Delica Canada | Mitsubishi Van Club

Hello Delica peeps,

Wondering if anyone has experienced issues with oil leaking into the alternator. I've got a 1993 L300 that I purchased a little while back. Previous owner said it needed new batteries, but it ended up being a bigger alternator issue. We pulled the alternator, had it rebuilt and put back in, only to have it fill with oil and fail again. Long story short, the shops I was dealing with didn't have experience with Delicas and nobody was catching that there was a blown seal in the alternator. So we took it out, had it rebuilt again, and again they missed the seal so the alternator, once replaced, immediately failed again. Ended up sending it to a different rebuild shop that caught the seal and replaced it. Alternator was finally charging again, but still had oil getting into it. So they pulled it again, added another seal, and told me everything seemed to be holding and charging well.

It's been 3 weeks, and I'm noticing some issues again. Little things like lights dimming and flickering, wouldn't start one day, so needed a boost. Makes me think things aren't right again.

I'm wondering if anyone has ever dealt with this issue. Could it potentially be the oil pump and not the alternator? I'm just already a little over my budget with this all. Ended up being $2000+ for the alternator issues. I'm tempted to order a new alternator but want to be sure it will actually resolve this issue. Wondering what I can do next? Any suggestions?

The alternator has a shaft sticking out the back, which drives a vacuum pump (to make vacuum to drive the brake booster and a few other things). The vacuum pump has oil in it to help it seal and make good vacuum. The oil is fed into the pump through a 10mm diameter flexible hose, and drains back out of the pump through a 30mm diameter rubber tube directly into the oil pan.

The alternator's shaft is sealed against the oil by an oil seal inside the alternator. It's just a regular oil seal. To work properly the alternator shaft must be clean and smooth where the seal sits, and the seal must be installed the right way round (lip towards the oil) and square in its bore.

There's a couple of possible reasons why a new seal might leak: It's been installed backwards, it was damaged when being installed (easy to do if you're not careful), the alternator shaft is too worn to seal, or the vacuum pump drain tube into the sump is blocked, causing an oil pressure buildup in the pump.

Perhaps have your alternator looked at by a mechanic or engineer rather than an auto electrician.

(I would just buy a whole new alternator. They're not too expensive. Keep your old one around though, you may need to swap some of the inlet and outlet fittings to suit the L300's engine layout).

2000$ for just the alternator! No warranty? I would be jumping up and down til I got my money back. I have gone through 3 alternators in 10 years but never back to back and it was always the oil leaking from the turbo which I just fixed along with the head gasket. I would definitely install a voltmeter that way you will know if it’s working.

Not sure where you brought your van to but they should give you back your money... I do all the repairs myself! give me a shout next time...!!!

I had a problem very similar to yours. It turned out to be a broken fuel return line that was leaking and migrating around to the alternator causing it to fail. Looked like oil, but it was fuel.


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cinjay wrote:I had a problem very similar to yours. It turned out to be a broken fuel return line that was leaking and migrating around to the alternator causing it to fail. Looked like oil, but it was fuel.

Petrol engine, I hope! If diesel is making it across the engine bay to the alternator something's gone very, very wrong.

Diesel. It did make it around somehow.


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