Mercruiser 5.0 LX 1992 Oil Leak After Impeller Change

[Gavman04]

So today I have had the struggles from hell trying to do an oil change. I warmed the engine up first running the outboard in a large tub that was filled past the water inlets the temperature on the gauge rose past 120 to about 125, this only took about 3-4 minutes (maybe not a long enough time?). Secondly I put about four feet of marine tubing which is connected to my oil extractor (pic included) down into the dipstick hole. I pumped and pumped and pumped and pumped but I was only able to get maybe 1/2 a quart out of the engine it only comes out in very small quantities. I have been trying to figure this out all day, I'm thinking I must be missing something. I have the extractor waste tube dumping into a regular 5 gallon bucket, not enclosed, just a plain paint 5 gallon bucket. Thanks in advance for any insight.

 

[Rick Stephens]

That is the least working cooling setup I have ever seen. The water level on the stern drive is not high enough to prime the raw water pump. It HAS to be submerged. It will not suction water to prime. That type of pump cannot draw a vacuum to pull water up. I would bet the impeller is hosed. If you must run with the drive in a tub, the water level must come up over the top cav plate and fully submerge the water pump.

I have never used an oil suction pump like that. So I don't know how well it should work. The one I use has a vacuum pump attached to a sealed 2 gallon container with a suction hose coming out of it that fits down the dipstick tube. The longer the suction tube the less effective it is. I tend to pump it down and go do other jobs. They aren't very fast no matter how well designed.

Rick

 

[tpenfield]

It takes 15-20 minutes of engine runtime to really heat up the oil . . . so the oil was still cold after only a few minutes.

Bad setup with the little tub . . . the outdrive really needs to be submerged much deeper, as Rick pointed out. You are better off using 'ear muffs' to force water into the outdrive from the garden hose, as most folks do.

The tubing that can fit inside the oil dipstick hole will be really small in diameter and not pass much volume . . . you will be there all day even in the best of conditions. I tried doing that once (keyword = once). Just remember the cross sectional area of the tube increases by the diameter 'squared'. So a 1/4" I.D. tube has 4X the area (i.e. volume capacity) of a 1/8" I.D. tube.

A better approach that I have used is to take a larger tube that will securely fit OVER the dip stick hole/pipe giving a larger volume of tube to pump through. This works, because the metal dipstick tube on the engine goes down to the bottom of the oil pan (or nearly so). (at least it does on my engines) You can then use a smaller tube inside the dipstick tube to get and last bits of oil out, if need be.

I usually measure how much oil I suck out of the engine to see if I got most of it. (7 quarts on my engine, assuming it was at the full mark to begin with). If I come up short, then I use a smaller tube, as you did, to make sure I am getting all the way to the bottom of the oil pan, and pump some more.

So, I would get some ear muffs (buy them here on iBoats) and a larger I.D. tube and have another go at it, running the engine up to full temperature (and then some) beforehand.

 

[Gavman04]

With the water to the top of the tub it covered all the holes that the muffs cover. So why are the muffs okay and the tub not?

 

[Rick Stephens]

The muffs pressurize the intake. The pump sits a ways higher and is in the exhaust passage. Impeller pumps are not sealed tight. They are not capable of drawing water up from below. It would take a lot to redesign a pump that can produce suction at idle, flow a relatively small amount of water at low rpm ranges and move enormous amounts of water at high rpm. All and still be able to handle trash weeds sand mud etc.

 

[Gavman04]

I really appreciate you taking the time to let me know that. I'm using the muffs right now and it's been about 20 minutes in neutral, the temperature rose to 125-130 in 5 minutes and at 12 minutes it's been at about 155. I'm planning on turning off and letting it sit for about 30 minutes. Then trying the oil change again, any comments, suggestions, or concerns?

 

[Oshkosh1]

I really appreciate you taking the time to let me know that. I'm using the muffs right now and it's been about 20 minutes in neutral, the temperature rose to 125-130 in 5 minutes and at 12 minutes it's been at about 155. I'm planning on turning off and letting it sit for about 30 minutes. Then trying the oil change again, any comments, suggestions, or concerns?

Yes...don't wait. The hotter the better.

 

[Rick Stephens]

Not to beat a dead horse, but I would plan to inspect the impeller. If it ran a bit without water it will at best pass water from the hose which is supplying the water at pressure and pushing through the pump. A damaged impeller is liable to not work well running in the lake or river and needing to operate at full efficiency.

Since the motor is warm, go for the oil change. No need to wait.

Rick

 

[harleyman1975]

I agree change the impeller it might be damaged now. why take a chance wrecking a fun family outing to save a few bucks and an hour of time.

 

[TyeeMan]

I USED that same pump many years ago and it's miserable. So you need hot oil in order to pump it. Well, the pump body is metal so it gets really hot in your hands.
I ended up having to put zip ties around to rubber ends in order to make is suck and seal better. It still sucked! :lol:

For years I've been using an electric pump which has a hose that goes down the dipstick tube. It sort of works, takes forever but at least you can sit there and drink beer while the pump does all the work. :very_drunk:

After reading another post on changing oil I promptly ordered a Mightly Vac fluid extractor. Just got it, haven't use it yet but looks like it should fit the bill quite nicely.

 

[Gavman04]

Well the oil change went swimmingly. I got all the oil out in about 5 minutes. And yes, the tube was very hot, but it wasn't a big deal, I just put a rag around it and held it by that. Otherwise that pump was a dream. As far as the impeller goes, how will I know if it's screwed? If I run it in the lake on the trailer at idle for 10 minutes and the temperature is fine should I be good?

 

[Rick Stephens]

By looking at it.

 

[bruceb58]

I used that same pump for nearly 15 years pumping the oil out on my OMC and Volvo. They work great.

If I were you, I would get the oil change kit that screws into the drain plug. You then have the option of poking the hose out the stern drain plug ad letting the oil drain with gravity or suck it up using your pump with a much larger diameter hose.

https://www.amazon.com/Oil-Drain-Kit-thread-size/dp/B0000BYO1R

 

[Silvertip]

Ever seen the old Fram Oil Filter ad that said "pay me a little bit now" or "pay me a whole lot more later"? That applies in your case. You incorrectly ran your engine without sufficient cooling water. While the engine survived, the impeller may or may not have. Are you willing to take a chance on it being OK by heading out only to have an overheat occur with drastic results (head and or block cracks, blown head gasket, etc.) or should you simply replace the impeller and be assured you are good to go. We don't know for sure what you did and for how long so don't look to us to say "nope, you are good to go". An impeller is a lot cheaper than repairing or replacing a damaged engine. Besides, if the impeller has not been replaced in a few years it's time it was.

 

[Gavman04]

Roger that, I'll change it tomorrow.

Ever seen the old Fram Oil Filter ad that said "pay me a little bit now" or "pay me a whole lot more later"? That applies in your case. You incorrectly ran your engine without sufficient cooling water. While the engine survived, the impeller may or may not have. Are you willing to take a chance on it being OK by heading out only to have an overheat occur with drastic results (head and or block cracks, blown head gasket, etc.) or should you simply replace the impeller and be assured you are good to go. We don't know for sure what you did and for how long so don't look to us to say "nope, you are good to go". An impeller is a lot cheaper than repairing or replacing a damaged engine. Besides, if the impeller has not been replaced in a few years it's time it was.

 

[Gavman04]

Alpha one Gen 2 very small oil leak from water intake

Serial Number 0D670047. Alpha One Gen 2.

This is the link to all the pictures I could think to take. I don't know why, but boats won't accept any of the file types I tried to convert them to.

https://drive.google.com/open?id=0B5deTOa8JwmFa0dRZEhuV0c2OWM

Alright, previously Rick and another suggested that I change the impeller because I may have damaged it. So I did that, luckily the impeller was still in tip top shape and nothing seemed amiss, but no harm in replacing old parts. ANYWAYS to the problem at hand. I'm trying to be thoroughly detail oriented. I used a manual to remove ONLY the lower unit after I drained the oil. However, I had it in NEUTRAL when I uninstalled. I followed all the directions in the manual (ironically putting it in FWD was not written) when I reinstalled the lower unit I DID put the boat and the lower unit in FWD. After installation I tested it on muffs, it ran great, plenty of water out the exhaust and everywhere it should be. Cold water in, not burning but pretty hot water came out. Over night I noticed an oily area around the bottom water inlets on both side, there was no oil spots on the ground underneath.

Fast Forward to today, I read lots of other posts about seals being amiss and whatnot. Just now, I put the boat in forward, drained oil, pulled the lower. And it's on a stand. (is it able to support itself on its fin? or is that bad for it?) I took pictures But I am not seeing anything out of the ordinary (what I would imagine ordinary is based on pictures and forums) I put pictures on the google drive link. Any help would be sooooo appreciated. Ironically I'm trying to get this done by Thursday because one of my navy friends who knows nothing about boats is coming to do some boating with me.

https://drive.google.com/open?id=0B5deTOa8JwmFa0dRZEhuV0c2OWM

Cheers to All who can guide me!

 

[Gavman04]

This is the link to all the pictures I could think to take. I don't know why, but boats won't accept any of the file types I tried to convert them to.

https://drive.google.com/open?id=0B5...0dRZEhuV0c2OWM

Rick Stephens and another suggested that I change the impeller because I may have damaged it. So I did that, luckily the impeller was still in tip top shape and nothing seemed amiss, but no harm in replacing old parts and its better safe than sorry. ANYWAYS to the problem at hand. I'm trying to be thoroughly detail oriented. I used a manual to remove ONLY the lower unit after I drained the oil. However, I had it in NEUTRAL when I uninstalled. I followed all the directions in the manual (ironically putting it in FWD was not written) when I reinstalled the lower unit I DID put the boat and the lower unit in FWD. After installation I tested it on muffs, it ran great, plenty of water out the exhaust and everywhere it should be. Cold water in, not burning but pretty hot water came out. Over night I noticed an oily area around the bottom water inlets on both side, there was no oil spots on the ground underneath.

Fast Forward to today, I read lots of other posts about seals being amiss and whatnot. Just now, I put the boat in forward, drained oil, pulled the lower. And it's on a stand. (is it able to support itself on its fin? or is that bad for it?) I took pictures But I am not seeing anything out of the ordinary (what I would imagine ordinary is based on pictures and forums) I put pictures on the google drive link. Any help would be sooooo appreciated. Ironically I'm trying to get this done by Thursday because one of my navy friends who knows nothing about boats is coming to do some boating with me.

https://drive.google.com/open?id=0B5...0dRZEhuV0c2OWM

 

[Rick Stephens]

Good deal on the impeller. Glad nothing is bad. I never was a big fan of taking the lower off by itself. Miserable job lifting it back onto the upper and getting everything lined up and not damaging seals.

If you are using anything except the Mercruiser Service manuals you want to toss those. Other brand manuals tend to not only have a great shortage of detail but can be flat out wrong on stuff written in them.

Check your shift shaft that the propeller locks up when turned CCW with the shift shaft pointed straight forward. Then rotate the shifter all the wat counter clockwise (into reverse) and the propeller should lock if you turn it CW.

 

[Gavman04]

Rick Stephens , Any other thoughts on the other stuff I've got going on with it today?

 

[Rick Stephens]

What other stuff is happening?