[carl750]

Thermostat Bypass Hose - SOLVED

This is for 1976 Nuova Super 1.6 ...... the intake manifold looks like what is in the 1750 Berlina Parts Manual instead of the one in the 1973 Nuova Parts Manual.

I bought the hose recommended by Centerline. It looked right until I tried to install it. It appears to be a little too long. When installed it is kinked just below the thermostat housing exit. This multiple bend hose cannot be shortened and still fit over the caste aluminum hose pieces.

Is the 1750 block taller than a 1600?

Any suggestions?

Carl.

 

[Alfajay]

Is the 1750 block taller than a 1600?

Yes, 6.5mm taller = .256"

I didn't understand all that stuff about the 1750 Berlina Parts Manual and 1973 Nuova Parts Manual. But I assume you have a carbureted 1600 using a drop-in thermostat manifold.

I have used Centerline bypass hose p/n RH480 successfully on 2L engines with a drop-in thermostat manifold. But sure, your hose needs to span 1/4" less height than it would on a 1750 or 2000. Is that enough to cause it to kink? Perhaps. Still, it's only 1/4" - you sure you can't shorten the hose a bit?

Might the problem be in the water pump? Does the bung for the bypass hose on your Nuova Super 1.6 waterpump come off at the same angle as the bung on a 1750/2000 pump?

 

[papajam]

Yes, 6.5mm taller = .256"

Am I mistaken in thinking that the height difference is 15mm?

 

[Alfajay]

Am I mistaken in thinking that the height difference is 15mm?

I am assuming that the height difference boils down to the difference in stroke. My notes show the following stroke dimensions:

1300 75mm
1600 82mm
1750/2000 88.5mm

Carl called his car a "Nuova Super 1.6", which I assume means a 1600. So I arrived at 6.5mm as 88.5 - 82mm. If Carl's Super has a 1300, the height difference would be 13.5mm

 

[papajam]

Aah!
My assumption is the difference in height between the top of the water pump and the deck;

1300 - 0mm
1600 - 25mm
1750/2000 - 40mm

 

[Alfajay]

Aah!
My assumption is the difference in height between the top of the water pump and the deck;

1300 - 0mm
1600 - 25mm
1750/2000 - 40mm

Well, that does make more sense. I can believe that a 15mm height difference would cause kinking problems with Carl's bypass hose, while the 6.5 that I suggested did seem small.

So I assume that 1750/2000 rods must be quite a bit longer than 1600 rods to result in a 15mm taller deck height, since the crankshaft throw difference is only 3.25mm.

 

[carl750]

Yes it is a 1600 / Webers. But I am finding some things look like Berlina parts .... which were already well into production by 1976.

I hate to put the old bypass hose back on ....... it may well be the original from 1976, but I am running out of time to get this back on the road for a Midwest Alfa weekend.

 

[Alfajay]

This won't be a quick solution, but you might try Classic Alfa, OK Parts, alfa-service, and the other European parts suppliers - one of them might carry a bypass hose for a 1600.

For a quick solution, how about installing the new bypass hose and letting it kink. A flow restrictor was installed in bypass hoses by the factory. Your kink may approximate that restrictor. Even if it is completely impassable, I don't think the car will overheat; just come up to temperature more slowly. A new/blocked bypass hose would be better than an old/burst one.

 

[Anfanuts]

My friend Jim tells me that his stock 73 Super 1300 has a screw in thermostat. He has said that all Supers (1300 & 1600) had screw in thermostats. I have not verified this in the Parts Manuals. Substituted engines or heads may have drop in thermostats. My 2L Alfetta-engined Super hoses fit fine so they can be found.

 

[carl750]

Problem solved. I pushed like hell on the waterpump end and got it on another 1/4" ... and amazingly it was just enough that the kink popped out.

 

[carl750]

I pushed like hell on the water pump end and got it on another 1/4" ..... amazingly that was enough that the kink popped out!