# Mercury mariner



## Bign0703 (Oct 3, 2021)

Hey guys 
I just purchased a 1997 mercury mariner 25 hp. Runs great but needs a throttle/shift cable. I've searched everywhere and all of the parts sites I usually order from and can't find one at all. Everytime I search the serial number it shows a 9.9hp but the tag even shows 25hp on the motor. I will attach a picture with the tag. Could anyone point me in the right direction for one?

06564056
1997
25he
25hp mercury mariner


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## Bign0703 (Oct 3, 2021)

Here are some pictures of it and the tag


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## overboard (Oct 3, 2021)

Try this---- Crowley Marine parts, select your engine, and enter the required info, it will show up as 25EH parts and it does look like it is available as part # 43242T03.


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## Bign0703 (Oct 3, 2021)

overboard said:


> Try this---- Crowley Marine parts, select your engine, and enter the required info, it will show up as 25EH parts and it does look like it is available as part # 43242T03.



Thank you!!!! I don't know how but I didn't even think of looking at Crowley! I know I was completely stumped after searching for 3 hours! Really appreciate it!


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## overboard (Oct 4, 2021)

You're welcome, hopefully the info. that I provided is what you needed and correct, you could also call Crowley and ask them to confirm using the serial number.


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## Bign0703 (Oct 7, 2021)

Overboard it was spot on! I ordered the throttle and shift cable and new bushings for the tiller but they had to get everything from mariner so waiting on shipment. I really appreciate it. Absolutely love this forum!


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## overboard (Oct 8, 2021)

Very good, glad to hear you got the parts that you needed and glad I could help you out.


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## Bign0703 (Dec 8, 2021)

Ok guys. I'm in a pickle with this thing. Replaced the entire impeller assembly along with the water tube seals and she won't pump a drop. I've heard several say these motors have to be submerged to pump and won't pump off a hose but don't know for myself. I plan to dip the lower into a tank and running it with a drill to see if it is pumping but anyone have any idea what could cause this. When it's on a hose it acts as if all the water is flooding the mid section but not going through motor.


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## onthewater102 (Dec 9, 2021)

When you say flooding the mid-section do you mean you have water pouring out of your driveshaft housing area (behind the swivel bracket)?

If so it sounds as if the water tube isn't seated correctly up under the powerhead, it may have kinked the rubber grommet seat at the top or misaligned all together.

Always good to double check mud-wasps haven't been at work in the tell hose or fitting by running a wire around in the end.

I wouldn't advise running it on a drill. It's a 2 stroke, so it needs the oil in the fuel. If you pull the plugs out and crank it you risk damaging the finicky ignition components if they're not grounded. I would just fire it up normally and shut it down if it isn't peeing in 10 seconds or so of running provided you're sure it's getting water to the impeller. The impeller is the sensitive component to being run without water circulating. 

The motor will eventually overheat without cooling water, but that takes a while to build up the heat, whereas you will damage the rubber if it's spinning without water to lubricate the impeller itself in a very short amount of time.


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## Bign0703 (Dec 9, 2021)

Correct. I replaced the tube seals and double checked and they seem correct and seated properly.

And no I have the lower back off I was planning on using the drill to turn over the driveshaft itself. But I've never dealt with many Mercury's and never had a motor that wouldn't take a hose attachment besides older models that aren't set up to do so


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## Pappy (Dec 9, 2021)

I take it you are running on "ear muffs"?
Are they the round ones or squared off ones?


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## Bign0703 (Dec 10, 2021)

Yes sir, and the square. They are seated great. I picked up a plastic barrel today and I am still waiting on my set of round muffs with the through rod. I happened to left my last set in a boat and the guy said he didn't see them so I had to go get some til my new ones come in. I've just never had one act like this even with the square muffs. But I also rarely touch mercury/mariner outboards either


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## Pappy (Dec 10, 2021)

I cannot tell you how many customers we have had come in with a burned up water pump from running on the squared off muffs. They may look like they are sealing but the pump will pull air past the edges. 
We absolutely quit selling the squared off ones several years ago.


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## Bign0703 (Dec 13, 2021)

Yeah I had the squared ones myself. They've gotten me by but that's all I can say haha. I'm hoping my new ones will be here within the next few days. They were the best I've ever used. Circle with the rod that goes through and locks down. Never had an issue with them.


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## Pappy (Dec 13, 2021)

By the way, when you are running in a barrel or bucket the water level has to be a few inches above the parting line where the gearcase meets the exhaust housing. That will insure your water pump is fully submerged and capable of pumping.


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## 2manband (Dec 15, 2021)

I have almost exactly the same motor except its a year older. (1996) I had the same experience. Bought it used, it started and ran well but we couldn't get it to pump water on muffs in the seller's driveway so we shut it down after after a few seconds and I negotiated a discount on the purchase price. 

I brought it home and replaced the impeller. Then I couldn't get it to pump water on muffs in my driveway either. After a lot of checking, head scratching, short runs and stops, and about 2 hours of screwing around, it was pumping warer with gusto. Here's what I learned:

It's hard to fit the lower unit in a barrel if the previous owner installed a hydrofoil. 

It's hard to run it on muffs, I think because the pickup hole is pretty tiny. You need a lot of water pressure, a really good seal on the muffs, and the kind of muffs that feed water to both sides of the lower unit. I have very high pressure city water at my house. Other places it may just not be possible to muff this motor succesfully.

It takes a little time for the thermostat to open and start discharging water. Those are harrowing seconds when you're not sure if the impeller is working. I go by feel - if the cylinder head is too hot to touch for more than a few seconds, time to shut it down and cool off.
At idle, the thermostat will cycle the water discharge on and off - you can feel the cylinder head getting hotter and cooler as it flows water or doesn't. While it's under power and pushing a boat around, it discharges water continuously.

I had to pull my lower unit off recently for another reason and checked the impeller. It still looks fine, no sign of burning. So I must've gotten enough water to it to lubricate it, just not to pump properly.

So I think you'll find you're good to go after the barrel test.


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## Bign0703 (Dec 19, 2021)

I appreciate that info. I don't normally deal with mariner or mercury but I picked this one up for 125 running so I couldn't pass it up. Soon as my parts come in imma get her together and drop her in the barrel and see


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## onthewater102 (Dec 20, 2021)

No thermostat in these motors.


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## 2manband (Dec 26, 2021)

https://www.boats.net/catalog/mercury/outboard/25hp/25hp-marathon-0g044027-thru-0g760299/cylinder-block-and-covers

Thermostat is listed here as #37 in the exploded drawing?


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## Bign0703 (Dec 28, 2021)

Yea its definitely suppose to have one. Mine unfortunately has been removed. Still haven't has time to mess with it yet


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## onthewater102 (May 17, 2022)

Apologies, I've had a few of these and I've been lucky enough to have the variants which didn't have thermostats, but I see now in block configuration #2 under my s/n there is a model variant that has a t-stat.


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## Pappy (May 17, 2022)

You are not waiting for the thermostat to open to see water from the overboard indicator. You are waiting for block to fill.


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## FuzzyGrub (May 18, 2022)

That thermostat recently "tricked" me on my '98 Merc 25EH. I had very low water output from a wasp free pee hole. Upper cyclinder got too hot to touch, running in a barrel. Since I have had the motor for over 10 years and not changed the impeller, figured that had to be it. The impeller had no broken vanes and they were still relativey flexible. I did see some wear on the housing and short output hose had some cracks. Got it all back together, and flow didn't improve. Thought I messed up with missing the tube. Took it apart again, and as far as I could tell, was aligned. I finally just removed the thermostat, and walla, nice stong flow. There wasn't time to order and receive stat, so took boat to camp and ran without it just fine. The new 120 degree stat arrived and will install next time. It is a simple two minute job. At least the agrevation encountered will help drive that mistake into my memory.


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## RaisedByWolves (May 18, 2022)

Bign0703 said:


> Ok guys. I'm in a pickle with this thing. Replaced the entire impeller assembly along with the water tube seals and she won't pump a drop. I've heard several say these motors have to be submerged to pump and won't pump off a hose but don't know for myself. I plan to dip the lower into a tank and running it with a drill to see if it is pumping but anyone have any idea what could cause this. When it's on a hose it acts as if all the water is flooding the mid section but not going through motor.



You missed the hole.


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## Bign0703 (May 26, 2022)

Oh yes. I finally got it lined out. The upper seal and base gasket were shot! Got them replaced and she runs as good as new now



Pappy said:


> By the way, when you are running in a barrel or bucket the water level has to be a few inches above the parting line where the gearcase meets the exhaust housing. That will insure your water pump is fully submerged and capable of pumping.


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