Lower Crankshaft seal bad??

[Wkoch]

If I have a leak in my lower crankshaft seal what would the symptoms be???<br />I took my motor in ( 87 28hp evinrude) to get looked at. It was hard to start once it cooled of and didn't idle well. I couldn't figure out what was wrong. <br />They did some tweaks to get it running better but also said the lower crankshaft seal might be shot. $500!!! Would this cause a decrease in the compression?? Compression is the same in both cylinders at around 100. <br />Just getting ideas befor I decide to tackle this job.<br /><br />I have had backfiring only once or twice and there is no oil/gas leaking anywhere.<br /><br />Any ideas??<br /><br />Wkoch

 

[Spidybot]

Re: Lower Crankshaft seal bad??

On a 2-stroke the crancase is a part of the air/fuel mix flow's way to the combustion chamber. If not tight the cylinder will not fill/exhaust properly which will lead to reduced perfomance and other running related issues.<br /><br />Strange, however, that no oil or fuel is visible as the crancase pressure would force a little amount out if the seal is not tight? Could it be that it comes out in a way or place that you cannot see?

 

[Wkoch]

Re: Lower Crankshaft seal bad??

Not sure what is going on. I guess I will tear it down and check evrything out. I have never done anything this big to a boat motor. I do have 2 shop manuals so that should help. Question is is it as bad as it sounds to tear everything down?? Estimated time on how long this might take?<br />I know I will have to get a gasket for the tear down. Anything else? I might need? Should I replace the reeds while I am at it?<br />Have hdd motor for 2 years only but I imagine everything on this unit is original equip.<br /><br />Thanks for any advice.

 

[G DANE]

Re: Lower Crankshaft seal bad??

Wkoch<br /><br />If lower seal IS your problem, its replaceable without disassembling a lot. Pull powerhead. A couple of bolts underneath ( 6 I think ), and two nuts above, at sides of powerhead, a bit tricky to get at.<br /><br />You dont need to strip powerhead. Lower seal carrier is held by three small bolts. Seal ( $ 20 ) is easy to change, remember to clean everything and check oring around carrier. Clean up end of cranckshaft if needed. Then back on.<br />No big deal if you have a manual and go step by step. UU I tried to mail you a photo, but got mail back - new adress ?

 

[CamaroMan]

im just going to post here since this still comes up in google searches. If your crank seals are shot (like mine) - the drive shaft will have black soot all over - esp near the top.. pull the lower unit and inspect the drive shaft.. if the crank seals are gone ull prob see oily mucky water spitting out the mount seals as well.. a good sign those are shot too -

basically the leak allows the fuel mixture to go into the lower leg instead fo burning.. my lower plug was wet from fuel and power was about half.. the middle plug was half wet and top dry and tan.. some ppl say the seal leak can allow water IN to the lower cylinder, and it will be clean as a whistle.. if u look thru plug hole with piston at tdc - if u see a shiny new looking piston crown - do not run as is.. u can sieze the piston and ruin the bore / powerhead (big ouch)...