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CumminsApart, Cummins Technician
Category: Heavy Equipment
Satisfied Customers: 89
Experience:  Factory trained Cummins Technician- Automotive, Agriculture, Marine and Power generation
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My alternator is leaking oil and I replaced the alternater

Customer Question

My alternator is leaking oil and I replaced the alternater last year and just recently replaced the hose going to the vacuum pump that is on the back of the pump but it is still leaking oil....What else could the issue be
Submitted: 7 years ago.
Category: Heavy Equipment
Expert:  CumminsApart replied 7 years ago.
Hi There,

The vacuum pump is lubricated by engine oil, you will find one hose to supply oil from the engine and one hose to return oil to the oil pan. First try the return line, see if it is clear and free from sludge and build up that would restrict oil flow back to the engine, this will cause the internal oil seal to leak. Also check that both hoses have not gone hard and brittle, if this has happened oil will be weeping out of the hose.

Another reason the internal seal would leak is if the engine had a high crankcase pressure, this pressure puts a strain on all seals and gaskets in the engine, and the weakest start leaking first. If an engine has high crankcase pressure it will most likely be using oil, be down a bit on power, use more fuel and may smoke when cold, even have hard starting in the cold.

If the internal oil seal is leaking, and there are no other reasons, it can be due to misalignment of the vacuum pump to the alternator part. In anycase, you will need to get it replaced as they won't stop leaking once they have started.

good luck

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