Ford Power Stroke engine
|Power Stroke engine|
|Manufacturer||Navistar International (1994-2010)|
Ford Motor Company (2011-present)
|Also called||Ford Powerstroke|
|Configuration||90° V8, Inline-5, V6|
|Displacement||3.0 L (183 cu in)|
3.2 L (195 cu in)
6.0 L (365 cu in)
6.4 L (389 cu in)
6.7 L (406 cu in)
7.3 L (444 cu in)
|Cylinder bore||3.74 in (95 mm)|
3.87 in (98.3 mm)
3.9 in (99.1 mm)
4.11 in (104.4 mm)
|Piston stroke||4.13 in (105 mm)|
4.18 in (106.2 mm)
4 1⁄4 in (108 mm)
|Valvetrain||OHV, DOHC 4 valves x cyl.|
|Compression ratio||17.5:1, 18.0:1|
|Turbocharger||Single Garrett variable-geometry with wastegate and air-to-air intercooler|
|Fuel system||Common rail Direct injection|
|Oil system||High pressure oil pump|
|Cooling system||Water cooled|
|Power output||130–600 hp (97–447 kW) |
|Torque output||350–935 lb⋅ft (475–1,268 N⋅m)|
|Dry weight||≈920–970 lb (417–440 kg)|
|Emissions control technology||Bosch DPF, EGR, Denoxtronic-based SCR and DOC|
|Predecessor||International Harvester IDI (1983-1994.5)|
|Successor||6.0 Power Stroke|
Power Stroke is a name used by a family of diesel engines for trucks produced by Ford Motor Company since 1994. Along with its use in the Ford F-Series (including the Ford Super Duty trucks), applications include the Ford E-Series, Ford Excursion, and Ford LCF commercial truck; the name was also used for a diesel engine used in South American production of the Ford Ranger.
From 1994, the Power Stroke engine family existed as a re-branding of engines produced by Navistar International, sharing engines with its medium-duty truck lines. Since the 2010 introduction of the 6.7L PowerStroke V8, Ford has designed and produced its own diesel engines. During its production, the PowerStroke engine range has been marketed against large-block V8 (and V10) gasoline engines along with the General Motors Duramax V8 and the Dodge Cummins B-Series inline-six.
- 1 7.3 Power Stroke
- 2 6.0 Power Stroke
- 3 6.4 Power Stroke
- 4 6.7 Power Stroke
- 5 3.2 Power Stroke
- 6 3.0 Power Stroke
- 7 Applications
- 8 Other engines with the Power Stroke name
- 9 See also
- 10 References
- 11 External links
7.3 Power Stroke
The first engine to bear the Power Stroke name, the 7.3L Power Stroke V8 is the Ford version of the Navistar T444E turbo-diesel V8. Introduced in 1994 as the replacement for the 7.3L IDI V8, the Power Stroke/T444E is a completely new engine, with only its bore and stroke dimensions common with its predecessor (resulting in its identical 444 cu in (7.3 L) displacement). In line with the IDI diesel, the Power Stroke was offered in one-ton versions of the Ford F-Series/Ford Econoline product ranges.
The Power Stroke is an electronically controlled, direct injection engine with a 4.11 in × 4.18 in (104.4 mm × 106.2 mm) bore and stroke creating a displacement of 444 cu in (7.3 L). It has a 17.5:1 compression ratio, and a dry weight of approximately 920 lb (417 kg). This engine produces up to 250 hp (186 kW) and 505 lb⋅ft (685 N⋅m) of torque in automatic transmission trucks from the last years of production, and 275 hp (205 kW) and 525 lb⋅ft (712 N⋅m) of torque in manual transmission trucks. The oil capacity is 15 US qt (14 L; 12 imp qt). The oil pan holds 15 US qt (14 L; 12 imp qt) while the top end holds an additional 3 US qt (2.8 L; 2.5 imp qt), making for a total of 18 US qt (17 L; 15 imp qt).
The 1994.5 to 1996/97 DI Power stroke has "single shot" HEUI (hydraulically actuated electronic unit injection) fuel injectors which were AA code injectors unless from California where as they received AB code injectors. It ran a high pressure oil pump (HPOP) to create the necessary oil pressure to fire the fuel injectors. This generation of Power Stroke utilizes an HPOP with a 15° swash plate angle. The 1995-1997 trucks use a two-stage cam-driven fuel pump, whereas the 1999-2003 trucks use a frame rail mounted electric fuel pump. The 1999-2003 trucks also had a deadhead fuel system and a "long lead" injector in cyl. number 8 due to lower fuel pressures with the deadhead design (AE code injector). The California trucks from 1996 and 1997 have a 120 cc (7.3 cu in) split-shot fuel injectors; other trucks did not get split-shot injectors until 1999. Single-shot injectors only inject one charge of fuel per cycle, whereas the split-shot injector releases a preliminary light load before the main charge to initiate combustion in a more damped manner. This "pre-injection" helps reduce the sharp combustion 'knock' as well as lower NOx emissions by creating a more complete burn.
The '94.5-'97 engine utilizes a single turbocharger non-wastegated with a turbine housing size of 1.15 A/R. In 1999, an air-to-air intercooler was added to cool the charged air from the turbo for increased air density. With the new cooler, denser air would increase the horsepower potential of the engine, while also reducing exhaust gas temperatures (EGT). The turbine housing was changed to a .84 A/R and a wastegate was added halfway through the 1999 model year. The 1999 engine also received 140 cc (8.5 cu in) injectors, up from 120 cc (7.3 cu in) in the early model engine. With the larger injectors, the HPOP capability was increased by utilizing a 17° swash plate angle to meet the requirements of the new, higher flowing injectors.
Despite being regarded as one of the most reliable engines ever put in a car or light duty truck, the 7.3 Powerstroke was not without its own issues. A common failure point was the CPS (camshaft position sensor). The failure of this sensor would create a no start condition or would shut the truck off mid operation. An easy way to diagnose a failed CPS is through movement of the tachometer when cranking. If the tachometer does not move, the CPS is most likely bad. The fuel filter/water separator also tends to be a minor failure point across the trucks. The filter housing tends to develop cracks in the aluminum housing and leaks fuel. The heating element contained in the filter housing also can short out, blowing a fuse and causing a no start condition. The turbocharger up-pipes are a large failure point, with the pipes leaking from many different points but mainly from the joints. Leaking of the up-pipes causes the engine to lose power and for EGT's to increase. The EBPV was also prone to failure. tired from age it would open up when cold and get stuck on causing a jet engine like noise coming from the exhaust. Most of the issues that came out of these motors were electrical due to old, fraying and, melted wires. The UVCH (under valve cover harness) was prone to losing contact with either glow plugs or injectors which caused rough starts or a misfire depending on the year. 1994-1997 has two connectors going into each bank whereas 1999-2003 they had one connector going into each bank. made troubleshooting the harness easier in the early years. Besides the electrical the 7.3 also had a weak valvetrain. Valve springs did not have a very high seat pressure leading into valve float at high RPM's often causing bent or broken pushrods. Aftermarket springs and shims are available to solve the problem however. Besides those minor things, the engine came with forged connecting rods (good for 600 hp (447 kW)) until 2001 they went to PMR's (powdered metal rods) which were plenty strong for a stock motor but if there was alot of aftermarket parts, they were a weak link at about 450 hp (336 kW) and up. Some early models were fortunate enough to even be sold off the lot without a catalytic converter as emissions didn't quite effect the diesel industry too much yet.
The 7.3L DI Power Stroke was in production until the second quarter of model year 2003 when it was replaced by the 6.0L because of its inability to meet newer emission requirements. Nearly 2 million 7.3s were produced from International's Indianapolis plant.
6.0 Power Stroke
The 7.3 L (444 cu in) Power Stroke was replaced by the 6.0 L (365 cu in) beginning in the second quarter of the 2003 model year. The 6.0L Power Stroke, was used in Ford Super Duty trucks until the 2007 model year but lasted until 2009 in the Ford Econoline vans (model year 2010) and in the Ford Excursion SUVs until after the 2005 models when Ford discontinued Excursion production. The engine has a 3.74 in × 4.13 in (95 mm × 105 mm) bore and stroke creating a displacement of 5,954 cc (6.0 L; 363.3 cu in). It utilizes a variable-geometry turbocharger and intercooler, producing 325 hp (242 kW) and 570 lb⋅ft (773 N⋅m) torque with an 18.0:1 compression ratio, with fuel cutoff at 4,200 rpm. Many 6.0 L Power Stroke engines experienced problems,
- Fuel injection system: Split-shot HEUI (hydraulic electronic unit injectors)
- Valve train: OHV 4-valves per cylinder, 32 valves total (16 intake valves, 16 exhaust valves)
- Turbo configuration: Single; variable vane geometry (VGT)
Oil Cooler/EGR Cooler - The sources of the main issues with the 6.0L were the in-block oil cooler, and the EGR cooler materials. The oil cooler is located in the valley of the engine block, underneath the cartridge oil filter set up. The sealed outer portion of the oil cooler is submerged in engine oil, with coolant flowing through the center passages. Over time, the oil cooler will develop small cracks in the aluminum tubes from the constant heating and cooling of the engine. This situation usually results in oil pushing its way into the cooling system. The sludge created from the mixture of oil and coolant creates a high pressure environment in the EGR cooler (due to the viscosity change in the coolant), leading to cracking of the EGR cooler's coolant passages. Once the EGR cooler cracks, it begins to leak coolant into the intake system and is then routed into the engine's cylinders to be burnt. The burning of coolant in the cylinders then causes a steam buildup, thus increasing cylinder pressures and the stretching of the head bolts; which leads to head gasket failure. The early EGR coolers (2003-2004.5) were also susceptible to premature failure without oil cooler issues, also resulting in head gasket failure.
High Pressure Oil System - With the use of Split-shot HEUI fuel injectors, high pressure oil is required to pressurize the fuel injectors. The main high pressure oil (HPO) system components are; High Pressure Oil Pump (HPOP), HPO manifolds, Stand pipes and branch tube. The HPOP is located in the engine valley at the rear of the engine block. Early build years (2003.5–04.5) are well known for premature HPOP failure. This is due to the poor quality materials used in manufacturing. The HPOP is pressurized by a rotating gear, meshed with a rear camshaft gear. The early model HPOP gears were known to be weak, and develop stress cracks in the teeth resulting in gear failure, thus causing a no start issue for the engine. Early models also had the ICP sensor located on the HPOP cover. The high amount of heat in this location, combined with the exposure to debris in the oil was known to cause ICP sensor failure also resulting in a no start condition. This issue was addressed by Ford with the late 2004 engine update, bringing a new HPOP design, along with relocation of the ICP sensor to the Passenger side valve cover. The newly designed pump is not known for frequent failure, however a new issue arose with the update. In the late model engines, Ford also redesigned the HPO stand pipes and dummy plugs in the HPO manifold, using poor quality o-rings. These o-rings were prone to failure causing a HPO leak, and eventually a no start condition. Ford addressed this concern with updated Viton o-ring washers fixing the issue. With the new HPO system design also came a Snap To Connect (STC) fitting. Some models had issue with the prongs of the STC fitting breaking causing the fitting to lose its sealing property and again, a no start condition for the engine. Another frequent (but not always catastrophic) issue with the HPO system is the Injection Pressure Regulator (IPR) screen. The IPR screen is located in the engine valley with the oil cooler. The material used was susceptible to failure and neglecting to replace the screen during an oil cooler replacement could lead to the debris being sent through the HPOP causing complete failure.
Head Gaskets - Ford/International used four Torque to Yield (TTY) cylinder head bolts per cylinder for the 6.0s and 6.4s. TTY bolts offer some of the most precise clamping force available but can be problematic. In certain situations (Oil cooler/EGR cooler failure, high boost/load levels brought on by performance upgrades) TTY bolts can be stretched beyond their torque mark by increased cylinder pressures. This has never been addressed by Ford due to the fact that other malfunctions or abuse must occur to stretch the bolts. Some in the aftermarket will replace the factory bolts with head studs in an attempt to protect the head gaskets from future failure. If this is done without addressing the underlying issue, the head gaskets may fail again bringing along a cracked or warped cylinder head. In contrast, the Powerstroke 7.3s and 6.7s have 6 head bolts per cylinder while the 6.0, VT365, IDI 7.3s and 6.9s only have five. 
Electrical and fuel
Numerous PCM recalibrations, attempts to "detune" the engine, fuel injector stiction (caused by lack of maintenance and proper oil changes) along with several other driveability and quality control problems have plagued the 6.0. The FICM (fuel injection control module) has been a problem, where low voltage in the vehicle's electrical system due to failing batteries or a low-output alternator can cause damage to the FICM. In addition, the placement of the FICM on top of the engine subjects it to varying and extreme temperatures and vibrations causing solder joints and components to fail in early build models; mostly in the power supply itself. The FICM multiplies the voltage in the fuel injector circuit from 12 to 48-50 volts to fire the injectors. Low voltage can eventually cause damage to the fuel injectors.
6.4 Power Stroke
The 6.4L Power Stroke was introduced for the 2008 model year. It was the first engine introduced to the light truck market that utilized dual turbochargers from the factory. This was the first Power Stroke to use a diesel particulate filter (DPF) in order to nearly eliminate particulate emissions. The new DPS and active regeneration system greatly hindered the engine's fuel economy capability, though the engine proved to be comparatively strong and reliable. The engine was ultimately retired after the 2010 model year, as Ford replaced it with its own in-house built 6.7L Power Stroke.
The engine has a 3.87 in × 4.13 in (98.3 mm × 104.9 mm) bore and stroke, resulting in a total calculated displacement of 6,369 cc (6.4 L; 388.7 cu in). Despite having to meet emission regulations, the engine was able to increase horsepower ratings to 350 hp (261 kW) and torque to 650 lb⋅ft (881 N⋅m) at the flywheel. Horsepower and torque are achieved at 3,000 rpm and 2,000 rpm respectively. It also features a compound VGT turbo system. Air enters the low-pressure turbo (the larger of the two) and is fed into the high-pressure turbo (the smaller of the two), then is directed into the engine or intercooler. This system is designed to result in reduced turbo lag when accelerating from a stop. The series-turbo system is set up to provide a better throttle response while in motion to give a power flow more like a naturally aspirated engine. The 6.4 L also has a DPF and dual EGR coolers which are capable of reducing exhaust gas temps by up to 1,000 degrees before they reach the EGR valve and mix with the intake charge. The DPF traps soot and particulates from the exhaust and virtually eliminates the black smoke that most diesel engines expel upon acceleration. The engine computer is programmed to periodically inject extra fuel in the exhaust stroke of the engine (known as a "regeneration" in the F-Series) to burn off soot that accumulates in the DPF. This engine is designed to only run on ultra low sulfur diesel (ULSD) fuel which has no more than 15 ppm sulfur content; using regular diesel fuel results in emission equipment malfunctions and violates manufacturer warranties.
The 6.4L has had one recall (safety product recall 07S49 was released on March 23, 2007) that addresses the potential for flames to come from the tailpipe of the truck. This problem arises from the DPF which is part of the diesel after-treatment system. A PCM recalibration was released to eliminate the possibility of excessive exhaust temperatures combined with certain rare conditions resulting from what is becoming known as a "thermal event".
- Fuel injection system: High pressure commonrail
- Valve train: OHV 4-valve
- Compound VGT turbo
- Advanced multi-shot piezoelectric fuel injection control
- Piston ring failures in #7 & #8 cylinders due to regeneration process. During regeneration, fuel is injected during the exhaust stroke in order to increase the exhaust temperature for DPF cleaning. This exposes the piston rings to excessive heat which eventually causes the piston rings to lose tension, causing low to no compression (compression skip) and excessive blow-by.
- Rocker arm tips impacting (especially on lower geared trucks) due to higher pressure on valve-train (that was not upgraded from the 6.0 liter engine design) after 100,000 to 150,000 mi (160,000 to 240,000 km).
- Turbo-charger bearing seal failures (which in turn allows engine lubricating oil to leak past the bearing seal) due to regeneration process pushing high exhaust temperatures thru the turbo-charger. This condition will precipitate premature clogging of the DPF, which then causes the engine to stay in regeneration mode. If this condition is not corrected quickly, the leaking seal will eventually allow all the engine oil to be pumped out of the engine thru the exhaust, causing complete engine failure due to lack of lubrication.
- Higher incidents of cavitation erosion of the front cover due to the larger water pump impeller speed, causing coolant to leak into engine oil.
- EGR cooler failures allowing engine coolant to flow back into #8 cylinder while engine is shut off, which causes the cylinder to hydro-lock and possibly bend the piston connecting rod as well as other damage to engine when it is subsequently started.
- Cylinder head valve-guides do not have bronze sleeves, which allows for excessive wear and oil leakage around the valves (also an issue on the 6.0 liter).
- If aftermarket tuning is installed that introduces too much advanced fuel injection timing, cracking of the cylinder heads can result due to excessive combustion temperatures.
- Very high cost of service and repair parts compared to other versions of the Powerstroke.
6.7 Power Stroke
Emissions controls include exhaust gas recirculation, Denoxtronic-based selective catalytic reduction (SCR) from Bosch, and a DPF. Output was originally 390 hp (291 kW) and 735 lb⋅ft (997 N⋅m). but shortly after production started, Ford announced that they made an update to the 6.7L diesel. The new engine control software makes the engine capable of 400 hp (298 kW) at 2,800 rpm and 800 lb⋅ft (1,085 N⋅m) at 1,600 rpm while achieving better fuel economy and without any physical changes to the engine.  The 2015 engines are rated at 440 hp (328 kW) and 860 lb⋅ft (1,166 N⋅m). Ford claims the bump in horsepower is from a new turbo, new injector nozzles and exhaust improvements. For 2017, the torque had risen to 925 lb⋅ft (1,254 N⋅m) at 1800 rpm, Horsepower remains the same.. To compete with the Duramax and Cummins engines from GM and Ram, Ford has increased output for the 2018 model year to 450 hp (336 kW) 935 lb⋅ft (1,268 N⋅m). Previously, the Duramax motor had a 5 hp (4 kW) gain over the Powerstroke in 2017, and for 2018 the Cummins motor had a 10 lb⋅ft (14 N⋅m) torque gain over the Powerstroke if the Powerstroke's output hadn't been increased for model year 2018.
- Valve train: OHV 4-valve
- Turbo configuration: 'GT32 SST (single sequential turbocharger)' --single 64 mm (2.5 in) turbine and dual-sided compressor
- Fuel injection system: High-pressure common rail, Bosch CP4 injection pump, piezo electric injectors
|Turbo configuration:||'GT37' --single 72.5 mm (2.85 in) turbine and 88 mm (3.5 in) compressor|
|Fuel system:||High-pressure common-rail, Bosch CP4.2 injection pump, piezo electric injectors|
|Engine:||Power Stroke V-8|
|Displacement:||6.7 L (406 cu in)|
|Bore and stroke:||3.9 in × 4 1⁄4 in (99.1 mm × 108.0 mm)|
|Block:||Compacted graphite iron|
|Heads:||Aluminum (reverse flow)|
|Valvetrain:||OHV, 4 valves per cylinder; 32 valves total|
|Horsepower:||450 hp (336 kW) at 2,800 rpm|
|Torque:||935 lb⋅ft (1,268 N⋅m) at 1,600 rpm|
|Emissions equipment:||EGR, DPF, SCR|
|Engine dry weight:||970 lb (440 kg)|
3.2 Power Stroke
The 3.2 L Power Stroke is an inline-five engine that debuted in the U.S.-spec Transit for model year 2015. The engine is a modified version of the Ford Duratorq 3.2 L diesel engine that has been adapted to meet emissions in the United States. To aid in economy, emissions, and reduce NVH, it has a high pressure common rail fuel injection system and piezo injectors that can spray up to five different injections per compression event. It has a water cooled EGR system to reduce the temperature of the exhaust gas before being recirculated through the intake. A unique feature to the emissions system is that the diesel oxidation catalyst (DOC) and the DPF have been combined into one singular unit as opposed to the traditional two separate units. Exhaust treatment continues with SCR which is done by the injection of diesel exhaust fluid in the exhaust to reduce NOx. The engine features a variable geometry turbo which allows for intake air flow tuning on the fly to increase power and fuel economy. The engine also features a variable-flow oil pump to avoid wasting mechanical energy pumping excessive amounts of oil. It has cast aluminum, low friction pistons with oil squirters to keep them cool during heavy-load conditions, a die cast aluminum cam carrier to stiffen up the valve train and reduce NVH, and to increase low end durability, the crankshaft is cast iron and the connecting rods are forged. The block itself is an extra rigid, gray cast iron with a closed deck. The power figures for the 3.2 L Power Stroke are 185 hp (138 kW) at 3,000 rpm and 350 lb⋅ft (475 N⋅m) at 1,500-2,750 rpm. The Euro Duratorq 3.2 makes 197 hp (147 kW) and 350 lb⋅ft (475 N⋅m) of torque.
- Fuel injection system: High pressure commonrail
- Valve train: DOHC 4-valve
- Turbo configuration: Single variable geometry turbo
- Combined diesel particulate filter and diesel oxidation catalyst
- Urea injected selective catalytic reduction
3.0 Power Stroke
A 3.0 liter Power Stroke turbo-diesel V6 will be introduced in the new 2018 Ford F-150 as a medium duty engine to compete with the Ram 1500 EcoDiesel V6. The 3.0-liter Power Stroke diesel generates 250 hp (186 kW) and 440 lb⋅ft (597 N⋅m) of torque, providing a towing capability of 11,440 lb (5,189 kg). EPA-estimated fuel efficiency ratings are 30 mpg‑US (7.8 L/100 km; 36 mpg‑imp) highway, 22 mpg‑US (11 L/100 km; 26 mpg‑imp) city, and 25 mpg‑US (9.4 L/100 km; 30 mpg‑imp) combined.
The Power Stroke engine has been used in the following applications.
Ford E-Series (full-size vans)
- 1995–2003 7.3 L
- 2004–2010 6.0 L
Ford Excursion (full-size sport utility vehicles}
- 2000–2003 7.3 L
- 2003.5–2005 6.0 L
Ford F-Series (full-size pickup trucks)
- Mid-1994–Mid-2003 7.3 L
- Mid-2003–2007 6.0 L
- 2008–2010 6.4 L
- 2011–present 6.7 L
- 2018– 3.0 L (F-150 only)
LCF (low cab forward)
- 2005–2010 4.5 L
- 2015–present 3.2 L
Other engines with the Power Stroke name
- In South American models, the Ford Ranger 2001 up to 2012 use a Power Stroke engine in their diesel versions. A 2.8L diesel engine was developed by Navistar/International Engines from an inline-four Land Rover Defender diesel 2.5L engine, with 130 hp (97 kW) (waste gate) or 133 hp (99 kW) (VNT). A 3L common rail four valves per cylinder and 160 hp (119 kW) (waste gate turbo) became the electronic version of the Power Stroke. It has only the block and connect-rods in common with 2.8 L Power Stroke
- The above-detailed 3.2L Duratorq I5 is branded as Power Stroke in US-spec Ford Transit vans.
- 4.5 liter Powerstroke was a v6 powerstroke with the same turbo design as a 6.4 liter. The geometry of the engines is the same as the 6.0l minus 2 cylinders. The 4.5l and 6.0l share some of the same engine parts. The 4.5l came stock with 200 hp (149 kW) and 440 lb⋅ft (597 N⋅m) of torque.
- Ford's Power Stroke Diesel History Power Stroke Spotters' Guide
- "what is best powerstroke - Ford Powerstroke Diesel Forum". www.powerstroke.org. Retrieved 2015-10-27.
- "Launch in Limbo". AutoWeek. Retrieved March 5, 2007.
- Jamie Lareau, Automotive News (2010-02-25). "2011 Ford Super Duty: Pickup has more pickup and more mpg". AutoWeek. Retrieved 2010-02-25.
- http://detnews.com/article/20100803/AUTO01/8030349/1148/rss25[permanent dead link]
- "440 Horsepower Powers Stroke". Retrieved 6 March 2014.
- "6.7L Power Stroke Spec and Information". Retrieved 6 September 2017.
- Gonderman, Monica (June 10, 2014). "Second-Generation Ford 6.7L Power Stroke - Torque Specs, 440 hp and 860 lb-ft of torque". Diesel Power Magazine. Diesel Power. Retrieved 20 November 2014.
- "2015 Ford F-Series Super Duty Features Improved Power Stroke Diesel". Ford Motor Company. Ford. September 26, 2013. Retrieved 19 November 2014.
- "Archived copy". Archived from the original on 2013-01-13. Retrieved 2013-02-16.CS1 maint: Archived copy as title (link)
- "2018 Ford F-150 Power Stroke Diesel By The Numbers". Retrieved 2018-12-01.
- "7.3 DIT Powerstroke Direct Injection Turbocharged Diesel Engine, "F" Series Super Duty Features, Description, Service Features" (PDF). Ford Motor Company. 1999. Retrieved 19 December 2015.