OMC COBRA 5.8 EFI and ESA

[Rhc]

Will overfilling drive oil cause shifting problems?

 

[Scott Danforth]

No

Describe in detail what is happening

 

[Lou C]

Exactly. A too high oil level could be bad seals causing the drive to pull in water, but has nothing to do with shifting problems.

 

[Rhc]

Exactly. A too high oil level could be bad seals causing the drive to pull in water, but has nothing to do with shifting problems.

To clarify -- When I removed the drive oil fill cap, there was pressure which spewed oil over the top. I had noticed an oil leak when on hose muffs but could not see where it came from? I remembered overfilling in error but forgot to syphon out excess. As indicated in past threads I did experience poor shifting from in gear to neutral. That condition was less noticeable with longer runs in the lake. As discussed i believe the shifting problem is likely related to poor shifter. Remember i have changed all cables and had the lower drive rebuilt by TC Marine as recommended. He said there was little problems in drive by did change clutch dog and machined both Fw and Rev gears at point of contact with clutch dog.
So do you agree the overpressure condition could create hydraulic pressure at the clutch dog?? -- resulting as poor synchronization?

 

[Lou C]

No those gears are always running in gear oil
Your not shifting from in-gear to neutral is a likely result of:
1) an out of adjustment shift cable
2) ESA system not functioning
3) idle speed too high, or after being set correctly it starts drifting up
When you trigger the interrupt switch by hand with the engine running in neutral it should lower the RPM to about 450 rpm. Normal idle should be not more than 600 rpm. If your ESA is not working it won't want to go to neutral and if your idle is too high, the ESA won't be able to lower the rpm enough for it go to to neutral.

Was the gear oil milky or not?

 

[Rhc]

No those gears are always running in gear oil
Your not shifting from in-gear to neutral is a likely result of:
1) an out of adjustment shift cable
2) ESA system not functioning
3) idle speed too high, or after being set correctly it starts drifting up
When you trigger the interrupt switch by hand with the engine running in neutral it should lower the RPM to about 450 rpm. Normal idle should be not more than 600 rpm. If your ESA is not working it won't want to go to neutral and if your idle is too high, the ESA won't be able to lower the rpm enough for it go to to neutral.

Was the gear oil milky or not?

View attachment 1731450020651.jpeg

 

[Lou C]

Looks like you have a leaky seal somewhere; the drive sucked in water when it cooled that’s why the level was high.

 

[Rhc]

Looks like you have a leaky seal somewhere; the drive sucked in water when it cooled that’s why the level was high.

Thanks for your input as always. I’ll keep you posted on any additional findings.

 

[Lou C]

Common leak areas on the Cobra are the water pump adapter seal and the shift rod seal.

 

[Rhc]

Common leak areas on the Cobra are the water pump adapter seal and the shift rod seal.

I am hoping you can review the following exchange with AI. Do you think the information is correct. I certainly see foam in the oil I removed and the pressure when I opened it up was high enough to “spew” out. Remember this drive was just rebuilt at TC Marine. It seems to make sense to me.

USER REQUEST:
Just to be clear, I overfilled the drive oil earlier in this season . When I drained the drive at the end of season there was excess pressure build up in drive and that spewed oil out when I removed the fill cap. Can you explain how this pressure build up could have caused poor shifting?

User:** Can you explain how this pressure build up could have caused poor shifting?
**Assistant:** Let's break down how the excess oil could have caused poor shifting in your outdrive:
1. **Hydraulic Pressure Build-Up**: When you overfill the drive oil, the excess oil creates additional hydraulic pressure. This pressure can interfere with the proper engagement and disengagement of the clutch dogs. The clutch dogs are responsible for smoothly engaging and disengaging the gears, and any disruption in their operation can lead to rough or incomplete shifts.

2. **Foaming of Oil**: Overfilling the oil can cause it to foam. Foamed oil is less effective at lubricating the moving parts within the outdrive, which can lead to increased friction and wear. This can also contribute to poor shifting performance.

3. **Oil Spewing Out**: When you removed the fill cap and noticed oil spewing out, it indicates that the pressure was high enough to force the oil out of its normal pathways. This is a clear sign that the hydraulic system was under too much pressure, which can negatively impact the clutch dog operation.
To prevent this issue in the future, it's crucial to maintain the correct oil level in your outdrive.

 

[Scott Danforth]

You have a leaky seal, it allowed water into the gearcase, and expelled oil.

The AI BS is BS.

All sealed gearcase will "burp" if the gearcase is opened when its warmer than when it was filled, and "gasp" if cooler.

That is just the fundamental law of PV=nrT

 

[Lou C]

Did TC rebuild the whole drive or just the lower or upper? I would contact them if it’s a recent rebuild. If you want to check it yourself here’s OMC’s specs:
Pressure test, first 6 psi then 16-18 psi
Vacuum test first 5”Hg then 15”Hg

Yep there’s no way a high gear oil level causes shifting problems. It’s usually a sticky cable, bad adjustment, non functioning ESA, high idle speed, crudded up bell crank in the pivot housing or a problem in the lower unit itself.

 

[Rhc]

Did TC rebuild the whole drive or just the lower or upper? I would contact them if it’s a recent rebuild. If you want to check it yourself here’s OMC’s specs:
Pressure test, first 6 psi then 16-18 psi
Vacuum test first 5”Hg then 15”Hg

Yep there’s no way a high gear oil level causes shifting problems. It’s usually a sticky cable, bad adjustment, non functioning ESA, high idle speed, crudded up bell crank in the pivot housing or a problem in the lower unit itself.

The rebuild was for the lower part only. They found little problems. Changed clutch dog plus small machining of both gears at point of contact with the clutch dog. He also changed the rubber sleeve between Lower an upper section. I’ll see if he will check seals?