What would cause an alternator to fail? - Updated

[scot850]

Actually that is only part of the story. This is a general question, but is specifically for my young friend who recently bought a somewhat neglected 06 P! V70 T5 AWD. Car has about 160, miles, but had a replacement engine fitted by the previous owner (not sure if they actually did it) by an 08 C30 T5 motor with about 25,000 miles less on it.

The car has had some 'interesting' repairs done or, not done in it's recent past. The current owner has had the car for only about a month and in that time the original Reman Bosch alternator that was in the car when bought failed. He needed the car, and cost wise as a student bought an Amazon 'special' alternator. That has lasted about 2 weeks and died.

The plan is to return the Amazon special for refund and take the Bosch one to a local rebuilder who has a high rating, for a diagnostic and cause of failure, followed by a rebuild of that alternator. Hopefully that will shed light on possible failure cause is natural wear and tear death or forced failure. Once I know what caused the failure (hopefully just a worn voltage regulator), I'm thinking the 3.4 star rated Amazon special with only 9 reviews is just typical of the crap sold today that either works or not. Of the reviews 2 had bad out the box units and 2 had units fail not long after install. We can't remove the current alternator as ideally if we could get that tested we could ID if the failure is the same and therefore outside influence or just a piece of crap.

As many know my love of electrics is 0/10. I know enough to be dangerous, but in 50 years of driving I have only had a dynamo or alternator fail due to wear of the brushes. Replacement got them running again.

So the question for those with better knowledge, is what else should we check that could cause an alternator to fail?

1) Ground leads
2) Battery fault - not had any battery issues or starting issues.
3) Starter - Failing and drawing too large a current or causing strain on the alternator
4) Battery lead issues - high resistance, damage.

Anything else we should check?

UPDATE: Talking to the owner, he mentioned that the alternators, both the original and the Amazon one, both got really hot even after a short run of say 10 mins to the point you couldn't touch them. He is wondering if they should get that hot or if they have cooked themselves. If this is the case then why?

Further update: The battery was replaced 4 weeks ago and 2 weeks later the first alternator failed, then 2 weeks later the replacement failed. Should there be anything there with the new battery? I have suggested he get it checked out as well as the charging system.

Appreciate any guidance!

Neil.

[yanga001]

Alternator electrics are usually a diode bridge with a regulator if i recall correctly. If you can post some pictures of the part then we can make a better determination of what failed. Excessive current draws can cause regulators to overheat and fail.

If the battery is fine then I would check the alternator mounting points. Maybe a really poor ground connection on the block is causing excessive heat generation and is "cooking" the alternator.

The alternators have a fan built into the rotating assembly so they should not get hotter than to be expected in the engine compartment.

I recently rebuilt my last alternator with some SKF bearings, replacement ring assembly, and replacement voltage regulator. If the bearings are fine then a voltage regulator change is trivial on the P80's. The P2's use a slightly different assembly if i recall.

[scot850]

The owner texted me to say he had found a used alternator in the junkyard where I sent him. I've told him to get the battery checked before running the car. If it is ok, then he plans to send the Amazon unit back to them for refund and tack the original Bosch reman unit to a local alternator and starter shop for checking over and ideally ID the issue or what failed in the alternator. Then have that unit rebuilt. Depending on what he finds out we can then start looking further. I have also suggested looking at engine grounds to see if any are missing or damaged as well as checking the battery cables for damage.

Thanks,

Neil.

[MoVolvos]

.
Check battery voltage without ground cable and check voltage while running. Should be 12.4 to 12.8 volts respectively. While running and charging should be min of 14.5 volts. Friend just got a Costco battery and though the initial voltage was close to 12 volts after driving a bit it was up to 12.8 volts. Charging voltage in car was 14.8 volts much like my Volvo.

All of our big box auto parts stores provide free in car testing. If yours also drive it after you get things buttoned up and have it check.
.

[scot850]

Well the junkyard alternator got the car back up and running. How long it will last is a good question. I have sent a link to the owner for the V50 wiring diagram which has a useful ground wire ID drawing and approximate area on the car where they are.

Hopefully he can work with them or I can help if needed.

Neil.

[abscate]

When I make a store run later today, Ill make a temp measurement on the 1999

[scot850]

When the Amazon unit was removed the plastic cover for the connector nut for the wire was melted to the nut............!

Neil.

[abscate]

When I make a store run later today, Ill make a temp measurement on the 1999

15 minutes with the high beams on for load,,,170F

[scot850]

Thanks for that Abscate. Appreciated.

Talking with the owner, he has found out where the engine was swapped. It was done by a local European car 'specialist'. Having contacted the last owner he said they were not used to working on Volvos (no surprise there), and that the wiring was difficult and complicated??

I know newer Volvos with the Canbus are a bit challenging for the like of me, but how hard can it be? Biggest issue is finding decent wiring diagrams for cars that actually give a clue what is connected to what and some sort of wiring color code.

The engine fitted was from an 08 C30 FWD, and the car in question is an 06 V50 T5 Turbo. The C30 motor is an update version of the original 06. B5254T3 to B5254T7. I have not been able to find out what the changes were yet between the engine to know if there were any significant changes requiring wiring changes. I am thinking this may be where the issues lie. Good grief, this is not going to be fun. I think we will make a visit to the shop as like any nightmare, you probably never forget it!

We need to get this sorted before we can move on with the rest of the more minor issues (lots of them!)

Neil.

[scot850]

Well if looks like I opened a can of worms for myself. Found a thread on Swedespeed which is full of some typical no knowledge speculation, but there is some curious stuff like Volvo changing the alternator supplier from Denso to Bosch and requiring a wiring change kit which I can not find anything about. The parts website talks about a 3 pole and 2 pole connector, but the car in question only uses one of the 3 wires in the connector and it is the middle one called A:1??

https://www.swedespeed.com/threads/s40- ... tby=oldest

Anyway, to answer Abscates question on temperature, so far after a 30 minute run it measured at 176F. That was in daytime. Last night the owner took a run out of town for about a 45 minute run and it measured at 172F.

The engine bay and position of the alternator makes it sit in a poor airflow area above the AC compressor and just around the corner from the turbo which is on the back of the motor at the same end. The huge air intake also reduces air flow. I'm now thinking that putting the IPD skid shield back on, especially in summer may not be a good idea.

Neil.