New issues regarding oil

[TwistedFish]

Hi all, I recently ran into some new issues.

I bought a 1991 explorer XL 5 speed a couple of weeks ago, and it's a project truck (thats okay, i wanted it to be one). I've changed the oil, and the spark plugs. While changing the oil, i noticed a bit of an oil leak coming from the pan, and also the drain itself (even when the plug is tightened all the way). Additionally, when changing the spark plugs, i found oil on the spark plug threads and gasket (not the electrode). This, coupling with the fact that the truck had the "check oil" light on before i changed it, leads me to believe i have an oil leak. Anyone have any advice on what i should do here? I also have other pressing issues, such as a rough start and searching idle (meaning it goes up and down, cant find the right idle) which can cause me to stall out when being idle at a stoplight for a while. Any advice would be greatly appreciated. Thanks!

 

[BKennedy]

Clean the mass airflow sensor, it might get rid of the rough idle.

These engines have issues with oil leaks. They usually are the valve covers, the rear main seal and the pan. Valve covers are not very difficult and if the outside of the spark plugs have oil on them, then its either the valve covers of the lower intake, or usually both. Rear main seal requires pulling the transmission or engine, pan requires pulling the engine up high enough to clear the cross member. The drain plug is a easy fix, get a new gasket or entire new drain plug with a integrated gasket. The check oil light is for oil level only.

 

[TwistedFish]

Clean the mass airflow sensor, it might get rid of the rough idle.

These engines have issues with oil leaks. They usually are the valve covers, the rear main seal and the pan. Valve covers are not very difficult and if the outside of the spark plugs have oil on them, then its either the valve covers of the lower intake, or usually both. Rear main seal requires pulling the transmission or engine, pan requires pulling the engine up high enough to clear the cross member. The drain plug is a easy fix, get a new gasket or entire new drain plug with a integrated gasket. The check oil light is for oil level only.

Oof, pulling the engine sounds like a b****... any suggestions on doing that at home? Without an engine crane, is there any way to do this? Or would i just have to take it into a shop? Thanks for your reply!

 

[TwistedFish]

Clean the mass airflow sensor, it might get rid of the rough idle.

These engines have issues with oil leaks. They usually are the valve covers, the rear main seal and the pan. Valve covers are not very difficult and if the outside of the spark plugs have oil on them, then its either the valve covers of the lower intake, or usually both. Rear main seal requires pulling the transmission or engine, pan requires pulling the engine up high enough to clear the cross member. The drain plug is a easy fix, get a new gasket or entire new drain plug with a integrated gasket. The check oil light is for oil level only.

Hey, so i actually disconnected the maf (and removed it to clean it) but had an idea, which was to try and start the truck without the maf to see if it was indeed the problem. Aaaaand, the truck runs exactly the same with or without it. So that kind of rules out the maf being the issue. Any other thoughts? I know it’s a symptom of TONS of problems, but anything particularly common?

 

[MidwesternTexan]

The check oil light is NOT just for the oil level!! It's that it's not pumping enough volume/pressure of the oil!!

AND, oil on the threads- could mean the they correctly used an anti seize substance- that should ALWAYS be put on the threads when installing/checking new plugs!!

Good luck on your project.

 

[TwistedFish]

The check oil light is NOT just for the oil level!! It's that it's not pumping enough volume/pressure of the oil!!

AND, oil on the threads- could mean the they correctly used an anti seize substance- that should ALWAYS be put on the threads when installing/checking new plugs!!

Good luck on your project.

Bu- but it went away when i changed the oil.... :/

 

[BKennedy]

The check oil light is NOT just for the oil level!! It's that it's not pumping enough volume/pressure of the oil!!

AND, oil on the threads- could mean the they correctly used an anti seize substance- that should ALWAYS be put on the threads when installing/checking new plugs!!

Good luck on your project.

Please see attached PDF from my Ford 1994 Explorer Electrical and Vacuum Troubleshooting Manual (sorry its sideways). "The check oil" dash light for 1st generation Explorers only comes on at start and for low oil level. It has a separate oil pressure indicator that will show low oil pressure at the gauge.

I have never used anti seize because I live in a dry climate and its not necessary, and it doesn't look anything like oil soaked spark plugs.

I'm not sure disconnecting the MAF and having the same issue would rule out it being dirty. Rough idle on my Explorer that I have owned since 1995 was usually always caused by a dirty MAF. It runs rough without it connected because it can't read the amount of air entering the intake. Spark plugs and wires, sometimes a coil pack will cause rough idle. Vacuum leaks will do it too.

 

[TwistedFish]

Please see attached PDF from my Ford 1994 Explorer Electrical and Vacuum Troubleshooting Manual (sorry its sideways). "The check oil" dash light for 1st generation Explorers only comes on at start and for low oil level. It has a separate oil pressure indicator that will show low oil pressure at the gauge.

I have never used anti seize because I live in a dry climate and its not necessary, and it doesn't look anything like oil soaked spark plugs.

I'm not sure disconnecting the MAF and having the same issue would rule out it being dirty. Rough idle on my Explorer that I have owned since 1995 was usually always caused by a dirty MAF. It runs rough without it connected because it can't read the amount of air entering the intake. Spark plugs and wires, sometimes a coil pack will cause rough idle. Vacuum leaks will do it too.

Well, i took it out to clean it, and found that it really wasn't that dirty, unless maybe im missing something where it'll idle rough if there's even a little bit of dirt in it? On the other hand, it is a 29 year old truck, with what appears to be the original vacuum lines and hoses, so i was sort of leaning to a vacuum leak issue. The guy (who i bought it from) also said it's sucked up water before, so thats never good, but other than that it doesnt really seem to be in too bad of shape. I'm new to working on fords, so I'm still unfamiliar with the little quirks they may have. Also, it's DEFINITELY oil on the spark plug threads, not antisieze. Any thoughts on the issue? I recently changed the spark plugs, but because of the rough idle and start up, its pretty hard to tell any difference.

Posted below: Photos of engine bay and possible reasons for vacuum leak

 

[BKennedy]

The Mass Airflow Sensor, if it has any visible dirt, is too dirty. Its a easy thing to clean, just spray it with carb or fuel injector cleaner, let it dry and reinstall. Don't touch the filaments with anything or you can damage them. If you changed the plugs, then maybe its due to plug wires.

First, I would spray that engine compartment down with Simple Green or other degreaser and hose it off, its filthy. I off-road my Explorer more than I drive it on the pavement and the engine doesn't look like that.

That second picture is a pre heater that uses the exhaust manifold to heat air to help the engine get to operating temp faster in very cold weather. It slips onto the fitting on the bottom of your air cleaner box. If its not checked during smog inspections, then I would remove it as its not needed.

What's going on with the heater core? Are the hoses connected to each other to bypass the core?

Vacuum lines are fairly rigid with soft rubber connectors. You can get the connectors at most auto parts stores. I replaced all of them on mine a few years ago when one cracked and started sucking air. The vacuum line you have in your hand is to activate the pre-heater that isn't connected to the air box. It should go to a T near the vacuum reservoir, which is that black thing between the heater core box and the coil pack. It should have a vacuum line running off of it to the tree on the driver side of the upper intake towards the rear. If you are missing those lines, you probably have a leak. Any missing plugs or lines that leave one of the ports on the tree open will be a vacuum leak. you can start by plugging any open ports and see if it idles better.

Get yourself a Haynes repair manual for torque setting and basic repairs, and one of these OEM 1991 Ford Explorer Electrical and Vacuum Trouble Shooting Service Manual | eBay (best priced one I have ever seen)
A troubleshooting manual from Ford are what I used to completely rewire my vehicle after it had a electrical fire that melted all the wiring under the dash. They have detailed wiring and vacuum diagrams, and help with diagnostics.

 

[TwistedFish]

The Mass Airflow Sensor, if it has any visible dirt, is too dirty. Its a easy thing to clean, just spray it with carb or fuel injector cleaner, let it dry and reinstall. Don't touch the filaments with anything or you can damage them. If you changed the plugs, then maybe its due to plug wires.

First, I would spray that engine compartment down with Simple Green or other degreaser and hose it off, its filthy. I off-road my Explorer more than I drive it on the pavement and the engine doesn't look like that.

That second picture is a pre heater that uses the exhaust manifold to heat air to help the engine get to operating temp faster in very cold weather. It slips onto the fitting on the bottom of your air cleaner box. If its not checked during smog inspections, then I would remove it as its not needed.

What's going on with the heater core? Are the hoses connected to each other to bypass the core?

Vacuum lines are fairly rigid with soft rubber connectors. You can get the connectors at most auto parts stores. I replaced all of them on mine a few years ago when one cracked and started sucking air. The vacuum line you have in your hand is to activate the pre-heater that isn't connected to the air box. It should go to a T near the vacuum reservoir, which is that black thing between the heater core box and the coil pack. It should have a vacuum line running off of it to the tree on the driver side of the upper intake towards the rear. If you are missing those lines, you probably have a leak. Any missing plugs or lines that leave one of the ports on the tree open will be a vacuum leak. you can start by plugging any open ports and see if it idles better.

Get yourself a Haynes repair manual for torque setting and basic repairs, and one of these OEM 1991 Ford Explorer Electrical and Vacuum Trouble Shooting Service Manual | eBay (best priced one I have ever seen)
A troubleshooting manual from Ford are what I used to completely rewire my vehicle after it had a electrical fire that melted all the wiring under the dash. They have detailed wiring and vacuum diagrams, and help with diagnostics.

Wow, you really know your stuff... As for the heater core, it doesn't seem like the hoses are connected to eachother, though i could be wrong.

The "tree" doesnt seem to have any missing hoses, and the ones that dont run to anything are infact plugged. They could be cracked though, its dark so it's hard to tell.

Additionally, i added more detailed pictures of the entire engine bay, just in case you see anything that may look off (other than the obvious dirt). I'd really appreciate it. Thanks so much!

 

[BKennedy]

I have been working on my Explorer since 1995, so I hope I know its systems. It looks to me like you are missing some vacuum lines. They might just be plugged at the tree, but there should at least be one running to the vacuum reservoir.
Here is what they look like on my Explorer. I have a shock hoop support running across the top of the engine, but you can see the vacuum lines. The line with the elbow and white T on it runs to the HVAC controls, with the other line running to the reservoir. The line pointed at the camera is the one you had in your hand in the pictures you posted.

Picture of vacuum tree on driver side towards firewall. All the vacuum lines come off of this.

Pre-heater on passenger side exhaust manifold. That disconnected hose should run from this to the air box

 

[TwistedFish]

I have been working on my Explorer since 1995, so I hope I know its systems. It looks to me like you are missing some vacuum lines. They might just be plugged at the tree, but there should at least be one running to the vacuum reservoir.
Here is what they look like on my Explorer. I have a shock hoop support running across the top of the engine, but you can see the vacuum lines. The line with the elbow and white T on it runs to the HVAC controls, with the other line running to the reservoir. The line pointed at the camera is the one you had in your hand in the pictures you posted.
View attachment 317732
View attachment 317733

Picture of vacuum tree on driver side towards firewall. All the vacuum lines come off of this.
View attachment 317735
Pre-heater on passenger side exhaust manifold. That disconnected hose should run from this to the air box
View attachment 317734

Interesting, thanks for your insight! I've heard the manual transmission Ex's have fewer vacuum lines... is that relevant here (I have a manual) atleast for the plugged hoses? Also, anything i could do immediately that would rate at a higher "importance" than others? Thanks

 

[BKennedy]

The auto trans uses one vacuum line from that tree, which would be plugged on yours. I would just start by plugging vacuum lines and see if the rough idle goes away. Clean the MAF, its probably time to change the plug wires. Its usually one of those things, or a combo of all of them that causes your issues.
Diagram of the 1994 vacuum lines, not sure if the 1991 is different.

 

[TwistedFish]

The auto trans uses one vacuum line from that tree, which would be plugged on yours. I would just start by plugging vacuum lines and see if the rough idle goes away. Clean the MAF, its probably time to change the plug wires. Its usually one of those things, or a combo of all of them that causes your issues.
Diagram of the 1994 vacuum lines, not sure if the 1991 is different.
View attachment 317751

how would you recommend plugging them? just tape or something?

 

[TwistedFish]

The auto trans uses one vacuum line from that tree, which would be plugged on yours. I would just start by plugging vacuum lines and see if the rough idle goes away. Clean the MAF, its probably time to change the plug wires. Its usually one of those things, or a combo of all of them that causes your issues.
Diagram of the 1994 vacuum lines, not sure if the 1991 is different.
View attachment 317751

So, interesting find. I should have done this before, but anyways: while the truck was running, i unplugged the MAF sensor, and it seemed to find an idle relatively quickly. Plugging it back in brought back the same searching idle. I tested it both with unplugging while the engine was running, and unplugged then started the engine. In conclusion, it seems to find a steady idle better with the MAF sensor unplugged. However, why wouldnt i have a CEL? Either way, even though the searching idle seems to be fixed, the jury is still out on my (extremely) rough starts. They get worse the hotter the engine gets, at some points just intermittently cranking, if you know what i mean. Additionally (not sure if this is causing it, but important to bring up), I do have a blueish black smoke coming from my exhaust. I dont have a muffler, or much of an exhaust line after the cat converter, but i dont think that would be the issue.

On another note, I tried the vacuum leak test, and while some of the hoses and plugs look a little questionable, they can be ruled out as the culprit... the truck runs the same whether or not they're plugged.

Thank you so much for your continued support, it really means alot. Any thoughts?

 

[RangerX]

I’ll throw a couple thoughts in here.
I’m not as smart as BKennedy, but like him, I’ve owned my truck since 1995, so you get to know a little bit in 25 years.
Two things you might check, that I’ve had happen. One, take your plastic air intake tube off (carefully, it’s old and fragile) and flip it over and look at the bottom side for holes, mainly at the accordion pleats. Those disintegrate and cause unmetered air into the engine resulting in idle issues. You can’t see the underneath without removing the tube.
Two, look for an oil leak at the valve cover gaskets, especially the back outside corners. Maybe oil is leaking from above the plugs? Just a thought. Do all plugs have oil or just certain ones?

 

[TwistedFish]

I’ll throw a couple thoughts in here.
I’m not as smart as BKennedy, but like him, I’ve owned my truck since 1995, so you get to know a little bit in 25 years.
Two things you might check, that I’ve had happen. One, take your plastic air intake tube off (carefully, it’s old and fragile) and flip it over and look at the bottom side for holes, mainly at the accordion pleats. Those disintegrate and cause unmetered air into the engine resulting in idle issues. You can’t see the underneath without removing the tube.
Two, look for an oil leak at the valve cover gaskets, especially the back outside corners. Maybe oil is leaking from above the plugs? Just a thought. Do all plugs have oil or just certain ones?

Hey thanks for lending your advice! Any advice is good advice for me, like i've mentioned im not too experienced on ford engines. Anywho, I'll definitely give the intake tube a look. Also, the oil on the spark plug threads was only on 2 out of 6 of them. Thanks!