1993 OMC 5.8 EFI and drive system conversion to Volvo Penta

[Rhc]

I have owned this boat and OMC motor drive system since new. The model is 58FAVRJVN serial T01255989. I find it more difficult to adjust the interrupters and cables to retain easy shift changes. I am considering information from https://www.marinepartsexpress.com/PDF/volvo/SX_Cobra.pdf. This deals with conversion to Volvo SX Or possibility DP R? It looks reasonably straightforward. I understand the purchase of a motor mounted water pump is required, is that available? My engine/drive is pristine and has about 475 hours. I’ve done my own maintenance.
I would like to make the shifting much easier and understand the cone drive system by Volvo will accomplish this? Although it is a consideration, the motor electronic control module is not available anymore, I am banking on the EMC to be reliable so changing the engine is not likely an option given its low hours in top condition?? Can you advise me on the feasibility of conversion, cautions and material costs. Is it better to locate a USED Volvo compatible drive and a new “helmet” for drive fit up to OMC transom? Hope some can help —- Rhc

 

[Lou C]

This has been done, and V/P also used that same 5.8 Ford engine on the early years of the SX model. If the shift cable is in good shape (low drag) and adjusted properly, the drive lower unit is in good shape (gears and clutch dog as well as shifter mechanism inside) the original Cobra with dog clutch shifting can shift VERY well, mine does and has only needed a few repairs over the years. If you can't do it yourself though then it can be very tough to find someone who knows how to set these up right.
So that's where the conversion might make sense but only if you can do it with used parts, and a reman drive. Otherwise way too expensive. There are other details that go along with it, one you have to add a crankshaft mounted raw water pump, the other is you may need to add spacers inside the trim rams to keep the drive from raising up too high when trimmed all the way up, and there was also some issue I recall mentioned with the trim ram rod/bushings. Not sure what the solution to that was.
The engine issue with the ECM, is something else, that has a system that there are no parts for except used. The best way to deal with it is to convert it to a conventional carb set up. Simple, parts are everywhere (Holley 4160 4bbl) that's what was used before they went to this "improved" efi system. I would not spend a nickel on that EFI system, too many parts are NLA. You'd need a Ford 4 bbl intake for the 5.8, the carb and see if you can use a mechancial Carter fuel pump. The carb, and pump can be bought new, the intake you'd have to get used, from Ebay. Another complication is the distributor, you'd have to find a marine unit that can work with out that ECM. Earlier models used a Prestolite points unit. Might be able to find that on ebay as well....Hardin Marine sells a Petonix marine distributor for this engine, that would nicely solve that problem.
So if you convert to the SX and run it till you have an issue with the ECM/EFI, you have options to make the engine maintain-able with aftermarket parts, and not have to worry about all the NLA OMC stuff.
Not a simple job as you can see...make sure the boat is really worth it.
My way of dealing with this is that I have a lot of spares, spare drive, transom mount, and all related parts (trim pump, power steering actuator, pump, exhaust Y pipe, etc anything that can't be found easily). The shift cable adjustment I taught myself to do about 10 years ago, I adjusted it once and it's been fine ever since. The key to this job is not to take short cuts, make sure each step is done right, then keep the engine in good enough tune so it will run reliably at 600 rpm and not stall when the ESA lowers the idle to 450 to shift out of gear. Doing these things mine shifts with 2 fingers almost as smooth as a Volvo, is quiet, no odd noises, etc. The rest of the boat (wood rot) gave me fits, the OMC stuff I have not had much trouble with at all, surprising I know.

 

[Rhc]

This has been done, and V/P also used that same 5.8 Ford engine on the early years of the SX model. If the shift cable is in good shape (low drag) and adjusted properly, the drive lower unit is in good shape (gears and clutch dog as well as shifter mechanism inside) the original Cobra with dog clutch shifting can shift VERY well, mine does and has only needed a few repairs over the years. If you can't do it yourself though then it can be very tough to find someone who knows how to set these up right.
So that's where the conversion might make sense but only if you can do it with used parts, and a reman drive. Otherwise way too expensive. There are other details that go along with it, one you have to add a crankshaft mounted raw water pump, the other is you may need to add spacers inside the trim rams to keep the drive from raising up too high when trimmed all the way up, and there was also some issue I recall mentioned with the trim ram rod/bushings. Not sure what the solution to that was.
The engine issue with the ECM, is something else, that has a system that there are no parts for except used. The best way to deal with it is to convert it to a conventional carb set up. Simple, parts are everywhere (Holley 4160 4bbl) that's what was used before they went to this "improved" efi system. I would not spend a nickel on that EFI system, too many parts are NLA. You'd need a Ford 4 bbl intake for the 5.8, the carb and see if you can use a mechancial Carter fuel pump. The carb, and pump can be bought new, the intake you'd have to get used, from Ebay. Another complication is the distributor, you'd have to find a marine unit that can work with out that ECM. Earlier models used a Prestolite points unit. Might be able to find that on ebay as well....
Not a simple job as you can see...make sure the boat is really worth it.

So glad to find a subject matter expert! Your details are great and very helpful. I have assumed the shift difficulty was due to set up of interrupter switches? This is usually where I check the cable lengths etc. Would I be better to consider the lower drive -- it seems you can buy a new or reman for about $ 1500 or say less than 2k? I have opened up my lower drive and did not seen excessive wear. I did have a senior tech look over the pieces and he did not see a problem. I am not sure if that information was good and it was from 4/5 years ago so things could have changed. Can I trust the parts source company's on line? Do you have a recommendation for replacement drives? New or renan? Used sounds to risky given the difficulty to rework locally. Is the difficult shift changing more likely to be the in drive. It could be least expensive option and hope for the best on the rest? I expect to use the boat for less than the next 5-7 years max due to my age. Is a used motor/drive change out to a used set would likely to cost 10k + ? Not sure if that would be justified? Before I do anything I wait to here your input. If required could we exchange phone numbers?? Thanks again.

 

[Lou C]

It depends on what shifting difficulty you are having....not going into gear....popping out of gear....or not coming out of gear. The last is the most common problem.
To start, the adjustment process begins with the drive off. You check the shift rod height against factory specs, and make sure it shifts from N, to FWD, to REV without too much effort.
Next the shift cable gets disconnected at the shifter bellcrank and up on the engine bracket. You measure the drag in both directions, with a fish scale. It should not exceed 2.5 lbs.
While you're there, clean out the pocket where the shifter bellcrank lives, you can get crud in there that jams up the bellcrank and causes difficult shifting.
Next you adjust the transom shift cables using the 2 special OMC tools to ensure proper adjustment. Then re-install the drive, and adjust the remote cable. You want equal travel on both sides of neutral.
Lastly make sure the ESA system works, it should only be triggered when shifting out of gear with the boat in the water with a load on the prop.
This is a very abbreviated version of what you have to do, I'm not sure if you covered all these points in the past, but that's basically it.
As far as where to get parts, and reman drives I don't really know, I used a local mechanic who was great but they retired. I like TCI Electronics/Marine in Canada, I called them to discuss rebuilding my spare drive and they obviously know this drivesystem. If I need a reman I will probably use them.
For regular parts I’ve used marine engine dot com, and Crowley marine dot com. For NLA parts, I use NLA marine & eBay.

 

[Rhc]

So glad to find a subject matter expert! Your details are great and very helpful. I have assumed the shift difficulty was due to set up of interrupter switches? This is usually where I check the cable lengths etc. Would I be better to consider the lower drive -- it seems you can buy a new or reman for about $ 1500 or say less than 2k? I have opened up my lower drive and did not seen excessive wear. I did have a senior tech look over the pieces and he did not see a problem. I am not sure if that information was good and it was from 4/5 years ago so things could have changed. Can I trust the parts source company's on line? Do you have a recommendation for replacement drives? New or renan? Used sounds to risky given the difficulty to rework locally. Is the difficult shift changing more likely to be the in drive. It could be least expensive option and hope for the best on the rest? I expect to use the boat for less than the next 5-7 years max due to my age. Is a used motor/drive change out to a used set would likely to cost 10k + ? Not sure if that would be justified? Before I do anything I wait to here your input. If required could we exchange phone numbers?? Thanks again.

So glad to find a subject matter expert! Your details are great and very helpful. I have assumed the shift difficulty was due to set up of interrupter switches? This is usually where I check the cable lengths etc. Would I be better to consider the lower drive -- it seems you can buy a new or reman for about $ 1500 or say less than 2k? I have opened up my lower drive and did not seen excessive wear. I did have a senior tech look over the pieces and he did not see a problem. I am not sure if that information was good and it was from 4/5 years ago so things could have changed. Can I trust the parts source company's on line? Do you have a recommendation for replacement drives? New or renan? Used sounds to risky given the difficulty to rework locally. Is the difficult shift changing more likely to be the in drive. It could be least expensive option and hope for the best on the rest? I expect to use the boat for less than the next 5-7 years max due to my age. Is a used motor/drive change out to a used set would likely to cost 10k + ? Not sure if that would be justified? Before I do anything I wait to here your input. If required could we exchange phone numbers?? Thanks again.

Your input is excellent and very accurate . Thank you. My main problem occurs when docking the shift will not move from forward to reverse without significant pulling. Similarity when I go from reverse to forward it is a restrictive motion. Do cables stretch that much and in some 3 year time line?
My first action will be to measure the selector shaft height As you indicated. I believe I have managed to complete all the other tests in the past as you have suggested. I have the original OMC manuals that came with the drive. These manuals do cover in detail the settings that you indicated. I will double check but was done three years ago. Should these settings move that quickly?
I’m not sure that I have checked the shaft height you referred to, so will start there.
I have confirmed the lower drive is available from your recommendation at TCI electronics for about $1600. Now how do I determine if the lower drive set up and condition could be the underlying problem? What would I look for in the drive to determine its condition?

 

[Lou C]

You should always hesitate in neutral when shifting from Fwd to Rev & vice versa. Check to make sure that the ESA system is lowering the idle speed when you shift from Fwd or Rev to neutral. Your normal idle should not be higher than 600 rpm in gear. If you trigger the ESA interrupt switch is should lower the idle to 450 rpm. If not you will have the problem you describe. The adjustments don’t change but the cables can wear and get stiff or they can stretch if you have to force it out of gear. A properly adjusted Cobra with functioning ESA & good cables & proper idle speed will shift to neutral with just 2 finger pressure on the control. Mind does…