magnuman

I went out on the boat yesterday and was just hitting around 5,000 rpm and trimming the drives up to about 3 on the indicators, when all of a sudden my port drive felt like it had spun a prop. I had lost forward gear on the port drive. I still had reverse and neutral but no forward. I have just had this transmission rebuilt.
At the end of last season I was just about to take off on plane the boat shuddered, I could smell burning under the hatch and I lost my forward gear in that drive, hence the rebuild. At the time the transmission fluid smelled like it burnt and there were fine metallic particles in it.
Yesterday there was no smoke, the transmission fluid is fine and the boat did not shudder at all, and I was fully running. Is there any type of engaging pin that could have sheared?
I have a 1976 27' Magnum Sport with Twin TRS drives that are hooked up to the original Mercruiser trannies.
Any help would be appreciated!

Mbam

Does not sound good. I am suprised the oil is not burnt. Regardless of the cause, most likley you will have to pull it out. If you have the electric shifter, make sure it is working.

Audiofn

Mbam could it be the pump? I know that reverse on those transmisions is engaged with the band, so if the pump was bad then it would work as he is describing and not burn up the fuel???

Jon

Mbam

Unlikley, the band apply pressure is supplied by the same pump.

mfb357

If those trannys are Borg Warners you need to watch the fluid level. They are very sensitive to low fluid and will burn out. Also you may want to check travel of linkage(does it go all the way into forward). Those things are really bullet proof as a rule. Good Luck. MFB

Biggus

Sounds to me like you broke the gear in the pump.It`s a fairly simple fix, pull the tranny and the pump is located at the front of the case.

I have broken many of them when I had my old 24 Superboat.

fishead

Call Curt at Thermco Marine Transmissions in Stuart FL.I do not have the number but he rebuilt my Tranny when the pump disintergrated.Something went wrong with the tranny again at the end of the season and he told me to pull it and send it to him and he will fix it because he stands by his work.Good guy and Knows the mercruiser tranny.

magnuman

Thanks for the replies.
The trannies are Mercruiser not the Borg Warner. They have a mechanical shift, which is working fine. Transmission fluid level was fine. I checked it before I ran the boat, while the engine was running.
I am located in California and the shop that repaired the trannny in the fall is pulling it this Wednesday. We will know what happened at that time. Hopefully it's something that's easy. Although pulling the engine is never that easy!

magnuman

Biggus,
Do you know the reason you were breaking the gears?
Is there a long term fix?
I don't run the boat that hard.

Biggus

I think the reason was that I had way too much HP and the tranny couldn`t handle it. I had a twin turbo Gale Banks big block and was spinning a 29p Mirage Plus prop.

I have several friends with the Merc trans and the front pump gear seems to be a weak link, they always crack at the keyway because it is the thinnest part of the gear.

Good luck, Kurt.