* Brent crude down almost 3 pct; U.S. crude off 2 pct
* Gasoline down 4 pct; pares some loss on Bayway refinery outage
* Gasoline crack smallest since Jan, diesel crack at 1-week low
* Chinese Q3 GDP growth slowest since 2009
* Nuclear deal to be implemented this year, Iran says (New throughout, updates prices and market activity, adds gasoline and diesel coming off lows after refinery outage)
By Barani Krishnan
NEW YORK, Oct 19 (Reuters) - Crude oil fell about 3 percent on Monday after a tumble in gasoline futures added pressure to a market already slumping on slower growth in China and signs that Iranian oil will return to market soon because of a nuclear deal likely to be implemented this year.
A stronger dollar and softer equity markets on Wall Street added weight to the petroleum complex, traders said. USD/ .N
"The products markets seem to be taking a hit over concerns the refinery maintenance season has peaked, and there could only be inventory builds from here," said Pete Donovan, broker at New York's Liquidity Energy.
The front-month in Brent LCOc1 , the global crude benchmark, was down $1.44, or 2.9 percent, at $49.02 a barrel by 1:35 p.m. EDT (1735 GMT).
U.S. crude CLc1 was down $1.15, or 2.4 percent, at $46.11, in lighter volume trades ahead of Tuesday's expiry for the November contract CLX5 as front-month.
Gasoline RBc1 tumbled early Monday, falling as much as 5 percent, on worries U.S. refinery utilization could pick up with declining maintenance work. Ultralow sulfur diesel HOc1 was down nearly 2 percent.
Both gasoline and diesel prices came off their lows on news that Phillips 66's 275,000-barrel-per-day Bayway refinery in Linden, New Jersey -- one of the largest on the U.S. East Coast -- was shut after a transfomer malfunction. ID:nL1N12J19D
The refining profit for gasoline, known as the gasoline crack CL-RB1=R , was at its lowest since January. The diesel crack traded near a one-week low.
China's economy grew at the slowest pace in six years in the third quarter, according to official data released on Monday. urn:newsml:reuters.com:*:nL3N12J1EK
Data also showed that Chinese oil demand fell slightly in September. urn:newsml:reuters.com:*:nL3N12J15F
Iran's nuclear negotiator said on Monday he was hopeful for an implementation before year-end of the nuclear deal between Tehran and Western powers. A senior Iranian oil official also said the OPEC member will boost production by 500,000 barrels a day within one week of the sanctions being lifted. urn:newsml:reuters.com:*:nL8N12J1PV urn:newsml:reuters.com:*:nL8N12J2A7
The Buzzard oilfield in the North Sea, the largest contributor to the Forties crude stream that helps to set the global oil price, was, meanwhile, gradually ramping up production after a four-day outage. urn:newsml:reuters.com:*:nL8N12J1KH
Austrian oil producer OMV OMVV.VI lowered its forecasts for crude prices, envisioning $55 a barrel for 2016; $70 in 2017; $80 in 2018 and $85 a barrel from 2019 onwards. urn:newsml:reuters.com:*:nL8N12J0N7