1986 Toyota pickup Alternator Riddle

Hi, All,

I have a 1986 Toyota 4x4 pickup with a 22R engine. In the last three years I have replaced my alternator 5 times. They usually last 6-9 months then die. The first couple of occasions I thought I received defective alternators. After the second time I started to look else where for the source of the problem. The fourth time I replaced the alternator, I also replace a my power-steering pump which was leaking fluid onto the alternators, yet the fourth alternator died two weeks later. I hope replacing the power-steering pump fixed the problem, and I just received a defective alternator. However, because this has been such a persistent problem I am reluctant to believe that is the case. If anyone has any insight into my persistent and irritating problem, I would really appreciate the advice.

What is the mode of failure? If it’s bearing failure, than you either have a pulley alignent problem or you’re overtensioning the fan belt.

If it’s failure to keep the battery charged, you have an electrical problem. Post with more details.

If it’s just that it seems to die and leave the engine unable to start occasionally, you may have a blown fusible link or some other intermittant electrical problem.

If it’s in any way electrical, have any of the removed alternators been bench tested? That might be a good idea the next time you remove one.

The alternators fail to keep the battery charged, and yes, I always have them tested at the auto-parts store. The results are always the same. The alternators no longer put out any power. Yes, before the alternators fail completely, I often have trouble starting the truck. I will turn the key and get a click and nothing else, yet after a couple turns, sometimes it will start. But once the alternator fails completely, the truck’s battery drains and it will no longer start.

Sorry about my grammar and spelling above. I’m anxious to figure this out and didn’t proof read my post.

no apology necessary.

The alternator on that engine mounts on the same side as the exhaust manifold, just forward of the manifold itself. Could you have an exhaust leak or a missing heat shield, frying the alternators? Any carbon deposition on the indicating a leak?

The new alternator that I just put in yesterday failed today. I am completely baffled.

Thank you for the lead. That definitely sounds plausible. Could an exhaust leak fry an alternator in one day? The new one I just put in yesterday failed today. The fifth one in 3 years.

In 86, Toyota was using two models of alternators, sometimes on the same line of vehicles. One had a built in electronic voltage regulator and the other used the old mechanical external voltage regulator. I’d check to make sure you are getting the right model alternator, but I don’t think you can install the wrong one unless someone did some creative wring at some time.

However, if you have the type with the external regulator, you should replace it as well.

It definitely could.

However Keith posted a good suggestion below that’s also a good possibility. I was unaware that they’d used a seperate regulator on some of these.

It sounds like there’s something else going on here, but in general the alternator placement on the 22R Toyota trucks was a rare lapse in design judgement. They’re practically touching the exhaust manifold and they’re mounted low enough that they pick up all sorts of dust and grime if you take the truck off-road. Short alternator life is not at all unheard of on these rigs.