fengel

I have a 1987 toyota dyna with a 2l diesel. I am having trouble getting my fanbelt adjustment tight enough. My alternator has the screw 'wormdrive' type adjuster for tightening the belt once the locking screw is undone. It tightens to a certain point, then I can keep tihtening the screw but the belt doesnt tighten further - almost as though the altenator is hitting an obstruction - although I cant see one. Can anyone offer help?
Also can anyone tell me what the attachment on the back of the alternator is which has a big tube going to the sump, and a thin tube to what seems like a vacuum line. Many thanks

myyota

Are you sure that your using the right belt ?, or maybe the belt is old and and streched ?.

blake.nemitz

The tube on the back is most likely your vacuum pump. It's part of the alternator like isuzus

fengel

yes thanks. The belt is not stretched but is eaten away a bit by rust and pitting on the pulleys. Any idea how to fix the pulley rust and prevent more? I wonder if there is something to spray on pulleys to stop further rust but also prevent slip. I have mucked around with sandpaper on the pulleys but hard to do a good job.
I think I have solved the adjustment problem. The adjuster was hitting the end of the travel in the lock bolt slot because the model of belt fitted was too long. Managed to free up the adjuster to allow to alternator to push closer to the engine when backed off, so I could fit a model of belt 10mm shorter. Hope this now allows better adjustment of the tension.
Do you know anything about the vacuum pump on the alternator. I presume it is to create enough vacuum to assist the brakes - is the manifold vacuum not enough on these engines? I wonder what maintenance the vacuum pump might need

fengel

Yes I assume the hose from it goes to the brake-assist unit. Is the manifold vacuum not enough to do the job on these engines? I am wondering what sort of maintenance the pump requires - and what happens if the alternator craps out and needs replacement - do I need to buy a special toyota one? or is it common to have mountings on the back of alternators to bolt on the vacuum pump? I was thinking of getting a more powerful alternator to charge camper storage batteries as well.
thanks

bbrideau

The 2L does not create vacuum. That's why you have a vacuum pump on the alternator.

blake.nemitz

isuzu makes a big alternator vacuum pump combo up to 170 amps i believe, and being a diesel the air intake is always wide open and rpm is changed by fuel only.