Ford 6-Cylinder Maranisation Case Study

The Twenty Three Step Diesel Engine Marinization Process

The basis of this content is from a piece provided by Dick Johnson and first published back in 1978. The content remains valid and provides a useful background explanation describing how a Ford 6 Cylinder normally asperated 120Hp motor is converted for marine use.This a very basic outline covering the fundermentals.

Buying a second-hand vehicle engine and converting it with a special marinization kit can save thousand pounds or more over a new marine engine. This stop-by-stop description of the marinization of a 120hp Ford diesel engine highlights this is not a difficult one for someone with mechanical aptitude and can be completed within a day or two if you crack on.

A marinization kit is a collection of parts that can be simply bolted on to an automotive motor, transforming the motor into a marine engine. Buy a second-hand engine from a breaker's yard, install the kit and start boating! It is not quite so simple, but that’s the basis of the idea. Such kits have served the small petrol engine market well in the past, but there is an increasing need for diesel engines in cruisers as the cost of petrol climbs and the shortcomings of the high revving, car-type petrol engine are exposed. Heavier boats need power and thrust and  not engine speed, and this is best found in a slow-revving diesel driving a big propeller, likely through a reduction gear. The problem has been that while petrol engine marinization kits have been readily available, their diesel counterparts are thin on the ground at least in the larger sizes.

One of the few such kits comes from specialist engine builders such as Lancing Marine.It is suitable for all forms of the six cylinder Ford 2700 engine but the one we built was a naturally-aspirated engine putting out about 120hp. Turbocharged versions can run to 250hp however they are a little more complicated.

A brand new marine engine of this type will probably set you back many thousands, but building your own on a second-hand truck unit will conservatively save you more than half the cost. Second-hand engines whilst scarce can be obtained from breakers yards cheaply. The all-important question is the one of engine condition and the mileage that it has done in its original truck body. Engines that come from newer, crashed vehicles are the best, but if none are available try to get one from a fleet truck. They are likely to have had the best maintenance, unlike the one from a small firm which might have been saving a few pounds by delaying oil changes etc.

Mike Bellamy of Lancing Marine believes that there is a simple way of telling if the engine you have chosen is good enough to be considered for boat use. Get it on the floor in a clear space, couple a battery to it and start up with the exhaust manifold removed. What you hope you won't find is consistent white smoke from one or more of the exhaust ports which likely indicate damaged valves or pistons. If there is smoke from a port, squirt oil or upper cylinder lubricant down the inlet. If that fails to stop the smoke then change the injector and see if that resolves. If it does, the engine is satisfactory for marine use. If it doesn't most reputable dealers will allow you to take the engine back within 14 days and exchange it for another.

Mike also believes that the engine will not need a full overhaul and reconditioning for most boat uses. Unlike a petrol engine, the diesel is not overstressed by continuous running in a boat and provided if it runs without too much mechanical noise and the oil pressure is correct, it will be good enough for marine use. The engine should be removed from its old home in the truck with the rubber mountings attached, and the wiring and hoses cut off. The gearbox should also be removed before you buy the unit as it is not needed and will add to the price. Get the engine home and give it a good clean up with a degreaser and plenty of scrubbing.  

The 23 Step Process

1. Block up the engine securely on the ground or on a platform so that it will be easy to work on and so that it will not fall on you when exerting pressure to loosen stubborn bolts. You are now ready to start the operation. The first step is to unbolt the fan if present from the front of the engine.


2. Next, the inlet and exhaust manifolds are removed. A quality socket set is essential for this job as the securing bolts are deep within the castings. The inlet manifold is retained for use on the marine engine, the exhaust manifold joins the scrap pile.


3. The air cleaner now comes off but check for the oil inside. The fuel filter is usually bolted to the air cleaner bracket but do not disconnect the pipes, just remove the fastening bolts and let it hang on the pipes for the time being. The cleaner and piping are consigned to the scrap.


4. Round to the back of the engine now, and before starting to remove the bell housing make sure that the engine is blocked up on the sump, clear of the flanges and mounting feet. Unbolt the bell housing but keep the bolts. The housing and clutch Cylinder which is attached to it Should join the scrap.


5. With the housing off, unbolt the clutch and dump it.


6. The rubber sump vent pipe is next to go, just a simple slackening of the pipe clip and then it can be pulled clear.


7. The air brake compressor is next. Three bolts here but the compressor is gear driven and might take some prising off the block. Do not however force anything between the two flanges as this is a gasket face to keep the timing case oil tight. As with the bolts you undo, screw them back into their old holes finger tight, so that they will not get lost.


8. Moving to the top front of the engine, take off the thermostat housing and thermostat. The housing goes on to the scrap pile but the thermostat can be reused providing it is in good condition. Any doubts though then just replace it.


9.  Directly under the thermostat at the bottom of the engine are the rubber mountings that held the engine on the chassis. Usually they are in the angled position but as we are going to use the engine upright one mount has to be moved from the side to the bottom so that the new mounting bracket will allow the engine to be installed upright. If the mountings are in good condition not torn or severely softened by oil - they can be re-used. With the rubbers properly in place, bolt on the front engine mount supplied with the kit.


10. The rear engine mounts are simple right-angled castings with marine flexible mounts attached. They bolt to the side of the flywheel housing with four bolts, in holes already cast into the engine block.


11. The engine can now be supported on its mountings on a simple cradle made from suitable timber or steel. Make your support high enough to get the bottom of the sump well off the ground as the next job entails getting underneath.


12. 12. Remove the angled sump of the truck engine and replace with the upright sump for the marine unit. These are available from Lancing Marine or you might be able to swap with the scrapyard, or buy your own new sump from a Ford truck dealer. While the sump is off, check the condition of the big end and main bearings and clean off any sludge that might be within the crankcase. Make sure that everything is scrupulously clean before installing the new sump on a new gasket so to ensure a complete seal.


13. Thoroughly clean off the outside of the engine and paint to suit the colour scheme of your boat. It is just as well to use a light colour as it will show up any oil and fuel leaks and makes the best use of the available light with the engine compartment. Use a proper fuel and heat proof paint and give enough coats to achieve a good surface. The smoother it is, the easier it will be to clean. Ensure all gasket faces that will be taking new parts are masked off with masking tape.  


14. With your now gleaming motor looking like new on its stand start assembling all the marine components. First to be added is the sea water or correctly the raw water pump. This is a Jabsco gear driven unit that fits into the space left by where the air brake compressor was located. The existing bolts may be reused.


15. Next component to add is the oil interrupter. This diverts the oil flow through the filter, passing it first through a cooler. The oil filter complete with bracket - is removed, two bolts, and the interrupter are the bolted on. The filter then bolts on to the top. While you are about it you should replace the filter element.


16.  After the interrupter, the cooler needs to be fitted. This small unit is connected to the water pump and to the interrupter. Oil passes through it one way, and water the other. The cooler can hang from its pipes, or you could make up a supporting bracket that bolts to a couple of sump bolts.


17. While working on this side of the engine, it is as well to fit the throttle cable bracket. It bolts to two of the timing cover bolts and provides an anchor for the outer cable, It will be necessary to change the throttle arm on the injector metering pump from the inside to the outside in order for it to line up with the cable. Newer engines have the arm fitted to a shaft that is splined on each end, so it is a simple change-over. Older engines need a circlip removed and the shaft pushed out and replaced the other way round.


18. Round to the other side of the engine now, and the exhaust and inlet manifolds are mounted. The inlet is the old supplied with the truck engine, the exhaust is a special water-cooled Bowman marine unit. Fitting takes time to get right as this can be a bit tricky. The exhaust manifold is mounted first and is held in place by the two end nuts run on finger tight. The inlet is then offered up and the other bolts put in and tightened up. New gaskets should always be used. On the outlet end of the manifold goes the water injection unit which is an adapter to connect to a rubber pipe that acts as the water-cooled exhaust to dump. Various bends and angles are available. The cooling water is injected into the bend to cool and help silence the exhaust.


19. Two studs are now screwed into the bolt holes exposed when you removed the thermostat housing. The studs locate the fresh-water heat exchanger and header tank. The thermostat we mentioned earlier is fitted under the header tank and installed using a new gasket. A blanking plug or a sender for a temperature gauge is then screwed into the thermostat bleed hole. 


20. The end caps of the header tank can be turned by slackening the end cap securing bolt or dentral bolt on older units. The manifold end should have its pipe horizontal, the other side should point downwards. The pipes are now connected. The horizontal one has a pipe attached, running to the fitting on the far end of the exhaust manifold. The front-end fitting on the manifold is connected to the point where the cooling water is injected into the exhaust stream. This prevents air locks within the manifold. The other pipe on the header tank connects to the Jabsco water pump by a flexible hose and an angled coupling. The long lengths of rubber pipe can be avoided by adding sections of  copper tube in between bends.


21. At the back of the engine, the flywheel is next to receive attention. A flywheel connection between flywheel and gearbox provides torsional vibration damping so to avoid transmission issues. This drive plate is bolted on however you may find dowels present that normally used to drive the clutch get in the way. If they do, either pull them out or break them off with a sharp blow from a hammer. New bolts should be used for this item.


22. The bell housing which encloses the flywheel and drive plate is then fitted. The bell housing is designed to couple the engine to gearbox and absorb thrust from the propellor, this the motive diving force of the vessel. The bellhousing will be machined to accept the intended gearbox to the engine. This bolts on with the same bolts that held the vehicle housing.


23. The bell housing will also adapt straight onto a sterndrive such as the example Stern Power 101 outdrive coupling. Lower performance sterndrives attach direct to the engine as the gear forward, neutral, reverse is contained within the drive. Higher performance drives use an external gearbox, typically a Borg warner box coupled in the same way as a shaft drive installation.

Marinisation Kit Suppliers back in 1978!

Gallery Images

Click on an image for a larger view.