Q: '98 Hilux w/5L diesel - vacuum pump on alternator.

[Heretic]

So yesterday I was trying to get acquainted with what is what in the engine compartment.

It appears that the brake booster vacuum pump is attached to the alternator and one drives the other?

Does this mean that the engine requires a special alternator for this purpose?

Are these (the pump or the alternator) hard to come by? I see them online (Amazon wants $400+ for one!), but if I walk into a US parts store I probably won't be able to get one without a special order?

Also, is the 5L pump on the front of the alternator and therefor driven by the belt, and in turn drives the alternator? I think the 3L is the opposite?

Finally - which is more likely to go bad, the alternator or the pump?

TIA

 

[Eurasiaoverland]

Diesel engines do not generate significant vacuum in the intake system, so in order for the engine to generate vacuum, it needs a dedicated vacuum pump. This then provides vacuum to your brake booster.

The alternator is designed to take a vacuum pump, and therefore if you replace the alternator with a non vacuum pump type, you will have no vacuum system.

The vacuum pump is bathed in engine oil and should last the lifetime of the engine easily. In the event of wearing out, they can be easily rebuilt with new vanes. Similarly, the Nippon Denso alternators will go on for years with just a change of brushes (very easy) or possibly slip rings (specialised job). That is so long as you don't subject it to too much water/mud etc.

Whatever you do, don't replace these quality parts with cheap no name junk from Amazon, except as an emergency stop gap. A genuine alternator and vacuum pump would, I imagine, be well over $1000. As only diesel models use separate vacuum pumps, you are highly unlikely to find one at a US parts counter.

My 1993 2L has the vacuum pump on the back of the alternator. I would expect models launched after the early to mid 1990s to have the later type front mounted vacuum pump, it should be fairly obvious from looking at your alternator (just look for the oil supply / return lines).

 

[Heretic]

Ok thanks.

The pickup only has 130K km on it, so everything is fairly new - I think. It is new to me so I have to dig in and see what is what, but so far not a lot wrong, except the front shocks (I think).

I don't expect to do any deep water fording, at least not regularly, and I am not going mud bogging either.

I just like to know what critical items are likely to fail, that I should get now and have ready on hand to quickly bring the vehicle back online as parts in the USA for JDM imports are not plentiful and probably require special orders with a long lead time. If a supply chain backup happens again, and I need to order a part from overseas, then I could be stuck with an offline pickup.