Using Oil Mercruiser 4.3LX

[shekinah5678]

I have a 1992 4.3LX with Alpha 1 Gen 2 out drive. The engine runs great, idles good, starts rite up. The problem is that I have noticed some oil consumption. After about three or four full days of running around in the boat, some tubing, and a fair amount of WOT it was about a quart low. My estimate is probably 15 to 20 hours of use. After that I have made a point to check before and after every time I use the boat. After another couple of outings, probably 8 to 10 hours I am about a 1/2 quart low. I have noticed some oil in the bilge area very little more like oily water. I did put a new long block in and replaced the mechanical fuel pump with an electric one. Put a block off plate over the hole but I can feel oil on the block below it. Could this be the source of my oil loss? I know some oil use is normal but seems like to much to me. Is there any trick to check for leaks?
Thanks in advance for any help!

 

[Howard Sterndrive]

Re: Using Oil Mercruiser 4.3LX

Is there any trick to check for leaks?

just remember oil never defies gravity.

keep moving higher up from where you see/feel oil to find a leak. The leak is never at or below where the oil is.

unlike a car, there's no big fan, so the oil won't blow around...it just runs down and eventually drips off.

 

[AZSeville]

Re: Using Oil Mercruiser 4.3LX

Oil consumption can basically come from two sources.....internal leak and an external leak. Internal leaks primarily are from valves and piston rings. External leaks can be from just about anything that seals up the lubrication system. If you have oil in the bilge, that itself is not normal and indicates an external leak. The good news is that external leaks are usually much cheaper to repair than internal leaks. No easy way to find them but to look and see. Good luck.

 

[shekinah5678]

Re: Using Oil Mercruiser 4.3LX

just remember oil never defies gravity.

keep moving higher up from where you see/feel oil to find a leak. The leak is never at or below where the oil is.

Thanks I followed your advice and came to the oil pressure sending unit. It is very loose. Now I just have to fix it. It's kind of a pain in the butt tucked back behind and below the carb. It looks like there is an elbow fitting that threads into the block. Thats what is loose. The actual sending unit is tight on the elbow fitting. I hope it is just loose and not broken off at the block. Those do just thread in don't they? I'm going to consult the service manual I downloaded here before it was taken off. By the way "THANKS A LOT" to whoever did that!!

Anyway thanks again I'll keep you posted.

 

[1961_lonestar_holiday]

Re: Using Oil Mercruiser 4.3LX

i wouldnt think that 1 quart of oil for 20 hours of hard use is that abnormal. its a car engine, think some cars use oil and some dont.

 

[Bondo]

Re: Using Oil Mercruiser 4.3LX

Those do just thread in don't they?

Ayuh,... 1/8" pipe thread,... Use sealant,+ Not tape...

 

[solar7647]

Re: Using Oil Mercruiser 4.3LX

i wouldnt think that 1 quart of oil for 20 hours of hard use is that abnormal. its a car engine, think some cars use oil and some dont.

according to the OP Its a new long block, so every thing is bran new and there should be 0 oil consumption. Plus loosing oil is never normal, if any engine is using or loosing oil it is because there is a problem. People just tend to think its normal for a car to loose oil.

Plus oil in the bilge leads to polluting the water when the pump turns on, witch no one wants to see or be the receiver of the ticket for pumping oil in the water.

Considering its a new long block, i would recomend you double check all the bolts (that you can reach any ways) along with fixing your pressure sender. As the engine heats and cools a few times it will cause bolts to loosen so you could have several small leaks that may not leak a visable trail behind. Plus once you re torque them they should be fine.

 

[shekinah5678]

Re: Using Oil Mercruiser 4.3LX

Bondo thanks! I was able to get the elbow off with a little finageling of my hand, it was barely threaded in about one full turn and it came loose. I used thread sealer as you said and put it all back together. I hosed the bilge out and I will let the sealer dry over night and take it out to the lake to see if my problem is solved. I wasn't to worried about using oil just that it was in the bilge.

Thanks

 

[shekinah5678]

Re: Using Oil Mercruiser 4.3LX

"Solar" I know they are usually kind of worst case scenario but the service manual I have, under the trouble shooting section, sais that up to 1 quart per 5 to 15 hours of use is normal especially for a new or rebuilt engine. Nevertheless I will take your advice and check all the bolts I can get to.

Thanks