What causes this=impeller failure??

hismajst

Seaman Apprentice
Joined
May 22, 2010
Messages
35
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These are pictures of an impeller that was only 2 days old (1990 Force 120 HP L Drive model "B").I lost ALL water flow as I was running full throttle across the lake.The impeller was never ran in a dry state. The curled part would be the top most part of the impeller as it sits in the housing (facing the motor as apposed to the lower unit.). Removed and tested the thermostat and it worked just fine. Installed just the housing minus the thermostat and ran water through the motor to check for a restriction in the water jacket=none. I also removed the possibility of the impeller insert (#11 in the diagram) not being seated/clocked in the upper impeller housing (#10 in diagram) and forcing down on the impeller as that might cause this. Also I checked the seal between the upper plate and impeller housing and didn't see any obvious blow out. So has anybody seen this:confused:???From what you see in the pictures do you think this little curl would be enough to loose all water pressure?? Thank goodness for the cylinder head temperature kit I installed a week before, I was able to catch it in time. Also, does anybody know of a good water pressure kit (as in gauge AND sender) I could install on the head to note any trends in water pressure variations??

Here is a breakdown of the gear housing to give you an idea of the parts involved (part #'s 10-16).

Gearhousingbreakdown.png



Oh, and while I have got your attention could someone PLEASE get out their dial calipers and give me a thickness reading for this seal-#10 in the diagram below-(this is the upper seal for the impeller pump housing # 10 in the above diagram). I'm a bit confused which is the right one for a 1990 L drive.
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On the left is the seal that comes with impeller kit Sierra # 18-3251, and on the right is the one that came out of the housing the first time I removed the lower housing. I re used the one on the right this time around as the one on the left did not seem thick enough to provide a good seal.
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foodfisher

Captain
Joined
Feb 18, 2009
Messages
3,756
Re: What causes this=impeller failure??

Don't know how long it sat on the shelf. Possible exposure to chems, sun, extreme heat/cold etc. If another one repeats the damage, then I can't offer any explaination.
 

hismajst

Seaman Apprentice
Joined
May 22, 2010
Messages
35
Re: What causes this=impeller failure??

Fresh from a sealed bag. In fact I bought the entire kit with new housing and everything! I bought it from iboats. I should have also mentioned that I did use a non petroleum based lubricating grease during assembly of new impeller(I use non petroleum to reduce the chance of swelling, as I have found that rubber can "absorb" the lubricant and swell if the impeller sits too long before seeing water). Not to scare anybody, as all my friends use petroleum based grease (i.e. Vaseline) to assemble their impellers and have never encountered a problem. I'm completely stumped!:confused: I have installed a new impeller and housing (this second time around just as I did before this failure). I will let you know how it goes after I take er out this weekend.
 
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