Engine Died then came back to life

[76C10Stepside]

Found a Haynes S10 manual I forgot I had and ran the following Alternator and Ignition Coil tests today. Opinions, comments and suggestions welcome!

Note: When I started the engine (last driven last night), it had good cranking power, took several revolutions to fire (typical on this truck when cold), but also felt like there was some resistance to turning over (kinda "thunky"), but otherwise no unusual noises (not even the alternator noise I've been hearing often).


Alternator Tests:
1. Voltage across battery terminals with engine OFF. Should be 12.5 to 12.8 V.
RESULT: 12.65 (OK)

2. Engine running at high idle (1250 rpm, COLD). Should be 13.8 to 15.3 V.
RESULT: 14.91 V (OK). Note: Heat was ON for this test, but voltage in range.

3. Engine running at high idle (1250), heat, lights and radio ON.
RESULT: 14.84 V (OK).

Note: Did not try revving the engine, as it was COLD and already idling at 1250 rpm, and wanted to be sure I got all the tests run. GOOD ENOUGH?


Test Old Ignition Coil (per the Haynes manual):
1. Book says resistance should be "very high or infinite" (on "high" scale). Does not say, but assume this is the primary coil test. Says to test on the
RESULT: "1" (Ohm meter did not respond, stayed at 1) on 2000k Ohm setting (high on my multimeter). Seems to be an open circuit when no power supplied to the coil. OK?

2. Books says resistance should be "very low or zero" (on "low" scale).
RESULT: 030 (on 200 ohm setting, calibrated at 0). Is that a PASS?

3. Book says should "read high, but not infinity" (on "high" scale).
RESULT: 008

Test NEW Ignition Coil (to compare to old one):
1. "1" (Ohm meter did not respond, stayed at 1), same as old coil.

2. 026

3. 001

Notes: I assume the first coil test is to verify that the primary coil circuit is "open" when no power applied to the coil? For this test, the leads were on the top/left terminal (with the two plugs at the bottom).
This is my first time testing an HEI ignition coil.
Since the coil test instructions are rather vague (no specific values given), and there was very little difference in readings between the old and new coils, I assume the old coil is still GOOD.

[76C10Stepside]

The power steering works perfectly, and no noises, so pretty sure the intermittent noise is coming from the alternator. I guess it could also be one of the idler pulleys. It SOUNDS like it's coming from the alt.

Accurately pinpointing the source of engine noises from belt-driven components can be challenging. I had a mystery squeal on my other truck that sounded like it was coming from the water pump (using a vacuum cleaner extension like a stethescope), but after installing a new water pump (and finding the old one to be in perfect working order), the noise got worse. Had already had the alternator tested, and the bearings seemed fine too, but replaced it anyway, and the noise disappeared.

Since I can't seem to prove that the alternator is about to fail, or be sure it has anything to do with the intermittent engine "disturbing behavior" (not really sure how to explain this), I guess I'll take a chance on it and keep driving it as-is for awhile and see what shakes out.

[Mr_Rich]

I think the idler pulley could be the likely culprit. It's kind of funny since if you remove the belt and spin the pulley it will spin real nice, but the bearings have probably run dry and now transmit more noise into the bracket and engine block. Of course the alt. could do that too, but it would be a different kind of noise. The noise I'm talking about is kind of like spinning a roller skate wheel. That's about the best I could describe from memory.

[76C10Stepside]

Originally Posted by Mr_Rich

I think the idler pulley could be the likely culprit. It's kind of funny since if you remove the belt and spin the pulley it will spin real nice, but the bearings have probably run dry and now transmit more noise into the bracket and engine block. Of course the alt. could do that too, but it would be a different kind of noise. The noise I'm talking about is kind of like spinning a roller skate wheel. That's about the best I could describe from memory.

I know, right? If bearing is worn, it should spin longer due to less friction (and no grease left), but it acts like a good sealed bearing.

Picked up the new alternator after confirming that I can return it unused up to 30 days after purchase, and can get my core charge for the old alt as long as I have the receipt. If the alternator fails in the next 30 days I'll be ready!

I mentioned to the guy at the auto parts store that there's a vibrating noise when engine is in gear and sitting and when accelerating up to about 20 mph (started about 1 month ago), and wondering if a bearing on the torque converter might be on its way out (runs smooooth at speed, no issues with gear changes up/down). He suggested running the engine briefly while cold with the serpentine belt removed. If noise is from any of the parts driven by the belt, should run quiet. Might try that.

None of the parts driven by the belt are wobbling or anything. Have been wondering about the idler pulleys after reading a few posts here and there from folks who have had one go bad (have never had a bad one myself).

Parts store guy said the back bearing typically goes out first on the CS-130 alternators. The noise the alternator is making on and off is not the squealing I'm used to hearing with a bad/dry bearing.

Do you still have that PDF with instructions for rebuilding the CS-130? Thinking about maybe just replacing the back bearing if I can figure out how to remove it without taking the whole thing apart.

[Mr_Rich]

The file I have is an rtf file and this website won't allow that file. It is CS130 Operating Principles.rtf. Maybe a search will turn it up. I don't remember where I got it since it is five years old since I downloaded it. It is very informative. I'll warn you again that a CS130 is not quite like other alts. and you may take a chance and get hosed. Investigate some YouTube videos; I've had very good luck with those.

[76C10Stepside]

Originally Posted by Mr_Rich

The file I have is an rtf file and this website won't allow that file. It is CS130 Operating Principles.rtf. Maybe a search will turn it up. I don't remember where I got it since it is five years old since I downloaded it. It is very informative. I'll warn you again that a CS130 is not quite like other alts. and you may take a chance and get hosed. Investigate some YouTube videos; I've had very good luck with those.

I found many links to Delco Remy CS-130 service manuals online, but most were terrible and all but one required a subscription to download. All of them appear to be based on the same original, which contains many flaws. I created my own version based on the best of those found. I would attach it, but this forum limits attachments of "doc" file type to 100k max size (it's 12 times that size).

I inspected the back bearing and there is no retainer. Looks like it's pressed in. There is NO sign any grease has ever leaked from the outer seal on this bearing.

[sntrym95]

I just had a CS130 back bearing go bad it was a knocking sound. Since it was still under warranty from the local electric shop (it's a 220amp alt), I took it in and I watched them replace it.

You need to take the alternator apart as the bearing presses in from the inside so the whole coil assembly has to come out. Took the guy 5 minutes maybe to replace it. I diagnosed the noise with a screwdriver - flat end on the alternator and the plastic end to my ear. Tried a few different parts like the A/C compressor and idler pulley then the alternator to find it.

[76C10Stepside]

Originally Posted by sntrym95

I just had a CS130 back bearing go bad it was a knocking sound. Since it was still under warranty from the local electric shop (it's a 220amp alt), I took it in and I watched them replace it.

You need to take the alternator apart as the bearing presses in from the inside so the whole coil assembly has to come out. Took the guy 5 minutes maybe to replace it. I diagnosed the noise with a screwdriver - flat end on the alternator and the plastic end to my ear. Tried a few different parts like the A/C compressor and idler pulley then the alternator to find it.

Thanks, Mike! I'll try the screwdriver test. Did the coil assembly have any wires that had to be desoldered or cut to remove it? The service manual I found mentions that, but does not say if it's necessary just to replace the bearings.

I took a wiper motor apart the other day, and one of the field coil wires was broken, but I could not get to the field to resolder it (field coil permanently mounted inside). Ended up installing another motor.

[Mr_Rich]

Originally Posted by 76C10Stepside

Thanks, Mike! I'll try the screwdriver test. Did the coil assembly have any wires that had to be desoldered or cut to remove it? The service manual I found mentions that, but does not say if it's necessary just to replace the bearings.

I took a wiper motor apart the other day, and one of the field coil wires was broken, but I could not get to the field to resolder it (field coil permanently mounted inside). Ended up installing another motor.

The CS130 alts. can last a long time. That screwdriver trick (large screwdriver) was one my Dad taught me when I was young. The field coil wires are crimped to the diode trio, IIRC. I still have a disassembled CS130 in a box. I should take some pics for you. That 140 amp upgrade kit I mentioned earlier was called Quick Start, part no#D1-7140. I bought it at Summit Racing mail order at least fifteen or more years ago. A lot of these parts are obsolete and are going to be hard to find because there is more available for the newer 2K-up trucks.

[sntrym95]

Originally Posted by 76C10Stepside

Thanks, Mike! I'll try the screwdriver test. Did the coil assembly have any wires that had to be desoldered or cut to remove it? The service manual I found mentions that, but does not say if it's necessary just to replace the bearings.

I took a wiper motor apart the other day, and one of the field coil wires was broken, but I could not get to the field to resolder it (field coil permanently mounted inside). Ended up installing another motor.

Offhand I'm not sure if there were any wires he had to remove to get the assembly out, although I assume there's a couple, one for the charging post the other for the activation wire. Mind you this is a custom aftermarket 220a version, not the GM original so it might have plugs/connectors instead of something being soldered.

[76C10Stepside]

Thanks, Mike.