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visual inspection of reed valves on a classic 50

B

Belly_Up

New member
Hi all and Happy New Year!

I'm in the process of rebuilding both carbs on my 1986 classic 50 and I was hoping to be able to visually inspect the reed valves while the carbs are off the engine. I've read some grey references that they are located behind each carb intake, but I can't seem to see them. I've turned the flywheel by hand while looking into the block with both a strong light and a scope and I can't see any moving parts whatsoever. Everything is really clean, but I expected to at least see some movement of the crankshaft or other mechanical parts attached thereof. Any ideas :confused:
 
There are 4 leafs to the top/bottom left and right of the mating bridge on reed block , you can poke your finger in the intake and move them. As seeing anything mechanical move you will not.
 
A strong flashlight and a dental mirror will allow you to do some inspection on them.----I strongly recommend pulling the powerhead off to replace the lower crank seals and to look for blockage in the exhaust tube.
 
You can look, but it's probably a waste of time. Been runnign Mercs for 50 years without EVER seeing a reed valve failure.

Jeff
 
Hi Jeff,

So why is it that the reed valve assemblies don't have bearings? It seems like the high friction would require them and that their absence would lead to journal wear long before the main bearing needed servicing. Just curious.
 
Hi racerone,

Would it be easier to pull the lower unit and send a scope up the exhaust tube to look for blockage? Pulling the powerhead sounds... involved. I had the water jacket and baffle plate off of the motor last season and didn't notice a blockage from the top side... although there was a bit of carbon build up on the exhaust plate outlet but, it didn't seem excessive given the age of the motor.
 
Removing the powerhead is really not that much work.-------Changing the lower seals and bearing is likely due on a 1986 motor.---- I suppose if you have a scope then that would be a good way to inspect.
 
Been runnign Mercs for 50 years without EVER seeing a reed valve failure.
Click to expand...
The smaller inline crossflow engines have very very few reed failures, the newer loopers and V-6 have them pretty regular as I change a set about twice a month on the Optimax engines
 
Right, I guess--don't mess with Mercs newer than the '80s.

The reed valves assemblies in the older Mercs do have a "bearing" so to speak that's the aluminum of the cage itself.

What problem do you feel the motor is having?

Jeff
 
Most of this is an inquiry into the finer details of the mechanics which aren't very well explained in the manuals I have. As far as issues with the motor... Here is the basic timeline since I purchased the boat and motor in July 2012. There were 2 things going on. One was intermittent cut out of the motor. It would start and run seemingly fine then suddenly cut out without warning. Since removing the carbs I inspected the wire harness coming from the trigger and noticed that the wire leading to the switchbox for coil number 4 had a large section of its insulation shield chaffed off and the exposed portion of the wire was rubbing up against the engine block. I suspect this was the cause of the engine cutting out without warning. I will be repairing that shortly. The second problem was super heated water coming out of the tell-tale... heated to the point where it was steaming and too hot to touch. First thing was replace the water pump and impeller... good thing because it only had one vane left. This did not solve the temp problem. Finally, I found a breach in the fuel line between the inlet and the filter. Replaced and clamped. As I was squeezing the primer bulb I then noticed fuel spilling out from in between the stainer body and fuel pump body of the lower carb. This is when I decided to rebuild both carbs. I'm hoping that cylinders 3 and 4 were starving for fuel and as a result causing the temperature problem from running too lean, because if the carb rebuild doesn't solve the temp problem I don't know what the next step will be. I've verified that water flows freely in the block, so water volume is not a problem and there is no thermostat on this model. A more detailed explanation of the above can be found in 2 other threads I posted here to which you and racerone both responded.

http://www.marineengine.com/boat-forum/showthread.php?401802-1986-Merc-Classic-50-overheating
http://www.marineengine.com/boat-forum/showthread.php?402325-1986-Classic-50-fuel-problem

I know my earlier posts indicated that the overheat problem was solved, but with so many intermmittent episodes it was hard to tell and I can assure you it is still a problem. Thanks for the input.
 
I can't say for sure because I did not do the pump replacement. I had a friend do it while I was on vacation. He did not indicate if he found pieces. I will have to ask him. I'm guessing the answer is no. When I had the water jacket and baffle off the motor I blew compressed air through all of the passages and there did not appear to be any debris. The air flowed freely out of the other water holes. Say there was some sort of blockage... how would I go about correcting the problem? The water passage holes are pretty small although I'm sure they open up to larger channels around the cylindar walls. There is no diagram to show the flow layout in the block.
 
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What do the spark plugs look like? Brown/black = good combustion, black/sooty = rich combustion, white/gray = lean combustion and clean = water intrusion.
 
The plugs are cold fouled. I think mostly due to my fuel issues. I ended up flooding the motor quite a few times trying to get it started before discovering my fuel leak. There are no deposits to speak of other than wet oil-fuel due to drowning the plugs. I haven't run the motor enough since buying the boat last season to get a real sense for how the combustion performance is. I'm hoping a lot of these problems will go away once the fuel system is straightened out. I understand the overheating issue may still take some looking at.
 
At this stage on a " new to you motor " it might be worth removing the intake / bypass covers for a visual inspection of pistons and rings.---Will only take some time and a few $ for new gaskets.---No special skills required !! -----Well worth doing in my opinion.
 
@racerone

I did some reading this morning concerning removal and disassembly of the power head and at this point... I agree with you. Checking out things would be a worthwhile endeavor. I think I'm gonna grab some tools and gaskets and take the plunge. Thanks.
 
I always try to encourage folks to trouble shoot and do simple diagnoses on their motors.--Sure beats guessing and installing expensive parts, only to find out that the motor is beyond repair.
 
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