Showbus returned to Duxford in September and so I took advantage of the closeness to my storage location to take along both D302PEV and P337ROO.
The day itself went well with both vehicles receiving positive feedback. Having popped upstairs on 337 part way through the warm day to open the upper deck windows [to let some heat out] I noticed condensation on the rear offside window. This is right above the header tank for the engine cooling system and so as expected, it took about 2 litres of water when checked prior to departure.
Having driven 337 back home and parked her up, I became aware a few minutes later that she was leaking water from the back end. Further investigation showed water leaking from the header tank via a pressure release cap. And sure enough, the condensation was back on that upper deck window.
It was suggested that I may have overfilled it with coolant. I was always told to fill 'em to the maximum mark as a bus driver but it was explained that doing so leaves no room for expansion when the coolant heats up and so its better to fill it to just above the minimum mark. Once it cooled down I refilled it to just above the minimum mark as advised and took it out for a drive. Upon returning there was no loss of water..........so it would appear we solved the issue........
Canvey bus rally was yesterday and I went along with P337ROO as I planned to run in service.
Given the previous water issues, I ensured we left with the coolant just above the minimum mark and stopped off for diesel after about 40 minutes. A check at the back revealed no water leaking. Another check upon arrival at Canvey also revealed no water leak and no other obvious issues (ie, condensation or overheating).
I duly completed 4, or possibly 5 (I wasn't counting!) round trips on the museum to display shuttle before parking up. It was pleasing to carry healthy loads as it means I get to drive under full load conditions and it gives the vehicle a proper work out by doing the job it was built to do. Having built some trust in the motor I thoroughly enjoyed myself going round and round in circles.
Another check after the service runs revealed a very minor water leak via the pressure release cap - probably not even half a litre. I elected to not check the water level given the advice about not over filling it. I figured that I hadn't lost much and so with no condensation on that upper deck window and no other obvious signs of overheating we ought to be fine for the return journey.
Having given a private tour of the Island to some friends at the end of the event, we duly set off for the return journey............40 minutes in I started getting a low oil level alarm when stopping at traffic lights or roundabouts. I pulled into a layby to check it out and upon getting to back of the bus I was greeted with a significant amount of steam and some water coming of the header tank pressure release valve. 337 had overheated proper and it took a good 10 minutes to cool down enough to release the filler cap. A check of the oil showed it to be bang on the maximum mark!!
Just when I thought I'd turned a corner and found a reliable DAF after all the grief with 335........arrgghhhh!!!
Having learned a lesson when a fellow preservationist had problem at the Clacton rally, I now carry 20 litres of water on board so was instantly relieved to realise that once 337 cooled down we could soon have her topped up again and be on our way (assuming the engine hadn't been cooked). 20 litres later I had it just above the minimum mark on the header tank. Yep, that's not a typo - it had lost 20 litres - and it didn't loose all 20 when I stopped as the puddle underneath was nowhere near big enough. So when did it lose those 20 litres???!!
Anyway, thinking back to the day I drove it back from Sheffield, I had found it ran better at a maximum speed of 50mph. Up until this problem occuring I had been doing around 53/54mph for about 20 minutes. Having decided that driving slower may be a good idea I drove all the way back to the storage location (another 40 minutes) without going above 45mph. Upon parking up back at base I rechecked the back end................no water leaks and the coolant still just above the minimum mark as it was after refilling at the roadside.
Because of the issues with 337 and the likelihood of no quick fix, I'll be taking the old faithful, D302PEV, to Transport fest instead of 337.