94 Cobra (Volvo) SX - Outdrive Slipping (Time for a DP Conversion?)

[tjtheman007]

Hey all!

Researching through the forum, and the information here is great! Love the stickies as well. Been a long time browser, but finally decided to join. I'll get to it though.

I have a 1994 Four Winns 190 Horizon. It has the Ford 302 v8 (Cobra FL) mated to a OMC Cobra SX outdrive. (Volvo Penta SX) I know my year is tricky because it is the first crossover year for the Volvo outdrive.

Problem: Yesterday, first outing of the year, after I just replaced the impeller (The one right below the alternator on the motor) I took the boat out in the Kankakee River, did great putzing around, going slow all day. About to bring it in and I decided to open up the throttle. Great for a little bit, then all the sudden something let go. Engine RPM's shot up and boat's speed over water instantly dropped. Something slipped. Backed it completely off, put it into neutral. With the engine still running, I put it back into forward gently, and no problem. Went slow. Tried to give it more throttle, as soon as the RPM's start increasing, it just lets go. Killed the engine, started it again, put it into gear, fine going slow, again try to give it some forward throttle, lets go. I then backed off and we slowly crept to the boat launch, barely in drive. (Luckily we were only a couple yards away.) I did NOT hit anything in the water.

I checked my outdrive fluid literally right before launching the boat. (Put the drive down all the way, etc.) And it smelled and looked great; no water in it, good level, great coloring, etc. (Its been a little over a hear since I have changed the fluid, but I only put maybe 40-hours on it last year, and that is pushing it.) Upon returning, with the issue, checked the fluid again, metal flakes and burnt smelling.

My local marina is backed up until the very end of June. I'm ideally needing the boat back in the water the week after the 4th of July. Becuase of the timing, I have already decided to pull this myself. I'm very mechanically inclined and I do own the ACTUAL OMC manuals (Not just the "Solec" manuals) for my exact boat. I figure I can get this tore apart and that way source and order the parts I need in hopes they'll get here in time.

I'll be diving into those manuals tonight actually to prep for the tasks ahead.


Questions:
1. So, I already know I need to pull my outdrive as I found metal flakes in the fluid. Anything else that I should checkout? Anything specifically behind the transom plate as well?
2. With pulling the outdrive and needing to rebuild it anyway, am I able to upgrade to a Volvo DP unit? (The only thing I am unsure of is my transom plate looks a tiny bit different than the "real" volvo SX drive units.)
- I am not sure If I need to find just a lower and it will work with my OMC Cobra SX upper, or if I need to source the entire unit, upper & lower, along with maybe a new transom plate. Thoughts? Advice? Critiques? ANy helpful links I need to checkout?

Here are pictures of my setup. I can get more tonight/tomorrow if need be.

Thanks all for any assistance you can lend me!! Much appreciated.

 

[bruceb58]

I would try another prop before I threw in the towel on this drive. You may have just slipped the hub. Your prop looks like it's hit a few things so easily could be a hub.

Are you sure it didn't smell burnt before you took the boat out? If it is indeed burnt, that would point to the cone clutch.

BTW, if you want to convert to a DP, you just need the lower. If the cone clutches are slipping, that's in the upper.

 

[tjtheman007]

Thanks Bruceb58!

Yep, I'm sure the gear oil in the outdrive did not have a burnt smell prior to putting the boat in the water.

I can check the hub on the prop, but that still wouldn't explain the metal flakes or burnt smell of the gear oil in the outdrive after pulling it back out.
I need to pull the prop first anyway prior to pulling the outdrive, so we'll see. (That prop had those nicks on it when I purchased the boat 5 years ago. Nothing new there.)

For converting to a DP-s lower, do I need to retain my upper housing and find a 1.95:1 ratio lower? Or can I source an entire 1.95:1 radio DP-s drive? (I currently have the 1.66 ratio sx.)

Thanks again!

 

[bruceb58]

You will have to go online and do a search for what ratio is needed for your engine.

 

[tjtheman007]

Bruceb58,
I have searched a little. I know if i kept my upper, id just need to source a 1.95 ratio lower.

Let me rephrase my question though: where is the gearing done on an volvo sx drive? The upper section, lower, or both? If only lower, then i can expand my search for a complete working 1.95 dp-s drive that will also remedy my burnt clutch (or whatever the issue is) on my current drive.

If the gearing is done in both sections or just the top section, then I'll forgo the dual prop pipe dream and just either find a working replacement 1.66 ratio upper sx drive (or whole unit) or order the parts to rebuild my existing outdrive.

Sorry to be complicated. I just figured I'd try to make lemonade outta lemons and upgrade some hardware (duoprop upgrade) while fixing the main issue (rebuilt outdrive) if possible.

Thanks!

 

[bruceb58]

Gearing is done in the lower.

DP is a great addition to a boat. I would never have an I/O boat without one.

 

[tjtheman007]

So if the gear ratio is only set in the lower unit, if I'm looking just to replace exactly what I have, then technically I could find any good volvo sx upper 94-98 (or even until 2006?) (regardless of ratio tag listed) and bolt up my existing 1.66 lower unit (baring it's all fine and not damaged) and be good? Do i understand that right? Gearing for all sx drives is only in the lower? Uppers are all the same?
(This would help me source a good working upper easier as I'm fairly certain it's the clutch that is slipping)

 

[bruceb58]

My suggestion is to call a few of the many places online that sell rebuilt Volvo SX drives to make sure you get the correct answer.

 

[tjtheman007]

So, I made some phone calls today.

For the record, bruseb58, you have been a fantastic help!!! Thanks!!

Two things:

1. I called www.DriveMasterMarine.com today (main rebuilder of Volvo SX Drives) and they are more than happy to send me a rebuilt upper for about $2700 (American) shipped. (They are located in Canada.) Then I'll get about $500 back once the core is sent back to them. (So $2200 out the door for a reman-ed upper)
**Here are the juicy details** I also asked about where the gearing is done on a Volvo SX drive and they said it is a combo of both the lower and the upper, but that there are only 2 main upper units on SX drives. (So the main gearing changes do happen in the bottom!) Of the two main uppers, most use a 2.30/2.33 ratio gears to transition the input shaft down through the vertical shaft which connects to the lower unit. So, verifying with them and their parts book, the uppers are all the same on all 1.43, 1.51, 1.60, 1.66, & 1.85 gear ratio SX drives. I am unsure on the 1.79, but anything else, the uppers will differ. (**This is why to convert to a DuoProp, only swapping out the lower unit with a 1.95 ratio DP-S drive works for all 5.0/5.8/5.7 v8 engines!!)
SO this means if I have to replace my upper, I can look for any upper with those above gear ratios. This helps broaden the search.

2. Called more marina's close to me today to check for any used SX Drives they might have on hand...
Well, Bruceb58, for a second time I was told to check my prop hub first. You might just be right, and I may have overreacted initially. If that is the case, I will HAPPILY eat crow. The prop hub spinning does make sense after hitting a certain load & RPM. I asked about the metal flake, and after I described it, the marina said that was somewhat normal. Just change your fluid first and see exactly how much metal comes out. It sounds more like only a spun prop hub with some normal wear in the outdrive.

So, my course of action now, is to first try the "Cheaper" route first on replacing prop hub on my Raptor Michigan Wheel prop (I believe mine is a replaceable prop hub design.) and replacing the outdrive fluid first. (While verifying just how much metal flake I "think" I saw.) If the problem still exists, well, good maintenance anyway to replace the prop hub and that is a TINY dollar figure to spend first before just ripping the outdrive off and sourcing a new one/parts.


*One IMPORTANT thing to note. If I do have to replace my upper housing on my outdrive, The early SX Drives (94,95 and some 96's) have an o-ring recess in the UPPER housing only.(Flat surface on the lower) Everything 96 -2006 has the o-ring recess in the BOTTOM housing only. (Flat surface on the upper) This means if I wish to reuse my lower, I need to find an earlier upper (94/95) with an o-ring recess to match the housings up. If I find a newer than 96 upper housing, I better find a new lower to go with it, otherwise there will be no recess for an o-ring to reside and the drive will never seal.
(If my outdrive isn't bad at all, and I still wish to convert it to a DouProp lower, I then have to source the almost non-existent double thick o-ring to mate my existing upper and new DP lower. These o-rings were called "quadrings" and from my research aren't produced anymore. - Not a worry at the moment. I'll cross that bridge if I have the opportunity too or source a cheap 1.95 ratio DP lower.)

 

[bruceb58]

Yes...I think that's why those earlier models are called SX-C. However, a complete SX-M will attach to your pivot housing so if your upper is toast, you can go that route.

 

[tjtheman007]

Thanks again for the help!!!
Short story: spun prop hub.


Long explanation:

So, as an update to this
- What I thought was metal flakes, was actually AIR BUBBLES! WOW I feel like an idiot!!!
- I DEFINITELY spun a prop hub!! It was dry rotted! Ordered 2 new props, works great now!!!

(Wow, I over reacted! Glad it was only a couple $$$ prop and not a $2k+ out drive replacement/rebuild.)









I also changed out the outdrive fluid, and the engine oil with Amsoil as well.
Upon draining the outdrive fluid, ran a magnet through, no metal shavings at all. lesson learned.






Just got back from a week out at Kentucky Lake. I can say that the boat did great!!
(The new Ballistic Prop I bought was a bit too aggressive though. stuck with a 21-pitch on a 14 3/8" diameter. In hind sight, I should have gone with a 19-pitch, not the 21-pitch. - I called Michigan wheel direct about that too and they said I should be fine sticking with the same pitch... nope. Was only getting 4000 rpm's max out if it (42-43 mph), when before with the old 21-pitch rapture I was getting 4300-4400 RPMs (45-47 mph). Now, on the Ballistic prop, cornering was MUCH better though!!! Huge difference. I do have a call in to Michigan wheel though to see is they would be willing to do an exchange for me for a 19-pitch prop. We'll see. )









Other prop I bought:
Turning Point 4-blade aluminum (2 different blade designs) Prop: