W140 electric smog pump

[majooo]

Hello,
I’m chasing P0410 code (Secondary Air Injection) in W140 – 1997 S 500 (2nd gen). So far I’ve changed the plastic tubing to the switchover valve. I’ve checked the switch over valve itself. Now I got the smog pump (secondary air pump) on the bench (000 140 35 85- updated electric pump) The pump spins up and blows plenty of air. I’ve attached it to a pressure gauge it was 2 psi steady. I’ve noticed a small leak where the body of the pump separates. I’ve tightened the 6 screws on the perimeter and the pressure increased slightly to 3 psi. I can still hear a little air hissing in that area, but don’t want to over tighten / crack the plastic.
These pumps are quite pricey, so your help is very appreciated.


How much pressure should the pump produce?
Can anybody recommend a good sealant (silicone, glue) to stop the hissing?
Is there a company that rebuild these?

And one more question: My neighbor has a spare pump from a car he sold (I believe it was E420- but I’m not 100% sure)
What is the difference between 000 140 3585 (my pump) and 000 140 3785 (neighbor’s)? They appear to be identical. Is there a difference in the pressure / volume?
Thank to everybody!