Oil injection

[Rich L]

I opened my oil reservoir tank the other day and noticed the tank was under vacuum when I removed the cap, is this normal? The tank on the motor was full of oil so I guess its working, It doesn't seem like the motor consumes a lot of oil. Any way to get a rough estimate on oil consumption, the motor is a 98 offshore Mercury 200 hp. The last time I went out my high temp alarm went off so I slowed to idle, 10 to 15 seconds later alarm shuts off. I should have listened to myself and changed the impeller. My uncle who owned the boat before swore up and down the impeller's good "kid" dont worry about it. I changed the t-stats last weekend but thats not it, so she's coming out for the impeller. Any good sources out there for water pressure gauges and temp gauge, I'm done with the guessing games.

[wingtime]

You should consider replacing the poppet valve while your at it too.  They are usually overlooked.   The remote oil reservoir is pressurized from a crankcase fitting that has a check valve in it.  Are you sure it was under vacuum when you opened it?  (It could be vacuum due to atmospheric pressure changes)   If it is not feeding oil to the engine mounted head tank you'll know pretty quick when the alarm goes off for low oil in that tank.

[Rich L]

Now that I think about it could have been pressure and not vacuum, I got a whooshing sound of air when I opened it. I just returned from pulling the boat out and dropped the lower unit is there any tricks to getting the lower impeller housing out. That sucker doesn't want to come out to easy and i didn't want to put to much prying force on the case. So what is the purpose of the poppet valve anyway is it like some kind of pressure relief valve?

[fitz73222]

The poppet valve just regulates water pressure and slows the water flow around the exhaust plate and cylinder heads so the water will absorb more heat before exiting. A faulty poppet valve can show up as an overheating issue with a perfectly good impeller and thermostats usually occuring at high speed. Whats the problem with the water pump disassembly?

[Rich L]

The lower impeller housing, is there something holding it in or does it just pry out .I'm sure I can get it out, I just didn't want to snap anything.

[fitz73222]

Hi RichL,

Did you remove the 4 screws that hold the housing down to the base? Assuming you did, the housing is only held in place by the rubber impeller tension against the housing and you should be able to pull it off with your hand or a light pry with a screw driver to break the gasket bond with the lower plate that the impeller rides on.

[Rich L]

Thanks fitz, the top housing,gaskets and impeller are out. I was talking about the bottom impeller housing. I'm not sure if something is holding it or if its just snapped into place?

[Capt. Bob]

Thanks fitz, the top housing,gaskets and impeller are out. I was talking about the bottom impeller housing. I'm not sure if something is holding it or if its just snapped into place?

If it's like my Yamaha (or OMC) the bottom plate rests on a "paper/cardboard" type gasket and is aligned with dowels (two I believe) so it may need a little extra persuading to come up.

[fitz73222]

Hi RichL,

You should not need to disturb that lower housing unless you are replacing the driveshaft seals and housing Oring. Sounds like you purchased a complete water pump kit that includes the lower housing. If you remove the lower housing you need to make sure there is no sand or grit around the housing when you remove it because one you do; you will be exposing the driveshaft roller and thrust bearings so cleanliness is essential. I believe your 200 has the old style water pump that uses the plastic housing with a stainless steel liner; if that is it then the lower pump base will just pry out by GENTLY using two opposed screw drivers and walking the housing out. If your engine has the new style pump with a solid stainless housing there are four screws to remove that are concealed under the plate gasket that must be removed prior to removing the lower housing.

Hope this helps...

[Rich L]

That answers my queston, probably wont take out the lower it doesnt look bad.

[fitz73222]

If you didn't have any water in the gearlube you should be good to go. Water shows itself as water(dah!) or a very white creamy to bright yellow creamy mixture similar to an Alfredo in appearance and consistency. Change the gearoil anyway using Mercury High Performance gearoil (the blue stuff).

[Rich L]

No water in the oil, all back together. Life is good. This weekend I'm going for the poppet valve as well.  Thanks for the help