How to inspect a Yamaha Outboard for mid-section exhaust corrosion?

PNW_Drifter

PNW_Drifter

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Hi guys, anyone know How to inspect a Yamaha Outboard for mid-section exhaust corrosion? It's really common on early 225hp and some 250hps. I have one, they say it's been done but who knows. I know this is a common motor on many Grady's.

Thanks
 
My first advice is that if you don't know what to look for, get a good mechanic to check.
If you want to do an inspection, you have to drop the lower unit first. Then shine a bright light up the exhaust tube and look for excessive corrosion or holes even. To see way up, you will need a endoscope.
If you don't know what to look for, you may not see it.
Finally, often the oil pan on those motors corrode and that may not be obvious unless the power head is removed and the pan, removed and inspected. If you are going to that extreme, you might as well replace the exhaust parts (yammi kit) and the pan. Usually it is advisable to also change the oil pump and drive shaft bushing.

Here is a link to several images of the corrosion
 
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Thanks for the reply seasick. I've done half of this when I bought it, had the entire motor on a pallet in my garage for 6 months with lower unit off. inspected with my Milwakie endocope, it's only 2' long. Didn't see those big corrostion marks "spots". The exhaust looked even black. But I didn't have that much light. I should recheck.

I bought the motor from a guy on this forum who keeps his boat at the Suzuki dealer in Port Alberni. The dealer used to be a yamaha dealer and he said he thought it had been done by another dealer in Parksville and he thought he could tell because of the bolts under the pan they he could see were greenish from the "kit" not coming with the original yam grey parts.

I will have to drop the lower again after my up coming fishing trip. Seems to be from some of those pics that not all the corrosion can be seen even with a scope. Have you heard of the water test where you run hose water up the pickup tube with lower unit off?
 
Checked my 2006 F250s in the Fall. Was told they looked fine but didn’t use the scope - just flashlight!
BB68F31C-7DDA-427C-9B5E-AB1D8570D0E6.jpeg92DADD61-EFC5-4B92-B338-C73384B3BD58.jpeg14EF00B1-80E1-4BD1-A2A9-190E5EC06D9D.jpeg
 
PNW_Drifter said:
Thanks for the reply seasick. I've done half of this when I bought it, had the entire motor on a pallet in my garage for 6 months with lower unit off. inspected with my Milwakie endocope, it's only 2' long. Didn't see those big corrostion marks "spots". The exhaust looked even black. But I didn't have that much light. I should recheck.

I bought the motor from a guy on this forum who keeps his boat at the Suzuki dealer in Port Alberni. The dealer used to be a yamaha dealer and he said he thought it had been done by another dealer in Parksville and he thought he could tell because of the bolts under the pan they he could see were greenish from the "kit" not coming with the original yam grey parts.

I will have to drop the lower again after my up coming fishing trip. Seems to be from some of those pics that not all the corrosion can be seen even with a scope. Have you heard of the water test where you run hose water up the pickup tube with lower unit off?
Click to expand...
The green bolts is a new one to me. If that is the case, it would be a good thing to know. I just looked up a kit from SIMs and it doesn't seem to come with any bolts. Perhaps someone else can chime in on the bolts.
 
I’ve been told (only tried it once) to spray some CLR into the hose before attaching earmuffs to the engine lower unit in order to flush the engine with fresh water and CLR periodically.
 
Thanks for the pic guys. It looks like this area (below) is the area you would need a bending endoscope for. Mines not that long. Maybe I'll get an iphone one, they are cheap now. Endoscope camera for iphone: $35! https://amzn.to/38eiMxA

1614968701509.png
 
PNW_Drifter said:
Thanks for the pic guys. It looks like this area (below) is the area you would need a bending endoscope for. Mines not that long. Maybe I'll get an iphone one, they are cheap now. Endoscope camera for iphone: $35! https://amzn.to/38eiMxA

View attachment 19189
Click to expand...

wow that looks bad. If my OB looked that bad shining a flashlight up inside, I’d probably have it taken case of ASAP. My F250s have a manufacture date (which may or may not be accurate) of March 2006. Seem to be ok so far!
 
grady33 said:
wow that looks bad. If my OB looked that bad shining a flashlight up inside, I’d probably have it taken case of ASAP. My F250s have a manufacture date (which may or may not be accurate) of March 2006. Seem to be ok so far!
Click to expand...

I just saw a mechanic on youtube fixing his 2007 F250 corrosion with JB weld. I wish we knew why some are affected. Look up on youtube if you want to see the video.
 
seasick said:
The green bolts is a new one to me. If that is the case, it would be a good thing to know. I just looked up a kit from SIMs and it doesn't seem to come with any bolts. Perhaps someone else can chime in on the bolts.
Click to expand...
Can you direct me to the kit on Sim?
 
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