ZF 30M Problem HELP

[hpeer]

I’m in Luperon, DR
I have a Yanmar 4JH4-TE with a ZF30M transmission

I just changed the oil in the engine and transmission. All was working well before. Now it seems OK in reverse but is NOT in forward. It will engage, but I can not get full RPM in (2,200 not 3,200). I get full RPM in neutral. I don’t want to say the engine is slipping but it seems to be laboring. I checked the tranny with an IR thermometer and it did not seem excessively warm. About 115°F, the engine is obviously warmer.

I was very careful to get the full level at the to of the dip stick, not screwed in as indicated in the manual.

The old ATF looked great, like new. The new ATF is a few years old, in original sealed bottle.

I started in a trip and ended up motoring about 1/2 hour in this condition. Now back at the dock.

Any ideas?

My “plan” is to get some more ATF in the morning and replace what is in there, run it a bit, drain and replace again. Hopefully that will do some good. Good idea?

Right now I’m during G&T and weeping.

[hpeer]

Stand down, I think I have it sorted. Exit panic mode. (Said to self)

I checked the level, it was a wee bit high. I pulled off 1oz.

But I got thinking, suppose it’s a FUEL problem. We made a long run to here from Sapodilla Bay. I forget how many hours. About 24 hrs. I didn’t notic a problem coming in.

But I decided to change filters. Neither the Racor or the Yanmar filter looked bad.

HOWEVER, when I bled the Yanmar filter the first 6 ounces of fuel came out BLACK.

As soon as I changed the filters everything seems to be OK. Runs right up to 3,200 fwd and rev.

Now I’ve got to figure out what is going on with the fuel. A different mystery.