Johnson 35 Super Sea Horse-how much water to test cooling

I have a 1958 35 Super Sea Horse that has been mothballed for years. I put a new impeller in it, replaced the thermostat, and placed it in a 55 gallon barrel. It is attached to my boat. The water line is approximately 3" above where the lower unit bolts up. Which is very close to being just above the impeller housing. When running it in the barrel, I do not get any water shooting out the exhaust and it overheats. Gets up to over 200 degrees on the head. If I pull the T-stat housing off, and rev it up, I will eventually get water to spit out. My question is, is the water too low for the impeller to pump water up? The water line is actually below the gear selector rod inspection window, where you would open up to disconnect it. I'm hoping it is just the water level issue, and may need to be put into the water for a test run. Just some opinions please. Thanks in advance.

I did turn the driveshaft clockwise on the install. So I'm pretty confident on the install. The grommets are new for the water tubes in the T-stat housing. I did not notice any deep grooves or pits in the housing, but I didn't pay that close attention. I could check that. So you're not too convinced on the water level being an issue? Just reading on different motors, some say that the water level should be half way up to the exhaust port, which I am not, from where the lower unit mounts.

Ha! I just purchased it. Couldn't pass on the price! Yes I have two tubes, I blew air through both tubes and I feel it out of various holes in the T-Stat housing. The lower unit is a NOS, as I had a crack in the orig. that I could not get to, to seal, and I would leak gear lube(improper winterization before me). I will look into a new plate, as well. I think I will try to remove the lower unit and spin the driveshaft w/ a drill and see if the water impeller is pumping. There shouldn't be any obstructions in the lower units water intake, but will do what I can to check.

I was putting grease on the bottom of the plate, but you recommend sealer, so I'll try that as well.

Thank You for your replies kimcrwbr1!!

Alright, I took the lower unit off, and hooked a drill to the driveshaft. If I have both copper tubes in the impeller housing, with the unit in the water, above the impeller, I get nothing coming out of the outlet tube. It just spits a little, but no continuous flow. I'm assuming that this may be normal as the return tube is allowing air back into the impeller not allowing it to pressurize. If not let me know! If I remove the return tube, and at the same depth in my barrel, water flows continously out the outlet tube. If I put the return tube back on, and with both tubes in while I submerge the lower unit, till the water is just below the opening of the tubes, I still get no water out the outlet tube. So same as when the water was "just" covering the impeller housing. I put the motor back together, with the return tube not connected, and with the outboard(which is attached to my boat) in my barrel, and the thermostat housing cover off, I get no water out the housing. Remind you that the water level is approximately 3"-3.5" above where the lower unit mounts to the outboard. I'm assuming that it is because of the depth of water in my barrel, that it is not covering the impeller appropriately enough, and not supplying enough water to flow up the outlet tube. Due to the motors mount to the boat, I can't lower the unit into the barrel any further. I attached a hose to the outlet tube, when I had the tube attached to the motor, and water flows out the T-stat housing uninhibited, out the left hole. (There are three in the housing-middle one has the spring/ball under the T-stat) Just looking for an opinion, but do all signs point to the motor just not being deep enough to allow water to properly cover the impeller in the barrel for a successful impeller test? Is there any harm in not running the return tube to the impeller when running it on the boat on the water? Or should I put it back in, when I test it in an actual body of water? I'm just trying to make things are in order before I launch her.

Both tubes need to be in.----Post pictures of the housing where the tubes go in.-------There were some variations.-----You may have a mix up of in parts here.----These pumps should be easy to inspect and repair !!

I just changed the lower unit, that was a NOS unit, that is shown as a replacement for the original on Marine Engine and other sites. This unit does not have that side water pickup, like the original one had. I assumed that it was just a design update, and not that big of a deal not having it. Are you saying/implying by not having that same design, the impeller is not getting the proper flow of water to the "suction port"? The boat/motor was my grandfathers, he was not the original owner, but I know it's been in my family for at least 40 years, but I'm pretty sure it's original. 1958 Glasspar, so I don't think it would have had an extension kit on there, unless, prevoiusly there was a motor change as well. The tubes going into the block I can add some permatex to them. When I pull the lower unit off, tubes slide out with the lower unit. I put anti-seize on the ports where they slide into the impeller housing, but will try the permatex on the upper tube ports.

Also, the tubes are one piece from the impeller housing, to the bottom of the motor, they just come out everytime I remove the lower unit. Just curious, what's the downside to not having the return port tube in?

The tubes usually stay up in the motor .---------------Simply put you must use BOTH tubes on this motor.---Any pictures ?

I don't have any pics at the moment. I'm at work! But will do this evening. Of the impeller housing I'm assuming you are referring to?

Yes, I have the two tubes. And I still have both gearboxes. I didn't check the water circuits, just assumed that as long as there is an opening for water to enter, it should work. But I will definitely get some pics and upload them. This is apparently out of my wheel house. And thanks for all the help. I'll get the pics up ASAP

OK, I know this is useless without pictures, but I can't upload from my current computer. I believe that the problem is with my new Lower Unit. The original LU had an intake w/ a screen on the port side of the LU, while the NOS one does not. I poured water down the original LU's impellers intake, under the impeller plate, and water poured out that very intake screen and out the tail part that has the screen on it. When I did it on the NOS LU which does not have the port side intake, and water ONLY poured out a small 1/8" hole that is on the starboard side, and no place else, including NOT out the screened tail piece. So common sense would tell me that the only intake that the impeller is getting on the NOS unit is through that very same 1/8" hole, which is by no means adequate to replenish the impeller when it is spinning. I ordered up a new driveshaft seal for my old unit, and will be throwing it back in to see what that will bring me. Hopefully it's an issue with the new lower unit, not actually being compatible, as per the Parts Fiche. I will try to post pics when I get a chance later. To Continue.......

As I said there is a subtle difference between lower units and water tube arrangements.-----On some lower units there was a third short tube I think.-----Pictures will sort this out quickly.

Yes racerone, the NOS unit actually has like two areas for tubes to set in the middle of the LU, which if you pour water down them, they come out the screened tail piece.

I believe post # 15 talks about " variations " in lower units.-------------------So you may have to find a grey haired mechanic who says---" havent seen one of those for a while "----- he could sort this out in minutes for you.

Futher investigation shows that the NOS LU is synonymous with a 1970 40 hp model. http://www.marineengine.com/parts/j...&manufacturer=Evinrude&section=Gearcase+Group According to the Parts Fiche, it has a different impeller housing cap, with a line that would connect down to the area in the LU made for other tubes to be put in. I think I may need parts # 2,3,5,61,62(2). Hoping that # 2 is bent to fit back to the area in the motor.

That is the variation that I referred to.-----I have not worked on one for quite some time.--------I believe you are now heading in the right direction.

kimcrwbr1 said:

You have the long shaft setup correct? If you get the long tube #2 it will need to be installed up in the bottom of the powerhead you may consider just replacing both if you need to pull the engine to replace the upper grommets? That way you just have the solid water tubes the full length?

Click to expand...

I don't have a spacer, so I'm assuming I have the short shaft. RDS-20. So based on that, would my parts list be correct?

Here are some pics of the port side of the NOS Lower Unit and my original. Along with a top view showing the additional tube slots in the NOS lower unit

And here are three more photos with top views of the NOS Lower Unit, and the weep hole on the NOS unit w/ a pencil as scale, near the current "fill port" for the water pump.(Due to not having the proper set up for this style LU.

I believe your parts list in post #27 is correct.----It will all fit without modifications.

I don't thionk it helps one bit to take the powerhead off to install the upper grommets !!---If indeed they need to be changed.

kimcrwbr1, Is there a way or trick to change the upper grommets w/o pulling the powerhead? Thanks for the advice, it's appreciated, I just remember getting the shifter linkage back on to the motor was a bear, if I could avoid pulling it, it's a bonus.

racerone, thanks for checking out my parts list.

Pulling the powerhead does not give better access to change thiose grommets in the exhaust housing !!

Alright, I reconnected my old LU and fired it up. With the T-stat housing off, and the thermostat out, it pumps water out the top with ease, if it's idling, it may stop momentarily, but if I goose it up a little, picks right back up. If I put the T-stat housing back on, and thermostat in, she overheats. Verifying with a laser pyrometer, by touch, and water sizzling on top. I did not permatex the tubes into the engine, I just wanted to see if all else was working. The thermostat is open when I take the top off. If I run it with the T-stat housing off, and the thermostat out, and put a screwdriver down the spring/ball release under the thermostat, opening it to the motor, it does run appropriately, and stays cool. I don't know what else is/could be the issue. I'm stumped. Either way, I don't get any noticeable water out the exhaust, but wasn't running it too fast either, as with the T-stat lid off, it is spraying a good amount of water all over the motor and didn't want to keep getting the flywheel soaked. The plugs are not showing any signs of water in the cylinders. Could exhaust pressure be building up and back filling the out water tube due to not sealing, and misdirecting things in the T-stat housing? Just trying to come up with an idea!!! I will permatex the tubes in and go from there on my next go around. But in the meantime, what you got for me?

I did check the thermostat, before putting it in, and it opened in that range. In the T-stat housing, facing the back of the motor, the water comes in from the left, the T-stat sets over a hole with a "poppet and spring" and then there is a third smaller hole. I'm assuming the hole w/ the poppet is the hole that leads to the block to cool it, as when I keep it open w/ a screwdriver, the motor stays cool. Does the hole to the right lead to the return? I will try running it w/o a T-stat in and see what happens, I guess. Is it possible, that due to the "low" water height, it loses pressure from the exhaust. As I stated earlier, at idle it will spray, out the housing, then stop, then pick up again. Or am I shooting in the dark with that one!!?

I've run it with the T-stat housing off, and the thermostat in, and OPEN, but I didn't notice water spraying out the T-stat. I'm pretty sure about that. W/o the T-stat, it does flow water out the top. I'm not sure if it is losing pressure, possibly from the grommets in the powerhead, possibly being worn enough, and expanding enough, that water is taking the path of least resistance and spraying out around those grommets, instead of traveling into the head. I have noticed that when I push down on the poppet, w/o a T-stat in, it keeps the motor cool, unless when there is no t-stat in, and when I am keeping the poppet open, allowing water to travel down, some is spilling over to the hole to the right, keeping the motor cool. But it is not a large stream spilling over to that hole. I'll order to grommets I guess, but try some permatex in the meantime.

I will permatex the tubes tonight, and test it tomorrow. The thing that I am leery about, it that once it is running and overheating w/ the T-stat in place and the T-stat cap on, and if I then remove it while it is running, I do not have water coming out the open T-stat. Makes me think that something changes w/ the pump due to pressure changes/air in the lines making it lose suction/pressure. I don't know if the exhaust pressure is causing this due to the low water level or what not. There is definitely a lot of exhaust coming out the bottom of the LU, below the water line, a lot of bubbling going on.