Gas in oil... (1 Viewer)

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My '76 FJ-40 died on me on the highway yesterday and I think I have the culprit but looking for opinions on noise I heard.

Was cruising along at 60 mph and noticed that the fuel gauge showed that my fuel level had gone down significantly (1/8+ of tank) in about 7-10 minutes of highway driving. I know FJ's make gas disappear like magic but I average around 10-11 mpg so something was going on. Before I could pull over to see what was up, engine died with some knocking/grinding noise from underneath.

Had it towed home and dug into it last night. First thing I did was pull dipstick to check oil level / appearance. To my shock the dipstick was almost completely covered to the top and the oil was very milky colored. I check the oil frequently and it was not over-filled. When I wiped off the dipstick the oil had a gas smell to it. Could this be where my gas disappeared to!?

Checked the forums and found this thread which makes me think the culprit is my fuel pump or more specifically the fuel pump diaphragm:

https://forum.ih8mud.com/threads/gas-in-my-oil.454718/#post-6310916

Question is....if this diagnosis is accurate, what was the knocking/grinding sound when it died? I plan to drain the oil, replace with fresh, check/change spark plugs, replace fuel pump and gasket and try to fire it back up but the noise I heard worries me. Any thoughts or anyone else experience this before?

Thanks in advance for any advice / input!
 

Howard705

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BAD BAD for the engine-gas doesn't lubricate. Hope it didn't wipe out bearings. I'd be fairly certain it's the fuel pump. I wouldn't try to run it on that pump. after drain/refill and new pump it the engine's ok run a bit and drain/refill again to flush.
 
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what Howard said, but I'm more worried about the milky color.... here's what my routine would be. Drain and refill the oil (without a new oil filter) I'd , put the cheapest 30w oil in it, disconnect the fuel line between the pump and the tank, then start it (add gas down the carb if necessary).... if it knocks, well, you probably know the drill behind that. If you got lucky, I'd replace the pump after verifying that the coolant level isn't low.

the knocking you heard was probably hydrolocking - normally it's through the intake, but if you fill the crank case up enough, you can also hydrolock it.
 
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Thanks gents, I'll follow that routine. Definitely hoping there's no major damage. Jim C advised to drain and leave the plug and cap out/off for 24-hours to let the gas vapors clear too - no need to make an FJ bomb! I'll update how it goes when I get to it.
 

JohnVee

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What kind of engine and carb? Mechanical or electric fuel pump? There have been a few of us with this problem this year. My issue was stuck floats on my Holley carb'd GM350 with electric pump. Same setup with a new carb works great now.


...via IH8MUD app
 
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JohnVee - it's the original 2F engine with 106,000 on it. Original carb, rebuilt by Jim C about 7,000 miles ago. Looks like the original mechanical fuel pump as well.
 
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Quick Update - I finally got around to draining the oil this morning. Checked coolant beforehand and it was low in the reservoir. Looked dark under the radiator cap too which was worrisome. Drained the oil and sure enough, coolant and water came out before oil. As a complete novice I am happy to learn but worried it is probably beyond me at this point. Doubt that there is anything wrong with the fuel pump at all now though it did seem like the fuel level went down very quickly.
 

JohnVee

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RuhRoh, Shaggy. You've got issues. BUT... Are you sure that it was coolant that came out? Are you sure that the radiator was full before this started? Are you sure that the gas gauge reads properly and moves at a consistent rate throughout its range? How long have you had this truck?
 

Howard705

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I'd check bearings before anything. Water does NOT lubricate. Add 5-6 qts oil-enough to run it. Watch pressure-listen to bottom end. If ok which I have doubts on-pressure test cooling sustem with plugs out-probably head gasket.
 
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RuhRoh, Shaggy. You've got issues. BUT... Are you sure that it was coolant that came out? Are you sure that the radiator was full before this started? Are you sure that the gas gauge reads properly and moves at a consistent rate throughout its range? How long have you had this truck?


Yes, definitely looked like coolant - greenish color, very water like, not thick. I check the fluids regularly so I am pretty confident that the radiator was full before this happened. The fuel gauge is another story and part of why I thought fuel had gotten into the engine. It does not read accurately and has not since I've owned the FJ. I've owned it for about 3-years now BTW. The PO replaced the fuel tank with a poly-tank that is likely not of the same size from what I understand from others comments on the forums. Thus the tank is typically empty when the gauge reads 1/4 full. Also have a vapor leak somewhere so when the top is on the cabin smells of gas when the tank is full. Tends to go away after using about 1/8 of tank. Been planning on replacing tank with OEM and finding where vapors are coming from then. Apparently there's other work that is going to come first now!!
 
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UPDATE - OK, I have removed spark plugs. Photos attached showing condition. #2 looks like the end got ground off. Not good eh!

I went ahead and disconnected the coil, clamped off fuel lines, and turned the key to see how it sounds per FJ40Jim's instructions. Much to my surprise it turned cleanly and didn't hear any grinding, clanging, etc. I have a video with what it sounds like, but can't seem to attach that.

Since there was no question a lot of coolant entered the engine, could it be possible that it luckily is just a head gasket? The condition o the #2 spark plug definitely would make me think there is some damage inside, right?

Thanks again or all the advice and the really generous offer SuperBuickGuy! Cheers!:beer:

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Yep, seems like #2 is not moving. If I put my hand near the spark plug holes I get a nice push of air out of all the others when cranking, but not #2.
 
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That #2 plug is UGLY!!---but don't dismay just yet--do edwjc' suggestion--pull the head to see what you've got--you might even be able to replace the piston - these engines are tougher than you think(to quote a MUD member--"It's only metal, we can outthink it")
I would disagree w/Howard on the lube qualities of water--it is a lube--in the normal range of ambient temps-witness pressure washers/water lubed/cooled drill presses, etc., but certainly not in the temp range of an internal combustion engine, as the heat tends to be close to the flash point of water at atmospheric pressure. This being the case, you MAY have averted disaster in the crankshaft area due to the lower temps there. Don't trash it yet till you see for sure.
 
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Howard705

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Pull the head-nothing to loose. There was clanging. That may have been what took out the plug. The lifespan is just a few minutes when all you have for lube is water on the bearings.
 

brian

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My money is on the big end of number 2 broken at the crank. Piston over traveled and smacked the plug. Part of the connecting rod broke through the block into the water jacket.
 

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