temperature regulation in Aprilias

[Scarpia]

When I first drove my aprilia home , it was a cold winters evening with snow on the ground.Running most of the way on only 3 cylinders (the car had stood for nearly 40 years) the engine temperature was of little concern as the driving snow and rush hour traffic in the dark kept my concentration on other things.

During the journey however the water temperature guage remained resolutely on zero and unsuprisingly proved to be broken.These capilliary guages are rather difficult to repair but this was eventually sorted out.
Like most of the older models the aprilia is a little "overcooled" in the radiator department and in anything other than warm weather can take quite some time to reach operating temperature with all the mechanical disadvantage that this implies.The aprilia was originally provided with
1)thermostatically opened radiator shutters (opening automatically by a wax filled piston and lever assembly)
2) a basic engine thermostat situated in a housing between radiator and block.
3) a cooling fan driven from an engine pulley

The wax filled actuator for the radiator shutters rarely works these days and are difficult to repair.
When I opened the thermostat housing, it fell apart and there were only some sorry rusting fragments of what must have once been inside. Suffice to say there was no temperature regulation available except going faster with the shutters open.

There are various points in the water jacket you can place a temperature sender unit and the final choice depends a little on the information you wish to have .Mine had been installed in a take off from the thermostat housing but as this was now broken I considered alternatives.  Popular positions are usually situated in the header tank but I actually preferred and retained the existing arrangement when I redesigned the housing. This way you can see from the gauge behaviour that the thermostat is still working and exactly when it starts to open as the engine warms up.Trade off is that you see a slightly less consistent temp. reading as the thermostat opens or closes but that's secondary providing it stays within the desirable range...

The wax filled plunger for the shutters has been left in situ and awaits possible repair at a future date, but I have little faith in these "modern" gimmicks so I opted for a little more driver control.Due to a twin carb conversion, the original hand throttle assembly is no longer intalled on my car which leaves a nice large lever "spare" under the dashboard. This is now linked via a bowden cable to the lever that operates the shutters behind the radiator and allows me to open ( or close) the shutters by hand depending on the reading on the water temp.guage
Top tip: gortex mountain bike brake cables are very smooth operators for these types of applications. I have used these also to successfuly improve  the sticky heating control problem in RH drive fulvias (but that's another story.)

All that remained was to design the housing within the original dimensions and source a suitable and replacable modern thermostat to do the job.With an outlet to the heater unit (also an add on of course ) and a take off for the water guage,  the housing (which needs to remain slim to fit next to the block) was in danger of getting crowded and demanded careful consideration.
The original thermostat was much smaller in diameter than modern car equivelents but a readily available alternative that fits and works perfectly is from a kawasaki motorcycle ( KLR 600) part number 49054-1053.

The thermostat housing can be seen in the photo's added below.The first two photo's show the unit and in the last photo you can just see it in position when mounted on the block. The lower take off is to the heater, the upper for the temp guage. Now I have as much driver information as in any modern vehicle and a great deal more control.Which is just how it should be...



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[davidwheeler]

Interesting.  I have to get a new radiator as mine is totally choked (any ideas, recommendations?)   I do have a rebuilt capillary gauge which I shall fit into the new header tank.  My wax thermostat body looks OK and I wonder if anybody has a plan of the associated leverage. Otherwise, I shall see about a hand control as you describe but I fail to see how a twin carburettor setup (mine is a Nardi) gives you a spare, I still have starting carburettor and hand throttle controls.
David

[Scarpia]

Mine was leaking badly in several places but I had it completely rebuilt.Unfortunately (for you), I had it done in Brussels as there still many old world type craftsmen to be found in the backstreets.To clean, repair, repaint and pressure test cost , wait for it, 55 euro.

Nothing externally looks wrong on my wax unit but it simply doesn't do anything.One day I will remove it and take a look.When I get a moment I will take a photo of the linkage if it helps.
A part of the hand throttle assembly was removed at some point on my car and I can only assume it was in the way of the new twin carb assembly when fitted which fouled the routing of the hand throttle cable. Very difficult to picture and figure out from the parts book I have.

[Scarpia]

Aprilia radiator on ebay (David Wheeler , you were looking for one i think)

http://cgi.benl.ebay.be/LANCIA-APRILIA-radiatore_W0QQitemZ120127350977QQihZ002QQcategoryZ126571QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

400 euro and you've got till 8 june.

[davidwheeler]

Unfortunately I have been On the Continong.  I passed through Belgium, too - but in a 2CV so not much room (or, of course, need) for a radiator.  I don't see a lot of point in a second hand unit, I think that, having rebuilt the engine, a new one is a wise investment.

[Sliding Pillar]

Good luck in finding someone to make a new Aprilia rad. The last time I had one done the bloke said he don't ever bring me another one!!! ......something to do with the big hole in the middle!!!!
Ade

[Scarpia]

Not suprised ; it must be a pig to make one. I cannot imagine these days finding anyone prepared to make a new one.A properly refurbished one will perform perfectly well anyway as it is more than up to the job when in reasonable condition.