1949 Dennis F1 Fire Truck Restoration

At last I have some progress to report. Dennis was an original Darwin Fire Brigade fire truck, which saw service in Darwin and Alice Springs before finally being decommissioned in the late 1980s and parked in a paddock in Alice. It was finally sold and transported to Adelaide, where over a period of time it passed through a couple of owners and was partially stripped for restoration, which never actually started.

I had found this vehicle during my research of the history of the NT Fire Service, and when the opportunity to buy it came up, I jumped at it with both hands. It finally arrived at home in July last year. Thanks to the previous owner Simon for assisting with the packing and despatch from that end.

Here

Looking forward to following your progress, mate.

hi bugly. i found Auto Surplus in Melbourne very helpful for suspension pins and bushes. good luck Max

Thanks MMKNJL ... I'll stick that on my list of contact places!

I dropped the oils from the engine, clutch and gearbox, which were all pretty thick and gluggy. I also removed the sump screen from the bottom of the engine, which also had quite a lot of sludge in it, and gave it a good clean. Through the sump screen hole in the bottom, I physically reached in and scraped out any sludgy build-up of old oil sitting up in the bowels of the engine that I could reach.





The felt filter is contained in an external cooling chamber, so this was also removed and the filter and canister cleaned. The filter was designed to be cleaned and re-used. This one however could be the original filter, which would make it more than 60 years old, and I'm pretty sure that a more modern paper element filter would provide better filtration. The felt filter was 155mm long, so I initially hunted for a filter of around this length. Brian from the NSW Fire Museum recommended the Ryco R205P, which the museum fits to their Dennis Ace fire trucks. At 153mm it was close, but even at this length there was a possibility of the unfiltered oil bypassing the ends of the filter. I really needed one about 10mm longer, but it appeared that to suit the diameter of 75mm or so, the longest filter available was 153mm.

Time for some lateral thinking ... what if instead of going longer, I went shorter? Bingo! Two Ryco R2053P filters at 73mm outside diameter and 83mm long end-to-end gave me 166mm, and at 33mm ID they were perfect!



The next task was to source a compression spring to tension down on the top filter. The spring removed with the felt filter I was convinced was not correct, as the internal diameter seemed too small. Internet shopping came to the party with a 60mm long 33mm I.D. spring, but when received it seemed to be about 10-20mm too long and a bit strong. I tied the spring with wire so that it was compressed to 25mm high, and popped it into Mum's gas oven when she was out shopping.



After baking at 250 degrees Celcius for 90 minutes, I allowed it to cool naturally and then removed the wire ties. Beautiful! It ended up 45mm long, and about half the original spring tension. I was happy with that!



The filters sitting nicely in the cooling chamber, and the tension spring perched on top ready to fit back onto the engine. I just need to make a gasket to fit between the cooling chamber and the filter mount. Four inch OD and three and a half inches ID, so this will be fairly easy.



The original recommendation by Dennis Brothers for F1 engine oil was Shell X-100 SAE50 where the vehicle was exported overseas to an ambient temperature of 90 degrees Fahrenheit. This temperature equates to about 32 degrees Celsius, which is the ambient temperature in Darwin. Therefore the oil chosen for the engine is Penrite Shelsley Heavy, which is recommended for 1920-1950s era petrol and diesel engines where the original recommendation was for SAE50 oil.

The Dennis engine clutch and gearbox use common oils, as the three chambers link together. Any overfilling or overflow from the gearbox enters the wet clutch, and the overflow from the clutch runs into the crankcase.

This engine also had a 240V sump oil heater, but although the heater will remain plumbed into the sump, the wiring will be disconnected. I won

Hi there

Great looking project - some thing I am passionate about being my occupation (Emeregncy Services)

We all retire eventually including our truck and its great to see there history being preserved. I also have a passion for the older (smaller) fire engines as I have 4 off....

Looking forwards to viewing progress

Wayne

Thanks MMKNJL ... I'll stick that on my list of contact places!

I dropped the oils from the engine, clutch and gearbox, which were all pretty thick and gluggy. I also removed the sump screen from the bottom of the engine, which also had quite a lot of sludge in it, and gave it a good clean. Through the sump screen hole in the bottom, I physically reached in and scraped out any sludgy build-up of old oil sitting up in the bowels of the engine that I could reach.

There will be a lot of gluggy stuff all around the sump, you won't reach it all by hand. I would suggest you drop the sump, remove the collector tray and and give it all a good clean out.

There will be a lot of gluggy stuff all around the sump, you won't reach it all by hand. I would suggest you drop the sump, remove the collector tray and give it all a good clean out.

I have found that the secret (at least for this restoration) is to ask questions and listen to advice.

Thanks Beaver, I'll do that this weekend. I notice that you are from the Museum as well ... very glad to get your feedback, as you guys would know these engines intimately by now! Dropping the sump will also give me a chance to check out the sump oil heater for sealing, and perhaps blank it off if necessary. By the way, what did you reckon about the double oil filters?

I removed the water jacket side cover this evening, and Murphy's Law said that I would snap off a bolt or two. In fact out of fourteen bolts, seven sheared off. So looks like I will have to drill the broken end out, and re-tap the holes for new bolts They were originally Whitworth, but may be able to change to BS with the tap. The cover plate looked great from the outside, but after cleaning it with a wire brush it was found that there was quite severe pitting on the inside, with two holes. So it looks like I need to make another cover plate. Apparently the earlier engines had a brass plate, whereas this one is pressed steel. Brian (Museum of Fire) suggested that a temperature gauge sender unit be fitted into this plate. Great idea, and I'll do exactly that.




Looking inside the water jacket ... my gawd, what a build-up of scale and crud! The drain tap was blocked solid, so I removed that and cleaned it out. I also had to sharpen up a welding electrode to act as a long bit to get up inside and clean out the drain. A lot of probing and scraping with bent lengths of fencing wire, and I managed to vaccuum up most of the scale from inside. Then set up a 25 litre bucket under the drain tap, dragged in the garden hose, and flushed through with three bucketfuls of water before I got rid of the sediment and the discolouration.

It's for sure I'll be using Penrite Coolant Conditioner in this truck from Day One!

More to follow ...

Bugly, if you've got a steady hand and a mig welder, you can weld on top of the broken bolts until it builds up enough to get some vice grips on them. The welding will shrink the bolt and they generally come out pretty easy.

Thanks bigcam - I haven't heard of this trick, but I'll try it out. Worst that'll happen is that I'll have to drill them out and re-tap anyway! Most of the bolts (as they do!) have snapped off flush with the block, but a couple are sticking out just a tad. I'll let you know how I go. Do you know if Whitworth HT bolts are still available at all?

Once you get your confidence up tou can do the ones flush with the block, you'll be surprised, a bit of weld on them and they usually unscrew pretty easy.