oil injection checkvalve 90hp 3cyl

[Bob Kimber]

2000 model 90hp 3cyl. Merc<br />sorry about long post, looking for some opinions,<br /><br />Went fishing last tuesday 40 mile round trip, checked motor before trip all OK, engine ran well, while fishing, took cowl off to show fishing mate location of main fuse, also checked vinyl line from oil pump to fuel line as sometimes a small air bubble forms when motor has been sitting for 2 weeks or so, everything was fine, cruised home at 4800 rpm (34mph) as the sea was the calmest in a long time - no problems.<br /><br />Flushed motor soon after arriving home - no problems, checked motor today vinyl line from oil pump has no oil in line but 1" of fuel in line above checkvalve - possible faulty checkvalve?<br /> # pulled plugs, look normal - slightly oily & wet <br /> # crowns of pistons look OK - no aluminium on plugs.<br /> # drained oil from internal tank - looks OK, no smell of fuel or obvious fuel dilution.<br /> # motor had no unusual noises, oil consumption from tank was normal for distance, ran OK when being flushed in a drum.<br /><br />Boat has 2 fuel tanks with 100% effective isolation valves (both off) before filter. Is it possible, as carb bowls would have been full, that enough pressure built up in fuel line (daily temp around 95 degrees) to force fuel into oil line past checkvalve? My gut reaction is to replace the checkvalve but because of Easter it will be Wednesday before I get to Dealer and the weather is good at the moment.<br /><br />Vinyl lines are in good condition and I have new spares, no access to manual until late this week as my cousin has my compression gauge and engine manual and is out of town with his family for school holidays.<br /><br />Any opinions - wait & replace checkvalve? - replace vinyl lines refill tank and bleed oil line, test run and chance a fishing trip?<br /><br />Regards Bob

 

[Laddies]

Re: oil injection checkvalve 90hp 3cyl

It sounds like the fuel tank is building pressure in it--Bob

 

[Bob Kimber]

Re: oil injection checkvalve 90hp 3cyl

Laddiesservice, <br />thanks for the quick response, it was about 2am (Aust time) when I posted so I may have left some info out. <br /><br />Do you think it is only pressure building up from the heat, because I am doing some work in my shed the boat has been in the sun all week? <br /><br />If the injection system was being pressurised through the checkvalve by the fuel pump would it be correct to assume the pressfit breather valve in the top of the oil tank would be blown out or dislodged?<br /><br />thanks for your interest.<br />Bob<br /><br />2000 model 90hp 3cyl. Merc

 

[Laddies]

Re: oil injection checkvalve 90hp 3cyl

loosen the oil cap and that should tell you if it's the breather vent

 

[Bob Kimber]

Re: oil injection checkvalve 90hp 3cyl

Hi Laddiesservice,<br /><br />Thanks for your reply, there is no excess pressure in the oil tank, what I was trying to find out was, if the fuel pump was able to pump past the checkvalve (if checkvalve was faulty) and into the oil injection lines and tank wouldn't the weakest link be the small rubber breather valve held in by a pushin plastic cap compared to the threaded oil filler cap.<br /><br />Is there some way to test the checkvalve such as removing vinyl line from checkvalve to oil pump then pumping primer bulb on fuel line as hard as possible to simulate fuel pump pressure on checkvalve to see if any fuel leaks through.<br /><br />I know this seems like I may be making a big deal over this, but when I picked up the spare vinyl lines some time ago the dealer not only did not have a checkvalve in stock he claimed they were worth about $80 AUS, I have seen them on Merc spare parts websites in the US for approximately $12 US.<br /><br />regards Bob

 

[Laddies]

Re: oil injection checkvalve 90hp 3cyl

Usally if the valves bleed back the pump will more than over come the valve, but I would certain replace it to stop trouble down the line. What else could one say and feel right about the advise. Bob