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Old 02-01-2011, 07:35 PM   #23
Marin
Scraping Paint
 
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Join Date: Oct 2007
Posts: 13,748
RE: lehman spare belt storage.

John--- The Johnson pump is a bolt-on replacement for the Jabsco/Lehman pump and pump drive. You simply unbolt the Lehman drive coupler and the Jabsco pump attached to it from the engine's accessory case and bolt the Johnson pump in it's place. It uses the same mounting holes. You will most likely have to change the hose between the pump and the engine's lube oil heat exchanger because the Johnson pump is shorter so the hose needs to be longer. You may not have to change the hose from the intake sea strainer to the pump, however.

The intake and outflow of the Johnson pump are on opposite sides of the pump chamber so on the FL120 an elbow fitting needs to be installed in each opening. On an FL120 the pump is positioned so the intake is on the bottom and the outflow is on the top. This is why changing the injection pump's lube oil becomes more challenging because the outflow elbow leaves very little room under the injection pump drain plug.

The recommended Johnson pump for the FL120 is the 3/4" model, the recommended pump for the FL135 is the 1" model. However at the suggestion of Bob and our diesel shop, we had 1" pumps put on our FL120s. Slightly higher water flow volume, which doesn't make any difference to the engine since its temperature is controlled by the thermostat, but it made a noticeable difference in the temperature of the transmissions. And any time you can reduce the operating temperature of a Velvet Drive, it's a Good Thing.

If you're interested in this conversion I suggest that you talk to Bob Smith or Brian Smith at American Diesel.
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