Having come this far it seemed logical to give the cooling system a complete overhaul.
Although the engine has done minimal hours since it was last overhauled by Rolls Royce in crewe (who bought up the rights to the FD6 when Fodens went bust)Its a bit of an unknown as to how well the previous owner cared for it - when I bought the boat it came with a 20l barrel of engine oil, which was advertised on the label as "a premium blend of recycled base oils"
Other than topping up the anti freeze occasionally I have always put off servicing and oil change (as I only have a limited number of oil filter cartridges and they are over £100 each if you can find a supplier! )
Main heat exchanger disassembled:
Seals for this heat exchanger are no longer available so some time was spent coming up with alternatives:
Ready to refit:
Oil filter bowl removed allowing access to engine oil cooler:
Oil cooler removed:
Showing the state of one of the coolant pipes on the oil cooler - To replace this involves removing the cooler and breaking several gasket joints onto the engine block. Better to do it all now than have to take it all apart again in a few years when it fails:
Oil cooler core - water flows through the middle:
Worrying amounts of hair stuck in the fins:
A quick check of the manual shows the cooler is pre oil-filter:
O Rings from cooler which had swollen so much I really struggled to get it apart:
Main components of Oil filter and cooler:
New UNF stainless fixings for oil filter bowl:
New old stock gasket for oil filter gives some idea of scale - the filter is huge. (note TBA logo, Turner Brothers Asbestos of Rochdale - the sign of a quality asbestos product) :
When I came to drain the sump and gearbox oil it became apparent that neither of the drain pumps were particularly effective. I stripped them down and one had a broken leather cup washer and the other had been replaced for an incorrectly sized rubberised cotton cup washer.
Part of the assembly had also been cross threaded and stripped then stuck together with loctite.
Leather washers of the correct size aren't available off the shelf and rather than getting them made especially I thought I'd see if I could modify them to take modern nitrile cup seals intended for hydraulic rams.
Damaged leather plunger washer:
I had to turn some brass rings to fit inside the new seals:
Next up I thought I had better check the thermostat - There was a stat in a cupboard when I bought the boat which I assumed was a spare, When I finally got the housing apart (which had seized onto the steel studs as someone had neglected to refit the copper washers which stop coolant getting forced down the threads of the bolts) it turned out there was no thermostat fitted.
I'm pretty certain this is a previous owners bodge as part of trying to fault find a stalling/overheating issue which eventually turned out to be water backing up in a large water cooled wet exhaust silencer and eventually causing enough back pressure to stall the engine. The silencer had been fitted by the navy just before decommissioning as they had been towing ammunition barges and decided the two stroke diesel with dry exhaust out the funnel wasn't a great idea near explosives!
I removed the water cooled exhaust when I bought the boat and have had no problems since.
Water rail/thermostat housing and header tank:
Correct gaskets vs lump of glossy cardboard:
Refacing where I had damaged the gasket face splitting it off the seized studs:
Testing the three port thermostat:
Another area of concern has always been the water jacketed exhaust manifold - Its always seemed to weep blue antifreeze crystals so I was worried it had become porus.
I have another which came from the engine out of the spares boat so figured I'd strip them both and see which was best
Manifold - the heat exchanger fits to the brackets:
Theres about 80 studs that hold the water jacket cover plates on and every one was a nightmare to get out:
Carbon build up in the exhaust ports:
Stripped down manifold:
The cause of the crystals seems to have been failing gaskets allowing water to creep up the studs and get beneath the paintwork.
I ordered new stainless studs for the manifold (from a company in the midlands which turned out to have made the originals in 1966! )
However £60 tooling setup costs per run of studs meant it was only economical to get them to make the most common one of the 3 different size studs used on the cover plates.
For the other two sizes I bought off the shelf imperial studs and shortened them in the lathe to suit then turned the correct unthreaded pip on the top and extended the threads as necessary.
I also repeated this process to make studs to replace the header tank lid and thermostat housing fastenings.
Standard stud, Shortened stud with pip turned, original stud:
New studs fitted:
When refitting my newly overhauled oil drain pumps I noticed the mounting bracket for the gearbox pump was loose.
For some reason known only by Self Changing Gears Ltd of Coventry they chose to use BSF fastenings to hold the rear housing onto the aluminium body of the gearbox. These had then been overtightened by some navy fitter when installing the sump pump and had pulled the threads out of the box.
access wasn't great but I set about helicoiling the two failed fastenings, as they're quite deep this was a bit of a pain and as neither of the holes was blind it made trying to remove the tang without losing it into the gearbox somewhat challenging!
Gearbox and pump with the two missing bolts just about visible:
BSF in aluminium! :
Specially modified pliers:
For something made in the late 60's I really can't believe that BSF was the thread of choice, Mind you I think self changing gears had become part of the british leyland empire by that stage so maybe it does make sense in a strange sort of way!
Thanks for reading