Alfa Romeo Winter Tips

4-Cylinder cars:

For later-model 4 cylinder Alfa’s commencing around 1969, a coolant bypass hose is installed between the thermostat and water pump. Proper operation of the bypass requires two essential elements: A thermostat with a bypass cutoff “hat” and a spring-loaded pressure valve in the bypass hose itself.

Note in the picture (now lost, will post if I can find it) the correct thermostat is on the right, and a pretender is on the left. When cold, the hat is extended to cover an opening in the thermostat housing, forcing more coolant to flow through the bypass hose, and when warm, pulls up to allow water to flow through the thermostat to the radiator.

Advantages of the use of the correct thermostat are to allow quicker warmup of the coolant as it circulates in the motor on a shorter path until warm. Note, this also means quicker use of the heater is allowed, as the heater is part of the “bypass” circuit (only the radiator is excluded).

The spring loaded valve in the bypass hose helps maintain pressure in the system, allowing coolant to remain around liners and in the head with less chance of cavitation.

Note, in California, Arizona, and other warm climes, it has been reported to me that the bypass hose spring valve is usually removed by a mechanic during the life of the car. Also, the same mechanic usually installs a “normal” non-hat” Stant type thermostat (installing a 160 degree rating, in place of the stock 180 degree).

This was usually done to provide a cooler running car, however it may have contributed to a worse running car, as the proper 180 degree thermostat temperature is required for proper running of “stock” SPICA cars and later K jet, L jet, or Mo-tronic injected cars. SPICA T/A extension, and XXX-tronic coolant temp sensor/resistors are dependent upon coolant temperature, and these systems will run rich when they “sense” cooler coolant temps.

So, if you suspect the required parts are missing, inspect the thermostat as part of your coolant replacement procedures. Also grab the bypass hose, and you should feel a hard metal object at the top of the hose near the thermostat housing. If you must install a new bypass hose spring valve, install it so the small opening is on TOP (so the valve spring compresses in the direction of coolant flow). Bypass spring valves and bypass hoses are readily available.

6-Cylinder Cars:

On my 164, I noticed in the sub-freezing spell last year that the rubber hoses at the fuel rail seeped a bit of fuel on startup after sitting overnight. It’s a ’91, so given the rubber is quite temperature abused in the 8 years on the fuel rail, inspection and replacement was warranted. I found some Gates “high pressure” fuel/oil/water line at A-1 coupling shop. It’s good up to 300 psi, more than adequate for fuel rail purposes. As with replacing the fuel filter on the 164, you may want to start the car, then remove the fuel pump relay (next to the radiator – see your manual) and let the car run out of fuel in about 30 seconds. Remove and replace the rubber fuel lines, using the old ones to cut the correct length on the new ones. I used 5/16” ID size.

Radiators – the Milano and 164 use a radiator with plastic side pods. An issue of Alfa Owner last year described an at-home remedy for side pod removal and replacement should the rubber seal between the radiator body and side pod leak. During that week-long super freeze we had last year, my side pods did leak a few tablespoons of coolant on start up every morning (due to cold rubber seals, and increase in coolant pressure), however once the coolant and seals were warm, the seepage stopped.

I didn’t replace the seals at the time, since the arctic weather ceased, however some sleuthing turned up three close-by radiator shops that have special machines to un-crimp and re-press the side pods to replace/repair the rubber in a very easy procedure (and inexpensive). Although new rubber is not available for our side pod seals, they indicated ones could be fashioned out of rubber stock, or RTV used along with the old seal (as described in the Alfa Owner article) to effect the proper repair – and they warranty the work to boot!