1996 Four Winns Sundowner with 5.0 Cobra engine and drive

[Lpgc]

Being a '96, a joint venture year, it's basically a Volvo SX-M drive.
When my EFI Ford 302 needs replacement, I'll have to investigate the GM route you suggest.

My drive is a Cobra, is that similar to a Volvo SX-M?

 

[Lou C]

The 94-98 Cobras built during the joint venture years are exactly the same as the Volvo SX of the same year the only differences are color (SX silver, Cobra Charcoal Grey) and one has an OMC model # the other has a Volvo model #.

 

[Lpgc]

The 94-98 Cobras built during the joint venture years are exactly the same as the Volvo SX of the same year the only differences are color (SX silver, Cobra Charcoal Grey) and one has an OMC model # the other has a Volvo model #.

Thanks.

I wonder if my boat is a '96 model, if the drive unit could have been made before '94?

If it was made between 94 and 98 will it really be 'exactly' the same as a Volvo SX leg or are there still minor differences in some of the components?

How much torque can the Cobra / SX leg take? I believe that transmissions / gearboxes (and legs) aren't really rated on bhp but are rated on torque(?), in which case a smaller engine making less torque but revving relatively fast could put more bhp through the same trans/leg than a bigger engine making more torque at lower rpm, would just need a smaller pitch prop on the high revving small engine than the lower revving torquey engine...

This is a pic of my Cobra leg's ID plate



I've been making enquiries about a replacement prop, dealers are telling me that a prop designed for a Volvo SX leg is compatible with my leg. But I did a bit of research and found a fairly local company who can repair my existing prop (ruined by the previous owner) for £50 with 4 day turnaround time... So I'll be getting this prop fixed, trying to fix the engine knock problem, testing the boat on the water again and then maybe buying a new prop (maybe of a different pitch after testing) when it seems the engine is running properly.

This is the state of the prop at the moment (pic below), looks like it's been driven over rocks... I spoke to the previous owner about it, he said "It didn't seem to make any difference to how the boat worked".

 

[kenny nunez]

If you do change to a 351 the distributors do not interchange.
Also while the repairs are being made have every pulley that you can remove sand blasted and powder coated. Or at least try to remove the rust where the belts ride and paint them with some epoxy paint. Rusty pulleys eat up belts.
Have you thought of doing a compression test? Sometimes a stuck intake valve will cause a rocker arm stud to be pulled up and will make noise.

 

[Lpgc]

Is there a website / resource where I can enter my engine/leg code / serial number and find a list of compatible part numbers?

The product number and serial number of my Cobra leg are clear (pictured in last post above) but the numbers on the stickers on my engine are faded and more difficult to make out...









I've read that the 302W engine in boat applications has a 351W heads and cam, also that the 351W has a different firing order to the 302W due to the cam. Is this (above pic) firing order the same as the 302W or 351W?

Also read on another thread on this forum (I may come back to this and edit to include a thread link) that someone fitted mid 90's Mustang heads (GT40?) and cam on their boat's 302W engine and got a dramatic power increase... Does that seem feasible? Any downsides such as more bhp at the expense of lower rpm torque? Would the marine exhaust system mate to the Mustang heads?

I've also been thinking - After a day on the river I stopped the boat at it's mooring and removed each plug lead from the dizzy in turn to see if the engine knock went away (mentioned in one of my posts above, I was trying to see if it affected the engine knock sound, if it did affect the engine knock sound it could point to the knock being a rod knock)... It didn't effect the knock but I noticed that the engine seemed to almost stop spinning during cranking on the key sometimes. I'm now wondering if the knock could be caused by a valve problem that in turn could have been caused by hydraulic lock of a cylinder due to water ingress, the pauses/hesitation during cranking could have been caused by further hydraulic locks. When I later removed plugs there was no sign of steam cleaned plugs like might be expected with water ingress to a cylinder from (e.g.) a HG problem on a car but I'm not sure whether I should expect plugs to look steam cleaned on a cooling system that isn't pressurised?

 

[dubs283]

Is there a website / resource where I can enter my engine/leg code / serial number and find a list of compatible part numbers?

Oooff! I tried several years ago to do just this on volvos website and could not locate any parts/schematics for the "crossover" engines

Story is OMC wanted to sell their sterndrive line due to failing market share/sales, warranty eating profits, and imo a poorly designed sterndrive package. Volvo answered the call and this was the birth of volvos sx cobra sternndrive package. I've heard one of volvos stipulations of the purchase agreement was the ability to market sterndrive packages they produced under the omc cobra brand. Reason being is they wanted to sell these packages to loyal omc customers by keeping/using the omc name. For four or five seasons (circa 1993-1996) volvo was allowed this permission.

I'm guessing volvo purchased the remaining ford long block assemblies from omc in the deal. The only ford powered factory produced vovlo product I've ever seen is these "crossover" packages. Volvo continued to produce and market their AQ series drives behind gm long blocks as well during this time. Once their proprietary right to use the omc cobra brand name expired they ceased the use of Ford engines and ceased production of the AQ series drives. At this time they began solely producing their own model sx cobra drives powered by gm engines

Based on the capital "T" in your drive serial number I'm fairly certain your package is a crossover package and parts lookup may be difficult

You may try brp for parts lookup for the crossover engine/drive but no guarantee for success

 

[Lou C]

What tells me that it’s definitely a joint venture product is the sticker on the engines that says manufactured by Volvo Penta Marine of Lextington Kentucky. Yours is labeled an OMC Cobra with an OMC model # and OMC parts numbers. But, the VP & OMC parts were identical and at one time the part #s were the same too. So what ever OMC part you look up that is NLA just look up the same part for a VP. I did this when I converted my old one piece V6 exhaust to the later 2 piece design. The 90* aluminum down pipes needed were NLA from OMC but were still available from VP. Same exact part same # too. Post a pic of your whole outdrive

 

[Lpgc]

@kenny nunez , thanks, our posts crossed, I started writing my last post, had my tea (evening meal), finished writing and posted then noticed your post. Yes I intend on doing a compression test and I'll keep in mind what you said about cleaning the pulleys up. I'm expecting to be able to buy belts from a local motor parts supplier, there won't be anything special about the belts?

@dubs283 and @Lou C Thanks for the explanation and advice on parts availability.

Post a pic of your whole outdrive

OK

I don't like the look of the rusty coloured liquid/water coming out of that small hole toward toe front of the lower unit... I know I should be checking the gear oil etc. Think I'll need to change any seals too?







The strap is there because (as said in one of my posts above) when I lift the leg on the hydraulics it gradually goes down by itself. Someone said if there's no sign of any leaks on the rams it'll probably be a problem inside the hydraulic pump?

 

[Lou C]

That’s definitely the joint venture drive made by Volvo; parts are the same as the Volvo. Get a new prop that’s going to cause vibrations. The drive not staying up is likely a valve inside the trim pump. That’s a problem I haven’t had yet though so can’t help on repairs. One thing I can suggest is check your power steering fluid for leaks; the power steering actuators often leak & make a mess in the bilge. New units are about $1,000 USD and not easy to install. It’s right up against the transom mount. Some have had success with rebuilding these.

That drain hole doesn’t look right to me. Get a better pic close up. My Cobra has a drain hole but it’s higher up right near the water intakes.

 

[Lpgc]

That’s definitely the joint venture drive made by Volvo; parts are the same as the Volvo. Get a new prop that’s going to cause vibrations. The drive not staying up is likely a valve inside the trim pump. That’s a problem I haven’t had yet though so can’t help on repairs. One thing I can suggest is check your power steering fluid for leaks; the power steering actuators often leak & make a mess in the bilge. New units are about $1,000 USD and not easy to install. It’s right up against the transom mount. Some have had success with rebuilding these.

That drain hole doesn’t look right to me. Get a better pic close up. My Cobra has a drain hole but it’s higher up right near the water intakes.

Just to clarify - which Volvo drive? Will all parts be the same?

I'll be getting a new prop.

I'll check for a PAS leak but the level in the pump hasn't gone down and there's no mess in the bilge. I have noticed there seems to be some play on the steering wheel, if I turn the wheel one way there's maybe 20degrees play when next turning it the other way, if it were a car I'd be checking steering joints and for play on the rack.

I'll take a closer pic of the hole later. It looks intentional rather than damaged but I wouldn't expect a hole in the final drive assembly.

 

[Lou C]

Volvo SX
Sold here from 1994-2005 or so

 

[Lou C]

The first couple of years they called it the Volvo SX Cobra, then they dropped the Cobra and it was just the SX.
The whole deal was like this....OMC ran into financial problems in the '90s with the Cobra shift cable recall and the Evinrude Ficht problems. Volvo wanted OMC's transom design because the cut out was the same as Mercruiser unlike the Volvo AQ drives, and that made it an easier sell to boat makers because only one cut out was needed. So they took the Cobra transom mount, modified it slightly and converted the drive to shift with a cone clutch in the upper gear housing like other Volvo drives. They sold both the Volvo (silver) and OMC versions (charcoal grey) up to '98 then they bought out the rest of OMC's interest in the sterndrive division, and it was all Volvo marketing after that. So if someone tells you that you can't get parts for it because it's an OMC, well it's also a Volvo, and if they don't work on OMCs, but they do work on Volvos, same answer.
the original dog clutch OMC Cobras had a lot of shift problems in the beginning but once they were worked out, those drives are VERY good, I have run one in salt water for 20 years with very few repairs.
Want to make your life easier, paint your OMC drive Volvo silver and call it a Volvo lol. No one will know the difference till they check the id plate.

to add to this confusing story, it is actually possible to convert an OMC Cobra dog clutch to the Volvo by replacing the pivot housing on the transom mount, adding the Volvo drive and an engine driven water pump. That's how close the designs were and many people have done this if they can't get OMC service any longer. Not cheap though due to cost of Volvo parts.

 

[Lpgc]

@Lou C , Thanks, that's reassuring and seems good news.

It probably also explains why prop vendors are telling me props for the SX drive are compatible.

So does my drive have the cone clutch or dog clutch? My dad bought a Winner Viscount (cuddy boat made in Wales) in the 80's, it had a 3L straight six Volvo engine (actual Volvo, probably the same engine as an old Volvo 760?) with triple carbs and was rated at 180hp, the Volvo drive on that had left hand prop, during shifting it momentarily cut the ignition... It didn't shift as smoothly as my boat seems to shift, that was probably a Volvo dog clutch setup?

I've read (probably on this forum) that the Volvo cone clutch setup is good, seems you'd agree?

If the worst came to the worst I could remove my boat's complete powertrain and fit a Mercruiser setup without any transom work?

How much bhp / torque will this Cobra drive handle? How does it compare to an Alpha drive (I'd guess a Bravo would handle a lot more)?

I still need to take pics of the rusty stained 'drain' hole, I'll do that and post pics tomorrow.

Hope nobody minds me posting so many pics on this forum?

Simon

 

[Lou C]

Yes its a cone clutch and that Volvo SX is the equivalent of the Merc Bravo in strength they were used behind Chevrolet 454s so no worries on that end. While you could convert it to a Mercruiser it would be very expensive although you wouldn't have to do any transom work. Since you have a Ford engine no recent Mercs used Ford engines, so a change over to Merc would be the whole works, engine, drive, transom mount etc. Don't think you can mate a Ford engine to later model Merc equipment. It's been Chevrolet all the way, with Merc since the 70s. Better to stick with what you have, if you can...
I would:
get a mechanic's stethoscope and try to localize the source of the noise
if it is from a valve lifter that's a repair that might be possible with the engine in the boat
if it is bottom end, it is a lot more involved, engine has to come out
try to measure the frequency of the sound, sometimes you can figure out if it is occurring at camshaft speed or crankshaft speed. Keep in mind that the cam shaft turns at half the speed of the crankshaft. So cam related noises would be at a slower frequency than crankshaft related noises.

If the long.block you source is from a truck the cam (if oem) ought to be of proper spec to suit your needs

I love ford products, I tell random strangers on the street how great ford products are without provocation.

Unfortunately ford has never had as significant a presence in the sterndrive/inboard engine supply as gm. The market is limited for marinized ford engines so automotive is an obvious avenue for replacement. Just make sure you properly marinize the long block

Ford v-8 engines even when improperly tuned run smoother than any gm product tuned to spec or otherwise. Ford long blocks can withstand much harsher environmental treatment from an operator/surroundings. They just keep going, and going, and going

I will say the same for subaru engines, amazing durability. But that's another conversation

Ah how about the EJ-2.5? we had one (1998 Outback)....the head gaskets failed at 109,000 and again at 186,000. Those gaskets I think were revised like 5 times.
Agree about Ford V8s, old school, hard to beat.

 

[Scott Danforth]

If you go up in torque, you need to come down in gear ratio.

The cone clutches will be fine. The lower may need to be swapped

 

[Lpgc]

That's more good news regards the drive @Lou C , thanks again.

I did think it possible to be able to fix a valve train related problem with the engine still in the boat, have to remove the engine to fix a bottom end problem.

I don't have a stethoscope but I'm often listening around engines with a bit of pipe to my ear hehe... I'd probably need the boat back in the water to have a proper listen. I don't have a big enough bucket to put the leg in and I expect exhaust noise would drown out the sound of the knock without the leg in water.

I wonder if there's ever been (maybe still is) a hydraulic lock issue that could have caused the knock.. Obviously a lock issue could cause bottom end problems but I'd guess it could also cause valvetrain issues, bent pushrods etc? **In one of my posts above I described how I removed each plug lead in turn to see if the noise changed (which could point to a big end bearing problem)**.. I stopped the engine each time I switched which plug I had disabled but the engine sometimes seemed to be hesitant to crank on the starter, then would crank as normal. At the time I put the cranking hesitancy down to it maybe needing a new battery(s) but now I'm thinking the hesitancy could also be caused by hydraulic lock.

I've got a decent borescope and have used it to see inside some cylinders (haven't had time to check them all yet) but it's difficult to have a good look inside anyway due to the recessed narrow plug holes and not being able to rotate the camera very well when it's inside. I could fit a mirror attachment to better see the valves but it seems too much of a risk that the mirror attachment might come off and not being able to get it out without taking the head off. Obviously the borescope couldn't help diagnose a problem such as a bent rod, bad bearing, bad lifter, etc. But it could show a problem such as a chuck missing out of a piston crown, some types of valve damage, bore scouring and it could show water ingress from a cracked exhaust.

I'll be doing a compression test.

Heh, its usually me (on other forums) explaining how to tell whether a noise is cam or bottom end related by it's pulse frequency... But like I said before, I'd rather you assume I don't know that kind of thing than assume I do know, you'll doubtless be more familiar with these engines than I am. I don't think the revcounter works properly on this boat and I haven't yet connected a test revcounter / scope to check rpm but I think it idles too fast in neutral. Assuming it's doing closer to 800rpm than 1600rpm when doing 5mph up river I'd say the knock is valvetrain related. A test I've done before (even done remotely for other people) but not yet done on this boat is to take a recording of the engine sound at a known rpm, upload the soundtrack to my laptop then use audio software to accurately measure the pulse frequency of any knock sound to compare against rpm and find out for sure if it's occurring at crank or cam speed.

Seems that parts availability for the drive is going to be better than previously thought now we know it's effectively a Volvo SX drive?
I can buy new (or at least replacement) marine manifolds for the Ford engine, bits for the Ford302W engine itself should be easy to obtain?
Not sure about other marinising parts for the Ford engine such as marine head gaskets / water pump. Assuming I can buy head gaskets, water pump, sump and freeze plugs that should mean I can buy any replacement parts I might need, or am I missing something?

** What's everyone's thoughts on ability to check for big end knock using the spark plug / cylinder deactivation method? It doesn't seem a very conclusive test to me and it could only test for knock at the start of the power stroke... but a knock that occurs on the bottom end only at the start of a power stroke would have cam rotation frequency not bottom end rotation frequency. I did the test anyway but it didn't change the sound of the knock.

Closer pics of the hole in the drive

 

[Scott Danforth]

I don't have a stethoscope but I'm often listening around engines with a bit of pipe to my ear hehe... I'd probably need the boat back in the water to have a proper listen. I don't have a big enough bucket to put the leg in and I expect exhaust noise would drown out the sound of the knock without the leg in water.

Never ever ever try to run the drive in a bucket. you need muffs, or the boat in the water

you need the impeller flooded to prime it. unless the bucket covers the outdrive, if you want to run on land, use a bucket

I personally would pull the drive and set asside, then hook the garden hose directly to the thermostat housing. as long as you have good water flow (about 40LPM) and good pressure you can keep the motor cool

also, if the motor went thru any overheat, you most likely toasted the exhaust flappers.

exhaust flappers without the rubber bits will clang away at the back of the motor.

Since you already own the boat. Pull the drive, then pull the motor. put the motor on an engine stand and pull the pan. that is a 45 minute job to get that far. from there, you will know the health of the motor

 

[Lpgc]

If you go up in torque, you need to come down in gear ratio.

The cone clutches will be fine. The lower may need to be swapped

Thanks, makes sense.

If I only swap from the 5.0 to a 5.8 could I keep the same lower and just fit a bigger pitch prop? I'm thinking Lou said the drive can take big block power torque so it should be able to handle a 5.8..

Just hypothetical for now, I'll see what's wrong with this engine (that's causing the knock) and fix it if the fix is easy / inexpensive enough, or if it seems a better idea to put a different engine in I might swap to a 5.8. Read a thread where someone said they put GT40 heads and roller cam on their boat's 5.0 engine which made for a dramatic increase in power... Will the marine manifolds mate to any 302W/351W heads?

 

[Lou C]

Ok that hole looks ok in that pic. Rusty water is probably from internal rust on the old cast iron engine & exhaust system.
BTW there is much debate on this forum about the value of filling the engine & exhaust manifolds with no tox antifreeze after draining for winterization. Some just drain some drain & add antifreeze. I do both for 20 years & get no rusty water when water drains out of the outdrive. 20 + seasons in salt water.
Running on land do NOT use a bucket or trough no way your raw water pump will prime. You can use good fitting muffs on the outdrive. Remember these are designed so that static water pressure fills the hose from the transom mount to the raw water pump, the drive has to be under water for that to work.
Those engines were commonly used in Mustangs, Explorers and F-150s. Replaced by the modular 4.6 overhead cam V8 in the early 90s in cars but the old design continued in trucks. If you need an engine or parts check shops that restore classic American muscle cars.
As far as 5.0 vs 5.8, you have to research the difference the difference in gear ratios used between the two. Volvo used both so that info is out there.

 

[Lpgc]

Thanks @Scott Danforth , our last posts crossed.

This would be the first time I've removed a drive and I didn't know there were flappers!

I could probably muddle through but I'd rather admit I don't know what I'm doing and ask for advice / links on major work like that. I can strip and rebuild an engine no problem but it's knowing what needs to be unbolted etc to get the engine out that I'd need info on. I do a lot of work on vehicles because I convert them to LPG, but it's different to being a 'normal' mechanic because I don't often remove engines / transmissions / etc. I can rig pull-lifts from a girder across the garage but it won't have the height to lift the engine out of the boat when it's on the trailer, same story with my engine crane.

Subaru's have been mentioned above... The only time I ever damaged a car when fitting an LPG (propane) conversion was when I was over tired and shouldn't have been working on the car... I didn't realise I dropped something into an inlet port on a Subaru H6 engine before putting the inlet manifold back on... I then set off to a local forecourt to fill the car's tank with LPG and the engine stalled with a bang when I slowed at a junction. Found the engine had ingested a little bolt that must have fallen off my sleave when putting the inlet manifold back on. I ended up buying the car from the customer, removed it's engine, stripped what I needed to strip and rebuilt it with a new piston and valves, put it all back together and sold the car. Heh, I'd much rather work on a pushrod engine than a more modern and complicated design like the H6. F150's were also mentioned, I've converted a lot of American pickups including F150's, Rams, etc etc... But for the purpose of converting to LPG I don't really need to take much notice of engine model, what heads it has, cam, etc, or how those components might be compatible between different models (including how heads for various Windsor engines might be compatible with different spec/year Windsors / compatible with boat manifolds), for my job I only usually need to be concerned with fuelling aspects.