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it's a 15 si-might not be original-usually see a 97A 17si on '85-86 injected with AC,15si comes in 70 and 85A versions,rating stamped on front face below the adjusting bolt.The 17si looks almost the same,but has little cooling notches where the front half meets the stator.
Thanks Y'all. It's bad. It was 100 Amp NAPA Premium unit and this is the 6th alternator that has taken a big dump on this car! Car has 32K actual miles on it. I drive it about 500 miles a year, and usually get 2 years out of an alternator. I am looking at buying a Power Master 150 Amp unit from Summit Racing. I couldn't remember which alternator it takes, and there is something weird about the NAPA books, because the unit the computer or book says fits it doesn't fit.
try a CS144 off of a ~1986.5-1995 cadi,buick,ETC-same size,mounting and basic appearance as a 15-17si but has more powerful PWM regulator(more output at low RPM),better brusholder,better stator lead connections usually 108A rating.CS144 was introduced ~3/86,so authentic on an '86.
The 12 is smaller than 15/17,would need different upper bracket and rear spacer.If car is close to stock,wont need 200 amps-"high amp"alternators often don't put out as well at low RPM and overload their regulators.The later model CS144 has slightly bulkier case than the earlier version-late version~1990-2000,140A.
Summit Racing's tech line says that a CS144 style case will fit my car with zero mods. In fact they believe that my car came originally with that style alternator on it. I purchased a PowerMaster 200 AMP unit in the original style finish. I want to have plenty of power onboard this car. We are currently running a subwoofer and aftermarket amp tagged into the Factory Performance Sound system. I want to add an aftermarket radiator and high flow fans in place of the stock dual fan setup. The car tends to overheat when pulling steep mountain grades and could use a better than stock cooling system. Thanks for all of the help.
they believe that my car came originally with that style alternator on it.
Uh... No. 86 was still the SI style alternator. 87 they went to the CS but not the 144. The CS144 wasn't used on any thirdgen from the factory. The CS144 was popular in some Cadillacs that use the same serpentine accessory drive as 88-92 thirdgens, so there's a conversion bracket that exists, and a few found their way into B4Cs, but they sure didn't come that way in 86.
It sorta goes without saying, but if your car is eating alternators, it's probably not the alternator's fault. The TPI alternator in 86 was rated over 100amps, it shouldn't have a lick of trouble supporting the stock equipment and a couple accessories like basic audio amps.
forgot about the TTA -that does have a cs144,but I have never seen a cs144 stock on an '86 or other 3G-though many other '86 GM, models got the 144 as soon as it was avalible:C4,GN,FWD cadi and buick,ETC-sometimes seems,by mid-'80s,3Gs were the last to get GMs upgraded parts or technology...I also wonder what went bad with OPs original alty.The Si alternators had a problem with crimped- on stator terminals getting a bad connection and burning up-soldering these fixes the problem
Twin electric fans pulling 40 AMP's. A/C pulling 25 AMP's. Head lights, running lights, and driving lights pulling 10 AMP's. Stereo, factory subwoofer amplifier, and aftermarket subwoofer pulling 15 AMP's. Wipers pulling 5 amps. We haven't counted the ignition and electric fuel pump. We live in the mountains and most of our roads are steep and winding, so most driving is a low speeds. 95 AMP's at slow speeds adds up to an overworked 100 AMP alternator. When a new alternator is installed the car struggles to maintain 12.5 volts. After a few diodes deteriorate the voltage runs 10 to 11.
do you know if the dual fans are original?-those were not "supposed" to be installed until 1987,but could be a mid-'86 change?My '82 got hot on me once pulling a long steep grade-was only about 70*but temp started creeping up,got to about 235 then could hear a roar from underhood as the clutch fan engaged and watched the temp gage drop right back down to 190.There are some new brushless motor electric fans out now that might provide enough airflow without pulling huge amps.Also a good oil cooler helps a lot too
The dual fans are NOT original to this car. My deceased wife Betty bought the car for my 50th birthday in 2006. The also deceased owner was a friend and we were familiar with the car. She bought the car new in 1986, so we are the second owners. The car had 25K actual miles on it. The first thing that I noticed is that the car ran 180 F with a 180 thermostat when going down the highway. When in stop and go traffic it would hover around 200F. When climbing a mountain grade the car would slowly increase temperature until it hit 240. If we pulled over and let it idle it would quickly cool back down to 200. I replaced the radiator with a heavy duty three flu unit. I bought a dual fan set up off of a later model thirdgen. I used a Painless fan controller to operate the fans since the car only has wiring and relays for a single fan. The original fan circuit trips a set of relays that turn on both fans, so one fan turns on at 190. The other fan comes on at 195F or if the A/C is on. If the aftermarket system fails the OE system will kick in at the OE settings which are around 230F. The car ran fine on the highway and in town, but still overheats pulling a grade. I added Royal Purple. We swapped the water pump for a high flow unit. All of the original parts such as the air dam is in place. The next thing I will try is a big aluminum radiator with a dual aftermarket fan set up, something like a BeCool.
And yet countless thirdgens are rolling around with the stock 105A alternator, with stock dual fans, aftermarket stereos, on and on without a problem. Just saying, without a much increased draw over typical conditions, the car shouldn't eat alternators. Use your best judgement, but if something else is causing the problem, you'll just be killing the upgraded alternator.
Thanks Drew. I have thought about what may be causing the demise of all of those alternators. We own eight vehicles, an RV with generator, boat, tractor, whole house generator, ect. I start all of the engines once a week and this car is no exception. I run the A/C units, and drive the collector cars up and down the mountain we live on. The collector cars never leave our property during the winter months to avoid damage from road salt. Maybe all of the time idling and moving slowly up and down our long driveway kills the alternators? They seem to die progressively over time until they can no longer keep up. I am also wondering if the stock cooling fans are pulling too much power, and am planning an upgrade to aftermarket fans with a higher CFM.
Sometimes the electrical connectors get a bit loose on the female side and cause issues like this. I went through 2 Alts before I snugged up the female sides of the plastic connector a tad with a pick. Been working fine since.
One problem we all face is poor quality replacement parts, espically the remanufactured parts offered by auto parts chain stores. NAPA used to be the go to place for quality parts, however there are so many chain stores selling cheap substandard crap, that even NAPA quality has suffered as they try to keep their market share.
07-05-2019, 06:00 PM
usually 108A rating.CS144 was introduced ~3/86,so authentic on an '86.
