Overheating 33HP 1965 Seahorse

ericswag · Nov 1, 2010

Have a 1965 Johnson 33 HP that sat in a garage for 20 years. Used hard and put away wet I assume. Changed all fuel hoses, gear oil and plugs, put muffs on her and she started up, but no water pumping. Pulled lower unit, water pump impeller was intact, but pump channels were caked with harded salt. Replaced impeller, pump housing and plate. Reassembled, put on muffs, only getting a fine mist out the exhaust, and engine overheated. Can not find a thermostat on engine. Any ideas on what the problem can be? This motor is also fairly hard to pull start (relative to smaller/newer OBs I own) is that normal? Also, anyone know the correct fule

il ratio (I am using 50:1 now). First time poster, long time boater. THANKS!

lindy46 · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

Welcome to the forum! Lots of great people here ready to help. Probably best to run that motor in tank of water rather than muffs. Get the water level above the level of the water pump and see how she does. Is it a salt water motor? If so water channels could be corroded. Those motors are a bear to pull-start. What, no electric start?

Big Pete · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

Hi and welcome

Agree what last poster said. but you could try a poke around and blast with hose in the inlets and outlets, could be blocked with crud, in the outlet hole or similar ..

ericswag · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

Wow, that was fast guys - thanks! Can I blast backwards thru the ehhaust hole without worry of getting water where it shouldn't be?. To answer your questions - the motor was used in salt water for most of its life (it was my neighbors). One other clue: when the engine got way hot to the touch I shut her down and pulled the lower unit (came off very nicely this time!) to make sure I hadn't screwed up the waterpump install. One curious observation was that the exterior WP housing and vicinity was all covered with a watery grey grease/oil emulsion. I thought that area of the motor stayed mostly dry, with just exhaust gas passing thru? At the time I wrote this off to grease slinging off the shaft or out of the little vent hole in the top of the pump housing (I greased the inner housing before installing the impellor). After poking around on this site, I am now worried about a blown head gasket - would watery grease on the top of the WP be a symptom? Finally, if the water channels are clogged with salt - how to go about unclogging them? Thanks.

Chris1956 · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

The WP housing sits in the exhaust housing, so watery oil is expected. That motor should have a thermostat on the cylinder head. The exhaust should spray fine mist at 140*F.

lindy46 · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

Try connecting a hose directly to the water tube and try to get it circulating. See if that cleans things out. I don't think the 33hp motor has a thermostat. Same as the single tube 30-35hp models from the '50s.

F_R · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

You are wasting your time and energy. Muffs won't work on that motor. You will have to put it in a tank to tell if the cooling system works. Have it deep enough that the water pump is a couple of inches below the surface before starting it up.

No you can't back flush it through the exhaust relief.

The stuff you describe in the exhaust housing is normal. It is exactly that, and exhaust housing. The oil that you put in the gas goes out the exhaust after it has done its job of lubricating the powerhead. It emuslifies with water in the housing.

Get it on a boat in the lake and you may find it is just fine.

ericswag · Nov 1, 2010

Re: Overheating 33HP 1965 Seahorse

Thanks Guys. Since the lower unit is off, I'll try the garden hose up the tube trick. Then, then give her a whirl in a tank and see what happens.

ericswag · Nov 13, 2010

Re: Overheating 33HP 1965 Seahorse

UPDATE: I ran a hose up the copper water tube and got some flow out the exhaust - but not much. Feeling adventurous, I pulled the head and cover plates off. Miraculously all the head bolts and cover plate screws came out in one piece. What I found was a lot of hardened salt in the passages in the removed head. The areas around the cylinder walls in the block were not that bad. So, I cleaned all the hardened salt out with a wire brush, got new head bolts, cover and head gaskets off EBay, and am ready to reassemble. From searching this forum I know now to chase and clean the head bolt holes, the correct pattern to tighten my new head bolts, and to put gasket cement on the cover gasket surfaces but not the head gasket. (I think) BUT - I can not find the proper torque specs anywhere. So - does anyone know the torque specs for the head bolts and cover screws for a 1965 Johnson 33 RX 13-B? I also am not sure if I should put some neversieze or gasket seal/threadlock on the new head bolts? Really appreciate the help from this forum! THANKS.

1946Zephyr · Nov 13, 2010

Re: Overheating 33HP 1965 Seahorse

You'll most likely need to pull the powerhead and clean the passages between it and the midsection. If someone let the motor sit, after salt water use and didn't flush it out, then this is the spot it will likely clog up with corrosion. There is no thermostat on this particular motor, so no worries there. You're lucky any water flows at all. I've picked up motors that were plugged solid and had to royally scrape them out throughout the water jackets. Salt water is the next worse thing for a motor, to boiling hot acid.

F_R · Nov 13, 2010

Re: Overheating 33HP 1965 Seahorse

Head bolts 168-192 INCH pounds. Exhaust cover 60-80 INCH pounds. OMC Gasket sealant is reccommended for the threads, not anti-sieze.

kfa4303 · Nov 13, 2010

Re: Overheating 33HP 1965 Seahorse

Hi ericswag. I have a 1966 33hp seahorse, which I just got running again thanks to the forum here. F R is right, muffs wan't work for these guys. You will need to get a tank (big plastic trash cans, or 55 gal drums work well) and fill it with water several inches past the waterpump intake. I try to fill it up to a few inches below the exhaust port on the leg. Don't expect a perfectly uniform "pee" stream like some other motors either. B/c the water from the impeller mixes with the exhaust gases they both come out together in sort of a sputtering mix. The temp of the exhast water is fairly warm, esspecially in a tank where the same warmed water may be cycled several times. My exhaust is about the temp of a cup of tea, but is usually a bit cooler on the open water. Once you're out on the water the stream will probably become a bit stronger as well. Your test tank will get some blackish, unburnt gas and oil in it and will probably become cloudy, but don't be alarmed, that's normal. Dial in a good idle in your tank then do the same once you're out on the water under load for both the lo and high speed needles. Lindy46 is also right, no thermostats on these guys either. Keep us posted. I'm curious to hear how your 33 does. They seem to be a bit rare. Lots of 25, 30, 35 info out there, but not as much for our 33's. Good luck!

ericswag · Nov 14, 2010

Re: Overheating 33HP 1965 Seahorse

Thanks Guys! This forum (and the folks who contribute) are outstanding. I will advise outcome once I've implemented all your directions.

ericswag · Nov 14, 2010

Re: Overheating 33HP 1965 Seahorse

SUCCESS! OK, so I did the 400 grit wet or dry sandpaper on plate glass trick to resurface the head, chased and cleaned the bolt holes in the block and cover plate with a tap (great idea!), reassembled with new head bolts and gaskets, put her in a tank and WOW does she pump now - not a mist at all but really like a garden hose (of course, she might of pumped like this in the first place if I'd used a tank instead of muffs). kfa4303 is right - she is an oliy beast in the tank! Head was warm, NOT HOT to touch after about 5 minutes minutes of running. Let her cool, re-torqued the head bolts and no more heating problem!

Now for the next issue: I pulled the plugs after the cool down. The top plug is heavily carboned up, the lower plug looks fine. Any idea why? She runs with a miss at low speed, sorta of a chuga chuga chuga chuga boom, chugga, chugga chugga chugga boom etc. Smooths out at higher revs. What do I work on next?

Thanks to all who helped - really enjoying this project and the forum...

lindy46 · Nov 14, 2010

Re: Overheating 33HP 1965 Seahorse

ericswag said:
Now for the next issue: I pulled the plugs after the cool down. The top plug is heavily carboned up, the lower plug looks fine. Any idea why? She runs with a miss at low speed, sorta of a chuga chuga chuga chuga boom, chugga, chugga chugga chugga boom etc. Smooths out at higher revs. What do I work on next?

Thanks to all who helped - really enjoying this project and the forum...

Plug will probably clean up once you put the motor on a boat and run at higher speeds. Is you miss like a sneeze? If so, try opening up the low speed needle a little and see if it goes away. Could be just a lean sneeze.

kfa4303 · Nov 14, 2010

Re: Overheating 33HP 1965 Seahorse

I agree with lindy46. You gotta get her out on the open water to really dial her in just right. All outboard are unique and need a biot of tuning once on the water. Running it in a tank will just give you a ballpark and allow you to see that all the major systems are working. You can re-check the plugs after you run her on the water for a while. A bit of oil on them is ok. B/c the pistons are lubed by the oil mixed with the gas, it's better to have a bit too much gas ("rich") in the pistons, than for it to get too little ("lean") which could cause real damage to the motor. A little excess ga/oil may foul a plug or two, esspecially while trolling, but plugs are cheap and easy to replace, if need be, but a lean-running two stroke can overheat and possibly sieze up, whcih is not easy to replace. Don't be surprised when she drinks the gas. These things weren't the most fuel efficient, but they do run strong all day long. Good luck!

jay_merrill · Nov 14, 2010

Re: Overheating 33HP 1965 Seahorse

Don't bother looking for a t-stat on your motor - it doesn't have one. People often get these motors confused with the Superquiet 40s, which do have t-stats.

Trying to check for water pump function with a hose on any motor isn't best way to go about things, because the hose pressure may feed the cooling system even if the pump is bad.

That said, I have a pair of modified rectangular muffs that I used to use on my '58 ERude Bigtwins, which have pretty much the same gearcase and midsection.. They were handy for flushing the motors or cooling when I wanted to do something like running some BRP Engine Tuner through them. I've been asked about them a few times. so I'll see if I can get some time to photograph one of them tomorrow.

???

ericswag · Nov 15, 2010

Re: Overheating 33HP 1965 Seahorse

Thanks guys. Yes, the miss is like sneeze, Ill fool with the jets a bit and see what I can do. The sea trial will have to wait for spring, because the second half of this project is restoring the 1964 Boston Whaler that the motor came with (my 13 year old son's "new" boat)! Thanks again for all the help, I'll probably be back after the sea trial!

1946Zephyr · Nov 15, 2010

Re: Overheating 33HP 1965 Seahorse

You might also want to check the condition of your ignition system too. If your coils are cracked, they will need replacing. Also check and make sure your points are clean and adjusted properly. Often times a weak and aged ignition system can make us believe we have carburetor issues when we actually don't.

ericswag · Nov 16, 2010

Re: Overheating 33HP 1965 Seahorse

Good point Zephyr (no pun intended!). Do I need any special tools to check the points (like a fly wheel puller)? I'll search the web for the parts. By the way, I have been searching for an original service manual but to no avail. Are any of the aftermarket "one size fits all" manuals any good?

Overheating 33HP 1965 Seahorse

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