Oil pressure and vacuum problem sometimes

[33B]

So I have a '87 Passat with 1.6 td. Sometimes when I start the engine the oil pressure light comes on and also no vacuum(stiff brake pedal). As soon as I rev it oil light goes away and I get vacuum (soft pedal) and no problems after that. Doesn't matter if engine is cold or hot.
Does vacuum pump need oil pressure to function correctly, if not is the intermediate shaft not spinning or getting stuck?

 

[Vince Waldon]

The intermediate shaft drives the the vacuum pump shaft which drives the oil pump, so that's why your symptoms are related.

As to why this is happening... the most common cause is the tang on the bottom of the vacuum pump shaft OR the slot in the oil pump driven by the tang (or both) wear out. One bolt to pull the vacuum pump out and you can have a look at both parts.

 

[33B]

The intermediate shaft drives the the vacuum pump shaft which drives the oil pump, so that's why your symptoms are related.

As to why this is happening... the most common cause is the tang on the bottom of the vacuum pump shaft OR the slot in the oil pump driven by the tang (or both) wear out. One bolt to pull the vacuum pump out and you can have a look at both parts.

I just installed a brand new vacuum pump, because on the old one the white part with one way valve broke. Symptoms didn't change regarding to oil pressure light. What to look for when looking at the oil pump shaft? Havent seen anything alarming.

 

[Vince Waldon]

The oil pump drive has a slot that the tang on bottom of the vacuum pump slides into.

The slot can wear and cause the oil pump to skip.

 

[33B]

Forgot to update, the oil pump was worn. From the increased amount of play it didnt prime on idle, u needed to rev it up so it can prime. Changed the oil pump no problems.