Oil in spark plug well

[Tim Lurker Find all posts View Profile Close Tim]

Long story as short as possible,

I went to change the spark plugs and the leads tonight to find one of the spark plug wells had a fair bit of oil in it. The plugs and leads were well overdue but the main catalyst was that it has been backfiring. From a quick search it looks like the most common culprut is a gasket/o'rings but can be far more serious.

First question is how do I go further about identifying what the actual cause might be, is there anything I can do find out without stripping it down? Second is should I keep this totally off the road until its fixed or would it be okay to drive for another couple of day's whilst I get the repair organised. Thirdly anybody got any ideas as to the likely cost of repairs?

Some other probably pertinent information.
*Car was backfiring at least in part to a couple of different air leaks making it run lean, although the old plugs and leads probably weren't helping. Its a bit of a vicious circle backfire leads to an air leak leads to more backfires.
*Car is dual fuel and has done about 200,000km on LPG, I have heard it can be harsh on the valves so I am suspect this may be where my problem lies. I have used flash lube for a large portion of that time but the periods between filling up I cant be sure of.
*Car has been noticeably missing (I think its what you would call it, lets out a couple of pop'pop noises as opposed to a loud bang of a backfire) only in the last few days but only occasionally when some times accelerating away from the lights after idling for a bit or accelerating up a hill after coming down a previous one.
*The plug from the well with oil in it looked like it has seen far less wear than the other's makes me think that cylinder hasn't been running for a while but I haven't noticed a rough idle (see next comment) and only a slight loss of power.
*Idle has been rough a few times but this has been due to a backfire sooting up the airflow sensor, I think it has now however beyond cleaning and now needs to be replaced.
*Has backfired on both Gas and Petrol.

Any help appreciated

[Tim Lurker Find all posts View Profile Close Tim]

other bits I forgot to add, no oil in coolant or visa versa and there was also a small amount of dried oil around the top of the plug in the neighbouring cylinder, this has me hoping that it might just be a gasket/seal.

[Tim Lurker Find all posts View Profile Close Tim]

To answer some of my own questions after a bit of goggling, looks like a compression test then a leak down test if the compression is low is the way to go. Second I replaced all the plugs and gave it a run, is running with a lot more power, didn't so much notice the gradual loss, will check the plug well after a day or so to see how much it is leaking.

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

So you've replaced the plugs? I had a single leaking plug well on the back left side a few months ago. I only discovered it during a rocker cover gasket and spark plug change, but it didn't effect the performance of the car in anyway. The plug well was half full of oil. I had to sit the coil pack tube in a container for the oil to drain out of it overnight. I cleaned the spark plug well a bit but pretty much all of the oil went into the cylinder. The spark plug tube seals were not in great condition after 345,000km. So I hammered them out with a 32mm socket and fitted new ones.
Put everything back together the next morning and started the car. It blew out a bit of blue smoke on start-up but it fixed the oil leak in the well.

If you need to replace the tube seals and want to save $500-$800 labour charge from a mechanic you can do it yourself relatively easily. You'll need to replace the
rocker cover gaskets too but it's a relatively simple job. Two people can knock it over in 3/4 of a day. One person allow 2 days. A second pair of hands definitely
makes it easier to get the drivers side rocker cover back on with all the crap that's in the way.
Buy a tube of Permatex Grey sealant or Toyota FIPG sealant for the half moons at the end of the cam rods. Also buy a cheap Torque wrench for $60. It'll be handy to have one anyway. You'll need to torque everything back to spec. Quite a good little job to wrap your brain around if you haven't ever done this before and not difficult in anyway. In the corners of the half moons, just be a bit more generous with the sealant to fill the gaps that the gaskets won't properly plug themselves.

Also fold a torn off strip of masking tape over the thread of every bolt you take out and number it with a Nicko pen. Write the corresponding number on the engine where the bolt came out from. All the hoses you unplug are of different thickness to one another thank god so that makes re-fitting the hoses an easier task.

I doubt this will fix your back firing issue but will put an end to the pesky spark plug tube seal leak you've got anyway. You'll also be due for new rocker cover gaskets within the next 50,000-100,000km if you haven't already got oil leaks from the rear or front of your rocker covers.

[Tim Lurker Find all posts View Profile Close Tim]

So you've replaced the plugs? I had a single leaking plug well on the back left side a few months ago. I only discovered it during a rocker cover gasket and spark plug change, but it didn't effect the performance of the car in anyway. The plug well was half full of oil. I had to sit the coil pack tube in a container for the oil to drain out of it overnight. I cleaned the spark plug well a bit but pretty much all of the oil went into the cylinder. The spark plug tube seals were not in great condition after 345,000km. So I hammered them out with a 32mm socket and fitted new ones.
Put everything back together the next morning and started the car. It blew out a bit of blue smoke on start-up but it fixed the oil leak in the well.

If you need to replace the tube seals and want to save $500-$800 labour charge from a mechanic you can do it yourself relatively easily. You'll need to replace the
rocker cover gaskets too but it's a relatively simple job. Two people can knock it over in 3/4 of a day. One person allow 2 days. A second pair of hands definitely
makes it easier to get the drivers side rocker cover back on with all the crap that's in the way.
Buy a tube of Permatex Grey sealant or Toyota FIPG sealant for the half moons at the end of the cam rods. Also buy a cheap Torque wrench for $60. It'll be handy to have one anyway. You'll need to torque everything back to spec. Quite a good little job to wrap your brain around if you haven't ever done this before and not difficult in anyway. In the corners of the half moons, just be a bit more generous with the sealant to fill the gaps that the gaskets won't properly plug themselves.

Also fold a torn off strip of masking tape over the thread of every bolt you take out and number it with a Nicko pen. Write the corresponding number on the engine where the bolt came out from. All the hoses you unplug are of different thickness to one another thank god so that makes re-fitting the hoses an easier task.

I doubt this will fix your back firing issue but will put an end to the pesky spark plug tube seal leak you've got anyway. You'll also be due for new rocker cover gaskets within the next 50,000-100,000km if you haven't already got oil leaks from the rear or front of your rocker covers.

Thanks for that, The new plugs and leads seem to have fixed the backfire problem. I have now watched a few you tube vids on doing the rocker cover/valve cover and tube well seals and am fairly certain the tube well seals are the problem. Certainly looks doable, just need to get the parts and find the time.