Tophat liners New article from Robinson
#1
09-12-2012, 02:18 AM
Tophat liners New article from Robinson
Robinson seems on top of the top hat retrofits and looks to build quality engines..
(I don't work for him, I just respect his diligence)
Link to article:
JE Robison Service — the blog
Here is the article
Wednesday, September 5, 2012
Flanged or Top Hat Liners in Land Rover Engines
The more I see of the 2003-4 Land Rover Discoveries, the more it seems their engines were fatally flawed. Ten years ago, 90% of the engine problems from overheating were due to heads warping or head gaskets failing. 10% were due to what people called "slipped liners."
The same was true for noise complaints. When someone came in with a rap or tick issue the problem was almost always a noisy catalyst or worn rocker shafts - comparatively simple fixes. Only a tiny fraction of noises were from internal motor problems.
Today, with the late Disco motors, those odds have flipped. When a 2003-4 Rover comes in with overheating trouble, the most likely cause is liner or block failure. A noise complaint is more likely to be from excess clearance in the piston-liners (in other words, prematurely worn out.) I've written several essays about how this happens so I won't repeat all that here. The question is . . . what do we do about it?
The solution that has emerged - both here at Robison Service and in the UK - is to rebuild the blocks using flanged liners so the cylinder head seals against the liner, not the block. Then we fit new pistons with proper clearances.
The photo above shows a typical failure. The block cracks at the base of a head bolt bore, between the back of the liner and the water jacket. With the stock liners there is no barrier to prevent combustion gases going round the liner and into the coolant.
The fitment of flanged liners solves that problem by making the liner top the sealing surface. There is no high pressure gas behind the liner, and the cracks are rendered irrelevant.
The photo above shows a flanged liner and a new piston. The o-ring seals the bottom of the liner to prevent coolant dripping into the oil sump in the event of a crack.
This is what a flanged liner looks like installed. As you can see the wide flange covers the entire sealing area of the head gasket.
We can do flanged liners in 4.0, 4.6, and overbore configurations. At this moment (Sept 2012), costs to do a block with flanged liners, new pistons, and all basic machine work in in the $4800 price range. Our American costs are similar to costs from RPI or Turner over in the UK.
We believe this is the only long-term solution to the problems in these late motors, and it provides a substantial upgrade for any older Land Rover V8. However, the liner repair is just the beginning when it comes to engine overhaul . . .
What else do we do when building a motor?
I recommend balancing any engine. Motors like these rely on sophisticated engine electronics to achieve smoothness. That will be considerably improved if the engine is mechanically balanced before assembly.
Front covers and oil pumps have been problematic on these trucks. The pump gears fracture, and eventually the oil pump fails. The result - engine failure from oil starvation. I recommend fitting a new front cover as long as these parts remain available.
Heads are another problem area. We recommend rebuilding the heads. This involved walnut shell blasting to get everything spotless, followed by crack test and a check for warping. Then we fit new guides, redo valves and seats and cut the sealing surfaces perfectly flat. If you're a perfectionist we can also cc the combustion chambers to ensure each cylinder is exactly equal.
This is a rebuilt head. As you can see the sealing surface is cut to a mirror finish. We true these heads to half a thousandth of an inch to minimize the change of gasket failure.
We also rebuild rocker shafts, and swap cams and lifters. Needles to say, every other part is cleaned and inspected before being overhauled, repaired, or replaced. That thinking should also extend to the external accessories like the water pump, injectors, and alternator.
We believe the engines we are building now are substantially smoother and better than what land Rover delivered new.
Till next time
John Robison
J E Robison Service
Springfield, MA USA
(I don't work for him, I just respect his diligence)
Link to article:
JE Robison Service — the blog
Here is the article
Wednesday, September 5, 2012
Flanged or Top Hat Liners in Land Rover Engines
The more I see of the 2003-4 Land Rover Discoveries, the more it seems their engines were fatally flawed. Ten years ago, 90% of the engine problems from overheating were due to heads warping or head gaskets failing. 10% were due to what people called "slipped liners."
The same was true for noise complaints. When someone came in with a rap or tick issue the problem was almost always a noisy catalyst or worn rocker shafts - comparatively simple fixes. Only a tiny fraction of noises were from internal motor problems.
Today, with the late Disco motors, those odds have flipped. When a 2003-4 Rover comes in with overheating trouble, the most likely cause is liner or block failure. A noise complaint is more likely to be from excess clearance in the piston-liners (in other words, prematurely worn out.) I've written several essays about how this happens so I won't repeat all that here. The question is . . . what do we do about it?
The solution that has emerged - both here at Robison Service and in the UK - is to rebuild the blocks using flanged liners so the cylinder head seals against the liner, not the block. Then we fit new pistons with proper clearances.
The photo above shows a typical failure. The block cracks at the base of a head bolt bore, between the back of the liner and the water jacket. With the stock liners there is no barrier to prevent combustion gases going round the liner and into the coolant.
The fitment of flanged liners solves that problem by making the liner top the sealing surface. There is no high pressure gas behind the liner, and the cracks are rendered irrelevant.
The photo above shows a flanged liner and a new piston. The o-ring seals the bottom of the liner to prevent coolant dripping into the oil sump in the event of a crack.
This is what a flanged liner looks like installed. As you can see the wide flange covers the entire sealing area of the head gasket.
We can do flanged liners in 4.0, 4.6, and overbore configurations. At this moment (Sept 2012), costs to do a block with flanged liners, new pistons, and all basic machine work in in the $4800 price range. Our American costs are similar to costs from RPI or Turner over in the UK.
We believe this is the only long-term solution to the problems in these late motors, and it provides a substantial upgrade for any older Land Rover V8. However, the liner repair is just the beginning when it comes to engine overhaul . . .
What else do we do when building a motor?
I recommend balancing any engine. Motors like these rely on sophisticated engine electronics to achieve smoothness. That will be considerably improved if the engine is mechanically balanced before assembly.
Front covers and oil pumps have been problematic on these trucks. The pump gears fracture, and eventually the oil pump fails. The result - engine failure from oil starvation. I recommend fitting a new front cover as long as these parts remain available.
Heads are another problem area. We recommend rebuilding the heads. This involved walnut shell blasting to get everything spotless, followed by crack test and a check for warping. Then we fit new guides, redo valves and seats and cut the sealing surfaces perfectly flat. If you're a perfectionist we can also cc the combustion chambers to ensure each cylinder is exactly equal.
This is a rebuilt head. As you can see the sealing surface is cut to a mirror finish. We true these heads to half a thousandth of an inch to minimize the change of gasket failure.
We also rebuild rocker shafts, and swap cams and lifters. Needles to say, every other part is cleaned and inspected before being overhauled, repaired, or replaced. That thinking should also extend to the external accessories like the water pump, injectors, and alternator.
We believe the engines we are building now are substantially smoother and better than what land Rover delivered new.
Till next time
John Robison
J E Robison Service
Springfield, MA USA
#4
09-12-2012, 09:58 AM
Administrator
#5
09-12-2012, 10:33 AM
#7
09-12-2012, 11:02 AM
from the blog:
John Elder Robison said...
Mbrosch, if you refer to the photos in the article you will see the answer to your question "why not pin the sleeves in place".
The answer is that the blocks crack behind the sleeves and combustion gas gets into the coolant passages. Pinning won't help that. The second problem is that nothing seals the liner to the head gasket, and pinning won't help that either. Flanged liners are the only thing anyone has found to address those problems.
I see that Robinson is FINALLY acknowleding that there are issues with the liners, but is still missing the point that the liners aren't ONLY moving because the block is cracked... The number of folks driving round in 2003/2004 "tickers", covering many thousands of miles without using a drop of water clearly don't exist in his mind or reality.
Pinning has been proven by probably a half-dozen folks so far as a fix for a ticker that otherwise is a healthy engine.
John Elder Robison said...
Mbrosch, if you refer to the photos in the article you will see the answer to your question "why not pin the sleeves in place".
The answer is that the blocks crack behind the sleeves and combustion gas gets into the coolant passages. Pinning won't help that. The second problem is that nothing seals the liner to the head gasket, and pinning won't help that either. Flanged liners are the only thing anyone has found to address those problems.
I see that Robinson is FINALLY acknowleding that there are issues with the liners, but is still missing the point that the liners aren't ONLY moving because the block is cracked... The number of folks driving round in 2003/2004 "tickers", covering many thousands of miles without using a drop of water clearly don't exist in his mind or reality.
Pinning has been proven by probably a half-dozen folks so far as a fix for a ticker that otherwise is a healthy engine.
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