ZF 220A Questions

[projecttarpon]

Couple questions and interested in thoughts with gear issue.

(1) When running, pressure rises to appropriate level and after running for a few minutes goes down to 230-250 psi on guage. Had transmission slip at cruise, immediately backed off. Ultimately looked like I needed to add a little oil, boat ran fine but pressure stayed low. No obvious leaks.
(2) At idle, pressure is also low and below specs.
(3) Oil looks good, no smell, looks like it just came out of bottle.
(4) Also, seems to be a little pause after putting it in gear before the gear engages – more than normal.

My thoughts. (1) oil screen needs to be cleaned and (2) possible leak in cooler (age of which I have no idea). Maybe a combination of both.

Can a leak in the cooler cause the oil pressure to run low like that? If there is a leak in the cooler, can there still be no apparent change in consistency or appearance of the oil?

Plan on replacing cooler and cleaning oil screen and change oil. Could it also be a pump issue?

Topic

[projecttarpon]

It is the newer version gear oil pump assembly, not the one with the arm that sticks out for the filter screen. Relief valve does not look like any oil has come out. Not sure if that helps or not.

[Tony Athens]

Yes, pump wear can cause low OP.. But much more likely it’s something else..Yes, clean the screen 1st.

1) Lets “see” good pics of the gear to ID the vintage of the gear-Oil pump area from below is what I what I want to see.

2) Oil / piston rights wear is common on old gear.

3) Relief valve need to be looked at–pics on this site

Tony

[projecttarpon]

Can a failing pump start to cause the decrease in oil pressure or is it more likely something else.

[projecttarpon]

Not that I have seen or noticed.

[Rob Schepis]

On that gear the gear cooler circuit does see full operating pressure. Any slick on the surface from the wet exhaust ?

[Author]

Replies