the whole time. At this time I went down and spoke to an old time BMC man at a Southside engines here in Perth Western Australia. His advice after close inspection of the engine was to try one more rebuild but use a Hastings oil ring part of Ford I believe. Same type as they used in Model T Fords. He commented "If this doesn't work then don't invest anymore money on engine". We went for another hone and cross hatch and oversize rings with the Hastings oil rings. When we finished the rebuild we held our breath and prayed. I have now done 3000 miles on the engine and not a bit of blue smoke. The engine runs as sweet as. Just goes to show that XPAG's are old technology and often respond to low tech rather than high tech

Best of luck with your rebuild
Regards Ed Floate TC 9549 TD 0260
EH Floate

I don't know if this helps but here goes. I had most of the machining on my engine done by a local racing outfit. It just so happens that it is the same outfit used by a certain major MG supplier not too far away, for their racing ventures. When I bought the pistons and rings (+0.080") from that supplier I noticed that the pistons had 3 grooves, but the rings (Hastings I think) were in sets of 4. The very experienced guy at the racing outfit said not to use the cast iron oil control rings but to use the three piece rings instead, so that is what I did.
Dave H
Dave Hill

I assume you have checked the ring gaps and that the ring grooves are deep enough for the rings? Both these issues can cause the rings to be too tight in the bores.

I am not a big fan of oil rings below the gudgeon. I reckon they would reduce lubrication of the skirt.

I have to use cast iron oil rings in my own cars because I have hard chrome bores, but I agree with Ed and Dave that the modern three (or four?) piece oil rings should work better in a normal bore. I used Hastings rings in the engine I built for my brother's car as it had normal bores.

Many years ago I had a problem with one-piece cast rings. The engine blew smoke. It improved slightly with use, but would not bed in properly. On disassembly it was obvious that the rings were the problem. They were shiny/bedded at the more flexible sectors, but hadn't touched the bore at the more rigid sectors where the bridges were cast between the rails. Obviously the/ rings were round when uncompressed but when compressed they flexed more where there was less metal and so went slightly octagonal! The supplier said it was a bad batch and a replacement set bedded in much better.

Bob Schapel
R L Schapel

I certainly checked the dimensions before fitting. After 500miles I checked the compression on all four cylinders and they were almost identical - I forget the number exactly but it was around 150 psi. I assume therefore that all is well.
Dave H
Dave Hill

Moss supplies pistons with multiple ring widths....



See
https://www.hastingspistonrings.com/assets/files/9/hastings_catalog_master.pdf


Len Fanelli

This thread was discussed between 14/12/2016 and 17/12/2016

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now