Crank Angle Sensor OEM Part Number

Started by Henry Goodman, June 14, 2019, 07:09:14 AM

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Henry Goodman

June 14, 2019, 07:09:14 AM
Can anyone help please, with the correct part number (OEM) for the crank angle sensor to suit a 1990 75 T/Spark? And where best to order one? Have tried the usual local and overseas Alfa guys and no luck.
Need it fix a recurring starting problem.
Thank you in advance.
Ric.

Henry Goodman

#2
June 15, 2019, 10:12:05 AM
That's a very kind of you. Thank you. I'm in Sydney so unfortunately cant take up the offer. I've decided to change both ignition switch and the CAS just to be sure. Its an intermittent electrical problem, starting from cold, re-starting from hot, and occasional failure to keep running. Its driving driving me nuts. With the Tour de Course coming up next weekend I don't want to be stranded out in the boonies of the southern highlands especially at this time of the year.

GTVeloce

#3
June 15, 2019, 09:48:30 PM
Random thought but check the condition of the green/black wire that connects to terminal 86 of the motronic relay (it's on the end of the four of the in the engine bay. See if it is hard or corroded and check the connector too. It is the primary switch for the engine management system and is fed directly from the ignition switch. If it has a poor connecter or high resistance in the wire you can get the symptoms you describe. It's also cheap and easy to test/replace.

If you look under the steering column, you have three wires exiting the ignition switch - red, black and brown. They go into a connector and from there the brown splits into two; brown and green black. The brown feeds your fuse box and the green/black goes to the motronic relay.

I once solved a most annoying problem by replacing that wire. After replacing most other things...

And as I said, the CAS usually either works or doesn't. Of course you could also have a problem in the wiring between the CAS and the ECU... Especially as that wire is shielded against interference and if the shielding is damaged you could get an erratic signal.

Henry Goodman

#4
June 19, 2019, 11:06:59 AM
The update is encouraging. I carefully checked over the infamous green/black wire and Motronic relay (thanks GTVeloce for the tip). Both looked fine.

I re-checked my two used CAS and noticed the inner metal sheath on both were frayed at the site where the cable is required to be bent back when the CAS is fitted in situ on the engine. In fact, I noticed one had a broken internal wire which could only seen under magnification.
Then a good friend Adrian popped round and gave a lend of his spare factory CAS which he knows works well and uses to test back to back on his fleet of 33s (same CAS as 75 T/S). We fitted it and the engine started first time and ran well. We then fitted a new aftermarket Bosch CAS (P/N 0261 210 036.). This is a modern plastic version, much cheaper then the OEM metal version, yet manufactured by Bosch to the same specs. Engine started/re-started and ran well. Took it for an Italian tune up drive last night and re-started hot. This morning it started first go from dead cold.

Is it fixed? Only time will tell. But I'll be carrying a spare ignition switch on Sunday, just in case.

GTVeloce

#5
June 19, 2019, 08:05:09 PM
This sounds very promising! Something very satisfying about finally getting it working well.

MD

#6
March 22, 2020, 08:49:11 AM
Transaxle Alfas Haul More Arse.

Current Fleet
Alfetta GTV6 3.0
Alfetta GTV Twin Spark supercharged racer
75 1.8L supercharged racer

Past Fleet
Alfa GT 3.2V6
Alfetta GTV 2.0
Giulia Super 2.0
Berlina 2.0
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