Gas leaking from exhaust manifold, gas in oil?

[HamHay]

Gonna' keep posting until someone takes pity on me and offers a reply.

1989 MJ, 4.0, 5spd, has been missing at all speeds lately. As per normal, block, head and valve cover areas nice and oily.

What I thought was oil at the exhaust manifold on the front-most cyclinder is actually gas. Pulled the plug and it was fouled with gas, checked the wire and it was OK, plug fires, too. All other plugs, wires, OK. Lots of carbon on the dist. cap posts, cleaned them, no change.

No smoke from tail pipe, backfiring, knocking and pinging or stalling.

Changed injector, and plug, no improvement.

Did a compression test with the following results:

#1 115psi (leaking cylinder at manifold)
#2 135psi
#3 140psi
#4 150psi
#5 150psi
#6 155psi

Checked oil level and it is high, and smells like gas. Is this indicative of a bad head?

Doesn't look good, does it? Anyone have an idea of what I'm up against? The truck only has 62K miles on it, but as the second owner, I don't know how well it was maintained before I got it.

Any info or thoughts are appreciated.

 

[jeepdude10000]

Have u changed your oil since? That fuel in the oil can damage engine parts,

and as for the other fuel leaking, all i can think of is a bad headgasket, but it almost sounds like the injector is stuck open, but u changed the injector, ond u could have lower compression if the fuel has washed the cylinder and is giong past the rings.

 

[87manche]

put some oil in that cylinder and do the compression test "wet"
If the compression goes up it's the rings, if it doesn't go up then it's likely something wrong with the valves.

 

[HamHay]

Thanks guys, a little direction is what I needed.

I'll check it "wet", and drain the oil. I suspect I'll be posting again soon.

Thanks again.

 

[HamHay]

Ok, got 10 quarts of stuff out of the oil pan that smelled mostly like gas. Fresh oil in and have not run it, just cranked to do a wet compression test.

With oil squirted into #1 cylinder it read 210 psi at first, then settled down to about 170 after four readings. Wet, the other cylinders were in that ballpark, too. I think the gas washed down the cylinder when I got my initial 115 psi reading.

With all plugs in except #1, I rotated the motor to TDC for #1, then backed it off to attempt to seat both exhaust and intake valves.

I screwed in a fitting and blew compressed air into #1 with the throttle wide open (about 30 psi). I could hear air escaping at the throttle plate, and at the oil fill cap. Not a lot, but it was there, could feel it at the cap. I rotated a little more back off of TDC, and a little past TDC and the flow changed in volume but never went away, especially at the oil fill cap.

It didn't leak out of the exhaust until it was past TDC, and nothing escaping from the dip stick tube.

Someone mentioned to me that the rings were likely bad if you could hear air escaping from the oil fill cap. That doesnt't seem right to me, seems like it would come up out of the dipstick tube if air was getting past the rings, and down into the crankcase. Besides, when I first turned the air on, at about 50psi, the motor sprung into motion...had to back it off to 35 psi just to get it not to move off of TDC when the air was applied, so it seems the rings are doing their thing.

At your mercy.

 

[jeepdude10000]

well im going to say rings should be ok, just watch for more gas in the oil after it runs for a while, other than that go ahead try it.

I would stiil watch injectors too, to make sure one is not stuck open, when the engine is running, tough each injector, u should be able to feel them click.

 

[HamHay]

Re: Gas leaking from exhaust manifold, saga continues..

I started it up, fresh oil and filter ,after squirting oil in cylinders yesterday, and it was the same, after only a few moments gas from exhaust manifold again.

While running, I unplugged the #1 injector harness and after a few seconds, no gas from manifold. I plugged the old injector into the harness and felt no click, or pulsation. Unplugged it and attempted to blow through it..impossible. Plugged it back in and was able to blow a small volume of air through it constantly.

Put the multimeter to the injector harness and got a constant 13.7-14 volts, as opposed to a rapidly fluctuating 2.1-3.8 volts on adjacent injector harnesses.

WTF? How could it be getting full voltage, like what's present at the alternator, on only one injector?

 

[langer1]

You have a bad output in your ECU keeping #1 on all the time. Change the ECU. The low compression reading on #1 is because fuel has washed all the Oil off the cyclinder wall and it should return to normal.
Don't drive it untill you fix it.

 

[langer1]

Well we kept going now what did you find?

 

[HamHay]

Unbelievable, Langer.

Right on the money.

I pulled the ECU today, and back-probed the injector outputs while it was was running.

Every injector output fluctuated between negative mV and positive 4.2v, except #1 cylinder output, which read a steady 14 volts.

Bendix unit, made in France, NAPA locally gets $109 for it.

I had an '85 XJ, 2.8 5 spd, with 200K on it that had many problems over the years, but the ECU was never suspect, so it's news to me that an ECU just f's up.

I'll bite the bullet and let you know how it ends up.

Thank you all for your help, and please don't let my "join" date mislead anybody.

I've been active on forums since at least 1998, and the aforementioned V6 carburated XJ was converted to a 3.4 liter, TBI 5 Spd entirely with the wit and wisdom of the folks here.

In fact, I gave that XJ away with a dead battery, and leaky clutch master cylinder, at 272K a few months ago to a downtrodden friend.

He just passed me in it an hour ago.

Again, thanks,
John

 

[Speed_racer]

Thats awesome you guys could track it down that quick. Must say, youre pretty savvy yourself there john.

Good wrenching, folks!

 

[bottleworks]

Make sure the resistance of your #1 injector isn't too low. It can burn the injector driver on in the PCM. Don't want to end up with the same issue in a month. Off the top of my head, I believe the injectors should ohm out at ~16 Ohms?...