I have a 93 magnum 40 mariner that i was running in some sandy shallow water ... thought i just burnt the water pump out of it ... changed the impeller , impeller housing , lower subplate, and lower houising . the old parts looked fairly good . put it back together with new parts and i have the same symptoms that made me change it to start with . the water pumps fine out the p-hole at an idle and but as the engine speed picks up ... the water gets hotter and hotter until its steaming out of the p-hole ... them the alarm kicks on .all takes less than a couple minuites . any ideas ... ??
Ok you guys. Help me to understand how you get sand in the engine when the water p/u is mid or front of the skeg above the gearbox......running in reverse?
I remember back when OMC had the pickup on the exhaust tube directly behind the prop it was a trap for sand, but with the Merc?
The Sales brochure for the '94 4 cyl 40 hp says that it has a stat. Would guess, if the '93 is also the "classic" 4 cyl that it has one also.
To function, the pellet of the stat needs to be in the water so you need a place where a 1" long, half inch in dia or so hootus can mount. That's what I would look for and it is probably under a small cover that's slightly larger than it is with 2 screws. Along side the top cylinder would be a good place to start looking.
Take it out, check the pellet for temp stamping (in degrees F) and check it's opening. A slowly warming pot of water on the stove with a candy thermometer will give you and idea if you are close which is all you really need to know. If you are 20 degrees over the stamped temp and it is still closed you just found your problem.
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Re: 93 MAGNUM 40 MARINER ...RUNNING HOT
Checked the parts diagrams. No thermostat. The later 3-cylinder models do, but no water jacket cover. those are lost-foam blocks. His is basically a Classic Fifity. The water jacket cover is what many people initially think is a cylinder head.
I always wondered how they could get packed with sand too. But working on the Wisconsin river, I saw it many times, and brand and horsepower seemed to make little difference. One telltale sign was often a prop with little paint left on the blades, rather shiney. My guess is that it is the result of many encounters with sand, although one guy bought a new motor and accomplished it in the first trip. I'm betting it has a lot to do with reversing to get unstuck.
__________________ Hey, Have you seen? They make Really Cool life preservers nowadays.
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Mark, just read your reply and wanted to take a minute and say,if Rickyc's engine is a 40 Magnum built by Brunswick then it is the 44 cu.in. powerhead that was built for over 40 years. They in that time never had a thermostat, I have repaired thousands of them over the years and really don't care what your brochure says.
When forum members wonder why more professional mechanics don't give advice it's because of the few wannabe's out there with all the answers that argue and belittle the free advice that is given. I for one am sick of it too and am DONE, so the wannabe's can have it. So step up and have at it, I am gone at least till I cool down some. Bob
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PLEASE, no service questions in PMs thats what the forums are for.
While you have the cyl block water jacket cover off, pull the lower unit and flow water up the copper water tube. You'll know right away what kind of flow you're getting up the tube into the motor and maybe it'll flush any debris thru.
Or, just try first blowing air up the water tube and see if you get anything out.
If it seems water is getting into the block itself, 'bout the only other thing I could think of is if maybe passages under the exhaust manifold covers are plugged. But usually if they're plugged you'll see lots of silt in in the block too.
I've seen silt, sand, and barnacle chips built up in the smaller Twins halfway up the block; in larger motors, the entire bottom of the block was covered almost up to the lower cylinder. So, it can happen, just doesn't seem to be the cause here!
One last thought, before the sand bar incident, I'm assuming it ran fine with plenty of cooling? If so, it wouldn't be a problem with the boat or sucking air, etc.
Let us know if you open 'er up further and what you find.......ed
Mark and Willy, I referenced my reply to Brunswick Marine published literature and a wild guess (on my part) as stated. The rest of my reply was what I would do in his case to deal with the problem. I don't have a marine repair shop with all it's attributes. Hope you aren't pointing at me.
I have had 2 of the Classic 50 blocks (and engines) mentioned and I was real curious about two things:
1. How come Merc kept that old cross flow design in the lineup for all those years, sandwiched in between 2 and 3 cylinder loopers?
2. Why would they redo the casting just to install a thermostat that they got by without for so many years?
So when the brochure lists the 4 cyl and indicates that it has a thermostat (not pressure relief, just says stat) then I expected it to have it........course publishers have been wrong before. d
But the slick thing about errors on here is that someone, usually in the know, jumps in and sets the record straight so all learn by the experience. Seems that seeing an error just triggers a response that may not be forthcoming otherwise.
AFTER FURTHER INSPECTION AND GASKET CLEANUP ...WHILE GETTING READY TO PUT THE WATER PLATE BACK ON ... FOUND THAT THE WATERCAVITY AT THE VERY BOTTTOM HAD THE REMANANTS OF SEVERAL LOST WATER PUMP FINS ...AND A COLLECTION OF SAND ALSO ... GOING TO PUT IT TO THE TEST THIS WEEKEND ... PRETTY CONFIDENT THAT WAS AN ISSUE ... THANKS FOR THE HELP
93 MAGNUM 40 MARINER ...RUNNING HOT
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