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Author Topic:   Mercury Outboard c.1987: Oil Hose Cracked

Sammy posted 04-09-2005 03:18 PM ET (US)
After winterizing the 1987 Mercury 90-HP (oil injected) last fall, the boat/motor sat under a storage canopy through the winter. Looked it over a couple weeks ago--nothing out of the ordinary. Three days later, there was a large puddle of two-stroke oil on the cement beneath the motor. You could say I was a little surprised.
The motor was stored in the tilt-down position, so a possible leaky oil tank cap wasn't the source. The under-the-cowling oil reservoir was empty. The tank did not have any visible cracks. When I wiggled one of the oil hoses, it immediately snapped in two. Looking over the rest of the hoses, all were very brittle. One of the hoses had cracked on its own--the source of the leak.
What are the odds? A sudden failure of an oil line while the boat has been sitting for several months rather than happening at about a 4000 rpm cruise in the middle of nowhere, of course at the worst possible time?
I've had the motor for less than a year so I'm not sure whether they had ever been replaced.
The new oil injection hoses and clamps cost less than five bucks and took just a few minutes to install. Rather than using the clear vinyl hoses that were on the motor, the Tygon F-4040-A Fuel and Lubricant hose seemed like a better choice.
Not sure whether this situation only applies to certain older Mercury outboards or to others as well. But it could pay big time to do a quick check.

Freeport Alan posted 04-09-2005 05:56 PM ET (US)
You must change them, it's really really easy.
Make sure there is no air in the hoses after changing them, either bleed it from the pump or top the supply line with oil by dribbling it in..
The plastic tube (as Mercury calls it on the package0 cost me $3. Cheap, simple, you are beyond overdue, as was I.
When you change it and see and feel the difference between the old and new lines it is amazing.
Also, what you do is mark the oil tank with a magic marker after you change the lines, run double oil first to make sure the pump is pumping.
jimh posted 04-09-2005 07:08 PM ET (US)
I'd really be surprised if that 1987 motor had oil injection. It probably just has simple gasoline and oil mixing in the fuel supply.
The only two-stroke motors that use oil-injection (to my knowledge) at direct-injection motors like the Ficht, E-TEC, OptiMax, or HPDI engines.
Sammy posted 04-09-2005 07:31 PM ET (US)
It is a simple oil pump mixing oil with the fuel. The Mercury Owner's Manual refers to it as the "Oil Injection System" (there's a specific section titled this way in the manual) - they even put the cute little deacls on the cowling that read "Oil Injected".
A basic system - just using Merc's terminology.
Sheila posted 04-09-2005 09:23 PM ET (US)
Jim, my 2000 Suzuki DT200 is EFI and has an oil tank in the engine. My understanding is that the oil was injected.
Now I have something to look up in my owner's manual.
John O posted 04-09-2005 11:41 PM ET (US)
You may want to stay with clear lines. They were OEM clear for viewing to see if the oil was flowing and if air is in the system.
jimh posted 04-09-2005 11:55 PM ET (US)
Maybe in 1987 "oil injection" meant oil mixed with the gasoline in the fuel line before it got to the carburetor or fuel injector. Again, I'd be surprised if that engine had an oil injection system where oil is actually injected or sprayed on the moving parts in the cylinders and crankcase of the engine instead of just mixed with the fuel.
But Mercury tends to be ahead of the others, so perhaps they did have something fancier than the OMC VRO system or the Yamaha Precision-Blend, which were oil/gasoline mixing systems is use at that same time.
Some newer two-strokes have oil injection pumps that meter out oil and inject it directly to the cylinders and other moving parts, without mixing it with the gasoline. However, I think even on the E-TEC there is one line from the oil injector pump that feeds into the fuel line, so a little oil does get mixed with the gasoline, too.
What caught my attention is that normally a system with "injectors" has lines that are under some pressure, but in most of these cases of oil lines in outboards there is very little if any pressure in the lines. After all, they are just clear plastic hose and cost a few pennies a foot. So it seems odd to refer to them as "injector" lines. I'm thinking of the diesel engine on my old sailboat; injector lines there were high pressure steel tubing.
In any case, injector or no injector, plastic hose from 1987 that has been operating close to a head source like an engine power head is probably ready to crack and fall apart. They sound like a good thing to check and replace periodically--like every 18 years in this case!
Freeport Alan posted 04-10-2005 09:38 AM ET (US)
I stayed with the clear tubing like John O suggested.
It's important to see that the lines are full and no air. Also I beleeve there is a little check valve that can be diagnosed by checking the smaller hose with the gas/oil mixture.
I've a feeling Mercury improved the hose over the years, the new stuff was thick, pliable and not easy to cut, quality looking stuff.
jimh posted 04-10-2005 10:43 AM ET (US)
[Changed TOPIC; was "Oil injection lines - maintenance."]
Sammy posted 04-10-2005 02:20 PM ET (US)
John O & Freeport Alan,
You make a good point about staying with the oil injection lines that allow visible confirmation that oil is moving throught the system - or is at least present in the lines. The Tygon line is a very pale, translucent yellow that clearly shows the two stroke oil.
If the old lines on my motor are original (a new OEM power head was installed in 1995, so they could have been changed at that point), that vinyl does last a long time. The interior of the vinyl lines I replaced had become stained from the oil over the years, making them almost opaque. Maybe Mercury chose vinyl for the lines to encourage replacement when the lines became opaque? The Tygon just seemed to be a better product.
As a couple of mechanics put it - check the lines annually. If the lines are very flexible - they are fine. If they are showing signs of stiffness - replace them. Better yet, just replace them every three or four years and you'll never have a problem.

jimh,
If you read through my earlier posts, the word "injectors" was never used. I only used Mercury's description of the "Oil Injection System", mentioned several times in the owner's manual. Decals on the cowling also read "90 Oil Injected" - and 2 Merc mechanics I spoke with refered to it as the oil injection system. It was an attempt to accurately reflect Mercury's labeling of their own product - even if later systems decribed in the same terms became more sophisticated.
I did send you an email with a scanned copy of one section of the original owner's manaual that makes three separate references to the "Oil Injection System" (highlighted in yellow).

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Author	Topic: Mercury Outboard c.1987: Oil Hose Cracked
Sammy	posted 04-09-2005 03:18 PM ET (US) After winterizing the 1987 Mercury 90-HP (oil injected) last fall, the boat/motor sat under a storage canopy through the winter. Looked it over a couple weeks ago--nothing out of the ordinary. Three days later, there was a large puddle of two-stroke oil on the cement beneath the motor. You could say I was a little surprised. The motor was stored in the tilt-down position, so a possible leaky oil tank cap wasn't the source. The under-the-cowling oil reservoir was empty. The tank did not have any visible cracks. When I wiggled one of the oil hoses, it immediately snapped in two. Looking over the rest of the hoses, all were very brittle. One of the hoses had cracked on its own--the source of the leak. What are the odds? A sudden failure of an oil line while the boat has been sitting for several months rather than happening at about a 4000 rpm cruise in the middle of nowhere, of course at the worst possible time? I've had the motor for less than a year so I'm not sure whether they had ever been replaced. The new oil injection hoses and clamps cost less than five bucks and took just a few minutes to install. Rather than using the clear vinyl hoses that were on the motor, the Tygon F-4040-A Fuel and Lubricant hose seemed like a better choice. Not sure whether this situation only applies to certain older Mercury outboards or to others as well. But it could pay big time to do a quick check.
Freeport Alan	posted 04-09-2005 05:56 PM ET (US) You must change them, it's really really easy. Make sure there is no air in the hoses after changing them, either bleed it from the pump or top the supply line with oil by dribbling it in.. The plastic tube (as Mercury calls it on the package0 cost me $3. Cheap, simple, you are beyond overdue, as was I. When you change it and see and feel the difference between the old and new lines it is amazing. Also, what you do is mark the oil tank with a magic marker after you change the lines, run double oil first to make sure the pump is pumping.
jimh	posted 04-09-2005 07:08 PM ET (US) I'd really be surprised if that 1987 motor had oil injection. It probably just has simple gasoline and oil mixing in the fuel supply. The only two-stroke motors that use oil-injection (to my knowledge) at direct-injection motors like the Ficht, E-TEC, OptiMax, or HPDI engines.
Sammy	posted 04-09-2005 07:31 PM ET (US) It is a simple oil pump mixing oil with the fuel. The Mercury Owner's Manual refers to it as the "Oil Injection System" (there's a specific section titled this way in the manual) - they even put the cute little deacls on the cowling that read "Oil Injected". A basic system - just using Merc's terminology.
Sheila	posted 04-09-2005 09:23 PM ET (US) Jim, my 2000 Suzuki DT200 is EFI and has an oil tank in the engine. My understanding is that the oil was injected. Now I have something to look up in my owner's manual.
John O	posted 04-09-2005 11:41 PM ET (US) You may want to stay with clear lines. They were OEM clear for viewing to see if the oil was flowing and if air is in the system.
jimh	posted 04-09-2005 11:55 PM ET (US) Maybe in 1987 "oil injection" meant oil mixed with the gasoline in the fuel line before it got to the carburetor or fuel injector. Again, I'd be surprised if that engine had an oil injection system where oil is actually injected or sprayed on the moving parts in the cylinders and crankcase of the engine instead of just mixed with the fuel. But Mercury tends to be ahead of the others, so perhaps they did have something fancier than the OMC VRO system or the Yamaha Precision-Blend, which were oil/gasoline mixing systems is use at that same time. Some newer two-strokes have oil injection pumps that meter out oil and inject it directly to the cylinders and other moving parts, without mixing it with the gasoline. However, I think even on the E-TEC there is one line from the oil injector pump that feeds into the fuel line, so a little oil does get mixed with the gasoline, too. What caught my attention is that normally a system with "injectors" has lines that are under some pressure, but in most of these cases of oil lines in outboards there is very little if any pressure in the lines. After all, they are just clear plastic hose and cost a few pennies a foot. So it seems odd to refer to them as "injector" lines. I'm thinking of the diesel engine on my old sailboat; injector lines there were high pressure steel tubing. In any case, injector or no injector, plastic hose from 1987 that has been operating close to a head source like an engine power head is probably ready to crack and fall apart. They sound like a good thing to check and replace periodically--like every 18 years in this case!
Freeport Alan	posted 04-10-2005 09:38 AM ET (US) I stayed with the clear tubing like John O suggested. It's important to see that the lines are full and no air. Also I beleeve there is a little check valve that can be diagnosed by checking the smaller hose with the gas/oil mixture. I've a feeling Mercury improved the hose over the years, the new stuff was thick, pliable and not easy to cut, quality looking stuff.
jimh	posted 04-10-2005 10:43 AM ET (US) [Changed TOPIC; was "Oil injection lines - maintenance."]
Sammy	posted 04-10-2005 02:20 PM ET (US) John O & Freeport Alan, You make a good point about staying with the oil injection lines that allow visible confirmation that oil is moving throught the system - or is at least present in the lines. The Tygon line is a very pale, translucent yellow that clearly shows the two stroke oil. If the old lines on my motor are original (a new OEM power head was installed in 1995, so they could have been changed at that point), that vinyl does last a long time. The interior of the vinyl lines I replaced had become stained from the oil over the years, making them almost opaque. Maybe Mercury chose vinyl for the lines to encourage replacement when the lines became opaque? The Tygon just seemed to be a better product. As a couple of mechanics put it - check the lines annually. If the lines are very flexible - they are fine. If they are showing signs of stiffness - replace them. Better yet, just replace them every three or four years and you'll never have a problem. jimh, If you read through my earlier posts, the word "injectors" was never used. I only used Mercury's description of the "Oil Injection System", mentioned several times in the owner's manual. Decals on the cowling also read "90 Oil Injected" - and 2 Merc mechanics I spoke with refered to it as the oil injection system. It was an attempt to accurately reflect Mercury's labeling of their own product - even if later systems decribed in the same terms became more sophisticated. I did send you an email with a scanned copy of one section of the original owner's manaual that makes three separate references to the "Oil Injection System" (highlighted in yellow).