Thread: new 3.9 block

About expelling the last air bubbles, think of the tide marks in an operating engine, the remanent air will be caught along the highest parts of the head passages, inlet manifold and heater circuit. These areas will be the least likely to affect the cylinder wall temperature.

Think of the stress on the block around a pressed in/shrunk in liner. The cast aluminium is under tension, and this tension varies with the temperature as the ally expands more than the liner every time the engine heats up. Aluminium expands 2.5 times as much as iron for a given temperature change. So the bottom line is that metal fatigue is what happens to the ally, exacerbated by any casting flaws/corrosion pits present in the cylinder area. Essentially it's the number and size of heat/cool cycles the engine goes through that will initiate cracking. Overheating will extend the size of the expansion range of the ally and cause a greater stress on cooling. The best lifespan of a standard Rover block will therefore be on vehicles that spend long hours at an even (lowish) temperature (touring) without cooling off or overheating. Definitely not commuting modest distances every day or climbing mountains with a heavy trailer.

So top hat liners appear to be the only sensible answer to the problems of loose liners. They don't rely on the friction of the shrink fit to seal.

Originally Posted by milld

it's done just 8000km only and is as new. I need to ask a few more questions but it's going for $2950. If I told you where it is..... I would then have to kill you lol!!!

That is about the money for a long motor but you don't see any around at 8K and hi comp at that. Sounds like its come from a road car??

To add to bee uteys comments above I reakon the average 94mm RV8 block probably only has 2 "overheats" up its sleave before the block wall between liner and water gallery is ready to let go.

On that basis mileage is irelevant as it doesn't take too much error or bad luck to overheat in a short period of time. As normal guarantees will never cover the true cost if it goes pear shaped, getting a used block pressure tested is must.

Bee utey , what you say make sense , but , why does there appear to be not that much of this liner slipping issue in the old 3.5 motor ? Reminds me of overheating issues on my old Holden,Chev,Ford Cleveland.Windsor V8's when boring out at or more than .060 . A few questions ? Is there a Crossover equaliser system fitted to the various EFI inlet manifolds ,as there wasnt for the carb manifolds . ? HAs anybody heat gunned the heads/block looking for Front to back and bank to bank differentials . ? What is the dominant area in the block that this liner problem occurs , is it the back , the front or the middle cylinders on which bank ? What are the water pressures (yes pressures not temperaturs ) at the various points around the system.?
Indeed is there a good diagram,drawing, whatever, that clearly shows the coolant path around the engine ? I am curious !

Originally Posted by cockie55

To add to bee uteys comments above I reakon the average 94mm RV8 block probably only has 2 "overheats" up its sleave before the block wall between liner and water gallery is ready to let go.

Just leafing through my old engineering books (long time no see), a graph shows where a particular material is subjected to a stress increase of 25% causing a 1000-fold factor in reduced fatigue life. So the moral is, don't cook yer motor. It's a lottery with very bad odds.

Originally Posted by 400HPONGAS

Bee utey , what you say make sense , but , why does there appear to be not that much of this liner slipping issue in the old 3.5 motor ? Reminds me of overheating issues on my old Holden,Chev,Ford Cleveland.Windsor V8's when boring out at or more than .060 .

See my post below, the thicker walls in the 3.5 block will reduce the stress in the ally walls below the critical failure stresses. A 25% reduction has the potential to make an engine last until it is worn out and rebuilt many times.

Originally Posted by 400HPONGAS

Indeed is there a good diagram,drawing, whatever, that clearly shows the coolant path around the engine ? I am curious !

Coolant path is in at the water pump, around the cylinders, up through the gasket at the back of the block (known choke point, ream it out!) then through the length of the heads and out the thermostat. A portion of the circulation returns to the pump inlet via the bypass hose. this is critical to keeping the block temperature closer to even.

Your suggestions on measuring temperature around the engine is a good idea, although it could be simplified to the temp at the thermostat and that at the front of the block (pump outlet, timing cover). Any other area should be between those two. Two temp gauges?

In my years I have repaired many P76 engines where temp excursions have caused head gasket "walking" failures. So I developed an improved bypass system where the water flow via the bypass is taken from a new port immediately below the thermostat. A bypass plate thermostat then closes off this passage on reaching full open temp. This has made engine temps stay rock steady on the gauge for most operation. A similar system is used on most modern engines. I have never had the opportunity to engineer something similar into the LR V8. Would be interesting to try.

This is also why I don't usually plumb LPG converters in line with bypass hoses. A reduction in bypass flow is not a good idea.

Originally Posted by 400HPONGAS

Bee utey , what you say make sense , but , why does there appear to be not that much of this liner slipping issue in the old 3.5 motor ? Reminds me of overheating issues on my old Holden,Chev,Ford Cleveland.Windsor V8's when boring out at or more than .060 . A few questions ? Is there a Crossover equaliser system fitted to the various EFI inlet manifolds ,as there wasnt for the carb manifolds . ? HAs anybody heat gunned the heads/block looking for Front to back and bank to bank differentials . ? What is the dominant area in the block that this liner problem occurs , is it the back , the front or the middle cylinders on which bank ? What are the water pressures (yes pressures not temperaturs ) at the various points around the system.?
Indeed is there a good diagram,drawing, whatever, that clearly shows the coolant path around the engine ? I am curious !

Perhaps it cracks because there is not enough strength between the walls after overheat and the fact is the 3.5 has a lot more meat and can take more abuse. A couple of landrover mechanics have also told me that it happens more so on engines converted to lpg. Not sure if it's true but it makes sense. That's why I was going to go for a high comp 3.5 but everyone says they are gutless. Top hat liners are the way for sure but the cost

It was the first cylinder on the left when facing the engine that went on mine.

Originally Posted by milld

It was the first cylinder on the left when facing the engine that went on mine.

And that's the one that cops the cold water every time the thermostat cycles open. More stress cycling. A sign of insufficient bypass flow perhaps, and a LPG converter plumbed in?