question Leyland 680 "porous" block

Not sure in this case, but it might be a core plug (Welsh plug) that has rusted through. If so, these can be changed.

No, it is definitely a rotten hole in the water jacket.

Shouts to me the block has been subject to some sort of electrolysation being used as a stationary engine. Very early Scania engines where subject to same problems (and used same block built under licence) the advice then was to add cutting oil to coolant but if you have that corrosion probably the block is to far gone. I had on of the first 110 scania in England as a wrecker and it developed a hole in block along side no 5 cylinder it looked like it had been drilled. the Scania agent said it was down to static electricity and and advised different fan belts cutting oil in water and putting earth leads all over engine

In 2007 we bought a brand new Renault 10 ton crew cab truck and fitted brand new slide bed aluminium from the US. within months of buying the whole tuck seemed to be turning to powder. any where aluminium was touching steel it was swelling and starting to corrode I suggested swapping fanbelts and adding cutting oil to coolant it never got any worse so what the actual problem is I don't Know

Swapping fanbelts - can you enlighten us a bit more on what effect that has please, Cosrec?

I don't know on the Scania that was what I told by an old boy who worked for the dealer he said it was some sort of static build up erosion caused by the material used in the belts. On the Renault it was one of two we built both brand new chassis. We kept one and sold one the one we kept just seemed to decide to self destruct. every where aluminium and steel touched on the engine started swelling turning to powder. I suggested what I had been told the belt was changed and it never got any worse. I Don't know

I suppose a fan belt of a different construction or material might be less prone to generating static. Difficult to know without methodical investigation whether that was the cause / cure or just snake oil, though.

On the 680 block, it's evident that you have one hole corroded through from the water jacket and possibly another. You have to assume, therefore, that whatever the cause or prevention there is extensive corrosion in the water jacket.

I'd say if you're going to end up with a lot of time and money invested by using this engine, and it'll be difficult to replace if there is a problem, don't use it. If you're not putting a lot of time and effort in, or it would be simple to replace if you do keep getting block leaks, give it a go.

Have a good look at the way the hole has corroded. If there's just a hole, and there's little or no surface corrosion or pitting around it, then it's probably rusted from the inside. If (as you seem to describe) there's crusty rust and pitting around the hole, could it just be that rubbish and water have been trapped between the block and the tin cover, corroding it from the outside? If so, it may be a good indication that the block is fairly sound.

You could also get one of the guys who does wall thickness testing, for example for testing pressure vessels, in to check the block walls over to see if there are other iffy spots.

In 2007 we bought a brand new Renault 10 ton crew cab truck and fitted brand new slide bed aluminium from the US. within months of buying the whole tuck seemed to be turning to powder. any where aluminium was touching steel it was swelling and starting to corrode I suggested swapping fanbelts and adding cutting oil to coolant it never got any worse so what the actual problem is I don't Know

Aluminium touching steel is a well known problem; anyone with experience of Land Rovers will know. Separating them with suitable interface material is the usual solution (or rather prevention).

Any thoughts on the 680 block?

If it were a Ford tractor block from that era, I wouldn't be at all surprised and depending on the location of the leak wouldn't have a problem with a suitable repair if in a location that could be accessed or covered by linering the bores but with Ford engines the problem is nearly always localised. Also I have more than once replaced porous liners in International and John Deere engines; I would say in every case there has been evidence that there has been a long term lapse in the provision of antifreeze/coolant inhibitor.

The stationary application could well have been part of the problem but I would think that standing with fresh water coolant (at that a fortnightly flushing too) for many years would be cause enough and the problem is general rather than localised; I will open out the hole with a view to plugging and have a look.

I work with steam boilers and only too well understand how metal can rot away.

I would imagine any attempt to chemically descale the internal surfaces would probably only open up holes which otherwise wouldn't show themselves.

Is there a product available which coat/stabilise the internal surfaces?

just done a real quick search because I know I aint dreaming this up

Engine destruction due to excessive voltage in engine's coolantIt has become apparent that many preventive engine failures, due to problems noted in the cooling system. Problems caused by an electrical current passing through the coolant from an electrical ground problem and generation of static electricity elsewhere on the equipment. This can destroy an engine in 24.000 miles regardless of the cooling system maintenance. The only way it can be stopped is to correct the electrical problem causing the current.

The enclosed maintenance tests were developed with the help of fleet maintenance superintendents, port engineers, and several people workings in equipment maintenance. To correct this potential for engine destruction we recommend it be incorporated in any preventive maintenance program. Examples of problems noted in the field that led to this test procedure are enclosed for your convenience.

Engine damage from an electrical current will be illustrated by pitted liners, all coolers, radiators, extreme aluminum corrosion, and abnormal water pump and head gasket failure. Aluminum corrosion, products will stop the flow of coolant through the oil cooler causing severe ring and bearing wear due to improperly cooled engine oil. Copper will plate out onto the iron components causing iron destruction. One may also notice abnormal rusting of cabs and other sections of equipment.

Field Problems That Led To This Test Procedure

1. Copper injector shells in a truck engine were being destroyed in 3D days because a broken cab ground strap allowed the electrical current to ground through the coolant.

2. A twelve cylinder marine engine was destroyed by liner pitting. As indicated by our laboratory testing of the coolant, the overhauled engine was again damaged. The starter, which was starting the engine with no apparent problem to the operator, was causing a 12 volt current to ground through the coolant.

Pitting destroyed engine blocks in a large towboat. The pitting was, caused by an electrical current due to two defective electrical switches on the after cooler systems and one switch on the air conditioning unit in the captain's cabin.

4. The aluminum top tanks of truck radiators were pitting on a new fleet of trucks equipped with rubber air bag suspension an the rear ends. The rear ends were generating a current, which passed up the drive shaft to the cooling system. Grounding the rear ends and transmissions stopped the problem before the engines were destroyed.

5. A large fleet of trucks made up of half tankers and half flatbeds, using the same brand of engines and trucks, lost sixty engines in one year. Fifty-four engines failed in the flatbeds while only six engines failed in the tankers. Tankers have a bonded ground system while flatbeds do not. The nine to one ratio indicates the potential for damage.

6. A truck hauling plastic pipe was losing the engine every 100,000 miles. The operator noted the load was glowing because of static electricity due to air brushing down the open-ended pipes. The operator covered the pipe with a tarp and the engine lasted over 300,000 miles,

7. Newer model electronic controlled engines, head gaskets, water pumps, radiators, oil cooler, and transmissions were being damaged. Capacitors in the computers were allowing a stored electrical current to enter the coolant when the engines where turned off or starting after a period when the engine was in not in use. The electrical current has been present even with the batteries removed from the unit.

8. Grounding systems with the computer grounded direct to the batteries are beginning to be used by several manufacturers. Contact your manufacturer service-engineering department if a current is noted.

I have also just out of shear bloody-mindedness come off the phone to an old gentleman who looked after a fleet of Scanias who told me it used to happen to about 1 in 10 of their trucks. there was no rhyme or reason it just happened. He was told the same as me cutting oil in coolant put extra earthstraps on and change fanbelts. He said within three months of taking deliver a new truck he could tell if it was going to have problems just by its appearance around engine

and anything aluminium anywhere on truck

Another question was the engine being used to drive a generator??

That is most interesting Cosrec; I hope you don't believe that I have in anyway suggested that anyone has made anything up. I am most grateful for you sharing this information; which is new to me, despite operating and repairing engines in various roles for 30 years.

However the Leyland 680 with the problem was on a fixed fire pump installation; having no fan belts or closed system coolant. It has no engine driven electrical system apart from a tacho generator; the starting current was presumably from a fixed 24v supply, there is/was some remaining control wiring attached to the frame some of which is copper covered fire proof stuff but I would think all of this would have been bonded properly. It is not beyond belief that it wasn't bonded properly and a current was permanently applied to the engine earthed through the pipes. However the engine appears to have been cooled by the fire pump feed water which in my experience would be cause enough of the problem over the probably 40 years plus it will have been standing like that. Could if I use this engine in a vehicle with the hole and suspect patch plugged say that the problem may not get worse as the causal problem will likely be removed? However I will rig up a temporary fuel system, a means of pressurising the coolant and run the engine up to temperature properly as the next step and see if it is leaking internally.

The tin cover hasn't anything to do with it; it was just incidental that removing it initially revealed the problem. Also I bought the equipment from a demolition contractor whom I don't suspect to be the kind of person to buy machinery apart from when it is redundant due to and incidental to a demolition i.e. it is not likely (but it may be so!) that the engine/pump has been replaced because this problem has already been noticed, like had I bought the engine from a "Cheffins" monthly type auction and the tin cover had no obvious spanner rash on the fixings as if it had recently been disturbed.

Yes - many thanks for the interesting info Cosrec. Food for thought.

Back to you original question No as far as I am aware have no knowledge of the 680 been subject to been porous in fact the opposite it had a very good reputation. I guess if you can make good with a repair you would be very unlucky to have problems again.

It is proving difficult (in the bus world) to source Leyland 680s nowadays, so you may have to "make do and mend" with yours. It may be worthwhile (once the initial hole is repaired) flushing the cooling system (or just the block) and running some propriety sealing product around it as a precaution.

Leyland ran an industrial section which although extensive hasn't been written about much. They used most of the conventional Leyland engines and used them typically for gen sets, all self contained mounted on a skid. Most notable differences were the sump and a non pressurised radiator. Oil was circulated through coils in the radiator.

They made an 'improved' version known as the L11 up to the early eighties. The bellhousing should line up ok .

They made an 'improved' version known as the L11 up to the early eighties. The bellhousing should line up ok .

Not forgetting the 680 Power Plus and 690, the turbo variant.