Mercruiser 120 engine seems to be using oil?

[Neutron68]

I've only had this SSV-177 for a year.  I've been finding and fixing it's problems over that time.

I see from 1978 vintage price sheets that SSV-177 boats shipped with Mercruiser 140, 165 and 470 engines (never with 120s).
http://i131.photobucket.com/albums/p286/Hyperacme/Glastron%20Price%20%20Specs/1978_2.jpg

The seller of my boat told me they had swapped in a different engine, so the engine was good.  That explains how a Mercruiser 120 got into an SSV-177.  It also explains why the engine temperature sender was a gauge-sender rather and not an idiot-light sender.  This SSV-177 had a TEMP idiot light, rather than a temperature gauge in it.  I put a temperature gauge in this spring, so I could tell if there was an overheat problem or not.  Thus far, the temperature gauge has never risen above 160.  It usually comes up to 150 and stays.

I've been pretty gentle to this Mercruiser 120 engine during this 2014 season. 
We've had it out for about 6 or 7 cruises with RPMs between 1000 and 2000. 

The cruises have all been like this one, from Friday night:
https://www.youtube.com/watch?v=IBYh7uswcno

When I've throttled up to 3000-4000 RPM, I usually don't run it that fast for more than 1 minute at a time.
I've not had it at 3000-4000 RPM more than 5 minutes total, this season, I would say.

I ended the 2013 season with a fresh engine oil change, so it was full and clean.
When I checked the oil after cruise #5 (of 2014 season), it was down to the very tip of the dipstick, below the Add A Quart line.  The oil is very clean and clear, not dark and dirty.  I don't see any oil down in the bilge area below the engine, so I suspect it's all going out through the engine and exhaust system.
Maybe this explains why the spark plugs were so sooty when I changed them last fall?

Short term, I'm going to keep adding new oil as it uses it.

Longer term, I think I need to get a mechanic to look at this. 
What should I ask a local mechanic to look for?

Eric

[Hyperacme]

" When I've throttled up to 3000-4000 RPM, I usually don't run it that fast for more than 1 minute at a time.
I've not had it at 3000-4000 RPM more than 5 minutes total, this season, I would say. "

You have far more self control then I do .... LOL

[Neutron68]

I just ran across this in the Mercruiser manual. 

when an engine is used  principally at slow speed conditions,
where  considerable  crankcase dilution  occurs, a  rapid  lowering of the oil  level
may  result  when  the boat is operated for some distance at high speed. This is due
to  the  dilution  from  slow  running  which  is  removed  from  the crankcase by the
heat  of  high  speed  operation.  This  is  a  normal  condition  and  should  not  be
mistaken  for  excessive  oil  consumption.

This seems relevant to long, slow cruises, followed by 1 minute of 3000-4000 RPM, doesn't it?

Eric

[buckz6319]

I've only had this SSV-177 for a year.  I've been finding and fixing it's problems over that time.

I see from 1978 vintage price sheets that SSV-177 boats shipped with Mercruiser 140, 165 and 470 engines (never with 120s).
http://i131.photobucket.com/albums/p286/Hyperacme/Glastron%20Price%20%20Specs/1978_2.jpg

The seller of my boat told me they had swapped in a different engine, so the engine was good.  That explains how a Mercruiser 120 got into an SSV-177.  It also explains why the engine temperature sender was a gauge-sender rather and not an idiot-light sender.  This SSV-177 had a TEMP idiot light, rather than a temperature gauge in it.  I put a temperature gauge in this spring, so I could tell if there was an overheat problem or not.  Thus far, the temperature gauge has never risen above 160.  It usually comes up to 150 and stays.

I've been pretty gentle to this Mercruiser 120 engine during this 2014 season. 
We've had it out for about 6 or 7 cruises with RPMs between 1000 and 2000. 

The cruises have all been like this one, from Friday night:
https://www.youtube.com/watch?v=IBYh7uswcno

When I've throttled up to 3000-4000 RPM, I usually don't run it that fast for more than 1 minute at a time.
I've not had it at 3000-4000 RPM more than 5 minutes total, this season, I would say.

I ended the 2013 season with a fresh engine oil change, so it was full and clean.
When I checked the oil after cruise #5 (of 2014 season), it was down to the very tip of the dipstick, below the Add A Quart line.  The oil is very clean and clear, not dark and dirty.  I don't see any oil down in the bilge area below the engine, so I suspect it's all going out through the engine and exhaust system.
Maybe this explains why the spark plugs were so sooty when I changed them last fall?
Eric, maybe this site will help you with reading spark plugs, it has helped me lots of times in the past, you can click on the pics to enlarge them for a closer look
http://www.timeinthegarage.com/2014/01/art-of-reading-spark-plugs.html

Short term, I'm going to keep adding new oil as it uses it.

Longer term, I think I need to get a mechanic to look at this. 
What should I ask a local mechanic to look for?

Eric

have you noticed and oil smoke when starting the engine up, while idling?

[Neutron68]

have you noticed and oil smoke when starting the engine up, while idling?

No, I've not seen or smelled any smoke from the engine. 
The engine starts easy and runs smooth.
I have noted a thin, black, oily film on the back of the transom.

The seller told me the engine had been replaced. 
I have no idea if any work (such as a ring job) was done to the engine when they swapped it?
I've been told that engines will use oil for a period of time following a ring job.

Eric

[buckz6319]

have you noticed and oil smoke when starting the engine up, while idling?

No, I've not seen or smelled any smoke from the engine. 
The engine starts easy and runs smooth.
I have noted a thin, black, oily film on the back of the transom.
on the back of the exterior transom, i'm assuming?

The seller told me the engine had been replaced. 
I have no idea if any work (such as a ring job) was done to the engine when they swapped it?
I've been told that engines will use oil for a period of time following a ring job.


Eric

Eric, i'm no professional mechanic, just a " Shade Tree " mechanic who loves to work on stuff. I am sure someone with more experience will chime in on this topic, and give some good sound advice.

that oil is going somewhere, and the evidence of that is there, through the engine and out the exhaust, but how is it getting into the combustion chamber...
possible valve issues?
Valves regulate the amount of fuel and air mixture allowed in the cylinders for combustion. While the valves have guides or sleeves to keep combustion gases from passing through them, the seals on the top of the valves keep oil in the valve cover from being sucked down into the engine. Seals, typically made of high-strength rubber, fit over the top of the valve stem inside a small collar. When valve seals begin to wear or fail they produce some obvious and unique symptoms.

Cold Engine
One of the most noticeable signs of worn or cracked valve stem seals will be just after a cold engine start. If the vehicle has been sitting for any length of time or even overnight, the top of the head inside the valve cover will be coated with residual oil that was pumped up earlier during running operation. The rubber valve seal has also cooled during nonoperation, which causes it to contract and leave a small gap. When the engine first starts up, residual oil gets sucked down through the bad seal and into the combustion chamber. A large cloud of blue-white smoke will be seen exiting the tailpipe just after start-up....but you said you don't see any smoke

Oil Consumption

Bad valve seals will cause excessive oil consumption. In an otherwise normal engine with good compression, rings and valve guides, bad seals will cause a loss of oil that can be detected on the oil dipstick. By keeping an accurate record of oil level on the dipstick, a noticeable oil reduction due to the oil being burned along with the fuel will be discovered. Bad seals will be confirmed if no oil leaks can be found on the engine to account for the loss.

just a thought...










 

[Neutron68]

that oil is going somewhere, and the evidence of that is there, through the engine and out the exhaust, but how is it getting into the combustion chamber...
possible valve issues?

Valve seals seem like a reasonable place to look. 

Is a valve seal replacement a pretty easy fix?
How easy those are to get to? 
Right under the valve cover?

Eric

[Rich_V174SS]

Changing the valve seals/guides requires removal of the cylinder head from the engine and pulling each valve spring off and removing the valve. Trying to do it with the head installed could mean dropping a valve into the cylinder, and even if you don't you have no way to hold the valve in place when reinstalling the springs.

[Glastronjohn18]

Trying to do it with the head installed could mean dropping a valve into the cylinder, and even if you don't you have no way to hold the valve in place when reinstalling the springs.

An old Hot Rodders trick is to use compressed air in each cylinder to hold the valves closed.  Just ask Jerry, he's probably done that many times.

[Neutron68]

Changing the valve seals/guides requires removal of the cylinder head from the engine and pulling each valve spring off and removing the valve. Trying to do it with the head installed could mean dropping a valve into the cylinder, and even if you don't you have no way to hold the valve in place when reinstalling the springs.

Ah.  This sounds like a job for a mechanic with the proper tools and experience!  I have neither.
Is the engine going to have to come out to get the cylinder head off, etc.?

So, no one thinks the description from the 1978 Mercruiser manual fits this oil consumption situation?

when an engine is used  principally at slow speed conditions,
where  considerable  crankcase dilution  occurs, a  rapid  lowering of the oil  level
may  result  when  the boat is operated for some distance at high speed. This is due
to  the  dilution  from  slow  running  which  is  removed  from  the crankcase by the
heat  of  high  speed  operation.  This  is  a  normal  condition  and  should  not  be
mistaken  for  excessive  oil  consumption.

Eric

[Jerry]

An old Hot Rodders trick is to use compressed air in each cylinder to hold the valves closed.  Just ask Jerry, he's probably done that many times.

Yes I have. but to do all of them it's better to pull the head (which if you drop a keeper you may be pulling more than the head). First figure out how much you use. A 20W-50 Racing oil in the summer would work fine, or STP. If you're only adding a quart every few hours, it may not be worth it. If it's more than that it's probably stuck rings, or a bad piston.

[buckz6319]

So, no one thinks the description from the 1978 Mercruiser manual fits this oil consumption situation?

when an engine is used  principally at slow speed conditions,
where  considerable  crankcase dilution  occurs, a  rapid  lowering of the oil  level
may  result  when  the boat is operated for some distance at high speed. This is due
to  the  dilution  from  slow  running  which  is  removed  from  the crankcase by the
heat  of  high  speed  operation.  This  is  a  normal  condition  and  should  not  be
mistaken  for  excessive  oil  consumption.

Eric
[/quote]
Eric
I would do a test with your boat
Check oil level make sure it is on the full mark, then go run her like most folks would,  open her up for a while,  slow down sometimes, then back to running open up and so forth, you may have or just run the crap out of it
Then check your oil level and rear of transom
See what u got on the dip then

[Jerry]

For what it's worth,, This is the tool you use to remove the valve springs with the heads on. It goes over the rocker stud and you depress the spring and remove the keepers (with air pressure in the cyl)  Be careful not to let the pressure drop, or you will have a valve where you don't want it.

[Neutron68]

On the topic of oil use rate, I'll keep watch of it.

Until I have better data, I have an estimate. 
When I noticed the oil down at the bottom of the dipstick (approx 1.5 quarts low?), we had done about 6 cruises of the lake...estimate 6 hours of runtime. 

That would be 1/4 quart per hour of oil loss/usage.

[Neutron68]

After a few more weekends of observation...
It looks like we use around 1/3 to 1/2 quart of oil per hour.
The oil is still golden and clean.

2 weeks ago, the local mechanic down the lakeshore also asked me if there is a cloud of smoke when I start the engine.
As I answered here, no, never a cloud of smoke when starting - even after sitting for a week.
His theory moved from bad valve seals to carboned-up piston rings.

He advised me to get some Delco upper engine and fuel injector cleaner at the local GM dealer.
http://www.amazon.com/ACDelco-X66P-Engine-Injector-Cleaner/dp/B0013FMW84

His instructions were:
1. pull all 4 plugs out
2. pour about 2 oz. of cleaner into each cylinder
3. let it sit for 2 hours
4. then, run the starter (with the plugs out) and let it blow the liquid out the plug holes (that made a mess)
5. put the plugs back in and reconnect the plug wires
6. start the engine and let it run at high idle until it stops smoking (took 1 or 2 minutes to stop smoking)
7. after that, pour the remainder of the cleaner into the carburetor with the engine running.

He said that should clean out carbon deposits in the piston rings.
I did see a few dark splats with the spray on the boat and seats when I cleaned up the spray.

After doing that I have not noticed much reduction in oil usage, if any.
But, I think I have noted a reduction in the of oil slick I see on the water when I run the engine?

Eric

[buckz6319]

back in the day....we used break fluid, poured down the throat of a carburetor to clean carbon, but doing this made the exhaust smoke white and thick, that the neighbors thought the apartments were on fire Lol...

sounds like your on your way to recovery...

[Jerry]

Seafoam works great.

[Neutron68]

Given the oil use symptoms, and lack of smoke cloud at startup, does it seem like piston rings are the most likely cause of the oil usage?

If so, how many times do I have to treat the engine with cleaner before it's cured?

Would I use SeaFoam the same way as I used the Delco Upper Engine cleaner?

Eric

[Jerry]

Seafoam works the same way. I would add it to the oil too, However - - Carboned up rings can't be cured with an additive, you really need to pull the pistons and clean the ring lands and put new rings in. A compression check and a look at the plugs should tell you if it's all the cylinders, or just 1 or 2. There really is no-such-thing as a "Mechanic in a can"

[Rich_V174SS]

.... unless he's in the men's room.