88 Force 85hp (3 cylinder). Engine sputters under heavy acceleration from idle.

[DunbarLtd]

Just add some sealer/ sillycone to the bolt.
You might need a washer to make it seal??

Motors with a lot of use and long time use in salt water the cover and the block gets corrosion and
milling both surfaces really helps make a seal.
The edges get eaten away making it harder to seal.

You can test the sending unit with an ohms meter.
Remove,put in pot and slowly bring up the temp

Ok thanks Jerry. I noticed the exhaust plate gaskets on my engine dont match the manual's description of order of parts to assemble. Looks like on mine they added 2 gaskets to the block then the spacer plate then the cover.

Im almost positive this is wrong but it looks like its a factory install. Like I said all the bolts looked like theyve never been touched but I could be wrong and whomever replaced the gaskets did it wrong.

 

[tg3690]

Dunbar....Also, the bypass valve is kind of hard to get to. The bypass cover is a small oval shaped cover with 2 bolts at the bottom left side of the exhaust port cover. When I was taking the cover off the lower bolt broke off. So in order to get access to it with a drill I unbolted the support plate and was able to lift it 4 inches or so. This gave me direct access to it and the drilling commenced. It did not end well, got off to the side and ate up some of the aluminum. After removing the spring and bypass valve I cleaned that cavity the best I could and then put the cover on with JB Weld. Only other option would be to have it welded, drilled and tapped for a new bolt since I damaged it. The JB Weld filled in the damaged area and permanently sealed the cover. And since there is no valve installed I will never have to replace it. Not a perfect solution but one that worked well for a 41 year old outboard.

 

[tg3690]

Ok thanks Jerry. I noticed the exhaust plate gaskets on my engine dont match the manual's description of order of parts to assemble. Looks like on mine they added 2 gaskets to the block then the spacer plate then the cover.

Im almost positive this is wrong but it looks like its a factory install. Like I said all the bolts looked like theyve never been touched but I could be wrong and whomever replaced the gaskets did it wrong.

Hope this diagram helps...

 

[tg3690]

That diagram came out small, but from the upper left the order is Exhaust port cover, gasket, exhaust plate, gasket, then to the head.

 

[DunbarLtd]

That diagram came out small, but from the upper left the order is Exhaust port cover, gasket, exhaust plate, gasket, then to the head.

What exactly is the function of the valve???

I have the manual and it shows the exact diagram you posted. So if thats the correct order then either the factory screwed up on mine or someone replaced them and didnt know what they were doing.

And hopefully the bolt wont break. This motor I dont think has ever been run in salt water. Most bolts Ive removed have come out fairly easily so Im betting itll be OK.

Its actually pretty clean for how old it is. Thats one of the reasons I bought it. Thanks for the info.

 

[tg3690]

What exactly is the function of the valve???

I have the manual and it shows the exact diagram you posted. So if thats the correct order then either the factory screwed up on mine or someone replaced them and didnt know what they were doing.

And hopefully the bolt wont break. This motor I dont think has ever been run in salt water. Most bolts Ive removed have come out fairly easily so Im betting itll be OK.

Its actually pretty clean for how old it is. Thats one of the reasons I bought it. Thanks for the info.

Did a lot of research on this myself....the bypass valve fits into a hole in the block and is held in place with a spring. At high rpms the water pressure builds up in the block and forces the valve to retract on the spring allowing water to enter the area between the exhaust port cover and the exhaust plate. This provides extra cooling at higher power settings and also serves as a way to relieve excess water pressure at high rpms to keep from blowing your water system gaskets. Your water pump/impeller creates a lot of pressure at high power settings.

My engine has never been in saltwater, but that one bolt on the bypass cover broke bigger than Dallas. I think that bolt corroded from the inside, maybe it is exposed to the water jacket somehow. Also, that one bolt on the port cover was hard to get out without breaking. That bolt extends out into the exhaust area past the exhaust plate so it gets toasted pretty good. You will see it if you replace those gaskets.

 

[DunbarLtd]

Did a lot of research on this myself....the bypass valve fits into a hole in the block and is held in place with a spring. At high rpms the water pressure builds up in the block and forces the valve to retract on the spring allowing water to enter the area between the exhaust port cover and the exhaust plate. This provides extra cooling at higher power settings and also serves as a way to relieve excess water pressure at high rpms to keep from blowing your water system gaskets. Your water pump/impeller creates a lot of pressure at high power settings.

My engine has never been in saltwater, but that one bolt on the bypass cover broke bigger than Dallas. I think that bolt corroded from the inside, maybe it is exposed to the water jacket somehow. Also, that one bolt on the port cover was hard to get out without breaking. That bolt extends out into the exhaust area past the exhaust plate so it gets toasted pretty good. You will see it if you replace those gaskets.

So its ok to run without that valve then? Why did you decide to remove it? Sounds like its necessary?

Also I checked the gaskets and i can see the spacer plate. I just didnt notice it before because its so thin but its in between the two gaskets. Still gonna replace them though.

One other thing....I noticed the timing adjuster bolt is "backwards". I took a screen grab from a video i watched and included the pic in this post. I hope it shows up.

This srceen grab was from a 125hp(same year) but I think mine should be the same.

Anyways on my motor the black things are on opposite sides so the slotted side of the adjuster screw is facing the inside.

Someone must have messed with this thing and didnt put it back correctly. How in the world can you adjust the timing if the slot on that screw is facing in towards the flywheel? Doesnt make sense. If my assumptions are correct would this perhaps cause an issue where the timing tower can not be advanced far enough resulting in lack of power at the top end?

Ive had this thing for 3 years and if thats true im gonna smash something. lol. This is the first time i noticed it was backwards. I looked at it many times and thought how in the hell can i get a screwdriver in there.

 

[tg3690]

So its ok to run without that valve then? Why did you decide to remove it? Sounds like its necessary?

Also I checked the gaskets and i can see the spacer plate. I just didnt notice it before because its so thin but its in between the two gaskets. Still gonna replace them though.

One other thing....I noticed the timing adjuster bolt is "backwards". I took a screen grab from a video i watched and included the pic in this post. I hope it shows up.

This srceen grab was from a 125hp(same year) but I think mine should be the same.

Anyways on my motor the black things are on opposite sides so the slotted side of the adjuster screw is facing the inside.

Someone must have messed with this thing and didnt put it back correctly. How in the world can you adjust the timing if the slot on that screw is facing in towards the flywheel? Doesnt make sense. If my assumptions are correct would this perhaps cause an issue where the timing tower can not be advanced far enough resulting in lack of power at the top end?

Ive had this thing for 3 years and if thats true im gonna smash something. lol. This is the first time i noticed it was backwards. I looked at it many times and thought how in the hell can i get a screwdriver in there.

I decided to leave the bypass valve and spring out because that bolt broke off and I did some damage trying to drill it out. My fix was to permanently seal the bypass cover. Did not want to install these parts and not be able to service them when needed. I asked JerryJerry about this on another forum and he said it was not absolutely needed. Mastertech Marine said the same thing. It is better to have water moving through there than NO water at all which was my situation with the plugged up valve. Am glad I checked it but regret screwing up the broken bolt. If both bolts would have come off I would have installed the valve and spring as designed.

 

[DunbarLtd]

I decided to leave the bypass valve and spring out because that bolt broke off and I did some damage trying to drill it out. My fix was to permanently seal the bypass cover. Did not want to install these parts and not be able to service them when needed. I asked JerryJerry about this on another forum and he said it was not absolutely needed. Mastertech Marine said the same thing. It is better to have water moving through there than NO water at all which was my situation with the plugged up valve. Am glad I checked it but regret screwing up the broken bolt. If both bolts would have come off I would have installed the valve and spring as designed.

Ok thats good to hear. Thanks for the information.

 

[jerryjerry05]

They changed the cover in 87-88 so make sure the gaskets are the right ones when ordering.
Made that mistake

The steel screws and aluminum block have a chemical reaction, dissimilar metals.
They corrode and that builds up around the threads almost welding them in place.
I've used a lot of things to help get them loose.
PB Blaster and a torch seems to work the best.

 

[DunbarLtd]

They changed the cover in 87-88 so make sure the gaskets are the right ones when ordering.
Made that mistake

The steel screws and aluminum block have a chemical reaction, dissimilar metals.
They corrode and that builds up around the threads almost welding them in place.
I've used a lot of things to help get them loose.
PB Blaster and a torch seems to work the best.

Ok Jerry. Noted on the gaskets.

So If I have to remove the timing adjuster bolt because the timing is off, whats the best route? Just take the intake and reeds off? I cant get a screwdriver from under to remove the black plastic clip the threaded adjuster screws into. The adjuster is in backwards for some reason. I can get to the outer clip because it has a nut on it. But the inner one has a flat head screw holding the black clip onto the trigger arm. So I have to get a small short screw driver under there but its impossible with everything assembled. Just no room.

 

[DunbarLtd]

I just watched some other videos and i can clearly see that their motors also have the timing adjuster bolt facing the flywheel. As in the slotted side.

Was this design done on purpose?

From other videos i also watched i see a 90hp for example with the slotted bolt facing outwards. This seems like it is the way it should be but on mine and the others ive seen(same year and motor size) the slotted end is facing the flywheel. Seems like a dumb design idea to me.

I dont necessarily want to change the timing at the moment i just want to make sure it is on there correctly and not possibly causing any issues.

Other small thing I noticed was that the trigger will rotate backwards after its full travel is reached after the throttle cam is pushed all the way forward.

Basically, the trigger will reach it's full extension before the throttle cam is all the way forward and then as i push the throttle cam to 100%, the trigger actually moves backwards just a hair. Maybe a 1/16 of an inch but the trigger is definitely moving backwards. Im not sure if this little movement affects timing or not @ WOT, but it is just something I noticed.

Is there any way to adjust this problem or is this normal?

Im not sure which way the timing works but it could be retarding (or advancing) the timing just maybe a 1/2 degree when i give it full power... theres a video ive watched where a guy showed the same problem but i can not find it at the moment.

Just trying to cover all the bases here so im not missing anything.

Other than this small issue everything else i inspected looks good.

 

[jerryjerry05]

I wouldn't worry about the trigger moving back.
Do the static timing.
Most don't run wide open.

The slotted screw, maybe adjusts easier when full throttle?

 

[DunbarLtd]

I wouldn't worry about the trigger moving back.
Do the static timing.
Most don't run wide open.

The slotted screw, maybe adjusts easier when full throttle?

OK sounds good. I do run wide open a lot. I fish a lot of spots so i like to get there in a hurry. Of course If i had the money Id just get a 250hp bass boat and be done with it, but i bought a budget boat and am trying to get as much out of it as possible, aside from just doing a complete rebuild....

After doing the exhaust gasket I will update and see how it ran. Im not convinced it will fix the problem but at least I will have solved the water leak. Anyways thanks again for the responses. Helps more than you realize.

 

[jerryjerry05]

Ordering gaskets.
In 87-88 they changed the bolt pattern on the bigger Forces.
Me(I know everything) looked up a 88 Force and ordered gaskets for the exhaust.
Got them in and they wouldn't fit
Make sure you order the right ones.

 

[DunbarLtd]

Ordering gaskets.
In 87-88 they changed the bolt pattern on the bigger Forces.
Me(I know everything) looked up a 88 Force and ordered gaskets for the exhaust.
Got them in and they wouldn't fit
Make sure you order the right ones.

Installed the tach last night. Went out today.

Sillycone on the exhaust cover bolt sealed the leak.

Water pressure while wot around 10-12psi. Still gonna do the water pump cuz its time.

Idle was 750rpm in gear. Got up to around 800rpm in gear at the end of the day around noonish. Temps outside were bout 100F. Increased heat have something to do with idle in gear rpms???

Air screws back to 1 turn out. Idle speed is 3.4mph +/- .2

Top speed was 30mph @ 41-4200 rpm on tach. First couple runs of the day.

Last run back to dock it picked up to 32.5 mph. So its still intermittent. Id say wot rpms are a little low. The added speed didnt look like it made the rpms go up much really.

I may empty all the cargo. I added 2 27 group batteries for small trolling motor. And have bunch of tools up front. Just curious what it will do with less weight.

Then I may have some better idea whats going on. If it still does it even with all the weight removed then I know something is up...

 

[jerryjerry05]

If your only getting 41-4200 then there's a problem.
What size prop?
What size/ make boat?

 

[DunbarLtd]

If your only getting 41-4200 then there's a problem.
What size prop?
What size/ make boat?

13.25" x 17
Bayliner Capri 17 ft 1988. Came stock with the Force 85hp.

 

[jerryjerry05]

1988 I drove one of these to an in water boat show in Annapolis, Md.
You should be running almost 40 and 5500rpm.
????

 

[DunbarLtd]

Ok good to know. Any ideas where to start troubleshooting?