XJ6 & XJ12 Series I, II & III 1968-1992

fuel in my oil??

 
  #1  
Old 09-19-2014, 02:15 PM
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Default fuel in my oil??

ok..... so, anyone that is paying attention to my posts will note that i had clumpy oil and low pressure, anyways, i got rained out today at work so i figured i would tinker with jag, went to store bought new oil and jusst for teh hell of it some marvel mystery oil, i put maybe half a cup in with the old oil and ran car to bring up to temp, ( not as easy as it sounds) i had hell of a time getting car to start and when it did id idled at 1500 and was smoking like a chimney!!! now there is no way that i know of that half a cup of MMO could cause any of this ( but of course anything is possible) i got her up to temp finally but the smoking never stopped, near the end she was running really lumpy and barely staying running. i gave it a little gas before reaching down to shut her off and she died all by herself with a puiff of what looked like brownish black smoke! ( smoke before was whitish grey, as with burning oil)
Ok so now she wont start back up but im not worried about that right now, i wanted to at least change the oil while it was good and hot! undo the drain plug and hot oil comes gushing out with more gusto than normal, like its thinned down, way down!!! i pull my big pan out from under the car and am happy to see no clumps, however my oil smells strongly like fuel!! and to touch it its barely slippery! super thin!!!

Now the onyl place i can think of that oil could possibly mix with fuel is via evap canister something gone wrong in there! am i right?? how can i test it??? anyone with any other ideas more than welcome too!! if it were a chevy i would suspect fuel pump but alas my car is still stock.

Thanks in advance,

Darren
 
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Old 09-19-2014, 06:32 PM
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I agree that a half cup of MMO in an 8 quart sump isn't likely to be the cause of this problem.

I'd say you have a major over fueling problem, possibly due to excessive fuel pressure among other possibilities.

A ruptured pressure regulator is another possibility. If you pull the vacuum hose off the regulator and see or smell raw gas, you've found your problem!

Drawing raw fuel into the engine from the cannister is another possibility...which of course means finding out why the cannister has raw fuel in it.

Cheers
DD
 
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Old 09-19-2014, 09:05 PM
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Check the ignition system too. The poor running suggests you have a serious misfire. And thus unburned fuel will easily get past the rings on the compression stroke, thinning the oil as you describe. Also do a compression test before your go too much further with this engine.
 
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Old 09-20-2014, 08:28 AM
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Pull the spark plugs. I have an idea that they are fouled, rather badly.


Remove the dip stick and check the oil level. if inordinately high, something got into the sump. sniff and see if it smells fuely. or touch a match to just over the oil film. if fuel contaminated, the vapor will ignite. Not so, if only oil.


If any doubt, do an oil filter change. Contaminated oil can raised havoc with stuff.


As spark plug access on the 4.2 is so easy, a compress test seems the firt thing to do in any diagnostic process.


I doubt the MM had any effect, good or bad!!


Carl
 
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Old 09-20-2014, 09:09 AM
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Might take a compression test. Rings could be washed and letting fuel into oil. Oil pressure is 40lbs. when running, fuel 40lbs., so when oil pressure low fuel is higher.
 
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Old 09-22-2014, 04:24 PM
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Default problem found!!!!

but how to fix???????

So i followed suggestions and checked plugs, all totally fouled!!! cleaned and reinstalled!, new 20-50 oil and filter and she fired right up with oil pressure o plenty!!! But still spewing black smoke!!! i reinstalled old cts, no change, it seemed i was back where i started with car only running somewhat smoothly if i create a vacuum leak, where next?? hmmmm so i pinched off the csi and she smoothed right out, no burbling from exhaust, and no smoke either!! so i disconnected it (electrically) and let her warm up to operating temp, she idled for a good 20 mins without even a hiccup ( just like the good ol days ) lol
Everything is beautiful with csi unplugged!!! but the instant i plug it back in, even when car is up to temp she instantly goes rich!!!! what am i missing?? what tells the csi to fire?? I have replaced the thermotine switch already in hopes of chasing rich running about 2 months ago!! where do i look next? also as a side note, when i had head off the wire connector for the thermotine switch pretty much crumbled away, so i got a new one, could i possibly have the wires on backwards?, any help here is greatly appreciated!


thanks in advance!


Darren
 
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Old 09-22-2014, 04:34 PM
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Pretty weird.

The Thermotime switch is a timer that grounds the cold start injector. It has a heating element to open and close. It uses "+" voltage from the starter circuit to heat the heater and "time out". Heat transferred from the water rail helps keep the switch 'open' (no ground to the injector) so the injector can't operate when the engine is warm or after the starter has been operate for more than a few seconds.

The cold start inject gets "+" voltage from the starter circuit....so that "+" voltage is applied only when the key is turned to 'start'.

So.....

You have "+" applied to the CSI when it shouldn't be *and* the CSI is being grounded by the TT switch when it should be. Two faults.

Any sign of wiring damage or wiring changes?

Cheers
DD
 
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Old 09-22-2014, 04:42 PM
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i thought i had fixed all the messed up wiring!!! lol guess not!!! I didnt have any actual broken wires other than the one at the thermotine switch! there was just lots of really brittle wires that i replaced one at a time!!! could i possibly have plugged something into the wrong spot??? i was pretty careful replacing wires with wires of same length and i put them all in looms too, so they all pretty much fell to spots where they would plug in!! of course all the damned plugs are the same and it possible i have mixed up aav and csi... does this sound like it would be the cause??? dont wanna switch em unless im sure they are wrong!!! in case it really screws something up
 
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Old 09-22-2014, 05:22 PM
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Do you have the S57 wiring guide? if not it's download-able from one of the stick threads at the top of this section. It has all the wires colors so it'll be easy to figure out were you might've gone astray

Cheers
DD
 
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Old 09-22-2014, 06:45 PM
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i do now!!! had the two switched!!! plugged wires in the right way and voila!!!! idle is back down and everything is smooth!!! Its a grand day indeed!!!
 
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Old 09-22-2014, 07:16 PM
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Right on, man. Right on !


Cheers
DD
 
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Old 11-21-2014, 04:33 PM
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Originally Posted by Doug View Post
I agree that a half cup of MMO in an 8 quart sump isn't likely to be the cause of this problem.

I'd say you have a major over fueling problem, possibly due to excessive fuel pressure among other possibilities.

A ruptured pressure regulator is another possibility. If you pull the vacuum hose off the regulator and see or smell raw gas, you've found your problem!

Drawing raw fuel into the engine from the cannister is another possibility...which of course means finding out why the cannister has raw fuel in it.

Cheers
DD
I had a Mercedes Coupe that I was working on for a friend. It had double the quantity of oil in the sump as it hjad been diluted with fuel. Exactly what others said; Pressure Regulator leak. Burton
 
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