February 7, 2019 at 8:17 am #166234
I have a Johnson A that I have just re-assembled after going through it completely. It start, runs and idles very well. The only issue that I am having is with cooling on the port side cylinder. It seems to be getting very hot. I have a nice stream of water out of the outlet on the back of the pivot tube. I can easily blow trough the water jacket on that side as well as both tubes. The only thing that I can think of that would cause the heat would be some excessive friction inside, however everything turned over nicely when going back together.
I am going to run it again with the two lines off of the top of the cylinders so that I can compare the water flow.
Has anyone else run into this issue without an obvious blockage?February 7, 2019 at 10:13 am #166238
I wouldn’t assume that because air and water is passing through the cylinder you don’t have some blockage. Taking
off the waterlines, blocking the bottom fittings, filling both cylinders with water, and then comparing the amount of water each cylinder held might be a better indicator.February 8, 2019 at 12:11 pm #166369
I pulled the water lines off and did as you suggested. The cylinders held similar volumes of water in the water jacket. I blew air through them again. When going back and forth, one small flake came out of the cylinder that was getting hot. I may have been enough to block the outlet on my last test run. After re-assembly, the port cylinder is still warmer than the strbord cylinder by 15-20 degrees depending on where you check, but it now runs cool enough that you can hold the cylinder while running.
The only thing left to do is better seal the fuel line fiting at the carb. It has a filter screen in there. I pinched two gaskets to go above and below the screen, but I am still getting a small leak. I am afraid to tighten the large nut too tight and break something. The original gasket seemed to be similar to heavy Kraft paper. I have used the thicked grey fiber type gasket stock.
After this, it will sit until warm weather allows for a lake test.
US Member - 1 Year
Topics: 0February 8, 2019 at 1:04 pm #166370
Might have a lot of rust in the water jacket of that hot cylinder preventing good water flow and cooling contact to the cylinder. Might have to remove that cylinder from the crankcase to completely clean out the water jacket.February 8, 2019 at 1:15 pm #166371
If you think there still may be some rust restricting the flow
of water through the cylinder you could fill the cylinder with
a 50-50 mix of water and muriatic acid. Let it sit about 5
minuets then drain it out catching it in a plastic container to
exam it. If you get a lot of junk do it again. When you believe
the water jacket is clear rinse out the cylinder well. You could
add a little backing soda to the rinse water to neutralize the
acid if you have some handy. Remember your dealing with an
acid here so use you best judgment when handling it.
US Member - 1 Year
Topics: 91February 8, 2019 at 8:15 pm #166394
The screen in the fitting below the carb should fit inside the gasket.It’s cup shaped and fits down inside the fitting,not under the gasket.That fitting is hard to keep from leaking.Make sure mating surfaces are clean and smoothe and use a single gasket.
US Member - 2 Years
Topics: 5February 8, 2019 at 9:10 pm #166396
Yes with the screen in the right place and a good gasket and clean mating surfaces I have had no problem with them leaking. I have 3 that have no problem. And yes do not over tighten.
US Member - 1 Year
Topics: 3February 8, 2019 at 10:57 pm #166401
I wanted to ask about the muratic acid idea- That works with cast iron cylinders? I’ve used it on aluminium before to remove heavy corrosion but never thought about it’s possibility for iron/steel.February 9, 2019 at 12:04 am #166404
I wanted to ask about the muratic acid idea- That works with cast iron cylinders? I’ve used it on aluminium before to remove heavy corrosion but never thought about it’s possibility for iron/steel.
Search You Tube for remove rust with muriatic acid.February 9, 2019 at 11:16 am #166436
Thanks for the info on the screen. This one might have been replaced. I will remove it again and fit it as described.
Canada Member - 2 Years
Topics: 401February 10, 2019 at 1:44 am #166495
I wanted to ask about the muratic acid idea. I’ve used it on aluminium before to remove heavy corrosion
Be careful with this stuff as muriatic acid is bad stuff and it will dissolve aluminum right in front of your eyes! In fact, I use it undiluted to dissolve aluminum which has wiped onto cylinder walls from scuffed or scored pistons. This only take a few minutes before neutralising the acid in a baking soda solution. Since it won’t dissolve cast iron or steel right away, it also gets used to remove rust and deposits from marine exhaust manifolds and risers and other parts which can’t be glass beaded or sand blasted.
I can’t emphasise enough to wear gloves, eye protection, and avoid breathing the fumes at all costs when handling this stuff! It’s dangerous!
Here’s a cylinder with aluminum transfer on the wall from the scuffed pistons. Honing alone won’t remove the aluminum so a bit of muriatic does before honing.
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US Member - 1 Year
Topics: 6February 10, 2019 at 9:22 am #166518
WRT Muriatic (Same as hydrochloric, but dilute and with impurities) acid, consider using phosphoric acid for cleaning rust and deposits. The parts will still need neuralizing but it’s much more people friendly.
I’ve had success with using CLR on some parts…. don’t like what it does to chrome.
Your results may vary 🙂February 12, 2019 at 5:52 pm #166690
I do have a gallon of Phosphoric acid here. I use it for removing rust from auto body panel that have surface pitting. I am goinf to run this motor in a bigger tank and see how it does. If cooling is still not right, I will have to pull that cylinder and investigate it further.
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