1998 Force 50hp possible oil/gas leak?

[gaangus]

Engine ran fine, idled for 15 min, I put it in gear and after a short time it just died. Then I could not get the thing to kick over. I put the fuel in the carb and it started fine, then died again. When I got home I notice what appeared to be oil (and smelled like gas) had seeped out between the seam of the trim housing assembly and the Drive shaft house assembly. I pulled the lower unit and it looks like oil had come down the drive shaft assembly. The top on the motor looked fine (no oil or gas spil). I don't see the leak anywhere. I am continuing to check fuel lines but no luck so far. Any ideas on this? Thanks in advance.

 

[roscoe]

Re: 1998 Force 50hp possible oil/gas leak?

It is normal for excess unburned fuel to exit through the motor leg.

But, if there is too much, there could be a problem.

If it has never been done, it is time to change the fuel pump diaphragm.
$20 kit from Mercury, 30 minutes do change it.

What happens is, the diaphragm leaks, and the fuel runs directly into the crankcase, causes a flooded condition, and then runs out into the lake.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

I will give it a go. Thank you for the quick response.

 

[jerryjerry05]

Re: 1998 Force 50hp possible oil/gas leak?

Do what Rosco says and then do a compression test.
Plugs burning OK?
Water in the cylinder?

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

Plugs looked fine and I see no water.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

I rebuilt my fuel pump about six months ago. I see no gas or oil around the fuel pump. I did notice this though......

When I pulled the lower unit, I noticed this 1/4 inch dark black oily sludge caked around the inside walls of part of my drive shaft assembly. The water tube and seal look fine with no sludge. This gack stuff is thick, almost resembling trailer hub grease, but black in color. I am going to pull the impeller to see if it got inside and gummed up the works there. I have included photos of my initial observation ( seeping of oil out between the seam of the trim housing assembly and the Drive shaft house assembly) and of the sludge. I did run this is a bucket for a short time when I was adjusting the shifting rod, but that wouldn't cause this would it? Has anybody seen this before?



Thanks

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

When I pulled the Trim Cover. I can see how the fuel/oil could drain from the lower cowl into this cover if the fuel pump were bad. I also noticed a herniated gasket sticking out. I am not sure if this an exhaust gasket or what? Is this a really bad thing and will it cause some kind of fuel/water/exhaust compromise? I looks to me like I have to pull the power head to fix it. Any thoughts? Is this causing my sludge issue?

 

[jerryjerry05]

Re: 1998 Force 50hp possible oil/gas leak?

Looks like there is some kind of leak somewhere.
The gasket if there anything leaking around it I'd worry.Looks like it's around the water passage.
That kind of buildup,not seen before.
Looks like lots of unburned oil/gas.
Wonder where it comes from?
The bottom seal under the bottom piston?
The fuel pump seal?Diaphram leaking back into the motor and the bottom seal leaking?
The stuff on the outside is unburned gas oil too.Probably from tilting the motor.

Do a compression test and maybe a leakdown test.
Get a mechanic to look at that one!!J

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

I found small drips of water coming out from the ruptured seal. Doesn't seem to big of a deal.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

I rebuilt the carb, replaced the fuel filter, blew air through all the fuel lines, rebuilt the fuel pump, flushed the gas tank, replaced the fuel, replaced the plugs and adjusted the mix. I got it running pretty well.

I also flushed the sludge out of the exhaust and tore down the lower unit to check for an oil leak or a compromised impeller. All was good so I replaced the oil and reassembled. Now that I have it running again and baseline service, I can look for changes and leaks. Next will be compression testing. Ran out of time as I wanted to catch the Olympis closing shows.

 

[jerryjerry05]

Re: 1998 Force 50hp possible oil/gas leak?

All that sludge and carbon would worry me.
Do the comp test and post the results.

FrankA you see the pics??Any idea??

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

Will do, but it might be a day or two away. Let me run something by you though...........

When I was adjusting my shift linkage, I was running my motor in a 50 gallon can. Although It didn't spend hours in there, it ran for a good twenty minutes off and on. Could the build up be recirculated oil from slushing around in the tub? When I ran the motor on ears, I saw no oil at all. I also noticed that the sludge collected near the bottom towards the lower unit and didn't appear up near the lower cowling. I have determined that the oil is not from the lower unit. Just a thought (or wishful thinking). Thanks for your help on this.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

Compression Test: 130/128-130. I guess this is ok for both cylinders right? I think I am ready for a water test drive. Last time I got stranded with the gators. Lets hope the stall issue was from switching fuel tanks and may have picked up some gunk from the new tank. Thats another matter for another day. It seems to be running good now after the Carb clean. I put in a new internal fuel filter and added a new inline 10 micron filter. Watching for oil deposits. Thanks for the help.

 

[emoney]

Re: 1998 Force 50hp possible oil/gas leak?

I'd drop the lower unit again, after you've water tested, just to make sure that sludge isn't back. I've ran plenty in buckets and never seen that.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

I pulled it out of the water and went to work cleaning carbs and changing all of the filters again, etc. etc.

Took her out on the water again. It idled better, but died in the water again, this time at full speed (in plain) after two minutes. I again rowed back to the dock, surrounded by chuckling gators. Now I don't trust it at all and I am freaked.

So here's the tech scope.......

Started the boat today on ears and it idled rough and eventually stalled out. More white exhaust than usual. After idling about 10 min, I did a compression check = 130 top 125 bottom. I noticed that one plug (top) had a thicker oil coating on the spark end. Then I noticed an oil leak from the prop. Fearing I had a lower unit leak, I pulled the lower unit off. Then I noticed that the entire exhaust duct running, all the way up to the lower cowling, down through the lower unit, was coated with a thick coating of wet oil. It resembled the same thickness and color that was dripping out of the lower unit.



Given the history, any ideas? I would like some idea of what the mechanic might say. Can he fix it, head gasket, complete rebuild?

I really appreciate your help.

 

[catfishcarl99]

Re: 1998 Force 50hp possible oil/gas leak?

wow. that exaust port looks like lower unit oil and water mix????? anyone agree??? engine oil is green or blue. that looks whiteish like lower unit oil after its sucked water in. i aint a mechanic and am not sure why it would be causing the running issue or it may be unrelated but to me looks like your lower unit is spewing oil up into your leg some how. and if that is a pin drive prop like my 89 in which the exaust comes out of the snout above prop and not thru and im almost certain your lower is the same then ide say your lower is definatly leaking. and it may or may not have anything to do with the running issue. but oil coming from the prop if its a pin drive prop with the plastic cone nut then your lower is leaking. engine oil would be dripping from the snout not prop. my guess is the sludge is burned lower unit oil. the leg gets hot while running.

maybe a crack in the lower somewhere is causing pressure and squirting oil up when its running??? ide say almost for certain thats NOT oil from the engine or gas mix. thats lower unit oil. maybe blocking exaust flow causing the ideling issues.

 

[emoney]

Re: 1998 Force 50hp possible oil/gas leak?

I agree about that looking like LU fluid. I definitely wouldn't assume that's fuel/oil mix. I think your lower is different though, isn't it? Can you take some expanded pictures from a little further away of the whole motor, and then the lower leg? Also, can you drain a little LU fluid and take a pic of that too?

These had the Merc lower units so I know they're not those "cone snouts". Isn't this a dual exhuast, or is that only on the larger hp?

 

[jerryjerry05]

Re: 1998 Force 50hp possible oil/gas leak?

Oils not gonna go that high.
That's comming from the exhaust down.
You probably have a bad gasket/seal under the head.
And possibly the lower crank seal is bad leaking gas/oil into the exhaust???
The fuel recirc system is probably not picking up the unburned fuel.It's going past the lower seal and mixing with the hot exhaust and water and turning that color.

Take some close up pics of the fuel pump side and any hoses and post.

Then take all the hoses off and check for blockages.
You check the fuel pump diaphram?
It could be back feed ing into the cylinder and forcing gas into the motor making it stall?

Stalling underway,a soft,weak hose could be collapsing?
Sucking air arond a bad fitting?

The compression is just showing the rings,cylinders are in good shape.

I'd pull the head and replace the seals and the gaskets.

 

[catfishcarl99]

Re: 1998 Force 50hp possible oil/gas leak?

Oils not gonna go that high

i wouldnt think so either but that pic looked like lower oil with water mixed frothy whitish almost. but it would take some pressure to squirt that high. weird. im no expert so ill let the mechanics dig into this as ive never seen this before. and on the lower. my fault. i seen 98 and was thinking same year as mine. mines 89 lol.:facepalm: mis read.

 

[gaangus]

Re: 1998 Force 50hp possible oil/gas leak?

Ok, well I decided to "grow a set" and pull the head to look underneath. The bottom adaptor plate gasket has disintegrated and I see evidence of the oil sludge in the crevices of the adaptor plate.
View attachment 169417
View attachment 169418
So I guess that means the oil is coming from within the powerhead.

I also see the nuts holding the adaptor plate to the head are really corroded and will break. What's the best way to handle this, send it to a machine shop? I think I need to get the plate off to pull the head apart to get to the oil leak.
View attachment 169416
Thanks for all the ideas so far.......