dang,,,grounded again

[kpgraci]

in preparation for launch day I put the motor (72 merc 7.5) through its paces, well, no tell tale. Pull the impeller, it looks fine, passageways all clear, seems like exhaust gas coming from the tell tale, may be steam. If I force water up the water tube (as though it were being pumped) I got nothing flowing through the engine...either a blocked passage in the powerhead or a blown gasket or a cracked block, or some other weird problem.

I have a yamaha 2hp that I can use but I don't think the shaft is long enough, it's an inch shorter than mine, and it was just ok. also not sure the 2 has enougn\h power to handle a 10kt wind and chop.

I can't go sailing because neither of my two outboards work. bummer.

 

[Erieau]

Crap. There's a flush out fitting on that engine. Have you tried connecting a hose to that?

 

[kpgraci]

I tried and failed to get the flush screw out, it was frozen. I'll give it a go tomorrow. Good idea, thanks.

 

[Joe11688]

The water intake pipe that comes up from the water pump in the lower unit to the power head is probably all rusted out. The power head needs to be removed in order to get at it. I would find a good honest reliable marine mechanic to do this job. Stay clear of dealers unless you know that they are reputable.

 

[Merlin Clark]

When my older 6hp Johnson overheated, I did as you and checked the impeller and when I pulled the thermostat cover, found it clogged with sand and salt. Not on my watch since my draft won't allow the motor to get near the bottom, but in the past someone had grounded the motor enough to suck up about a cup of sand which became one with dried salt.
With the foot off and the thermostat out (with the cover on) I hooked up a small (IIRC 500) bilge pump to the water tube and ran a solution of white vinegar and water through the motor for a couple of hours. The motor position over a tub to catch the water/vinegar and recirculate. This is where I ended up with the cup of sand, the vinegar broke down the salt and the sand washed out.
Good luck.

 

[DeniseO30]

Get a couple of oars and go sail! 22ft boat can be rowed if necessary

 

[kpgraci]

I heated and hammered on the flush plug all am and finally got it out. When I force water through it it just pressurizes, no water come out anywhere. Not knowing the internals of the powerhead that sounds like blockage to me. I put the motor in a tub and ran it with the flush plug removed, i expected to see water coming from it from the pump but again nothing. Does anyone know if the '72 merc model 75 has a thermostat? I don't think so but if it does that could be the problem. where is the thermostat located on other small engines?

I have a shop I trust, recommended to me by winkfish, a fellow sbo-er, I visited them last week for a part and they sure look and sound like they know what they're doing.

At this point I plan on bringing it to thme unless the thermostat angle plays out.

 

[kpgraci]

Get a couple of oars and go sail! 22ft boat can be rowed if necessary

You know, oar locks are on my list of things to do to the boat...never did though.

 

[Stu Jackson]

I heated and hammered on the flush plug all am and finally got it out. When I force water through it it just pressurizes, no water come out anywhere. Not knowing the internals of the powerhead that sounds like blockage to me. I put the motor in a tub and ran it with the flush plug removed, i expected to see water coming from it from the pump but again nothing. Does anyone know if the '72 merc model 75 has a thermostat? I don't think so but if it does that could be the problem. where is the thermostat located on other small engines?

I have a shop I trust, recommended to me by winkfish, a fellow sbo-er, I visited them last week for a part and they sure look and sound like they know what they're doing.

At this point I plan on bringing it to thme unless the thermostat angle plays out.

Ken, are you aware of this website?

http://www.marineengine.com/parts/mercury-outboard/index.php

 

[Joe11688]

The thermostat could be bad. Some are easier to get at than others. I would check that out next. There is a small fiber bushing at the end of the water intake pipe that connects to the power head and that can get constricted if the engine overheated.

A lot of guys are opting to spend the money to keep their old two stroke engines going. Last year I was one of them. I wound up shelling out $800 to get my 1999 Johnson outboard fixed and I'd do it again.

 

[kpgraci]

Thanks for the link Stu, the exploded views are helpful. Apparently no thermostat on this model.

 

[kpgraci]

So let's assume it will cost $1000 to repair my '72 merc 7.5. It costs $1500 for a new tohatsu sailpro with an alternator and a longer shaft than my original (both things I want).

I know many are investing in the old motors - is it just that the new stuff is not of the same quality? Is 2 stroke that superior in a small engine? Why would I go one way or the other?

 

[Brian S]

4 strokes have better fuel economy, but more finicky carbs, especially the idle jet. But 2 strokes are simpler, and just seem to run and run and run as long as they are properly lubed, don't overheat, develop piston slap, throw a rod, or break a reef valve.

 

[kpgraci]

Well, problem solved... Repair shop says they no longer work on older mercs - too many problems with corrosion (which seems to be my problem) and he does not recommend getting it repaired. I found a used but nearly new (5 hours) Tohatsu sailpro near me asking $1000. I'll just do that and work on the merc when it's too stormy to sail.

 

[GeorgiaBII]

Down here we get dirt dobbers making nests in engine water tale tell holes. Have you tried running a wire up the piping to check for obstructions?

 

[kpgraci]

Yep. Tried that and more. I gave up and bought a new motor.

 

[OdayDave]

Well, problem solved... Repair shop says they no longer work on older mercs - too many problems with corrosion (which seems to be my problem) and he does not recommend getting it repaired. I found a used but nearly new (5 hours) Tohatsu sailpro near me asking $1000. I'll just do that and work on the merc when it's too stormy to sail.

Sounds like a good deal. I had good luck with the Tohatsu (6 hp long shaft) I had on the 85 222 I had. I was careful to change the oil regularly and tried to use pure gas without ethanol when possible. We've got a few places we can still get the stuff in Wisconsin. Now that I've got a diesel, I've got other things to worry about, but with any motor, if you treat it right, it will be reliable.

 

[jibes138]

Get a new head gasket and then pull the head off the motor. This will expose the water cooling passages in the engine block. Use some type of home made tool to scrape out all the crud in the cooling passages. Put a rag in each cylinder first so you don't get a lot of debris in your cylinders. Use a pump or blow into the water pipe to see if the blockage is cleared. You should be able to use a bicycle pump or foot pump for a dighy with some duct tape or a rubber plug to blow air through the pipe.
I used to clean out an old 2.2 merc. this way every winter, put a lot of hours on that motor.
The water flush port is intended to flush out the motor after each use. It should allow water to flow through the engine block and head without obstruction. If you have no flow it is a definite blockage. These 2 strokes are really simple engines, no cam shaft or valves to deal with, just pull the head, clean it out, clean the surfaces of the engine block and head thoroughly and put on a new gasket and torque it back up. You are dealing with a 41 year old motor so buying a new (used) one is probably a wise choice.

 

[Merlin Clark]

Any tricks for breaking (s/s) bolts (threaded in aluminum) loose without just breaking them off?
I was working on an old one couple days ago and when I went to pull the t-stat the first bolt felt like it flexed (springs back just a tiny bit) so I stopped as in the past this is what I felt just before the bolt snapped off at the block.

 

[Joe11688]

A friend of mine who was an excellent marine and small engine mechanic told me about a trick that he used for removing stainless steel screws from an aluminum outboard cover. He'd place the Phillips screwdriver on the screw head and heat the screwdriver a little with a torch. This would usually loosen up the corrosion a little and allow the screw to turn.