Ammarine 404 (John Deere 6404)

[Woody5]

Is this the GM car block that was converted to diesel and installed in some Grand Banks trawlers? Is the Ammarine 404 (John Deere 6404) a good engine. If we’ll maintained in an older boat?

 

[TOM ROLLINS]

The John Deere 404 is a great motor. Almost bullet proof. Used extensively in industrial and farm equipment. Grand Banks Marinized them for 10 years or more. The marinized version is tough as well. Only weakness I know of is in the heat exchangers, they like all heat exchangers, require maintenance and replacement based on use and service. I had a pair of the the 404's for 8 years and loved them. They had over 10,000 hours on them and ran like they wanted to do it again. Proper maintenance, oil changes regularly, and feed them clean fuel. Parts are still available but might take a few days instead of on the shelf. Have a mechanical survey done prior to buying. It's money well spent and you will learn about them.

 

[Nick F]

Incredibly, the JD brochure actually boasts a high "Weight-to-Power" ratio !

 

[KnotYet]

To answer your first question, the Deere derived 404 is not the same as the GM
V6's and V8's. Those were legendary lemons. The Deeres are the real McCoy.

 

[Brianjerome]

AMMARINE 6404 1976 Grand Banks Oil Pan Leakijg

I've own my1976 42 Foot Grand Banks Trawler for 18 years. Twin Ammarine 6404 engine have run extremely well. Now have severe oil leak in port engine, Had oil in pan after winter storage and Lost 4-5 more quarts into pan on 45 minute ride to mooring after boat just launched. My mechanic of 30 years unfortunately died and I don't have a go to mechanic right now. l suspect it is leak from oil pan but can't see leak using camera. Need advice. Anyone have this issue and anyone have experience replacing or repairing oil pan with this engine and boat? Thanks

 

[Comodave]

I've own my1976 42 Foot Grand Banks Trawler for 18 years. Twin Ammarine 6404 engine have run extremely well. Now have severe oil leak in port engine, Had oil in pan after winter storage and Lost 4-5 more quarts into pan on 45 minute ride to mooring after boat just launched. My mechanic of 30 years unfortunately died and I don't have a go to mechanic right now. l suspect it is leak from oil pan but can't see leak using camera. Need advice. Anyone have this issue and anyone have experience replacing or repairing oil pan with this engine and boat? Thanks

Welcome aboard. You probably would do better starting a new thread just for this specific question.

 

[GB42-424]

Oil Pan

Before you drop the pan, I'd look closely to try to find the source. Check under the transmission bell housing (also peek in the timing window) for signs of a rear crankshaft main seal leak and around the engine oil cooler. If you drop the pan to replace the gasket, you might consider new crankshaft bearings while you have access. You'd need to lift one end of the engine with a ratchet chain hoist to make bearing replacement easier. The engine is 2000 lbs. On the port engine, the main seal, pan gasket, and oil cooler gaskets/o-rings are standard JD parts.

If you need a new mechanic, you'll find more still working on these in tractors than in boats.

 

[Nick F]

Quote - Before you drop the pan, I'd look closely to try to find the source.

I strongly agree with GB42.

Perhaps pressure up the pan a little with a hair dryer or shop vac on the oil filler. Mirror, borescope, smartphone, paper towels.