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not a mustang...but the expler forums don't have enough traffic, and it's the same engine, so hopefully you guys can offer some insight:

So to recap my recent problems with my 4.6:

Noticed an occasional 6th cylinder misfire code, very random, and not often.

Figured I'd get new plugs as part of my new ownership maintenance. Also noticed I was using up oil at a higher than what seemed normal rate - I check it all the time, just a habit.

Fast forward to this weekend, I popped off the engine cover and noticed liquid oil pools right around the valve cover/coils/boots/injector area. Like little pools of liquid oil - not just fuzzy sprayed oil on surfaces. I also noticed the 6th cylinder spark plug hole has been repaired, with some sort of extension, that put the plug electrode about 1" above where it should be - I a fixed that with a helicoil, and snugged down the plug and thought all was good in terms of the misfire...

Friday after this repair I left from Boston to Montreal - made it up there fine - checked oil, and coolant, all seemed fairly unchanged. Sunday when we went to leave, I immediately get two codes from my OBD BT adapter - I checked because I felt the bogging - 5th and 6th cylinder misfire. Stopped and pulled off the coils, wiped the oil from them and went on my way. 5th cylinder code disappeared - 6th still there...going to replace all plugs and coils, so we'll see what that does to the misfire code. now onto the confusing part:

I noticed when I dropped my buddies off, a good puff of smoke (wasn't white like coolant, maybe a light hue of blue, or evne grey) after accelerating from a stop (only code still 6th cylinder). I check the dipstick, it's down to about the last millimeter of the cross hatched area ( I topped it up to about 7/8 coverage on the hatched area before leaving sunday - 4 hour drive).

Would a leaking valve cover AND leaky intake manifold cause any of the leaked oil to drop into the intake and burn up upon accelerating from a stop? Didn't notice any blue smoke while driving, just acceleration from a stop. What else would be the oil consumption? I already bought a filter housing gasket, changing that tomorrow but I'm concerned with the liquid oil on top of the engine.

Yesterday I popped all the plugs off to check compression, and a couple had oil on the threads, I'm thinking the oil is almost pouring from the valve cover gaskets - I wanted to re do the heli-coil insert because that plug came out covered in oil - I used the high temp silicone, waiting for that to dry before i check compression. I noticed zero blue smoke when I started the car up and took it around the block before putting in the garage - however at idle it did have a really bad gas smell (assuming unburned from cylinder 6) and pulsing grey puffs of smoke coming from the exhaust.

Any opinions?
 

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not a mustang...but the expler forums don't have enough traffic, and it's the same engine, so hopefully you guys can offer some insight:

So to recap my recent problems with my 4.6:

Noticed an occasional 6th cylinder misfire code, very random, and not often.

Figured I'd get new plugs as part of my new ownership maintenance. Also noticed I was using up oil at a higher than what seemed normal rate - I check it all the time, just a habit.

Fast forward to this weekend, I popped off the engine cover and noticed liquid oil pools right around the valve cover/coils/boots/injector area. Like little pools of liquid oil - not just fuzzy sprayed oil on surfaces. I also noticed the 6th cylinder spark plug hole has been repaired, with some sort of extension, that put the plug electrode about 1" above where it should be - I a fixed that with a helicoil, and snugged down the plug and thought all was good in terms of the misfire...

Friday after this repair I left from Boston to Montreal - made it up there fine - checked oil, and coolant, all seemed fairly unchanged. Sunday when we went to leave, I immediately get two codes from my OBD BT adapter - I checked because I felt the bogging - 5th and 6th cylinder misfire. Stopped and pulled off the coils, wiped the oil from them and went on my way. 5th cylinder code disappeared - 6th still there...going to replace all plugs and coils, so we'll see what that does to the misfire code. now onto the confusing part:

I noticed when I dropped my buddies off, a good puff of smoke (wasn't white like coolant, maybe a light hue of blue, or evne grey) after accelerating from a stop (only code still 6th cylinder). I check the dipstick, it's down to about the last millimeter of the cross hatched area ( I topped it up to about 7/8 coverage on the hatched area before leaving sunday - 4 hour drive).

Would a leaking valve cover AND leaky intake manifold cause any of the leaked oil to drop into the intake and burn up upon accelerating from a stop? Didn't notice any blue smoke while driving, just acceleration from a stop. What else would be the oil consumption? I already bought a filter housing gasket, changing that tomorrow but I'm concerned with the liquid oil on top of the engine.

Yesterday I popped all the plugs off to check compression, and a couple had oil on the threads, I'm thinking the oil is almost pouring from the valve cover gaskets - I wanted to re do the heli-coil insert because that plug came out covered in oil - I used the high temp silicone, waiting for that to dry before i check compression. I noticed zero blue smoke when I started the car up and took it around the block before putting in the garage - however at idle it did have a really bad gas smell (assuming unburned from cylinder 6) and pulsing grey puffs of smoke coming from the exhaust.

Any opinions?

Is it just 5 and 6 that are getting saturated in oil? The first thing I would do is look for that oil leak which would have to be coming from the valve covers. I had a f150 that had tons of miles and I was having the same problem, mine was also leaking coolant at the manifold gasket...I changed both valve cover gaskets and intake manifold gasket and it fixed the wet spark plug holes which was causing my misfire. Does it look like the oil is coming from the valve covers? When you said you changed the "filter housing gasket" did you mean the oil filter adapter gasket that attaches to the block? That is one common area for oil leaks on these 4.6L engines as well.
 

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Discussion Starter #3
Well cylinder 5 and 6 gave me SES codes on my way back from Montreal, we stopped and I cleaned them off - the code for the 5th cylinder went away. 6th was still there. When I removed the plugs again to check compression, the plugs on 3 and 4 came out with oil on the threads (electrode was fine) so there was significant oil in there, definitely was oil, not coolant. When I took out the plug for #6 it was covered in oil, the electrode was all black with oil, I'm thinking the sealant used on the thread repair insert didn't have enough time to cure which caused the leaking valve cover gasket to spill oil into the plug, which then made its way past the insert threads and caused it to foul up the plug.

I redid the helicoil and have allowed the extreme temp RTV to cure for 2 days. When I get up to my garage tonight I'm going to check compression on that cylinder to rule out rings or stuck valve. For the other 7 cylinder I had compression readings of:

4 - 195 8 - 180
3 - 200 7 - 195
2 - 200 6 - ???
1 - 195 5 - 195

assuming #6 checks out, I'm going to replace the valve cover gaskets, and I bought a brand new intake manifold, so I'll pop that on, along with new plugs and coils for all 8 and see where we're at.

When you said you changed the "filter housing gasket" did you mean the oil filter adapter gasket that attaches to the block? That is one common area for oil leaks on these 4.6L engines as well.
Yes, I bought a new oil filter adapter gasket - haven't changed it yet, will do that after the family comes over for Easter on Sunday.
 

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Sounds like you have a solid approach. It's what I would be doing, all oil leaks even if it doesn't fix the miss should be fixed anyway. Wet plugs would defiantly cause this tho so I'm sure the oil is what's causing a majority of your problems. Also, when we gap our plugs on our mustangs it's been tossed around that a slightly larger gap is preferred to also help with random misfiring problems.
 

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Discussion Starter #5
elp....bad news. Cylinder 6, compression...20psi. I hooked up the compressor to the head, and could feel slight air coming out the exhaust - must be an exhaust valve @ cylinder 6.

new question - what's the typical cost for a head job? Assuming it's only one bent valve, do I need to replace all valves on that side? What's needed - deck/cut, valve seats, should I replace all the rocker arms/springs? Wondering if it's cheaper to just get a junkyard engine with less miles
 

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Discussion Starter #6
so I was reading another post regarding open valves - it appears it can be a couple of things - bent valve (removal of head), burnt valve (removal of head), bad lifter, or bad spring....I bought a borescope on amazon, I'm gonna take a look tonight, hopefully if everything looks ok, I'll just change the spring and rocker arm and give it a shot. Anything to avoid taking the head off at this point is worth a shot.

There isn't any metal on metal sound when running, so I'm wondering if the valve is stuck open, when the piston raises and hits it, maybe it just pushes it back closed as opposed to bending it? Can that happen?
 

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I would remove the valve cover and give it a good look over. What year is this explorer?

A Leak Down test will tell you exactly where the compression is leaving, but it definitely seems to be valve related.

If the oil has been ran low for a considerable amount of time and regularly low on oil I could see a collapsed lifter as the cause. They rely on oil pressure to stay pumped up.
 

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Discussion Starter #8
I took the valve cover off...I can't see anything wrong. And when I do the leakdown test (Crude variant - just hooked up my compression to the compression tester hose and set the pressure to 30psi) I can feel slight air coming through the exhaust, but I feel like it should be flowing much faster if the compressor is at 40 psi. I can't see any damage, and I had my father look at the valve train while I rotated the the crank by hand, he didn't see anything unusual.

I bought one of those borescope cameras, gonna take a closer look tonight. It's a 2002 explorer limited. I changed the oil about a week or two after I bought the vehicle (in January) and I noticed on some of the highway onramps that were long turns the low oil light came on, but nowhere else but around big turns, so I guess that coulda led to this from what you're saying.
 

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Wonder if your rings are bad on that cylinder...how many miles?
 

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127k isn't that many miles on the motor, I would think the rings would be fine but I wouldn't rule them out with a compression number like that.

If the piston was coming into contact with the open valve it would likely do more damage then just push it back up into the valve guide simply because of the direction it is hitting. Its hitting it at an angle and with a lot of force.

The spring and rocker arm would probably be the cheapest and easiest thing to try first, but I still am not sure what it could be honestly. I'm not as experienced when it comes to diagnosing things like this. The camera sounds like an awesome idea to see the valves up close without taking the heads off, I'm interested to see what you find. Keep us updated!
 

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The spring and rocker arm would probably be the cheapest and easiest thing to try first, but I still am not sure what it could be honestly. I'm not as experienced when it comes to diagnosing things like this. The camera sounds like an awesome idea to see the valves up close without taking the heads off, I'm interested to see what you find. Keep us updated!
I bought a new lifter/lash adjuster at O'Reilly last night and a rocker arm. I can't see anything wrong with the spring. I took the lifter out and put the new on in along with the new rocker. I took the front cam cap off and there is some scoring along the cam and the cap - is this junk (pictures below)

I also noticed there appears to be no oil restrictor as I've seen in some many other 4.6 engine posts/threads/youtube videos...any idea what's going on here:





 

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I'm no expert by any means, but can you feel actual grooves in the cam or the caps? Wonder what the head side looks like. If you feel actual grooves I would probably be more concerned. Most of the time the cap and cam will become grooved first. When I say I am not an expert I say that because maybe yours look normal for 125K miles, that's the part I am not sure about. One way to look at it though is the fact that scored cam caps shouldn't be causing your low compression problems in that one cylinder so I'd probably just put them back on. I wish someone with more knowledge would chime in on your thread to better help you lol
 

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Discussion Starter #14 (Edited)
I'm no expert by any means, but can you feel actual grooves in the cam or the caps? Wonder what the head side looks like. If you feel actual grooves I would probably be more concerned. Most of the time the cap and cam will become grooved first. When I say I am not an expert I say that because maybe yours look normal for 125K miles, that's the part I am not sure about. One way to look at it though is the fact that scored cam caps shouldn't be causing your low compression problems in that one cylinder so I'd probably just put them back on. I wish someone with more knowledge would chime in on your thread to better help you lol
yes, there are actually grooves, they are tiny, but if you run your fingernail over it parallel to the marks, you can feel them. I don't see evidence of metal shavings tho. I did have a tick, and I was wondering if that was lash adjusters due to low oil, but there's no oil restrictor like I've seen on so many other 4.6's

I forgot to mention that when I did the leakdown test I noticed air coming out of the cylinder #7 spark plug hole which is extremely odd - maybe a hole in the cylinder?!?! I'm going to remove the head and take another look, at this point it's pretty much the only option I have. I sourced an aviator engine for fairly cheap, and another 2v 4.6, so I will figure it out once the head is off.
 

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That does not look too bad to me. My engine with 170k looked about the same as yours.

A hole in the piston is very unlikely.....

Did you put the engine back together after doing the lash adjuster and rocker arm and re-do the compression test? Did you let it run a bit so the adjuster got pumped up again?

Let us know what you find when you take the head off.
 

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the car is up at my parents house - where the lift is - so I won't be able to put it back together and recheck compression till the weekend - if it fails, I'm gonna take the head off. I did notice when I checked compression with the valve cover off, no oil squirted out when I turned it over about 6 or 7 times - shouldn't oil come out regardless if the fuel pump is on/coils are off?!
 

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not a mustang...but the expler forums don't have enough traffic, and it's the same engine, so hopefully you guys can offer some insight:

So to recap my recent problems with my 4.6:

Noticed an occasional 6th cylinder misfire code, very random, and not often.

Figured I'd get new plugs as part of my new ownership maintenance. Also noticed I was using up oil at a higher than what seemed normal rate - I check it all the time, just a habit.

Fast forward to this weekend, I popped off the engine cover and noticed liquid oil pools right around the valve cover/coils/boots/injector area. Like little pools of liquid oil - not just fuzzy sprayed oil on surfaces. I also noticed the 6th cylinder spark plug hole has been repaired, with some sort of extension, that put the plug electrode about 1" above where it should be - I a fixed that with a helicoil, and snugged down the plug and thought all was good in terms of the misfire...

Friday after this repair I left from Boston to Montreal - made it up there fine - checked oil, and coolant, all seemed fairly unchanged. Sunday when we went to leave, I immediately get two codes from my OBD BT adapter - I checked because I felt the bogging - 5th and 6th cylinder misfire. Stopped and pulled off the coils, wiped the oil from them and went on my way. 5th cylinder code disappeared - 6th still there...going to replace all plugs and coils, so we'll see what that does to the misfire code. now onto the confusing part:

I noticed when I dropped my buddies off, a good puff of smoke (wasn't white like coolant, maybe a light hue of blue, or evne grey) after accelerating from a stop (only code still 6th cylinder). I check the dipstick, it's down to about the last millimeter of the cross hatched area ( I topped it up to about 7/8 coverage on the hatched area before leaving sunday - 4 hour drive).

Would a leaking valve cover AND leaky intake manifold cause any of the leaked oil to drop into the intake and burn up upon accelerating from a stop? Didn't notice any blue smoke while driving, just acceleration from a stop. What else would be the oil consumption? I already bought a filter housing gasket, changing that tomorrow but I'm concerned with the liquid oil on top of the engine.

Yesterday I popped all the plugs off to check compression, and a couple had oil on the threads, I'm thinking the oil is almost pouring from the valve cover gaskets - I wanted to re do the heli-coil insert because that plug came out covered in oil - I used the high temp silicone, waiting for that to dry before i check compression. I noticed zero blue smoke when I started the car up and took it around the block before putting in the garage - however at idle it did have a really bad gas smell (assuming unburned from cylinder 6) and pulsing grey puffs of smoke coming from the exhaust.

Any opinions?
You probably have coolent coming down the valley and filling spark plug holes with oil and coolent mustangs 4.6 are k own for missfires on 5 and 6. When. When they coolent and oil foul check thermostat housing on intake and oil isprobably leaking from power steering. Reservoir onto belt
 

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127k isn't that many miles on the motor, I would think the rings would be fine but I wouldn't rule them out with a compression number like that.

If the piston was coming into contact with the open valve it would likely do more damage then just push it back up into the valve guide simply because of the direction it is hitting. Its hitting it at an angle and with a lot of force.

The spring and rocker arm would probably be the cheapest and easiest thing to try first, but I still am not sure what it could be honestly. I'm not as experienced when it comes to diagnosing things like this. The camera sounds like an awesome idea to see the valves up close without taking the heads off, I'm interested to see what you find. Keep us updated!
h got bad lifters o
Check oil presure if it hit the piston. Your problems would be found
 
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