Gas in Oil???

[screllin]

Hi, we have a Maxum 1800, 2000. There is gas in the oil, alot of it. Any ideas on what could be happening. The engine was ruined over Memorial Weekend, has been totally rebuilt, just got the boat back 10 days ago. The stange thing is we had a new boat dock installed. An EZ dock, the kind you pull the boat up on (like a trailer). The dock was not set right and the first time we used it the boat was pulled up on atleast a 45 degree angle. (maybe more) It was scary. The next day the engine blew. It had gas in the oil. The mechanic could never figure out why the gas was in the oil. The engine was rebuilt and we thought we were in for a great summer. We were told to check the oil everytime the boat ran, before and after. We did and could see/smell no problems. We left the boat with relatives, they were supposed to be watching the oil carefully, guess they don't know what oil and gas smell or feel like, they blew the engine again, and there is gas in the oil again. So while the guys are trying to figure this out, I thought I would do something constructive and send a message. Any ideas, do you think the angle of the dock the first day contributed to the problem? This has perplexed everyone!<br /><br />Thanks Steph

 

[DJ]

Re: Gas in Oil???

I'm assuming this is an inboard outboard?<br /><br />The only way for gas to mix with the oil is for the gas to get past the needle/seat valve in the carburetor.<br /><br />Marine carbs are designed so that any overflow goes into the crankcase, not into the bilge.<br /><br />The severe angle that the boat is moored at could be contributing to the problem.

 

[screllin]

Re: Gas in Oil???

I would like to clarify/modify some of the content in my wifes' original post. The maximum angle that the boat could have achieved would have been about 20-30 degrees. This lasted for about 30 seconds. We realized that after having done this twice, that the rollers/winch on the dock were not adjusted properly. As a result, the winch broke but the damage (to the engine) had already started. We don't know if this angle could have shifted anything in the carb to permit gasoline to find its way into the crankcase. After the first repair, the dock was fixed and operates perfectly. The angle rise is minimal now. Since the first fix (engine), we have only put, at the most, 10 hours on the boat. These hours have been very easy break-in hours. We had left the boat after 6 of these hours, checking for gas evidence in the oil before we turned the boat on and everytime we turned the boat off. Relatives added the additional 4 hours. We had not been able to inspect the boat again until Saturaday 7/19. The oil level on the dip stick was at least an inch above full and smelled strongly of gasoline. I started the engine to realize my worst fear, the engine sounds the same as it did the last time it was ruined. The engine starts without a hitch, idles well with no exhaust smoke. What is happening!!!

 

[roscoe]

Re: Gas in Oil???

The angle of the boat lift should have had no effect. Many roads and launches are on a steeper angle than that. <br /><br />I hope that rebuild had a warranty. I wouldn't tell them about the relatives, etc, or they will try to blame it on you. Tell them you did as they told you, because you did.<br /><br />What was actually "blown" on the engine the first time?<br />Even with thinned out oil, you should have had enough lubrication and cooling from the oil/gas mix.<br /><br />I had a car witha faulty computer that controlled the fuel injection. Injectors stuck wide open and filled the block up with gas.

 

[mlslocks]

Re: Gas in Oil???

I would consider a faulty fuel pump. I had a mechanical pump go bad and it pumped fuel into the crankcase.

 

[screllin]

Re: Gas in Oil???

If the fuel pump was bad, am I wrong in assuming that the pump would not pump? I was under the impression that the fuel pump is constantly pumping and that the carb. and throttle would regulate the flow. If it was pumping too much gas into the carb, wouldn't the engine flood during opreration or at least be running visibly rich? This engine is a 4.3 V6 without fuel injection.

 

[screllin]

Re: Gas in Oil???

Roscoe,<br />To answer your question, the actual damage was a spun bearing.

 

[Dunaruna]

Re: Gas in Oil???

The arm on a mechanical fuel pump is lubricated via engine oil, a seal & the pumping diaphram stops oil and fuel mixing. If there is a pin hole in the diaphram and the seal is worn then fuel will enter the crankcase slowly - the diaphram can still pump enough to feed the carburettor. Check for visible oil leaks around the pump. With fuel in your crankcase you have got yourself a bomb (literally).I have seen rocker covers and side plates blown apart because of this senario - use extreme care.

 

[magster65]

Re: Gas in Oil???

I agree, there's only two ways for fuel to get in...<br />1) The carb is flooding so bad that it's getting past the rings (yes it's possible)<br />2) The diaphrams in the fuel pump have a small hole in them.<br />Check your fuel pump first and see if there's a clear tube running up from the pump to the carb base. My fuel pump has a dual diaphram and if fuel gets past the first diaphram it runs up that tube into the engine.