How hard is it to get the 800 Stringer to be a smooth running unit?

[vi]

Long Thread ---- I have been considering changing out my 79 OMC Stringer 800 out with a Merc Gen 1 305 Chev, I know alot of work. well it seems that there are alot of OMC guys that have been keeping theirs running with a lot less work than the swap. I am very mechanically inclined, with some physical limits. I have had two companies in two different states take a low hours well running unit and mess it up. Now I have a good OMC guy but cannot afford to pay his rate for everything. The drive is now a mechanical,with another different interrupter. It has a month of use on it as it was down May & June. I have an issue that I am having trouble with it dying when it comes up to the slip, good thong my dock box has give, when I back up out of the slip and try to go forward it dies, very dangerous to me and others,this is when the engine is warmed up. I redid the transom stringers and floor with some help, bad advice was to keep the low hour OMC at this time as there were alot of Mercs and Volvos around to replace it with.
At this point I'm thinking I'll run it till I can't get or afford parts. Alot of folks say don't buy a used OMC, but I have one and a used boat,Merc/Volvo, might be available as money better spent in a couple of years while I keep this one running. I purchased this boat new in 79 I thought I knew about its upkeep,kept garaged or covered, changed fluids etc. until I found the rot, and had the motor and drive looked at. The hull is now very solid a deep Vee. I appreciate any opinions.

 

[Bridar]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

Has it had any upgrades? Still running a breaker points distributor? Original carb? Eventhough its a 351 Ford engine, there are many possibililities to troubleshoot. Have you got a factory OMC manual?

 

[vi]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

No upgrades on the OMC the engine is a stock 351 Ford runs great. I think the stalling is related to the shift interrupter and have read several threads on I Boats about adjusting it. if this is the problem, I also played with the rpms. The OMC drive was upgraded from a Hydro mechanical to a mechanical, a new shift interrupter had to be installed to be compatible with the mechanical unit. I have the Seloc and Clymer manuals.

 

[southkogs]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

My personal opinion - changing drives when you were doing the hull work would have been the time. Now, with all that work done ... stay and fight out the OMC. They're not impossible to find parts for, and even a replacement drive is going to be more inexpensive than all the labor to rework the hull.

My shift is electric, so I don't know much about the mechanical shift. Are you having any problems once your out on the water, or is it only at idle working in port?

 

[Howard Sterndrive]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

I have an issue that I am having trouble with it dying when it comes up to the slip,

the title of this thread is somewhat misleading ...it sounds like your boat has an issue of the engine "stalling"

do you have a factory OMC manual? if so what year is it for? might want to get a 1982-1985 version to see how the ESA is supposed to work. Make it how the manual shows.

the installation of a mechanical lower and what ever sort of ESA or shift interrupt system that was installed is probably the area you want to look at. Was the shift converter changed? I don't know what is different in them, but they're different despite having the same part number hydromech to full mech.

Bypassing the interrupt or ESA system for diagnosis of the stalling is the first step. If that doesn't make the problem go away, you have a carb issue or other issue on the motor- nothing to do with "800 Stringer" per se.

Repowering the boat will be many times the amount of labor of just diagnosing a stalling problem.

 

[vi]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

Not having any trouble out on the water,just at the low speeds mainly from forward to reverse to stop the momentum of the boat. Its not a carb issue, I,m pretty sure just rebuilt it and she runs good. When my mechanic installed the new lower he put a new interrupter on as he said the mech required a different one, of coarse I just had a new one put on the hydro mech lower. My mechanic had me turn up the idle to 1800 rpms, this I did one time out and I could see it would just tear something up.Title of my post I guess means I don't want to go the labor to change the drive to a Merc and would like to get this drive more dependable. Most of my research says guys have a spare lower or drive as a back up.

 

[Howard Sterndrive]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

so no manuals eh..

I just had a new one put on the hydro mech lower.

a new one of what?

hydromechanical shift 800 series drives used no ESA or shift interrupt of any type.

You'll have to make a decision between hands-off or hands-on. If the latter, you need to buy a manual or two (one for 1979, and one for 83/84/85 whatever)
Keep taking it back to the mechanic or fix it yourself, but don't mix and match...that will just frustrate your mechanic and you too.
Some pics of your shift interrupt system might help us understand what you have there now. Do you have an ESA module? or do you have a Mercruiser style interrupt system using the OMC Cherry switch. Do you have points ignition or electronic?

The way to eliminate the carb is not to rebuild it, it is to not touch the carb, disable the ESA or whatever you have and see if the problem is still happening. It's a process of elimination.
As soon as you touch the carb, you have no idea if it was an issue. That's just an example that applies to the distributor, and ignition switch and everything else that makes the engine run right.

If the interrupt system was the issue, a mechanic would just adjust it. If that wasn't successful, they'd just unplug it. I'm surprised you can muscle it out of gear at that high rpm. You are destroying a $700 shift cable as well as smashing up the lower unit dogs shifting at those rpms. I would seriously question the "mechanic" that suggested 1800 rpm idle speed.

Reverse is your brakes. Treat the shift system like a safety system.

 

[southkogs]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

Most of my research says guys have a spare lower or drive as a back up.

Yup - I've got one myself. I'm also rebuilding one (VERY slowly) to learn more about it.

Not having any trouble out on the water,just at the low speeds...

Will it idle under 800 RPM? Or do you have to keep some "throttle" in it to keep it alive?

Title of my post I guess means I don't want to go the labor to change the drive to a Merc and would like to get this drive more dependable.

My experience so far has been to become my own mechanic ... that means a lot of posting here on iBoats and praying that Howard Sterndrive is watching the board that week Listen to him, he knows these drives.

 

[Zyen]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

...My mechanic had me turn up the idle to 1800 rpms....

this is just my advice (and opinion)....stay away from this "mechanic". he doesn't know omc mech drives (or dont care, which is worse) and is giving you a potential disaster (at worse) with the idle up that high. mine (4.3 v6 omc 800) idles ~650.
not to mention any mechanic suggesting a boat idle 1500 rpm.

If the interrupt system was the issue, a mechanic would just adjust it. If that wasn't successful, they'd just unplug it. I'm surprised you can muscle it out of gear at that high rpm. You are destroying a $700 shift cable as well as smashing up the lower unit dogs shifting at those rpms. I would seriously question the "mechanic" that suggested 1800 rpm idle speed.

Reverse is your brakes. Treat the shift system like a safety system.

out of gear isn't as much a problem for the mech shift like the hydro-mech and electric shift. the dog is different (slightly), as the mech shift uses constant tension on the cable to hold the tranny in gear, and not beveled ends on the dog. (mine are square cut)
however, i totally agree with the rest. that high idle will destroy your lower end and possibly the (very expensive) cable as well.


now, it sounds to me like the esa isnt adjusted right. the mech shift uses the esa to 'kill' half the engine while the operator is shifting gears FROM neutral INTO gear (either way....neut->forward and neut->reverse). after the drive is in gear, the esa is disengaged. both of these are done via microswitches on the shift convertor mounted at the rear of the engine. the factory manual has detailed information about setting these switches, and many other things, for correct operation.

the omc drives can be quite dependable if correctly maintained.

i also have a spare lower....just in case.

 

[vi]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

a new one of what?

A new shift Interupter or a different one.\
looks the same as the old one he took off. this one the brass colored thing..The thing the shift cable is attached to (white thing)was changed 2 mechanics ago, he said it was supposed to be replaced under recall and I was lucky he could find me the replacement, $$$, this guy was the beginning of my problems with boat mechanics.After mechanic # 3 was when I thought it might be easier to just change out the drive.
The carb I did earlier in the season before drive problem, motor runs great.
After leaving the dock I realized the higher rpm thing was going to just tear something up and I brought them back down about 700 rpms..
I am going hands on as you say Howard and am looking for the OMC manual as you say I'll probably need one for the mech lower. I don't know why the brass thing had to be changed but it was and I was told for the mechanical drive. The Motor is stock with points and manual distributor.
Its not that I have to muscle it out of gear, it comes out smooth but when I put it in forward or reverse it dies. It starts right up and goes in smooth.
Thanks again all for the help!

 

[Howard Sterndrive]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

that triangular plate and switch and weird cam is something fabricated up to try to get the job done, but I doubt it's ever going to work right...you're on your own for adjusting it because it is homemade.
If you get a factory manual, and set yours up with original parts (ebay) you can adjust it to spec and that will fix the stalling.
Sounds like you like your engine, might as well just fix it... shouldn't be a lot of work at all.

You do have an ESA module, but just laying in there... not the best.
I would just mount that up and then try to source a 1982-1985 shift converter box complete

Look for parts painted silver. e.g. -this is how the proper setup should look

That was the OMC colour used beginning late 1984 to the end of the stringers. That way you'll be sure you're getting mechanical shift parts.... then you know the 1984 or 1985 manual will work for adjustments.

shop.evinrude.com is good for looking at exploded parts diagrams online for part number verification.

 

[Howard Sterndrive]

Re: How hard is it to get the 800 Stringer to be a smooth running unit?

did some googling of your ESA part number - 0982494 , which comes up as a 1979 accessory ESA system. weird. maybe it isn't homemade... some sort of accessory attachment for difficult to shift hydromechanical drives?

anyways, I can't find any literature or adjustment procedures to go with it, but just following the procedure in a later service manual should get it diagnosed.
adjustment shown here:
http://www.crowleymarine.com/product_support/omc/mechanical.cfm

still might not be designed to work with a mechanical lower unit though.