Overheat diagnosis question

lonewolf41

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Jun 28, 2013
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I have the clear hoses hooked up to diagnose my overheat issue. You can see from the video that I am getting air before the raw water pump...and more after it...but I figure I should get the incoming air leak fixed first. I did this with the drive on muffs. My question is if this is valid or does the boat/drive need to be in the water for this test? If I am leaking at the muffs, then that would skew my results.

TIA.
 

alldodge

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The garden hose (3/4 inch) cannot supply all the water the impeller can move (1 1/4 inch). It needs to be done in the water
 

lonewolf41

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I was wondering if that was the case and why I asked...especially since the vacuum gauge was reading close to where it needed to be on the inlet side (~2" Hg at idle). Will dunk it in the river tonight and see what it looks like.

Thanks!
 

Scott Danforth

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my guess is you have not had the drive off recently. take a look at the water inlet casting. if you have an AQ series drive, you need to replace the casting every 2 years when you do the bellows.

regarding muffs and hose, as AllDodge indicated, the hose wont supply enough water to do much more than idle
 

lonewolf41

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Jun 28, 2013
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my guess is you have not had the drive off recently. take a look at the water inlet casting. if you have an AQ series drive, you need to replace the casting every 2 years when you do the bellows.

regarding muffs and hose, as AllDodge indicated, the hose wont supply enough water to do much more than idle

Actually, I just put the drive back on after replacing a leaking seal in the upper housing. I should have mentioned that I have an SX-M1 drive. I put a new o-ring (in addition to silicone sealant) on the water inlet pipe as well as a new inlet gasket where the drive meets the transom.

Thanks!
 

lonewolf41

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Well, I took it to the river and dunked the rear in the water and am still getting bubbles on the inlet side so will have to find a leak. Assume it is in the engine bay since almost everything else was under water. I double checked and all the hose clamps were tight, so not sure where it could be. I tightened the hose flush cap as tight as I could by hand. Even put a new hose gasket in there since the old one was pretty hard. Will pressure test tonight. Also wondering if a vacuum test would show anything.

Real bummer for a "drop in ready to run" motor. Which brings me to another thought. The raw water pump was originally hooked up backwards (figured this out about a week ago...long before this post). I had run the motor for a while on the hose connection before mounting it in the boat to check it out (due to other poor assembly issues). I assume the water pressure forced water into the cooling system even though it was hooked up wrong. It got warm, but didn't overheat. But I didn't really run it too long and it was mainly at idle or a little above. I didn't realize it was hooked up wrong until I got the motor installed and on muffs, then it would overheat. Finally figured out the wrong plumbing, but it still is overheating...just not as badly or quickly. I have a new impeller and water pump seal on the way. I did take the pump apart at one point (before I figured out it was plumbed wrong) trying to figure out the overheat and the blades looked good, but maybe it is toast now.

Hopefully it is readily apparent and easy to fix. Hey, a guy can dream can't he???

Thanks again for the feedback.
 

alldodge

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Little things can sure be pesky little gremlins to find
 

Scott Danforth

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check the inlet fitting - shown in the diagram below. its what the hose is connected to that runs to the transom shield (bottom of image)

W-Volvo-omc-cobra-sx-transom-parts.jpg
 

lonewolf41

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Jun 28, 2013
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Well I think I found it. Apparently at some point the power steering cooler got hit (among other things) and the lip on the inlet side was bent on the bottom so instead of a circle, it was D-shaped. It was dripping out of there. I reformed it and reinstalled the hose and I don't see any more water leaking. Haven't had a chance to run it yet, but the hose test showed it not leaking any more. Still think the water pump needs rebuilding...or at least a new seal...since there was a lot more air coming out of it than was going into it, but will see once I get the inlet air leak fixed and verified. Getting closer.....I think.

Thanks.
 
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