93 Force 120 Idle Problem.

[Tommyd327]

Hi everyone, I am new to the site and am wondering if someone can give me some feedback. I just bought a 93 Force 120 and the thing runs pretty good. Runs great at faster speeds. I am just having a little trouble when going through no wake areas. The motor seems to slow down too much and idle rough when in gear. When the motor is running and I take the cover off the idle picks up and I can idle forever. I think it is just an exhaust leak cuz I can see a little blue smoke in the motor compartment. I think the exhaust is choking out the carbs when the cover is in place. When it's not in place then there is enough fresh air getting to the carbs. I am just wondering how big of a deal is it to replace the exhaust gasket. Should I take it to a shop and how much should I expect to pay?

Thanks everyone,

Tom

 

[roscoe]

Re: 93 Force 120 Idle Problem.

Its not that hard to do, but could be labor intensive, depending on which gasket has to be replaced. Might be 4-8 hours labor.

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

Thanks for the help roscoe. I see you're not too far from me, I am in Waupaca WI. Have you worked on them in the past? I am not an outboard expert but I tinker. Is this something a backyard monkey can handle?

Thanks
Tom

 

[sdunt]

Re: 93 Force 120 Idle Problem.

If you don't have a parts book, you can get the diagrams here:
http://www.mercruiserparts.com/selectModels3.asp?type_id=FORC

 

[Frank Acampora]

Re: 93 Force 120 Idle Problem.

Before you change the exhaust gasket, check about 6 inches below the head for a broken or misplaced idle relief bellows. If it is missing or broken, it will let exhaust and some cooling water into the engine compartment instead of out the back holes. It is a black rubber bellows about 3 inch long and 2 inch wide. It has a spring and plastic grommet inside it. Sometimes the grommet melts and causes problems. The tapered end of the bellows should be quite nicely seated in the cast in ring on the rear shroud.

 

[roscoe]

Re: 93 Force 120 Idle Problem.

Yes you can do it.
Get yourself either a factory manual, or a Clymer repair manual, and give it a read.

You will need to lift the powerhead off, and examine the gaskets and adaptor plate, and then the exhaust bellows as Frank outlined above.

You've gotta get this thing running by July 7th, so you can join a bunch of us over on Petenwell Flowage.
Click the link for more info: http://forums.iboats.com/showthread.php?t=183975

HAve I ever worked on a Force 120? No actually. But I've worked on several other models (85, 70, 40, 50).

Keep us posted on your progress.

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

Hi guys,
I took the boat down to the lake last night and I don't think I have an exhaust leak. But, there is exhaust getting in to the compartment comming up past the big driveshaft gasket that surrounds the whole housing. I don't remember seeing the bellows Frank was talking about. Do I have to remove something to be able to see it or maybe it's just missing altogether? That kinda sounds like it could be the problem. I thought all the exhaust should be going out the prop but I can see something bubling when I have the motor trimmed down to the point where the lower cover kit touches the water which keeps the exhaust trapped in the housing and forcing its way up past the driveshaft gasket into the engine compartment. I really think it is something simple like this cuz when I take the cover off the thing purrs like a kitten and starts as soon as I turn the key.
What do you think?
Thanks,
Tom

 

[roscoe]

Re: 93 Force 120 Idle Problem.

ditto, time to pinpoint the problem.

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

Does anyone know where on the Internet I can find a schematic of this motor including the exhaust system and lower unit?

 

[valencehsift]

Re: 93 Force 120 Idle Problem.

Take off the cover, go to the back of the motor, look down toward where the peeholes are located but on the inside. You should see the black bellow coming from the motor and seating into the motor leg where the peeholes are. If you don't see it, it's gone. That is your problem! If you do see it, check for tears in it. I had the exact same problem, my bellow was split about 2 inchs, so exhaust fumes are going into the engine. This will cause it to die, fast with the cover on. This just happened to me last week. I ordered the part, but in the mean time, glued it back and she is working fine. You can take the back half of the motor leg off with ease. There are a couple screws on the very bottom and the rest you eill see going down each side and the rest ontop. Try that first, I will be you that is the problem. Let me know how it goes.

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

I checked the bellows and it is good working condition. I put the boat in the water and actually got in the water with some goggles and I could see the exaust is comming back out the hole where the shift linkage is, under water. But I took the lower unit off and there is no obstructions or plug ups where the exhaust comes out through the prop and exhaust snout. It seems like it must be missing a seal or gasket or something that is allowing the exhaust to come out the shift linkage hole. Then the exhaust travels up past the housing gasket and into the motor compartment. I looked at the schematic for the lower unit and it says there is a "Seal Exhaust" right around the shift linkage but I don't know if it is missing or I just don't know what it looks like. Maybe somebody has some advice?

Tom

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

It's time for an update.

Thank you everyone for your help concerning my idle problem! I am very happy to report my problem with the rough idle has been fixed. Finally a victory with a force. I looked at the link someone sent me for the schematic of the force engines and found that there should be an exhaust seal in the lower unit to keep the exhaust going out the snout and prop and not allowing it bubble up past the shift linkage hole. When I removed the lower unit there was no seal at all. So I ordered the seal from the local marina and put it in place. When trying to connect the lower unit back up to the rest of the motor, with the seal in place, it is very difficult to get it connected. I think someone at some time removed the lower unit and had trouble getting it back together so they just removed the seal. I can't believe the rough idling would have something to do with a seal in the LOWER UNIT. The motor runs like brand new. It idles forever and doesn't clunk out when I put it in gear. If anyone is having trouble with rough idle while the motor cover is on, you should remove the lower unit and make sure the exhaust seal is in place and in good condition. I've tried to attached pics so you can see what I'm talking about but I can't figure out how to past or attach them but The part number is F698735-1. If it weren't for all your help I would have proabaly paid those darn marina's hundreds of dollars looking for the problem. Every mechanic I talked to thought it was the carbs. Good thing I'm a cheapscate and wanted to do it myself. I think they would have messed with idle speeds and mixtures and never thought about the exhaust seal. So thanks everyone!

 

[glennrow]

Re: 93 Force 120 Idle Problem.

great news buddy.

 

[bcbaylinerboy]

Re: 93 Force 120 Idle Problem.

wow...cant beleive it..I also have a force 120..1994, and have the exact same problem ! I tried it also with the cover off and it runs great, cause the smoke is able to dissapate. well I took your part number and ordered it for myself. I hope this will solve my problem as well..And also the embarassment of constant stalling at the dock with cover on !!
Thanks to all. From Vancouver !

 

[bcbaylinerboy]

Re: 93 Force 120 Idle Problem.

blugoose7823 needs to read this whole thread. Same Problem

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

I am interested to hear if it fixes your problem also bcbaylinerboy so let me know what happens.

Tom

 

[bcbaylinerboy]

Re: 93 Force 120 Idle Problem.

I will let ya know, hope it works. Just waiting on those parts. Takes a while to getem up to the great white north !!..

 

[bcbaylinerboy]

Re: 93 Force 120 Idle Problem.

Thanks Tommyd for that exhaust
seal number..it finally came in...i installed it and just got back from 2 weeks vacation. The motor just kept idling !!!...awsome..no more exhaust leak..no stalling ..it runs great now....

 

[Tommyd327]

Re: 93 Force 120 Idle Problem.

Isn't that the coolest thing!! If you took it to a marina, they would adjust the carbs, and do all sorts of things and never find the $18 problem. They wouldn't think to look in the lower unit for an idle problem. I am so glad someone else got use out the information. Awesome!!!

 

[ElCapitan]

Re: 93 Force 120 Idle Problem.

Wow. I have the same problem, I think, with my 1993 Force 150. The problem began after a new lower unit was installed. Taking this to the shop first thing in the morning.