Transmission slipping or something else? |
Post Reply | Page 12> |
Author | |||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
Posted: August-17-2019 at 6:34pm |
||
I’ve been having an issue that feels like cavitation or slipping in my 84 2001 with the HO 454. Trans fluid is new and topped off with dextron vi synthetic. Prop is a new Acme 431
The weird thing is that I can hole shot it wide open and the thing pulls hard with no “cavitation/slipping/high reving symptoms”. The issue only shows up when you try to push it past 4000ish rpms and then the tach jumps to about 6500 rpms Trans fluid smells fine and not burnt. Below is a video showing the issue. Any ideas on this guys? How could the tranny only slip on high rpms but not during a hole shot? https://drive.google.com/file/d/1Hl-jq_ON8-BAm3yd-SK1pXSomlmV98nA/view?usp=drivesdk |
|||
8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
|
||
Chris,
Sounds more like cavitation to me. Is that with your new 431 prop? What's the cup on the 431? |
|||
KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
Post Options
Thanks(0)
|
||
In my best English I ain't never seen nuthin' that could break the prop loose at 40 or so mph Cup is .080 inches Is that ATFplus4 fluid Mav? |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
ATF dextron VI synthetic Had the same issue with the old prop for those that didn’t see my other post |
|||
RealDeez
Senior Member Joined: August-01-2019 Location: MI/IN Status: Offline Points: 130 |
Post Options
Thanks(0)
|
||
Sorry to jump my noob self in where I likely don't belong but could there be an issue with the hull that would cause cavitation at higher speed where it might not at low speed? Just spitballing.
|
|||
Lake James, IN
93 Sport Nautique |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
That’s a good point, everything with the hull checks out, all fins are straight and no hull damage |
|||
KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
Post Options
Thanks(0)
|
||
Everybody was a noob at one point Keep jumping in, it's a forum |
|||
KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
Post Options
Thanks(0)
|
||
Having seen the boat yesterday, like Mav says there's nothing wrong with the hull
Per a phone conversation, there was a question of whether the ARE shaft could be slipping inside the coupler so he put a couple of magic marker marks , one on the coupler and one on the shaft and they stayed aligned. That would have taken a broken or missing key to let that happen, so it seems that the coupling is OK Quite a few people use Dex 6 synthetic ATF without issues, but how long has that been in there? Was it changed after you first had the issue? Can you go from zero to 4000 rpm's and stay there for say a minute with no problems ? If you punch it from a dead stop does it get to 5000 rpm and around 50 mph or does it start having issues at a lower rpm before getting there? |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
The trans oil is fresh, I didn’t change it after the first test run when I noticed the problem, fluid is a couple weeks old. I can go from 0 to 4000 wide open and then let off and maintain 4000 all day with no problems. The issue will pop up when I open the throttle around 4000 rpms. |
|||
RealDeez
Senior Member Joined: August-01-2019 Location: MI/IN Status: Offline Points: 130 |
Post Options
Thanks(0)
|
||
Another noob post: does it change if you're towing something?
|
|||
Lake James, IN
93 Sport Nautique |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
I haven’t tried that yet, problem happened with two people in the boat and also three people, half tank of fuel both times |
|||
KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
Post Options
Thanks(0)
|
||
I think I'd call Joe at FFI marine in Ohio and talk about this with him, since the only thing left to slip is the transmission.
His number is below.
Or these guys in the link aren't too far away from you and they've been around a long time link |
|||
GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3357 |
Post Options
Thanks(0)
|
||
Last thing I can think of is put a pressure gauge on the fwd circuit and look at the line pressure while it's happening and see ifs sufficient, or drops.
Yeah likely could just be out of friction material |
|||
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
That’s a good idea. I ordered some Lucas extreme duty marine atf, I figure it’s worth a shot. https://lucasoil.com/products/marine-products/engine-oil/lucas-extreme-duty-marine-atf |
|||
GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3357 |
Post Options
Thanks(0)
|
||
Chris by friction material, I mean fiber on the plates, not a fluid thing
|
|||
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
I figured I was thinking maybe if they’re slightly worn the Lucas could help Another thing, the old oil I pumped out was still pink, definitely old oil though by the smell but no burnt smell or discoloring. You’d think that old oil would be discolored and burnt alittle bit by now |
|||
8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
|
||
Give it a try and report back but, I have a feeling the friction modifier will have the opposite effect. |
|||
8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
|
||
+1 |
|||
TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
Post Options
Thanks(0)
|
||
I didn’t hear any wind up that would lead me to think anything’s slipping. I suspect all is well and your tach is lying. Rpm’s didn’t change much by my ears. I would have expected a stronger response from a hammer drop at 40 with a HO 454 if it’s healthy, especially with the 431.
|
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
On that run we didn’t hammer down, did a gradual run up into the 40s, if you watch around 20 seconds you’ll see the tach jump and hear the motor rev up when trying to give it alittle more |
|||
gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
Post Options
Thanks(0)
|
||
I have to agree with Tim at 6,500 that motor would be screaming. I could run my ‘95 GT 40 up to 55oo and you knew it
|
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
I was thinking the same thing earlier, maybe the tach isn’t accurate, but then I realized I can hear the motor rev up all of a sudden, while seeing the needle jump same time, without the boat pulling as it should for the increase in rpms I’m hearing, although it was still pulling some and not totally 100% slipping as if in neutral |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
I did check the trans oil tonight, I found some milky condensation on the top of the stick, guessing that can be normal depending on conditions? The oil itself is clear and red. https://drive.google.com/file/d/1yW7rBrZMAYUMjBG_eN_vu__iNfmgg-V4/view?usp=drivesdk https://drive.google.com/file/d/1zc7nxoD9oB32dMzmOEua_HWBkNlVJLYr/view?usp=drivesdk |
|||
TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
Post Options
Thanks(0)
|
||
I saw and heard what you are talking about and it sounded like a few hundred rpm increase as the secondaries opened- very much expected (if not a little weak). Ignore the tach and take another video with a WOT run- and gps it (navionics). Your oil pressure looks pretty high and temp looks pretty low in the vid... hopefully you aren’t running the boat at 40+ until you let the engine warm up a bit. How much experience do you have with inboards (especially older ones)? |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
Not much mostly just car and bike motors, that temp gauge must be off when I shoot the motor with the infrared gun I’m reading in the 140s. I took the thermostat out a few weeks ago and put in boiling water on the stove, watched it open around 140 then close back up after cooling. The oil pressure I have no idea, I’ve seen hot idle in the 30s to 40. I’ll take another video next weekend. I want to agree with you on the rpms that’s what I had originally thought, to me I feel like the motor has more to give when running at 4500 which might be 3500 in reality. I did rebuild the carb and been messing with the float heights to get it running right. Adjusting the primary float height I had to ignore the sight hole for adjusting because of the motor tilt. (Lowered height until fuel stopped dripping in after shutting motor off) ) I also have 101 needle and seat instead of the 110, no idea if that’s right or not but that’s all the parts store had yesterday and needed new gaskets, and the new 110 in there felt sticky, I wasn’t sure how to adjust the secondary's, so that’s set at the sight hole, but the motor is tilted that way so maybe I’m not getting enough fuel on the secondary's and it’s that delayed sudden kick in I’m feeling? |
|||
TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
Post Options
Thanks(0)
|
||
Sounds like the secondaries coming in- it’s about the right spot for them to (low 4K rpm range). Is this a vac or mech secondary Holley?
|
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
It’s a mechanical secondary, Holley 800. Do you see an issue with running a 101 needle and seat on the primary? It had a 110 in there. Also how do I know if the float height is adjusted correctly on the secondary’s? |
|||
GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3357 |
Post Options
Thanks(0)
|
||
Ok I heated it with more clarity today
To my ear as well, that's not a true 6k, at all I see the speed climb 42 to 45 in short order when you give it some I believe the tach s lying, consider it was constructed for a points system, 37 years ago. And your not accustomed to the symphony of awesomeness the ensues when you lean on on ithis boat and get on it. |
|||
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
|||
Crmaverick
Senior Member Joined: July-06-2019 Location: Central MA Status: Offline Points: 190 |
Post Options
Thanks(0)
|
||
Man that would be ideal, it does sound awesome. I’ll take another video next weekend. I might try raising the float height on the secondaries |
|||
KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11050 |
Post Options
Thanks(0)
|
||
It looks to me like the tach is reasonably accurate at 4000 rpm and 43 mph on the left speedometer with the 431 Acme and it doesn't act up till he punches it and then it's accurate again after he backs off.
Something is making it act up. Have you checked your timing at idle with the new distributor and maybe checked it again at 4000 rpm.? You can do all that in neutral at the launch ramp. If not, a digital timing light with a tach as part of the light to give a double check on the tach would be real handy right now |
|||
Post Reply | Page 12> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |