Hi!

So my girlfriend has a 1989 Volvo 240 DL and it died while driving last night. Tested battery and it is good, and was told at Meineke the alternator is not charging.

When I tried to jump it this morning, I VERY STUPIDLY and accidentally misconnected the cables, resulting in a thin black wire burning and disconnecting from the engine. I was told this is the oil pressure switch connector.

I was told to replace the wire, get a new oil connector switch, new alternator and labor would be $380. ($47 for the oil stuff alone)

Now I am seeing alternators online for around $150.

Is it worth it to get one and do this myself? Is it very difficult? I'd like to do the alternator AND oil switch repairs if possible, we would save a couple hundred in labor.

Thanks so much!!

 

the alternator probably just needs a new regulator/brush assembly, these are like $25 and are installed with a screw driver in about 3 minutes.

having reversed polarity, its quite possible there's a LOT more wrong than just the oil pressure switch wiring. ECU, ICU, instrument panel, various relay modules that have electronics in them such as the interval wiper relay, etc etc, any of these could have gotten zapped by the reverse polarity.

 

How would I determine if that is the case with the alternator or if it really needs a new one?

I got in the car and tried testing all the electronics and everything seemed to work fine. Is there a way to figure out if anything else is messed up? I drove it about 3 miles after this and had no issues and dropped it off at the shop.

 

well, if the engine is running, the ICU/ECU are OK.

make sure all the idiot lights along the bottom of the instrument panel come on with the key, then go out when the engine is started. The alternator light is critical, its part of the D+ circuit that 'bootstraps' the alternator.

 

Okay got it, thanks. The car is still 3 miles away at the shop. I am not sure I want to give this guy the green light, so I may go pick it up and drive it back home...I guess this is a big risk considering the car could die at any moment...ugh

 

a fully charged battery in decent shape should run the car for an hour+ with the headlights off.

btw, I'm just noticing you said Meineke up there. ARRRRGH, avoid those chain shops like the bubonic plague.

 

Okay great, we are going to pick it up soon then and I will check the service lights on the dash to make sure the electrical is still okay.

We are still doing some internet searching. Found some used alternators for 70-100 bucks on ebay. You mentioned the regulator/brush assembly...is there a way to determine if this is the case, or if the entire thing needs to be replaced?

I really apologize for just throwing questions out. I am trying to do research on my own as well. My gf and I are very tight on money and have about a thousand other things going wrong at the same time so we are trying to handle this in the best way. and not get screwed by some shop. I figure we handle the alternator issue first and then the oil thing after since that is a less pressing issue.

I truly appreciately your help and insight pierce, thank you.

 

as the regulator/brush is like $25, the only way I know to verify that is the problem is to replace it then check the charging voltage with a volt meter. said charging voltage should be about 1.2-1.5V higher than the battery voltage, like 13.8-14.1V when the battery is 12.6V at rest. actually, 13.8-14.1V is about the max, as 12.6 is a fully charged battery.

note, btw, car batteries read a higher voltage when first taken off a charger... this is called 'surface charge'. if you wait an hour after charging, you'll get the batteries true rest voltage, 12.6V or whatever. also, the voltages are temperature dependent, if its very cold, the voltage is lower.

 

Okay got it.

I checked the "idiot lights" haha. The ones that come on when the key is turned one click (not started) are the alternator, oil, brake failure, parking break, bulb failure. When I turn the car on, they ALL go off, including the alternator.

Doesn't this mean the alternator is charging correctly? Hmm.......

**edit** okay so I'm told that fuse blew out a long time ago before she got the car and she never replaced it. But even then, considering the alternator light (and others) comes on when I turn the key (before starting engine), I feel like it would still work properly. maybe not...I don't know. hard to tell if the meineke guy would lie about replacing an alternator that didn't need replacing.

By the way I picked the car up from meineke and told him I was going to work on it myself, and he said he fixed the oil connection and to not worry about the $47. Impressed me considering it's a chain you know?

 

The best way to verify it is charging is to put a voltmeter on the battery and measure the voltage. First measure it when the engine is off. It should be above 12V. Check again when the engine is idling. It should read above 13V. Turn on some of the electrical accessories (headlights, blower motor, etc) and the voltage should stay above 13V.

 

a place like autozone will test your charging system for free if you don't have a voltmeter.

 

I'd rather lose my wallet at a bus station than stop at one of those chain places: they make their living by overselling and robbing people who don't know any better, adn are easily scared (kinda like the democrat party).
Each mechanic is required to "sell" $X per time period; that is, sell the customer something in addition to what they brought the car in for. And they don't care how they do it.

 

I agree. Last time I when my battery went dead in my Honda they checked and said I need both a battery and alternator. I said no to the alternator and replaced the battery. I went home and checked the charging myself and found the alternator to be just fine.

Voltmeters are cheap and it is so easy to check yourself.

 

Thanks guys. Had the battery tested (second time) and alternator also tested. Both were good in the car. Removed the alternator and took it to Oreillys and they tested it on their machine inside. It passed everything twice and they said it was good and I could just put it back in and use it. Voltage was about 14.5 on their machine. Told me to clean all connections and the battery/clamps as well.

I am about to put it back in. The radiator hose made it very difficult to get the alternator out and we didn't want to drain it.... probably should have. there was no clear path for it to come out we had to squeeze it though barely.

 

Question!!!

I was putting the old alternator back in and ran into something. This alternator has a capacitor which connects to the alternator (pos output) and has a metal square with a hole in the end on the other end. To what I understand this needs to be grounded back to the alternator to be wired in series. I also know the ground wire needs to be grounded on the alternator and also part of the car with no charge or significant conducting ability...in this case, something near/on the engine.from what I can tell.

Can I use a bolt to fasten both the ground wire AND capacitor piece for grounding on the alternator? Will they still both work effectively like they were grounded seperately? I understand they should ideally have their own grounding terminal on the alternator (as seen in image below), but it seems like when this was done last they used one terminal and bolt for both wires.

ORRR should I just get another bolt and use the hole next to where the capacitor is anchored?

This looks very close to my alternator, but without the protruding bolt used as a grounder. Essentially I want to add the ground wire to where the capacitor is bolted in, and have them share the same grounding terminal. (would the order make a difference?)



EDIT Here is my alternator. The blue is the grounding wire. I know how to connect the B+ and D+. This is without the capacitor.

 

hmmmmm.... ahah!

you could get a longer screw, and stack it like... screwhead - capacitor - brass washer(s) - ground wire - body of alternator.

 

So this order would be safe/okay? We just don't want to connect something wrong and cause a problem when we start the car.

I think we may just get another screw and attach them separately to be safe...

 

Final update!


So I put the alternator back in, grounding both the capacitor and ground wire to the same spot on the alternator casing. There was no where else to do it separately due to a stripped screw hole.

Cleaned the battery terminals and anything else that looked rusted or old.

Started fine, ran fine, drove it and got it tested. Alternator and battery perfectly okay.

I guess that's that? If it happens again I guess I'll replace the voltage regulator and brush.

Thanks for all the help everyone. Now I know how to replace an alternator on an 89 volvo 240