Replace alternator on 1987 Toyota

[KonCon]

Alright so another issue came up. Battery went dead and I was wondering what it was. I was able to jump the car to start it and with a little juice in it hook up a battery charger. When the battery was full, I checked and found that something was still drawing ~3.2 amps. I found out, that it's the alternator so I suspect that needs to be replaced. is that an easy job? I was thinking about renting a car lift bay in one of these diy garages as it will make it so much easier than in the street. Would that be someone with very little knowledge would be able to do? Also thought at the same time replacing the starter contacts as I've had issues with the car starting before and I suspect the contacts to be the reason. 

Thanks everyone

[AtlantaCamper]

Did you check the voltage on the alternator when the truck is running?  It should be in the range of 14 to 14.7 V DC.  If it's not then the alternator would be suspect.  How did you determine that the alternator is the source of the current draw?  If the alternator regulator is bad then perhaps I can see how it could pull current, but is it possible that the draw is from somewhere else?

 

This is how I replace the alternator (from memory so it may not be exact).  I prefer to take the radiator all the way out, but it can be done with it left in there.  You have to remove the fluid and hoses anyway and at that point it's just 4 bolts to get the whole radiator out.  I've caused damage to the fins on the radiator when I've tried to do it with it left in because there is so little space to work with if the radiator stays in there.  Procedure:  

• Disconnect the battery negative wire(s). 
• Remove Radiator.  remove upper air intake tube, drain the radiator, disconnect upper and lower hoses, disconnect and plug the transmission lines that go through the bottom of the radiator if yours has them, remove the 4 bolts from the radiator and pull it out with the plastic fan guard still attached.
• If you are going to keep the same belt then just loosen the alternator belt with the 12mm bolt on top of the alternator.  If you are going to replace the belt(s) then take them all off.  This is a good time to do any belt replacement. 
• Disconnect the main charging wire on the alternator.   You may have other wires to the alternator depending on what type it is. 
• Remove the 12mm bracket bolt and then the nut on the main alternator mount (14mm I believe).  Getting this bolt out can be tricky.  Don't mess up the threads as you do it.  You should be able to get the alternator out at this point.  
• Reverse the procedure to assemble.  You probably won't be able to get all of the radiator fluid in at first so run the engine and it should burp the system and give you the room to get the rest back in.
• Test the voltage when running to make sure it's above 14V and thus charging.

5 hours ago, KonCon said:

Also thought at the same time replacing the starter contacts as I've had issues with the car starting before and I suspect the contacts to be the reason.

I'd start by checking the wires carefully from the battery to the starter.  It could be a lack of current due to a failing connection for example.

[extech]

be sure to disconnect the negative battery connection before any type of work

[Maineah]

3 hours ago, AtlantaCamper said:

Did you check the voltage on the alternator when the truck is running?  It should be in the range of 14 to 14.7 V DC.  If it's not then the alternator would be suspect.  How did you determine that the alternator is the source of the current draw?  If the alternator regulator is bad then perhaps I can see how it could pull current, but is it possible that the draw is from somewhere else?

 

This is how I replace the alternator (from memory so it may not be exact).  I prefer to take the radiator all the way out, but it can be done with it left in there.  You have to remove the fluid and hoses anyway and at that point it's just 4 bolts to get the whole radiator out.  I've caused damage to the fins on the radiator when I've tried to do it with it left in because there is so little space to work with if the radiator stays in there.  Procedure:  

• Disconnect the battery negative wire(s). 
• Remove Radiator.  remove upper air intake tube, drain the radiator, disconnect upper and lower hoses, disconnect and plug the transmission lines that go through the bottom of the radiator if yours has them, remove the 4 bolts from the radiator and pull it out with the plastic fan guard still attached.
• If you are going to keep the same belt then just loosen the alternator belt with the 12mm bolt on top of the alternator.  If you are going to replace the belt(s) then take them all off.  This is a good time to do any belt replacement. 
• Disconnect the main charging wire on the alternator.   You may have other wires to the alternator depending on what type it is. 
• Remove the 12mm bracket bolt and then the nut on the main alternator mount (14mm I believe).  Getting this bolt out can be tricky.  Don't mess up the threads as you do it.  You should be able to get the alternator out at this point.  
• Reverse the procedure to assemble.  You probably won't be able to get all of the radiator fluid in at first so run the engine and it should burp the system and give you the room to get the rest back in.
• Test the voltage when running to make sure it's above 14V and thus charging.

I'd start by checking the wires carefully from the battery to the starter.  It could be a lack of current due to a failing connection for example.

 

8 hours ago, KonCon said:

Alright so another issue came up. Battery went dead and I was wondering what it was. I was able to jump the car to start it and with a little juice in it hook up a battery charger. When the battery was full, I checked and found that something was still drawing ~3.2 amps. I found out, that it's the alternator so I suspect that needs to be replaced. is that an easy job? I was thinking about renting a car lift bay in one of these diy garages as it will make it so much easier than in the street. Would that be someone with very little knowledge would be able to do? Also thought at the same time replacing the starter contacts as I've had issues with the car starting before and I suspect the contacts to be the reason. 

Thanks everyone

Starter contacts problems were very common on the older starters basically a click and nothing happening the contacts are replaceable. Try removing the main battery wire on the alternator then trying your current test again. Yes it is possible that a diode is bad but it's not common.

[KonCon]

I determined it's the alternator because I followed the cable that is drawing the current and it ends in the alternator. 

 

Regarding the contacts: yes @Maineah. This is exactly the issue I'm facing from time to time. 

[linda s]

I'm sure you can do the job and it's not all that complicated. The problem is getting it out. The power steering pump won't let you pull it out the top. Of course you can remove the whole radiator, big job, but I managed by just draining the coolant and removing the lower hose. I'm pretty sure I took the auto-trannie hose off too. plugged that one with a pen. Then with some twisting and turning the alternator will come out the bottom and new one goes in the same way. 

Just in case check your isolator. Remove wire that goes to the coach and see if it's showing any voltage at that terminal. If it is that might be your problem. Much easier and cheaper repair.

Linda S

[KonCon]

Where do I find the isolator? See attached pictures measuring the current on the wire going into the alternator. The wire previously goes through this little box. 

[linda s]

You're looking for something like this. Mines on the firewall but might be on a fender wall. 

Or this

[KonCon]

Found this.... 

None if the wires draw any current 

[linda s]

Yup just like mine. So I guess you have more work to do. So sorry.  Seems like your really getting dumped on

Linda

[KonCon]

OK so the alternator is done. 

Went on a camping trip to Mt. Rainer with a friend. Got there, no problem. Next morning, charge and break light on. Stopped and checked the voltage on the battery. I think it was something like 17 V or so so the battery was still being charged, but the alternator got really hot (a tiny bit of smoke coming from it). Drove to the top and did a hike. Decided to not stay another night and drive back home (about 3 hrs). The charge and break light did not come on until 1 hr before home. Luckily we made it home. Out of curiosity checked how much the alternator was drawing when the motor was off and it was between 8 and 9 amps. Alternator was really hot and battery was drained quite a bit. Anyways, will have to switch it out. Would this alternator be the correct model?
https://capitaloneshopping.com/p/db-electrical-and-0079-new-alter/DJHJ6WJWTH?extReq=true&run=9b5171c6-154c-4395-bb10-8a5af2c266ef&offerId=67b194f6-69b6-4e96-a2b4-bf88f9685364

[extech]

is the regulator separate from the alternator? if so it is bad. voltage should be regulated to less than 15v

[KonCon]

Sorry for the dumb question but what does the regulator look like 

[extech]

[extech]

looks like it's mounted on the alt.

[linda s]

No our regulators are internal. Doesn't mean it isn't bad, just means the whole alternator is bad because of it. I have boughten new alternators that were bad a few times. One of them a high end very expensive one. Disappointing how much stuff is junk nowadays.

Linda S

[KonCon]

Any recommendations which one to buy? 

[linda s]

Keep it simple, buy local. If anything happens no shipping to get your money back. NAPA has the best quality parts of any major chain

1987 Toyota Pickup Alternator | NAPA Auto Parts (napaonline.com)

The expensive one is a Denso so closest to OEM

Linda S

[KonCon]

Thank you Linda. Will pickup this one. Still debating if I should try to swap it out myself or have someone so it. I'm not experienced at all with this stuff. Do you think it's something I would be able to do? If not, what would you expect to cost to have someone do it? 

[linda s]

I'm probably old enough to be your grandmother and I did mine. Couple of wires, couple of bolts and a lot of twisting and turning to get it out the bottom. Adjust the belt when you get it all back together with a lug wrench for leverage so it's tight enough. Not too tight though. Belt should still give at least a half inch when you press on it. Piece of cake. 

Just checked past posts. The fan cowl does need to come out and all the hoses on that side.

Linda S

[KonCon]

Sold.... I'll try it!!!  🙃

[KonCon]

On 8/25/2023 at 10:38 AM, linda s said:

I'm sure you can do the job and it's not all that complicated. The problem is getting it out. The power steering pump won't let you pull it out the top. Of course you can remove the whole radiator, big job, but I managed by just draining the coolant and removing the lower hose. I'm pretty sure I took the auto-trannie hose off too. plugged that one with a pen. Then with some twisting and turning the alternator will come out the bottom and new one goes in the same way. 

Just in case check your isolator. Remove wire that goes to the coach and see if it's showing any voltage at that terminal. If it is that might be your problem. Much easier and cheaper repair.

Linda S

OK trying to get it out of the bottom but there's this other hose that's blocking it (see picture). Do I have to drain this one as well? 

[extech]

thats a trans cooler line. i would find something to plug the hose, and something to fit over the nipple after disconnecting .  even a baggie with a rubber band. fluid will drain, but not a flood

[linda s]

I did say all hoses on that side. I stuck a fat pen in mine and didn't loose enough trannie fluid to even measure

Linda S

[KonCon]

Thanks for the input on the hose. I feel like I'm an expert now when it comes to fiddle a alternator out on the bottom. First took out the old one, put in the new denso one only to realize the thing where the plug goes in was not aligned so not possible to plug. Returned it and exchanged it for a remanufacture one as this was the only one they had. Put that one in and when I wanted to tighten the upper screw, it would not tighten so it turns out the thread is not good. Will go back tomorrow and exchange again. What a mess. Anyways hopefully I can get it done tomorrow. Once the part is good, it shouldn't be longer than another hour. 

[IdahoDoug]

Yeah, reman parts quality took a dive 5 years ago and Covid worsened it. 

[KonCon]

I just ordered another new one and will return the reman one when I pick it up 

[extech]

if the plug isn't in the right place they should reclock it . really easy to do and is standard operating procedure

[KonCon]

Alternator 3 is in and running. Not pulling any amps when off. When on, I'm measuring 14.44 V at the battery. Is this good? 

Thanks everyone 

[extech]

that is what you are looking for

[KonCon]

Nice!!!!  Thank you so much everyone. Off to the next one ☺