Gas in the oil pan....any ideals?

[Nowturbo]

I have a 74 450SL that ran fine until one day I went to start it, it would now fire and after cranking it and trying to search for the reason I found it was pumping gas into the oil pan. I changed some return hoses on the back of the engine for the fuel injection, change the oil, and it started and ran fine.
Forward a week or so and it done it again. No start, crank it to look for problem, it puts gas in the oil again. Before I strike a match to that oil, has anyone got any experience they would like to share with me? Geez, I thought my diesels used to drive me batty Thank You Bob

[Softball60]

I'm not an expert and believe me there are some real knowledgeable people on this forum.

A couple of ideas


Depending on your piston rings a minor amount of gas will get into the oil pan. That is part of the reason for changing oil every 3-5K, longer for synthetic.

Nothing like you mention about your issue is normal.

Question

Had you done some previous repairs. You stated that the car was running fine then the gas problem then you changed hoses and oil ran fine for some time then the same problem

Why did you change hoses on the back of engine?

Possible items:

1. Stuck open fuel injector (not familiar with the 450 system but my 560 has injectors)

2. High pressure (Fuel pump) in the gas line pushing gas past the piston rings

3. Head gasket going bad. Did the car run poorly after you changed hoses and changed oil?

That's a couple of things

Hope this helps to get you started

[Nowturbo]

Agreed, there are some real good folks on this forum. I had not worked on the car before, in fact I have only driven it about 4 miles or so. Just got it last Xmas and had not done anything to it. I had started it and moved it around the property a bit over the last year, and it was always fine...started after less than one revolution after setting for two months, and ran great all around, still does. I was selling it and took the guy for a drive, was going to get it to him and the thing went wacky. The return line looked like it was kinked so we changed it, checked all we could visually check, serviced the oil, and it started and ran fine. Week or so later, done it again. I will hang out here and maybe if I get enough info, I can attack it from another angle than I already have. Thank you for your input, I will use all the possibilities that I can get. Bob

[97 SL320]

Does you car have D jet ( wires running to each injector ), L jet ( wires running to each injector and a electronic air flow meter before the throttle body ) or K jet ( mechanical inj, no wires to each injector) ?

D and L jet can have a stuck open injector but the car should still run.

K jet uses pop type injectors so a stuck open one won't cause the problem you have.

D and L jet sometimes use a fuel pressure regulator that looks at intake manifold vacuum. If the regulator diaphragm fails, it can allow fuel into the intake causing a no start and eventually fuel in the oil. Pull the vacuum hose and look for liquid fuel.

All 3 systems use a cold start injector, this can be leaking / electrically active for too long when cranking. ( it typically turns on for a few seconds at sub 40* F temps from what I recall )

Too high fuel pressure can only be caused by a kinked return line.

A failing head gasket won't cause the issue you are having.

[rowdie]

The 107.044 is D-jet through '75 MY. '74 is a M117.982 with D-Jet.
Could be a stuck open injector but it shouldn't idle or run great if so.
Pull and inspect the spark plugs. They should have a uniform appearance.

[meltedpanda]

it should be a Djet
Check function of cold start injector, if stuck open would cause for a hard or no start, especially if you have other injectors stuck or non functioning. How many miles on them?
Look at plugs as mentioned by jim, are they wet and black?
When you turn key ( not to start position) does the fuel pump spin up and stop as it should. Let us know some of these details

There are a few of us Djet left around here, we can figure it out or go crazy together trying

[97 SL320]

On D jet, check the vacuum hose from the intake manifold to vac sensor. If not connected the motor will run rich and put fuel in the oil.

Have a look at 70's Porsche 914 / Volvo / SAAB / VW as they use D jet.

[Nowturbo]

Thanks for all the feedback. Have been in the house with the flu, so it will be a few days before I take wrench in hand. I will look at the plugs then... and the car is stock and I investigated so I know it is Djet. My brother and I had discussed the cold start injector so I am glad you brought it up. I do not know anything about the car like I said, I got it, kept it, and now I am selling it because am not in a situation to restore it. It is drivable and drove good from what I could tell in the small time I drove it. I know that if I went over and changed the oil, it would start and run great until it done the same thing again. I am just trying to make sure that the person who buys it can maybe drive it a little while he is fixing it up instead of me knowing that it had a situation when he paid for it. As long as what I know about the car is good, anything after is something that happens to HIS car. Anyone who has more ideals, just put em down and I will put more info on the car in a couple of days. Bob

[meltedpanda]

feel better then let us know, I am curious about the fuel pump spin up

[Nowturbo]

Hello,
Just a little uptodate. I am still a little flu-like, what a tuff battle. I have not worked on the car, but went over to the bros house and it started and ran like a champ. Been going over each day and letting it warm up and drove it around a bit. Dangdest thing I ever did see. If it doesn't sell in the next week or so, I will check some things out on it. I am hoping that my Bronco sells first so that I can maybe keep the SL. I could make it real nice for about 3500-4000. It is a lot better shape than I first thought. Anyway, if I find out the mystery, I will post it. Bob

[190E 2.3 rur rur rur]

gas is flooding from an un metered source. STOP cranking it over. change oil even if you just have a few quarts on hand.

take the vacuum hose off your fuel pressure regulator.
if theres fuel present on the vac side.. its ruptured. fuel gets sucked in and
ends up down below.

have to get that fuel out before you ignite it by accident.

[Nowturbo]

I changed the oil before I started it, and now that it has happened twice ,if it does not start after about 3 turns, I don't go any farther. I will check that vacumm hose when I get to the car and mess with it. That for sure is an unmetered source because it did not take long to make a mess of things. Thanks for the insight and I will reveal the answer to the problem as soon as I solve it. Bob

[meltedpanda]

does the fuel pump stop spinning up when the key is placed at number 2 position?
Have you checked the function of the CSV. These things , in addition to the vacuum line can all be doen without starting the car
Also , stuck open or leaking injectors will not take long to foul the oil. They will leak down after the car shuts off, giving a false impression that the gas is flowing in only when running. pull a plug or two, wet/or dry - color ?

[Nowturbo]

Well, actually messed with it a bit today. the fuel pump seems to work like it should, about two seconds, then stops. Would not start, checked spark, had spark. Pulled plug and it was wet, took hose off pressure reg. if that is the one that is in front of engine,left side and has hose that splits off and goes to each side of intake about half way back. It was wet with fuel, hit starter and it pumped gas out of open tube (with two plugs out, it tried to start). It has a fuel line that comes off the rail in the front and connects to it, took that off and plugged it, put everything back together and if fired up. It ran rough from being flooded, then smoothed out, ran for 40 sec., then died like I hit it in the head with a hammer. Has not started since... of course I only worked about another 5 min on it...Oh plug was wet again. I will deal with it another day, read more of all of your input, use what I learn from you all, and attack from another angle.
Thank You..........Bob

[97 SL320]

Don't crank the engine when the plugs are out unless you disable the ignition. A stray spark will light off the raw fuel floating around.

A vacuum referenced fuel pressure regulator will have 3 lines, two that are about 5/16 diameter are fuel and one in the 3/16" range is engine vacuum that should be dry.

You will need to pull the plugs and clean / dry them. Also let the engine dry out.