Fuel in oil
 

Good morning Chevy nation, I am in need of some help. My fiancé has a 1993 Chevrolet C1500 5.7L that was her daily driver, now the truck sits because her father found fuel mixing with the oil and was causing the engine to start knocking. I was thinking it was the head gasket but before I go and just start replacing head gaskets I wanna be 100%sure it's that before I replace. I was reading that it could possibly be the PCM pushing too much fuel into the system. Any help would be appreciated.

A leaking injector or running rich would be about the only cause, how long does it take before its noticeable? or since the oil was changed? Those TBI engines ran a little rich anyway

At the current moment I do not know how long ago the oil was changed, she just told me about it recently. I can find out and post back as soon as I find out. How would I determine a leaking injector?

I found out that the last time her oil was changed, it hasn't been done in 6 months, however at that time the oil was fuel soaked as well. Her dad said it has been like this for over a year. Any help on this please.

I`d suspect a bad injector or fuel pressure regulator. Too much gas is getting past the rings and piston into the crankcase. Pull every plug, lay them out in order and compare them to each other. Look for one or more to be wet with fuel. Knocking? Has the oil level risen or just get the smell from the dipstick? Change the oil asap.

Thank you for replying, yes sir they said the truck does have a knock when she's running as well. Thoughts as to why? I'm going to be working on it next weekend, we got new intake manifold gaskets and a throttle body gasket set, new oil and filter. I want to replace the plugs as well.

Good evening, I know it has been a while since logging into here and since posting about this truck, but here these past couple of weeks I have been working on the old '93. I replaced all the gaskets topside, pulled both heads off and cleaned under them and the piston heads, replaced every spark plug, wire, gasket, and changed the oil since getting antifreeze in the oil from pulling the heads. I put everything together and started filling the coolant up when the head started leaking, once again tore it down and cleaned it up, not too sure why it was leaking when the gaskets were flush and sealed, so I resealed them and torqued everything down as I did before. I get it all back together, put the number 1 cylinder at top dead center and then refill the oil since I did not fill it after taking the engine apart the first time. I get it all 100% together, check and make sure everything is tight and then I hook up the battery and try starting it and I get rotation but no start. I pull the number one plug and check for spark and sure enough have spark, I check the TBI and see if I'm getting fuel and yup there's fuel there. I decide to put the engine at TDC and pull the distributor cap and find the rotor at 180 off so I fix it back to number 1, put it all back together and I try starting it again, I get backfire and then crank that's it. I am continually trying to crank it and it will occasionally backfire with still no start. I'm not too sure what it could be. Here's a list of everything that's been replaced: head gaskets, intake manifold gaskets, valve cover gaskets, rotor button, distributor cap, all wires, all spark plugs, water pump gaskets, TBI mounting gasket, oil pressure sensor, both coolant temperature sensors, pcv valve, and the TBI is used off a donor 1993 5.7L at a salvage yard. I see the TBI spraying fuel, I unplugged one and tried starting it and nothing, tried unplugging the other one and plugging the first one back in and starting it still nothing. I bumped the ignition to achieve TDC as well as manually placed it. I really hope this thing didn't jump timing and I hope that the timing chain isn't bad. The engine sounds different than before I took it apart, it sounds a lot tighter, like maybe the starter cant spin the engine fast enough to start it, but it sounds like all you hear is the starter when you engage the key. Could the specs in the Haynes manual be incorrect for the rocker nuts? The book says nothing about the 5.7L torque so I went with the 7.4 since it was a little more than the 4.3L but I'm thinking it may be too much, anybody have the torque spec for it maybe? And anybody agree with me on the torque being too tight? Again any help will be appreciated, I am willing to try anything. I apologize for the long posting.

So I am a dummy and didn't realize that I had to tighten the rocker arms per the lashing, so I took a look at the pushrods last night and now I have to replace all 16 because of my stupid mistake. Will post back when new ones are in.

Did you check the cylinder heads for distortion?

Yes sir they were perfectly alright before placing them into the vehicle.

Good work! Keep us updated, please.

So I got all the new pushrods into the engine and tightened down to the proper tightening sequence, went to try and start the truck and we got the engine to rotate, still no running. I pulled the distributor cap off after putting the engine at TDC and its still on. I tried restarting the engine again and no start. We are getting spark and fuel, you can see the fuel coming out of the injectors and smell the fuel. I'm at a loss right now as to what else to test. Yes I pulled out the timing light and checked the timing and it is at 0 degrees before TDC so the timing is good. Any ideas? Any other troubleshooting options? Any help is appreciated.

Also just for information purposes, I have both valve covers off and the air filter housing off at the moment so the pcv valve isn't in its hole, I don't think that has anything to do with it not starting though.

Still too tight?if the lifters bled down,now your filling them with oil pressure,back every one off a half turn?

Alright I shall try that and see what happens and report back as soon as I can, would it be possible the ICM on the distributor went out?

Also do I have to go through the sequence to loosen them like I did to tighten them or can I just loosen them up?

Count the threads above nut,all pretty close to equal,back off to close to the same,no matter where the motor is at,some can have the proper,hand spinning pushrod method done,feel out a good thread count and go from there,crude,but works,Chevy Chase once said"be the motor" or be the ball

Makes sense, Ill try it and see what happens

I think you squashed the lifters,now they are pumping up,too tight,my guess,so valves aren't closing,no vacuum to pull fuel in

I tried working on the truck, but it started downpouring so I got chased inside, it has only recently stopped raining. I am going to try and loosen up the nuts the half turn tomorrow morning, when I loosen up the nuts do you think it will get the vacuum it needs or do you think I may have a problem with the lifters and need to look at replacing them? I also pulled out the distributor and exchanged it at the auto parts store thinking maybe the ICM on the distributor may have gone bad. I exchanged it under lifetime warranty. Ill put it back in tomorrow as well.

Good question on lifters,I think they pumped back up, holding the valves a bit open,from your relashing them?give it a try

So I loosened up the nuts like you had said, I reinstalled the new distributor and tried firing it up getting a rotation only until I tapped the accelerator pedal. I stopped after it backfired. I tried starting it again and still the same thing. I can hear the sucking whenever we open the throttle plate but still only a backfire. What's my next move? I feel at so much of a loss, I've never had an engine give me so much of a hassle as this one.

Darn truck,ok,a bit ago you said you were 180 out and corrected it, maybe,or now off?are you feeling for the stronger of the two puffs at plug hole with finger?my bad thinking you had no vacuum,cause of valve lash

Just reread,you verified #1 tdc,so when you are cranking engine,have you turned distributor clockwise to retard timing a bit?backfire in intake is,intake valve still open with spark,too advanced

I have tried turning the distributor clockwise but still the same, I'm going to try setting the distributor at TDC once more and hope and pray it starts, maybe you are right maybe the distributor is 180 off but I watch for the exhaust valve to close as I begin TDC. I haven't really felt for the "poof" of the piston since cranking the engine myself by hand.

Just a way I do it,leaves the valve cover on,no oil cleanup,one test to try,finger in plug hole,spin motor with plug in wire,puff and spark,same time?

I shall try that, now do you have someone else crank the engine or do you manhandle the motor?

Yep,remote switch or a helper,for safety I would disconnect injectors,but it's a no start,so safe,but no need to flood engine,so close,stinks, just overlooking something

Currently my helper, my father in law, is resting for work and is unable to help me and I don't have a remote switch unfortunately. Ill have to wait until tomorrow morning when I get off work to try it, I'm praying that this thing is as simple as resetting the timing because it is seriously frustrating me. One thing I never do however is give up, I will dig and dig and dig until I find the root of the problem. I appreciate your time and patience and I will post back upon working on the truck again, should be tomorrow morning.

Sorry I haven't posted in so long, I started a new job overnight. I had my wife try and start the truck while the spark plug is out and its sparking before the blow of the cylinder, I am unsure of my next step, Any help is appreciated now.

Confident on #1tdc,?the stronger of the two blows,have assistant bump starter,short cranks,give a holler"good" when balancer line approaches mark,finish by hand rotation,line marks up,where's rotor pointing?

Alright so we just cranked the motor to get the puff and the cylinder 1 to tdc using the harmonic balancer, I currently have the marker on the harmonic balancer at 0.

I just checked youtube,many good videos on the subject,give it a look,be better than I can explain

May I ask what you had looked up on youtube? I appreciate the help I really do.

I googled,93,tbi Chevy distributor timing,I mentioned that,cause sometimes I leave important steps out,but,at tdc1#,is rotor facing #1 cylinder?

So after pulling the cap off after getting her to TDC after blowing out, she was 180 out, I put everything the way they belong and tried it and guess what? she fired up. GOD that took forever. Now to put the valve covers back on and get her running without spewing oil everywhere. I greatly appreciate the help geo1 you've been the greatest help. Ill post back if I have any other issues.

I'm sorry I haven't been on here in a while, been busy with work and the holidays and working on vehicles, but I just wanted to let everyone know that helped me on this that I am grateful for all the help. The truck still has a couple of issues but I have to post in a different section of the forums for the help. Thanks again.

Good evening Im having an issue with the truck once more. I took the truck to work a couple of days, I had the distributor loosened so I could adjust it and the bracket backed out a little bit and the distributor popped up so much that the oil pump wasn't running, now when I am driving the vehicle under load it rattles like the timing is off a couple of teeth, could the timing be off again? I need this truck running 100% so I need some help. Once I got the timing correct the first time it wasn't rattling any longer, but since the distributor got pushed up it started rattling again. What should I do? Should I remove the distributor and reset the timing? Any help is appreciated.