1983 Johnson 7.5, steamy water from tell-tale.

[redfishsc]

Howdy. My 1983 Johnson 7.5 has slowly reduced what it's peeing since I bought it about a month ago. It looked normal at first (esp. compared to my worn out 6hp of the same generation). But on my last trip, a guy at the dock noticed it before I did, that it wasn't doing much at all, just slowly dribbling out as if it had prostate trouble. I had just run the motor for 45 minutes at WOT (around 8 miles) and it peed just fine, but it slowed down when I approached the launch.


Today I put it in the barrel, and it went from just spurts, to steam and dribble, to only steam and air. The water that was dribbling out quickly became scalding hot before it went to steam. I also cannot feel any real amount of water coming out from the exhaust down near the prop, I am assuming that I should feel at least some water flow, by hand (in neutral!), correct?, Just seems like there is insufficient water flow.

I cleaned out the tell-tale rubber hose-- not obstructed. I also put some compressed air down the tell-tale outlet, and it happily exited from the lower unit as it should. Also checked out the whole system for any other obstructions (the screen intake esp). But no change--- no pee. In other words, I cannot find an obstruction. The screen on the lower unit is not clogged, and I can't see any clogs up inside that area if I remove the screen and look up in with a flashlight.

Any other suggestions on where to look for obstructions?




As a last ditch effort the impeller despite knowing that the one in it wasn't all that old (2 years, but barely used). The old one was not in bad shape, but it was rusted to the drive shaft-- was a bit difficult to remove, but I did get it off and put the new one in.

I was CERTAIN to make sure that I had the tubes aligned on the water pump when I reassembled the lower unit. Of course it's still possible that I wiggled them apart by accident as I was figuring out how to get the lower and upper units to realign but I'm skeptical that this is the issue.

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

By the way, the thermostat is missing from this motor. The guy I bought the motor from was DEFINITELY the sort that would have removed it. I'm assuming the motor is otherwise fine to run without the thermostat, right? I do have a thermostat on my other parts motor I could put on.

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

FWIW, I pulled the foot off and found that the plastic gearcase cover was damaged and the brass inserts around the bolts were corroded. The gearcase cover looked as if it had been overtorqued because the corners were broken out. The hole was about 3/16" around, not sure if that would be enough to break the seal, but it does explain (I think) why I was getting exhaust through the pee hole.

Any other suggestions?

I need to order a handful of gaskets and seals (and a new impeller), and would be a good thing to replace any other routine tidbits since I have the foot off.

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

Update.

I replaced the water pump today but no luck, I still get only exhaust smoke and water droplets from the tell-tale. I need advice!

I've ruled out an obstruction in the foot near the prop. What I haven't ruled out is an obstruction up in the pipe above the water pump where the lower unit mates with the midsection. But I can blow compressed air and get a lot of air bubbles blowing down through the foot.


I do know that this motor has had the thermostat removed, but that isn't the actual problem. Any suggestions would be very helpful!!

 

[nwcove]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

possible head gasket issue.

 

[rocket72]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

Did you replace the gear case cover?
Also is there water in your lower unit oil?
If your pump is working properly the water is going somewhere. Hopefully not into gearcase and out the seals. I went into some shallow water once and the outboard sucked up some beach sand. Made it through screens and packed into pump also plugging outlet. I would think your intake screens would filter out anything large enough to plug your water pump outlet but sand is a little diff.. You could probably blow air through sand even if it was packed in your cooling system lines. Just a few thoughts. Hope it helps. Rocket

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

Thanks guys, I'll answer your questions below.

I just flushed out the system as best I could through the thermostat cover and up the water pipe in the midsection. This didn't change anything. Used a strong jet of water and also 120psi compressed air.

When spraying water into the thermostat orifices, I get a good stream of water through the tell-tale (motor off). Tell-tale isn't blocked.

I ran the motor for a couple minutes with the thermostat cover off, and I get no water flow through there. If I spray water straight into it, the motor pees normally (hot water at first, then just "warm"). This seems to rule out blocked passages in the block.


I think the problem is in the pipe just north of the water pump. My grommet isn't bunched up, and I ran a clothes-hanger down through it. My next step I suppose is some weed-eater cord or some stainless steel wire poked into various places. PLEASE suggest to me the best way to try to clear this, since it seems to be a blockage between the water pump and the engine block.

possible head gasket issue.

OK, so without having a spare head gasket laying around, is there any way to check this? I suppose I could check compression. I have a compression gauge but I don't know if my plug adapters will fit... need to check. '

The fact that I have exhaust coming out of the pee hole should tell something, but I do not know if that would happen in the event of something being blocked up or not. When I removed the thermostat cover and sprayed water into it while the motor was running, the tell-tale worked just as it's supposed to. I suspect that rules out a blown head gasket but I can't say for sure.


Where does the water exit the system, through the exhaust?

Did you replace the gear case cover?

Yes, the cover is off a spare parts motor and in very good shape. Brand new gasket.

Also is there water in your lower unit oil?

No water. It was just straight gear oil when I drained it. That was several weeks ago, I don't recall what color it was but I do remember it wasn't cloudy or watery. Replaced it today with new.

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

More news, I think I found the culprit, but unfortunately it's an obsolete part. Perhaps Seaway has it, I will call them in the next day or so.


It's the rubber retainer that holds the copper water tube in place. It was all bunched up, whoever installed it last seems to have really made a mess of it. It was plugged up with crap.


Now I have to figure out how to engineer this. I do have a spare parts motor that I can try to dig this out of and hope that it's in useable shape.

 

[raczekp1]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

i think you can cat it out from rubber hose, no need to disassemble next motor

 

[redfishsc]

Re: 1983 Johnson 7.5, steamy water from tell-tale.

i think you can cat it out from rubber hose, no need to disassemble next motor

I would definitely attempt to cut it out of some rubber hose if I can. The one on the spare motor was also rotted. Since I know how to remove the block now, it's really fairly easy on these small motors anyhow. But unfortunately the rubber on this one was also rotted, although not quite as bad.