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MG TD TF 1500 - Cylinder liners
|My XPAG engine has developed a water leak between the block and cylinder liner. (fitted about 6 years ago to compensate for cylinder bore wear) I don't want to use a chemical sealant in the water for fear of blocking the radiator, so the engine has to come out and be examined.|
The block is an early oval hole version.
Any thoughts of going bigger and upgrading to 1350cc using liners and pistons from NTG would be greatfully appreciated, as would advice on the potential pitfalls from fitting new liners of any size.
The pic shows water (stained with red dye) seeping out under pressure.
|D P Jones|
|Di detect that that block has been linered once before? It appears that the seepage is along the circumference of those liners. Possibly they were not sealed properly. If so, new liners installed professionally and properly sealed may be the answer.|
|Did the boring out to accommodate the liner break through into the water jacket? I thought if this happened the block was scrap. I know with prewar MG engines that the maximum that can be taken out of the block is about +70 thou. Liners have to be of a certain thickness to maintain rigidity and thus they can only be bored to +20. Since virtually all blocks have now been linered there is no demand for pistons above +20. I thought I was getting a bargain at the mg spares Day at Stoneleigh when I bought some +40 pistons for my M Type at a knock down price. My linered block was already at +20 so I had to buy new liners, standard pistons and bin the +40s|
|I can see that thin wall liners have been fitted, but it is puzzling that there are leaks around the tops of the liners - you might want to check if there have been leaks from the bottoms of the liners, directly into the oil.|
However, this indicates two points;
1. The cylinder walls are cracked or were bored through during the machining process, although this does not necessarily condemn the block. It is worth noting that the cylinder wall thicknesses were a bit variable with the early oval hole blocks. The later round hole blocks had slightly thicker and more consistent cylinder walls.
2. The machining for the liners may have been slightly oversize, as there should be no leaks - especially with an unpressurised water system.
My XPAG round hole block had thin wall, approx 1.3mm, liners fitted over 20 years ago to give 1380cc, and I know that the machining went through the wall of at least one cylinder (even with a round hole block). However, sufficient of the original cylinder walls was left to support the top surface of the block, which is important. For fitting (down to steps with chamfers to clear corner rads), the block was warmed slightly and the liners chilled (not sure how) to give a good 'interference' fit. The liners, after installing, needed honing to match the pistons, and some slight machining to length, but only down to the original top face of the block. The block does not leak.
If you want to retain the existing capacity, I suggest you look for liners with a larger OD, either to fit the existing boring, or possibly requiring slightly more boring. I have not used the NTG kit, but if you do, make sure your machine shop does not overbore for the liners, or remove metal from the top of the block.
|R A WILSON|
|"Virtually all blocks have been linered". My block never has been, it is now bored.080 we have a lot of our cars in our club that are bored up to .100 . most blocks in the club are either stock or bored. don't know of to many that are linered here in damn cold MN. Maybe that is because most of the cars made came here and not to Europe where the supply is smaller, just a thought|
|I'm not planning to pull the head again to satisfy my curiousity but I'm just wondering, can you tell if the cylinders have been linered just by looking? Jud
|J K Chapin|
|I agree with Tom Maine - to say that most blocks have been sleeved is an enormous reach, and unjustified. I think I have seen one sleeved block in the last 10 years of doing T-series engines, and that was on one cylinder where a chunk was missing at the bottom of a cylinder (thrown rod?).|
If boring in the .100" region there is certainly the possibility of breaking through a water passage, which in theory is not good - it can cause uneven cooling and hot spots. But in practice, it causes no real problem. Many years ago I had overbored an early XPAG block for 1500 liners, and broke through 2 cooling passages; unfortunately, I had no other option than to proceed. The engine turned out smooth, reliable, and with no problems at all, and lasted some 70,000 miles before the .060/.040 crank broke.
|Just a thought, but I wonder what the OD is of the NTG 1350cc liners. As might be expected, the NTG website does not mention it, and it is now too late to ring them. I have not cut up a block, but going by section drawings in workshop manuals, the cylinder wall thickness of the oval hole blocks looks to be a fraction over 6mm.|
|R A WILSON|
Before you give up on your present linered block you might like to conider getting it resin impregnated to seal the liners into the block. A few years ago, a company called Ultraseal in Slough did this work on a 1500 XPEG block of mine which had been fitted with liners but not very successfully Had the liners pressed out by South Cerney Eng. (near Cirencester) which showed numerous ares where the machining had broken into the water ways in all 4 cylinders and therefore normally scrap. Since 1500 blocks are virtually unobtainable I took a chance and had new liners fitted and the block resin sealed. This produced a satisfactory result. Ultraseal pressure tested the reworked block first before and after doing the resin sealing. I know this method has been used by some of the T Racers wanting 1350 and larger bores.
It is a bit of a gamble but so is buying another secondhand block.
|Boring for liners which breaks into the water jacket is not a problem at all. Both my TD and my PA have liners. The PA engine, despite being a solid ball of rust when I rescued it, was not only bored for liners, but the cylinder walls were so rusted and cracked, that the walls were broken out and flanged liners were installed. The liners were custom made by LA Sleeve in California. They consist of a .100" flange at the top for support, and a .100" thick wall. Thus they are a wet sleeve which have been well and truly sealed to the deck and crankcase.|
Although I only have a few hours on the engine so far, no problems have appeared.
Since PA engine blocks are rare and this was the original engine to the car, I sought the advice of a competent machinist and we were able to save the engine.
|If there is no seepage at the bottom end why not use a solid copper head gasket?. This will completely seal the top end.|
As the TD is not a pressurised system it is not under stress.
As for not many sleeved blocks, that may be the case in the USA but not here. I have worked on many friends cars and most are sleeved. My engine has been sleeved and is now on its first rebore. Most UK cars did short runs which knackered them up very quickly. when my TF was my daily driver it did 5 miles to work and 5 back every day only really getting hot on my days off.
Ray TF 2884
|Jud - I don't know if your question was ever answered. If you look at the original picture, you can see a thin line around the top of each cylinder, which is the sleeve. A sleeve is a tube of metal inserted into an overbored cylinder to reduce the diameter of the bore back to standard, used when there is a damage or wear to the cylinder wall.|
|Thanks Tom. I didn't look carefully enough when I had the head off and I don't think the photo is clear enough to tell. I guess I'll find out fi (when?) I have the engine out for a rebuild. Good to know that sleeves can salvage even a pretty knackered up block. |
|J K Chapin|
|You could try resin sealing, as Roy has suggested, but you will notice the extra performance if you go to 1350cc, as the compression ratio will also increase. I also think your machine shop will be able to source appropriate liners from a wider range direct from the manufacturers - this is what happened in my case. Your machine shop might even have other sources for your pistons.|
|R A WILSON|
This thread was discussed between 04/01/2015 and 07/01/2015
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