andrewtran Senior Member Joined: 23 Feb 2014 Posts: 1 Location: Minneapolis Expertise: Just starting
Posted Sun Feb 23, 2014, 11:29am Subject: Low Pressure on Oscar
After reading a ton about espresso (including a lot of posts on this forum), I finally took the plunge and picked up a used Nuova Simonelli Oscar. I've been experimenting with different doses (7-9g for a single shot) and grind sizes (2-4 macro and all the micro-adjustments on a Baratza Vario), but my extraction times are still way too long. About 30 seconds until anything comes out and at least 1.5-2 minutes to get anything close to a 1oz shot. There's also a lot of coffee grounds left over on the screen after each attempt (sometimes even a piece of the puck).
I've tried replacing the grouphead gasket and cleaning the screen. I also backflushed the machine (water seems to only come out of the right hose in the back...). I opened the machine up as well and didn't see any evidence of scaling. I suspect the problem is low pressure from the pump. But this is my first espresso machine so I'm not sure if I'm overlooking another easy, more obvious issue. Any suggestions or advice would be greatly appreciated. Thanks.
plindy Senior Member Joined: 27 Nov 2002 Posts: 78 Location: Seattle Expertise: Just starting
Espresso: NS Oscar Grinder: SJ Pharos Lido HG-One
Posted Mon Feb 24, 2014, 2:10am Subject: Re: Low Pressure on Oscar
Try removing the screen and diffuser plate from the group head and measure the amount of water in 10 seconds. 4-6 oz ? Is the screen just slightly larger diameter than the diffuser plate ? Does the diffuser plate have 4 or eight holes ?
These questions will determine pump delivery to a grounds rather than pod equipped diffuser and screen.
Water from back-flush should only exit from the right side
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No SEO style postings will be tolerated. SEO related posts will result in immediate ban from CoffeeGeek. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.