How long have you run it after replacing? It is generally hard to get all the air to purge out of the system quickly. I always turn the wheel stop to stop and shut off the engine with the P/S reservoir cap off. I do this over and over until no more froth shows up. The froth is aerated fluid from the pump - as it works air out, it is mixed with fluid. There is a lot of waiting upon purging. OR, you can modify another "spare" power steering cap and pull a vacuum with a mighty vac to pull a low vacuum on the system while you initially run it. You may get some pump whine while pulling a vacuum, but after it is purged and the vacuum is let off, it returns to normal...FWIW.

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Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi