starter motor solenoid issue alfa romeo

Hey all, I recently bought an Alfa Romeo 164Q as a project car and been fixing all it's electrical faults as I go...

Anyway my issue at the moment is that the car doesn't always crank after a long drive - no click from the solenoid, just dash lights and when I turn the key they dim a little but no action... Battery is an optima D34 gel type in the boot as per standard. These cars seem have a relay for EVERYTHING!

Now I had a go at fixing it myself by bypassing the car's weird electrical system by running a straight run of 12volt + directly from the battery to a relay in the engine bay and using the original starter motor's trigger wire to make the relay turn on and hopefully allow the relay to switch the power going to the solenoid from my direct 12v power wire.

I just need confirmation that I have wired it up the right way and that I'm getting the direct battery power to the solenoid when I crank over the engine please. It took me half a day to wire it up under the car cutting and soldering the trigger wire!

The largest relay I could find was a NARVA 30/40 amp with resistor, hopefully that's enough - the one for the starter in the car is a 50amp... At the moment the car starts fine but I just hope I have wired it all up right!

You should have a fuse between the battery and the Relay.

Fuse according to the size of wire you have run.

The best way to sort electrical problems on these was to hit the control box under the passenger sear with a hammer.
Gorgeous engine bay esp.the V6 but the rest; what a nasty piece of junk.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Thanks awdeclipse :)
howie, so clever... We all have brand preferences, I don't care about yours...

Post-PS: Place the relay between the heavy starter +12V terminal and the solenoid. That should overcome the relay under-rating issue mentioned below. (Don't drag the relay's +12V supply wire from the battery!)
I now return you to my pre-PS:
...........................................................


Yeah - Howard is another that prefers quality systems. We both tend to muse over alternatives.


Be warned that although starter-motor solenoids usually take 20A to 30A, that current doubles if the main/heavy battery to starter-motor cable is disconnected/faulty.   
Hence the fuse suggested above is well worthwhile - especially if the relay is under the original rating.

FYI - I recall replacing an Alfa fuse-link. They used a similar idea to the old Jap wire flinks, but the Alfa stretched theirs all the way from the battery +12V thru the IGN switch to the ignition coil's +ve. I had to replace a few adjacent cables too. Hopefully their practices have changed.)


PS - Optima - a Gel Cel?!!

Unfortunately Peter it isn't preferences, it's practical experience.
Those vehicles are a POS.
164SQ I'm not being clever I talk from cynical experience and 30 years ago I was regularly working on Alfas and Lancias for a Central London dealership.
I could write a book on the problems with them before delivery.
Reliability = Japanese, UK assembled Japanese, BMW.
French, Italian, current VW/Audi = nightmare.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

My preference is to not work on them, nor have anything to do with them. That is also from practical experience.

I don't like 3 meter long fusible links. Even though my and other Jap cars didn't have IgCoil fusing back then, I can't recall any fusing.
However it seems to be "not uncommon" in alfas etc.

I agree that Italian electrics were shocking - I put Jap electrics on my Ducati (and Jap carburetors for that matter - better than the original Amals and the later Delorto pumpers).

Alas my problems were pre-control boxes. Kicking the ceramic-relay box was my equivalent....

Thanks Guys :)