Mercury classic 50 overheating

[Coltrickle]

Re: Mercury classic 50 overheating

I have to agree with oldman570.. He and CharlieB helped me a great deal on my classic fifty.. However after 2 months of chasing several problems on my motor I can honestly say that you never know what you will find... I replaced my water jacket cover( what you called a head gasket) and my exhaust gaskets for about 20 bucks!! And a couple hours of my time.. I do however have above average mechanical skills.. When I removed my exhaust cover there must have been enough impeller fins for 2 impellers.. They were clogged in the water jacket leading to the outside exhaust cover... Once I removed them my stream increased 10 fold.. I replaced the impeller twice to no avail due to intermittent steam from tale tale.. Just be wise in what you do and if you don't have the best of memories there is nothing wrong with taking a few pics during disassembly.. Godspeed

 

[sjoefl01]

Re: Mercury classic 50 overheating

Quick question:
Do we have to pull the powerhead or can we take the lower cowling off without it?

 

[Maxz695]

Re: Mercury classic 50 overheating

On m y 70 HP I can remove the side exhaust cover and baffle without removing the powerhead. The rear cover too. But if after checking these for fins and crap, the powerhead wil have to be removed to get into the exhaust base plate. This would be the first area the fin would go and block the water port to the engine. My intake hole for water is small and a larger piece of impellor could not get through it easilly. It shouldn,t take you more than a few hours to complete the job. the power head isn,t that heavy that after unhooking it and unbolting it you can lift it up yourself. Just be sure to seperate the shift shaft as it will inhibit the removal do to it,s legnth. I took a long 2 1/4 inch roofing nail cut the point off and used it to knock out the roll pin in the upper shaft arm. remove the water tube also when removing as not to bend or damage it when you lift it off. Also be careful to lift the [powerhead straight up as not to damage the stud threads. If you have trouble removing the base due to rusted are corroded nutt,s spray them very well with a lubricant (PB Blaster) over a few days and take a small wood chisel and a hammer and make an indent just off center of the nut with the chisel for placement in the diriction (counter clockwise) the nut must go to remove it. When your sure you have enough meat not to chip off place your chisel and give it a few hard wacks to get the nut loose. This may have to be repeated all the way around a corroded or rounded nutt. Take pictures of your wiring and componants to help you reinstall everything.

 

[sjoefl01]

Re: Mercury classic 50 overheating

Yesterday I got together with a couple of buddies and pulled the exhaust plate cover. When we pulled it apart a big piece of something fell out. We could not determine exactly what it was or where it came from. I thought it was melted impellers but my buddies thought it was carbon. Other than that nothing was obvious. The gasket looked like it had probably failed in a couple of places but you couldn't be sure. We pulled the foot and blew air through all of the water passages we could find. There was quite a bit of sand that came from one of them out of the copper pipe in the foot. We were going to do the same thing with the cylinder cover (head). The bolts were seized on it pretty bad. We took a vote. Rather than break a bolt and turn this little job into a big job we decided to put it back together and see if we were living right. Well it turned out, we were. The stream looked like the utube video I had seen and increased with RPM. We put it in the water and ran fast all afternoon with a nice cool motor.
I really do apprieciate all of your help. In a month or two when it gets really cold I'll be back here. I need to replace all the gas lines and filters. I'm sure I will need a little advice from people that have been there. For now, I'm going fishing!!!

 

[sjoefl01]

Re: Mercury classic 50 overheating

I do have one more quick question. We had a terrible time trying to get the water pump seal seated in the copper pipe in the foot. Surely there is some sort of mechanics tip for this. The side of the pump is open to give access to on of the screws that hold the pump together. If you look into the pump there is a serious downward taper in the opening although the pump seal seemed to have the same outside diameter. The inside of that seal tapers in to the center and then tapers back ou at the end. It is only about a half inch long. It looked like if that seal didn't get in there correctly the water would spray out the side of the pump and bypass the engine. Unless we had the wrong seal or the wrong idea about how this works it is a terrible design. We kept pushing the seal up on the pipe while trying to get all the gears and shafts lined up. If you tried to push the seal in the pump first it wanted to turn sideways and bind between the pump housing and the copper tube.
Surely there is a better way.

 

[ajgraz]

Re: Mercury classic 50 overheating

Good you got her going.

I know that on my 78 70hp, the water tube (copper pipe) only goes into the outlet of the water pump maybe 5/8" into the rubber seal. I too wondered if that is enough, but it pumps water and pees, so I guess it's OK.

 

[oldman570]

Re: Mercury classic 50 overheating

The seal for the water tube should be put into the water pump housing and should bottom out in the housing. Some seals have tits on the side that have to be pushed down in the housing and lineup with the holes in the side of the housing and will need to be pushed into the holes. The splines on the drive shaft should have some grease put on them but not the top of the shaft. There is a seal tube that goes on the shaft splines and is for keeping any water from getting into the splined area of the shaft and creating rust.
Enjoy the Best of Boating and do the needed maintance on time. JMO
Oldman570

 

[Maxz695]

Re: Mercury classic 50 overheating

Many don,t look for this oldman but it is imparative to have the splines greesed or the will wear. Re splining a shaft is comparitive to replacement as you will have to do a total brakedown to replace the main drive shaft in any event! Not to mention and i,s not the first I,ve heard of the crankshaft as the splines have corroded away

 

[on_ice]

Re: Mercury classic 50 overheating

Yesterday I got together with a couple of buddies and pulled the exhaust plate cover. When we pulled it apart a big piece of something fell out. We could not determine exactly what it was or where it came from. I thought it was melted impellers but my buddies thought it was carbon. Other than that nothing was obvious. The gasket looked like it had probably failed in a couple of places but you couldn't be sure. We pulled the foot and blew air through all of the water passages we could find. There was quite a bit of sand that came from one of them out of the copper pipe in the foot. We were going to do the same thing with the cylinder cover (head). The bolts were seized on it pretty bad. We took a vote. Rather than break a bolt and turn this little job into a big job we decided to put it back together and see if we were living right. Well it turned out, we were. The stream looked like the utube video I had seen and increased with RPM. We put it in the water and ran fast all afternoon with a nice cool motor.
I really do apprieciate all of your help. In a month or two when it gets really cold I'll be back here. I need to replace all the gas lines and filters. I'm sure I will need a little advice from people that have been there. For now, I'm going fishing!!!

I'm going to bump this thread because it's not that old and I have the exact same motor with the exact same issue. I've already replaced the impeller but the engine still sends an overheat alarm and the tell tale gets hot. Where is the exhaust plate cover and how do I pull it? Any other suggestions?

 

[on_ice]

Re: Mercury classic 50 overheating

So a bit more snooping on the web led me to figure out what the exhaust plate cover is:

http://www.**********/parts/search/...89 & Up/End Caps and Exhaust Cover/parts.html

Looks like I would be pulling part number 31 (Cover - Exhaust Manifold) and number 29 (PLATE, Baffle - Exhaust Manifold) and I probably need to replace parts 28(GASKET, Cylinder Block to Baffle Plate) and 30(GASKET, Baffle Plate to Exhaust Cover). Does that sound about right for a start? Any other suggestions?

 

[sjoefl01]

Re: Mercury classic 50 overheating

Check the rubber seal on the water pump shaft closely. The last little push on the foot cannot be seen. It is entirely possible that was my problem. That plate is high risk for breaking a bolt. You need a machinist on call. If you open it there are a lot of passageways to blow air through. Check that pump seal really close first.

 

[on_ice]

Re: Mercury classic 50 overheating

Check the rubber seal on the water pump shaft closely. The last little push on the foot cannot be seen. It is entirely possible that was my problem. That plate is high risk for breaking a bolt. You need a machinist on call. If you open it there are a lot of passageways to blow air through. Check that pump seal really close first.

Are you talking about the seal that slides on top of the driveshaft down to the housing? Or the seal that the water tub plugs into inside of the housing? My issue is the motor pees plenty of water, it's just overheating.

 

[on_ice]

Re: Mercury classic 50 overheating

After reading the thread again it looks like youre talking about the seal that is on the inside of the housing. How do I know which way is up? Also, there is a little plastic piece at the bottom of that seal, which side of that is up? My water tube also pulls out of the bottom of the motor (I accidentally knocked it out) is that normal?

 

[sjoefl01]

Re: Mercury classic 50 overheating

You have a different deal than I did. My waterflow was stopping. I never knew for sure if it was a blockage or it wasn't picking up correctly.
Don't give up though. That's a good motor once it's fixed. I'm not an expert. I don't understand why some smart guys haven't jumped in. Maybe you should start a new thread. Describe everything you can and number your questions.

 

[on_ice]

Re: Mercury classic 50 overheating

Thanks. I'm going to dive in tonight and try a few things. I'll report back with what I find. Here is my thread

http://forums.iboats.com/mercury-ma...r-1988-mercury-45hp-pro-fifty-how-605104.html