fuel in the oiling system on the first run of a rebuilt engine
Thread Starter
Joined: Sep 2005
Posts: 972
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From: Northeast Georgia
fuel in the oiling system on the first run of a rebuilt engine To make a long story short....
We basically rebuilt my 1998 LS1 engine and did everything TO A "T" internally. We go to crank it, it won't crank, we charge it and leave it hooked up to the other battery, and go to crank it again, she cranks, and runs like a champ, sounds incredible, we turn it off after a few minutes. crank it again without the other car's battery hooked up, she cranks, sounds awesome, turn it off. go to crank it again, no dice.
it turns over, fires off a few cylinders but won't come on all the way.
i check the oil, there's fuel in the oil. and that brings us to now.
I'm thinking bad injector, but fuel system isn't really my thing, so I would really appreicate any kind of suggestions or explanations as to why there's fuel in my oil.
Keeping in mind the car never go warmed up enough for anything to go terribly wrong here is what we have replaced before we cranked it.
all new gaskets and seals, LS6 stage 2 cylinder heads (new valvetrain), MS3 camshaft, forged pistons, ported LS6 oil pump.
Stock injectors which are only about a year or so old, stock everything else.
I'm not sure if all that matters but I am just trying to cover all my bases to get to the bottom of this before I lose it.
We basically rebuilt my 1998 LS1 engine and did everything TO A "T" internally. We go to crank it, it won't crank, we charge it and leave it hooked up to the other battery, and go to crank it again, she cranks, and runs like a champ, sounds incredible, we turn it off after a few minutes. crank it again without the other car's battery hooked up, she cranks, sounds awesome, turn it off. go to crank it again, no dice.
it turns over, fires off a few cylinders but won't come on all the way.
i check the oil, there's fuel in the oil. and that brings us to now.
I'm thinking bad injector, but fuel system isn't really my thing, so I would really appreicate any kind of suggestions or explanations as to why there's fuel in my oil.
Keeping in mind the car never go warmed up enough for anything to go terribly wrong here is what we have replaced before we cranked it.
all new gaskets and seals, LS6 stage 2 cylinder heads (new valvetrain), MS3 camshaft, forged pistons, ported LS6 oil pump.
Stock injectors which are only about a year or so old, stock everything else.
I'm not sure if all that matters but I am just trying to cover all my bases to get to the bottom of this before I lose it.
did you just smell the dipstick or did you drain the oil?? If you are overly rich on a new engine where the rings have not seated yet you could get some washing of the cylinders which will make its way into the crankcase. Also on a side note that is a big cam so you will have some blow-by anyways. Get a vacuum pump now.
Thread Starter
Joined: Sep 2005
Posts: 972
Likes: 0
From: Northeast Georgia
did you just smell the dipstick or did you drain the oil?? If you are overly rich on a new engine where the rings have not seated yet you could get some washing of the cylinders which will make its way into the crankcase. Also on a side note that is a big cam so you will have some blow-by anyways. Get a vacuum pump now.
oh and the cam is not new, it's been in there for over a year without this issue.
Thread Starter
Joined: Sep 2005
Posts: 972
Likes: 0
From: Northeast Georgia
so does this sound like a tuning issue? I'm starting to lean towards that, but that kind of sucks since i can't actually get my car rolling long enough to get on a trailer 
put a fuel pressure gauge on it, start with the simple things first. Maybe you have an injector bleeding down. watch the gauge after priming the fuel system. I believe the spec is that it is not supposed to drop more that 10 psi in 20 min. If you have access to a scan tool you could also fire each injector one at a time and watch the gauge to make sure you have even drop on every injector.
Thread Starter
Joined: Sep 2005
Posts: 972
Likes: 0
From: Northeast Georgia
well, we got this figured out.
what happend was...
the car wouldn't crank on it's own, so we had to hook it up our truck to charge it and then crank it, once it was on, it would stay on, but there was no cranking it witout a charge.
when we would try to turn it over and the battery was dead, it was flooding out the engine and fuel was going threw the gaps in the piston rings and dumping into the oil pan.
SO yesturday we tried once again to get it going, and we did, we let it run for about 20 mins, and then cut it off, checked the oil, and it was gas free.
We got the second new battery we've bought in 3 months, and we're going to try and get it on the road this evening.
what happend was...
the car wouldn't crank on it's own, so we had to hook it up our truck to charge it and then crank it, once it was on, it would stay on, but there was no cranking it witout a charge.
when we would try to turn it over and the battery was dead, it was flooding out the engine and fuel was going threw the gaps in the piston rings and dumping into the oil pan.
SO yesturday we tried once again to get it going, and we did, we let it run for about 20 mins, and then cut it off, checked the oil, and it was gas free.
We got the second new battery we've bought in 3 months, and we're going to try and get it on the road this evening.
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you might want to change the oil a couple times after running for a minute or 2 each time. Gas is VERY HARD on bearings since it instantly breaks down the lubricant properties of oil. Glad you figured her out 
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