1982 Mercury 9.8 Coolant Passage Blockage

[scout-j-m]

Everybody looks at the economics in a different way.----That motor may well be better built than a new one today.-----If you need to spend time effort to find a few parts is easier than finding $3000 for a new motor.

It is very hard to beat the simplicity of this era of small twin cylinder, single carb motors.

 

[appleo]

Is there same washer in a mervury 3.9?

 

[racerone]

Same washer there.------Just a one cylinder motor instead of 2 cylinder.

 

[scout-j-m]

Totally forgot to update this.

I used a degreaser and cleaned up the lower cowling the best I could. I then reinstalled the powerhead with the new water grommet and a new gasket. Took a bit to get it started but when I did it was pumping water excellent and running nice and cool.

Discovered a few more issues, primarily that the coils are arcing and seem to be damaged. Spark is still strong though after I wrapped in electrical tape. Since the CDI was also bad I'm wondering if the motor overheated a few times and the heat damaged those components. I paid $100 for the motor which included a fair shape 6 gallon tank, paid $150 for a new CDI, and then about $40 in other small parts including a carb kit. Don't think I can justify buying new coils as I cant see this motor being worth too much more than $300 in my neck of the woods.

Appreciate the help guys.

I'm bumping this because in typical fashion the motor took a backseat to other projects. I got back on this 9.8 a few weeks ago, cleaning the carb again and trying to get the throttle linkage working smoothly. I had to pull the flywheel and remove the trigger and clean and grease all of the moving parts. It still won't advance all of the way as the throttle cables don't seem to have enough pull even with the locknuts fully threaded out. But anyways I got it to a good enough point.

Started in a barrel today with full submersion almost to the lower cowling a I'll be danged if it wasn't pumping water at idle. Pisser tube is totally clear but not even a drizzle all the way up to fast idle. Pop it in forward and give it some throttle and it starts flowing well and the initial few seconds of water are brutally hot but it does begin to cool the powerhead down at that point. My model does not have a thermostat to check. Guess I will pull the lower and and inspect it and if all looks good try to flush water up the water tube. Per my previous posts I checked the powerhead passages with compressed air after installing the new water tube grommet and my initial startup had good water flow. I can't remember the condition of the impeller I removed so I'm not sure if there may have been deteriorated pieces in the system. If my water pump seems fine should I pull the water jacket cover next assuming I cant get good flow up the water tube?

 

[scout-j-m]

I pulled the lower tonight. Nothing seemed to stand out aside from the plastic inlet tube/sleeve the copper water tube uses as a guide to seat down on the water pump outlet seal. Put the lower in neutral and submerged in a 5 gal bucket and used my 24v drill to turn the driveshaft. Had water flowing seemingly decent on both low and high speeds. Looked online and low is up to 550 rpms and high is up to 2000 rpms - so I ran it on high at about half trigger shooting for a speed a littler faster than idle. So I think water pump is fine. I blew air up the water tube, up the pisser tube, and up the flush port and all seemed clear and forced air out every other place including through the exhaust. I did notice their is no exhaust tube on my motor, but didn't see one in the parts diagrams so I'm assuming they don't have one.

I'm guessing there is some issue with the water tube to water pump connection. Before I turn any bolts on the powerhead I'm going to buy an adapter for a garden hose to tubing (3/8" ID?) or rig up some other connection that allows me to hook straight up to the water tube and supply water and see how it does. Manual says you should see at a minimum of 5 psi at wot so maybe I can rig up some type of pvc manifold with a garden hose inlet and flex hose outlet and add in a ball valve and pressure gauge in between so I can control the water pressure. I've been meaning to build one of these things for a while now exactly for situations like this and for other times a lower unit is temporarily out of service.

 

[pointblank1000]

Was their ANY rust on that motor? If so it's been in salt water. If the guy you bought it from says never in salt water......most likely been in salt water. Remove l.u. turn upside down shoot in pb blaster in the copper tube and flush hole and let sit. Salt water motors "to me" is good for one thing. Parts only.

 

[scout-j-m]

Was their ANY rust on that motor? If so it's been in salt water. If the guy you bought it from says never in salt water......most likely been in salt water. Remove l.u. turn upside down shoot in pb blaster in the copper tube and flush hole and let sit. Salt water motors "to me" is good for one thing. Parts only.

I have seen zero corrosion on this motor. I'm far enough away from the coast no one ever mentions it when they sell/buy. When I had the powerhead off to replace the water tube grommet the whole area within the exhaust and mating surfaces was just carboned over but not even too bad in that respect. Should be a pic a few posts back of that.

What the motor does have is some serious indications it was severely overheated in the past - the melted water tube grommet, totally melted powerpack, failing coils, seemingly partially melted water pump guide tube. I'm not sure what that tells me though. Just makes me wonder if it was due to a failed waterpump or if there were troubles in the past with getting the water tube to properly seal with the waterpump outlet.

 

[scout-j-m]

I bought a garden hose to 3/8" barb adapter plus some tubing. Couldn't find a good pressure gauge though. Gonna pull the lower again tomorrow and see if I can adapt the flex hose to the water tube and run it like that. Hopefully that will tell me that from there up is either clear or not. Then I will re-evaluate the water pump. I only put in a new impeller vs a whole kit so its possible else something has broken since I installed the impeller and first ran it after changing the water tube grommet.

 

[scout-j-m]

The 3/8" tubing was too large for the motor's copper water tube - but I was able to use a piece of what I think was 5/16" tubing I had laying around to go over it. Then the smaller tubing fit well into the 3/8 tubing and I clamped them together and used the barb adapter to hook it up to the water hose. Water seemed to flow freely within the motor even with the hose barely cracked open. I started and ran the motor that way as well and it seemed to cool just fine. So I now believe my coolant system from the water tube up is all good.

I also feel like the seal between the water tube and the water pump is good and not obstructed. I inspected the water pump again and the impeller is is great shape still and the key is also in place. Both plastic halves of the water pump seem ok, although they look like they may be original, or at least very old. The only thing I see a definite issue with is the water seal on the water pump cover. It appears to not seal against the driveshaft well at all. This definitely seems like it would reduce the function of the pump. I figure I will go ahead and get a new seal if not a whole new cover assembly....but my concern is will a new seal fit tight??? There are 2 different impeller options available with each having a different inner diameter based on serial number range. My motor uses the impeller with the small inner diameter. But there is only 1 seal available. Are the driveshafts tapered where the impeller rides on the early models which is why they use a larger ID impeller? Just hate to get a new seal and then it not ride tight against the driveshaft.

 

[scout-j-m]

Alright, got good news....I replaced the water pump cover with a NOS OEM one which included a built in driveshaft seal. After replacing it and reinstalling the lower I ran the motor in a barrel and had pretty good water flow and engine temps. I did notice it takes a bit for water to flow upon initial startup and it kinda sputters out in neutral idle and is pretty hot even though the block stays cool. It pumps well and cool at forward idle though. Maybe that's just how these behave or maybe there is some other slightly small issue. Either way it cools fine as is so I'm not going to fool with it anymore.

After doing all of this the motor runs quite well. It has excellent compression, good spark, I cleaned the carb, and now has good water flow. The remaining issue is a doozy though as the tiller throttle is practically inoperable. I mean that as in the full range of the twist throttle is about 1/3 of the actual travel of the motor linkages. I pulled the tiller apart and the cables are connected correctly and the cable adjustments under the hood are maxed out yet it still wont pull the advance or retard very far in either direction. I cleaned and greased the trigger assembly so it moves freely so I think the cables are possibly either the wrong ones or they are stretched out. At $40 apiece that's a pretty stout additional cost. Unfortunately I think this motor is doomed to be parted out as I'm at the threshhold where every additional dollar invested is money that will never be recouped in a complete outboard sale.

 

[pointblank1000]

You never know what the previous owner did to the motor. Assume the worst like the water pump impeller broke into pieces and got shoved into the block.

 

[scout-j-m]

You never know what the previous owner did to the motor. Assume the worst like the water pump impeller broke into pieces and got shoved into the block.

Yeah, this one has definitely faced some neglect paired with some interesting home engineering.

A lot of parts for these are no longer available so maybe on the bright side parting out what is good will help someone else out there fix their motor.

 

[pointblank1000]

EBay is LOADED with parts. Just keep your eyes open for them