1964 Mercury 850 Water Flow Issue

[Deus_Vult]

Hi guys I am mostly a lurker here, but I have a problem that has stumped me. Sorry for the long post, I just want to make sure people have as much info as possible.

Last summer I bought a 1964 Mercury 850 inline 6 outboard for $150, and the seller told me it had not run in many years. I have had some experience with these motors in the past, so I thought I would give it a shot at resurrecting it. Notable things I did were that I replaced the #6 spark plug wire (mouse had chewed through it), replaced the throttle cable (it had fallen apart), rewired the ignition switch inside the control box, rebuilt the fuel pumps, rebuilt the carburetors, rebuilt the entire engine wiring harness, rebuilt the water pump, disabled the reverse lock mechanism (could not get it to work for whatever reason even though all the parts seem to be there), tested compression (~120 psi for all 6 cylinders), and tested for spark (all good). I even replaced the wooden transom on my 1983 sylvan 16.5 ft deep v aluminum boat so that I knew for sure it could hold the motor (boat is rated for 90hp; the old transom was just rotten).

This week I was able to mount the motor to the transom using the overhead crane that my tech school has. Yesterday I was able to start it for the first time at home, and it fired right up after about 3 seconds of cranking and choke engaged. Seemed to run fine, the #1 carb float tangs needed some adjusting (was flooding when primed), but other than that it ran good after adjusting that.

The problem I am having is that there is no water flow out of the telltale hole, except for maybe 1 drop every 30 seconds, and that only barely trickles out.

Some notable observations:
1. I noticed that there is lots of water coming out of the back of the lower unit, where the arm for the reverse lock mechanism comes out of. I do not think this is linked to the water pump though, so it could just be water that is getting pushed out by the exhaust gases.
2. I took the lower unit off and tried turning the driveshaft by hand while the LU sat in a box full of water (what I am running the motor in) and could not see water coming out of the pump outlet. I do not know if this means anything, I personally was guessing that the impeller may need to be spinning a lot faster before it starts putting out a lot of water, but I just thought I would mention this just in case.
3. The copper transfer tube is kind of loose in the powerhead, but I can push it up there and get it to stay there. It just comes out with the lower unit every time I pull the LU off. Once again, not sure if this is bad or not, just thought I would mention it.
4. I hooked up the garden hose directly to said copper tube and tried flowing water through it. You could hear it going up the tube, not sure how far it made it into the powerhead but after about 10 seconds, it started spewing out around the sides of the copper tube where it goes into the powerhead, which to me indicates some kind of blockage. Also, when it starts spewing water past the tube, some of it trickles outside the back the motor driveshaft housing. I am guessing it just finds a gap somewhere and that's how it gets out. The reason I believe this is significant is that when the motor is running, I noticed that it was doing the same thing, which tells me that the water pump is working since water is getting up the copper tube, getting stuck, then spewing out past the tube.
5. I took off the water pressure plug that is on top of the powerhead and poured some water into it, but it just came right out of the driveshaft housing, so my guess is that it is going right out the exhaust manifold. Not sure if that is normal or not.
6. I tried sticking multiple things up inside the telltale hole to see if it was clogged or not. I am stopping on something, but I am not sure if I am just hitting a sharp bend inside the passageway or if it is a clog (unfortunately the telltale hole on this model is different than newer ones, no rubber tube, it just goes straight into the powerhead, and it is on the right side of the motor, not the left).
7. When the motor is running, there is water blowing out the upper exhaust port on the top of the driveshaft housing. Once again, I am not quite sure how water flow works on these things, so I don't know if this has anything to do with indicating how far the water is making it into the powerhead or not.

I feel like I have a pretty good understanding of how this era of mercs work. I tore down and rebuilt my 1967 merc 500 a couple years ago, the one problem I had was that I did not really understand exactly how the flow of water works in these things, even when the powerhead was completely disassembled. Anyways, I am leaning towards it being some kind of blockage inside the water jacket, but I am just looking for other advice, troubleshooting, and confirmation on my problem from more knowledgeable people. Let me know if there are any other tests I could do or clarify how the water flow works on these old inlines.

Sorry about the long post, I can get pretty carried away sometimes ha ha. Thanks in advance. I can post additional pictures if needed.

 

[Deus_Vult]

Hey guys I would delete this thread if I knew how to, I feel really silly right now; here I made this massive post only to find the answer 15 minutes later. I took an air compressor and blew into the telltale hole, then I hooked up the garden hose again. Water started coming out of the hole. And it turns out the "water spewing out" was just the water returning down the driveshaft housing through the exhaust manifold like it should. Sorry to bother you at this point. Thanks.

 

[Deus_Vult]

One thing that I did notice was that after I started the motor again just now, I saw that the water that was coming out of the back of the lower unit was also pushing out what looked like gearcase lubricant. I do know that that chamber leads down to the little "bleed" seep hole on the very back of the LU, and I am not quite sure what it is there for, except that I do know that gearcase lubricant will slowly seep out of it over time, and it has done this with all the mercs I own. Not sure if this is normal. That said, it is conceivable that this chamber could be pushing out the "bleed" lubricant that would normally come out that seep hole, since that chamber is exposed to exhaust gases that come around the water pump. There is no enclosed exhaust chamber inside the driveshaft housing like on my other merc outboards so exhaust just free travels down housing. If any of this seems weird to anybody who reads this, let me know. I will probably check the gearcase fluid level in a bit to see where it is at. I should mention that I did refill the gearcase as well prior to running it, so it could be excess bleeding out to the chamber.

 

[jimmbo]

Gearcase Oil should not 'Seep out' at any time. Have you put any of this seepage on your finger and smelled it? Gear Oils generally stink to High Heaven, and that stench is hard to remove, though Bleach, right from the Jug does kill it.
If oil is being pushed past the seals it is usually because the Seal(s) beneath the Water Pump are letting water past. A Pressure/Vacuum Test of the Case will reveal if it needs a Reseal.
The Lack of an Enclosed Exhaust Tube, was the Norm for all pre 1965 Mercs, in 1965 Mercury started implementing an entirely different Method of Silencing their Outboards, and a Water surrounded Exhaust Tube was part of the new Design, and eventually was fitted to all motors above 20hp.

 

[Deus_Vult]

Ok thanks for the information, very helpful. I do have some more questions now though.

First, how would you go about pressure testing the case? I assume there is some sort of fitting that would attach to the gear lube drain hole. Is there a specific tool to use?

Second, do you know what that little seep hole is there for? Like I said before, all my mercs have them and there is usually a small amount of oil or some substance around it.

Third, given that you said it is normal for these motors to have full exhaust flow in the driveshaft housing, is it normal for some of it to be exiting through that reverse lock lever hole on the back of the LU?

Thanks again.

 

[jimmbo]

What you are calling a Seep Hole, is Drain for Water.
Many people have cobbled together a Hand Pump, with a Pressure Gauge, to a Hose with a Fitting that will screw into the Vent or Drain Screw.
Regardless of mercury claiming about the newer system, there is still some Exhaust spillover into the Midsection, Idle Relief has to do so, or the engines would be able to start and run when in the Water. Some of that spillover is unburnt Fuel and 2 Stroke Oil, and it will appear coming out those Drains. As I said, take a Sample of it and Smell. Gear Oils do stink to high heaven, unlike Gasoline/2 Stroke Oil
Mercury also states in the Brouchure that Exhaust is Dry, which also isn't completely Accurate, as water will always come pouring out the Props when running on muffs. Maybe they made revisions after the Brochure came out, as an Uncooled Exhaust would certainly melt the Rubber Hubs in the Props.
I posted that cause it did explain the Water Surrounded Exhaust Tube that you had seen on other motors.
In 1968 OMC also started using that System on its first 3 cylinder Looper, and in 1969 on its V4 Models. Coincidently about 3 yrs after Mercury's Chief Engineer, Charles Strang left Mercury and joined OMC, after a Power Struggle between Kiekhaefer and the Head of Brunswick, went sideways

 

[Deus_Vult]

Ok so I did just take a sniff of that substance and it does smell exactly like gasoline. I did also notice when I took a look at the gearcase lube itself just now, I saw that it was a completely different color (blue) as opposed to that other substance (brownish). I will pressure test this gearcase in the future, but my immediate fears are put at rest for now I think. Thanks for your help, I really appreciate it.

 

[jimmbo]

Most Gear Oils are Amber, but I too have seen some that are Bluish.

 

[Deus_Vult]

Yup the stuff I use is quicksilver sae 90 gear lube, which is blue.