1949 Dennis F1 Fire Truck Restoration

After the post above, I went and removed the radiator and water pump to have a closer look at the cooling tubes. Beaver was right ... the tubes must be removed from their respective ends. The centre casting (refer to the workshop manual diagram above, #180 Cast Socket locating Oval Pipes) is not hollow, as I had assumed. It is recessed in both ends to hold the oval tubes in the correct location. Therefore I have to remove the welch plug to check out the rear tube. Due to the scale I found in the block when I opened it up a while back, I can't just ignore it. So now to get a 1.75 inch diameter welch plug.

What it really needs is to drill and tap the block to suit a 5mm thick cover plate with a welch plug in the plate. [smiley=thumbsup.gif] This would certainly help each time the tubes needed inspecting, simply remove four bolts and a plate. But then again, with the use of a coolant conditioner (Penrite Coolant Conditioner?) it shouldn't build up with scale again. At least not in MY lifetime!!

What it really needs is to drill and tap the block to suit a 5mm thick cover plate with a welch plug in the plate.

Righto ... question to the forum ... what do you reckon about one of these Dorman Autograde Expand-Tite plugs? This would allow removal when required to inspect and clean the internal cooling tubes, and would be a lot simpler that removing and replacing a welch plug each time. Has anybody had anything to do with these expanding plugs? With this one (Dorman #02605) the nominal size is 1-3/4" so would fit into the 1-3/4" hole, and the size range is 1-3/4" to 1-7/8" so it would expand up tight. It is deeper than the steel thickness, but this means that it would bulge a bit on the inside, which would aid in the sealing.

Bugly

You should be able to get a 1-3/4" welsh plug from any good bearing company and they are not hard to put in or take out.

Trevor

Never seen those plugs before but definately a good idea. On the one hand with protective antifreeze your tubes shouldn't need further checking, but on the other hand those plugs make checking real easy for peace of mind. Down to price really.

After the post above, I went and removed the radiator and water pump to have a closer look at the cooling tubes. Beaver was right ... the tubes must be removed from their respective ends. The centre casting (refer to the workshop manual diagram above, #180 Cast Socket locating Oval Pipes) is not hollow, as I had assumed. It is recessed in both ends to hold the oval tubes in the correct location. Therefore I have to remove the welch plug to check out the rear tube. Due to the scale I found in the block when I opened it up a while back, I can't just ignore it. So now to get a 1.75 inch diameter welch plug.

Although that centre casting is not hollow there must be a passageway for the water to get through to rear tube. Wonder if it is possible to make some sort of very long handled brush to get into the rear oval tube to clean it from the front ??

As for our water jacket being "clean" in the photo, the silt in the bottom was almost up to the inspection plate when we took it off. Took a while to get it all out, can tell you.

Although that centre casting is not hollow there must be a passageway for the water to get through to rear tube. Wonder if it is possible to make some sort of very long handled brush to get into the rear oval tube to clean it from the front ??

I poked and prodded down the front tube with a 3/16" steel rod, and the centre casting definitely has no through access to the rear. I'm now picking that the lower round tube is there to feed water straight to the rear from the water pump impeller chamber, rather than to aid in direct cooling. Due to the tube positions, it will be the larger oval tubes that will cool the exhaust valve area. The rear of the round tube finishes not too far from the rear oval tube, so this will be where it gets its water from.

There was a bit of scale up the round tube which I cleared out, and now by bending over double I can see right up the hole to the front.

The round tube has holes in it corresponding to the valve seats, to provide coolant direct to those areas. It will be important those holes are not blocked. There should be something in the text of your manual that explains how it works. The oval tubes, as I understand it, help coolant get to the back of the water jacket and keep an even temp in the block.

I had a win today with the cooling tubes through the block (I think!). First up, I knocked out the rear welch plug to expose the rear oval cooling tube. It was sitting up fairly high, and wasn

Bugly

I bet you are glad you got that book, imagine the dramas that could have happened once it was all back together and going.

Trevor

Bugs Can you let me have the chassis number for your F1 please