Replacing spark plugs

[KathmanduCruiser]

BMWSTOY,

Thanks to your tips, I was able to change the spark plugs myself. It is all done now. Took about two hours, but I enjoyed doing it and saved the $130 that the dealer was asking for.

Again, thanks for you description of the work.

Mine at 120K appeared to be in need of changing, although not too terrible.

The steps I used: Take off the air filter cover and then loosen at the intake and take off this entire piece to screws holding the cover near the hoses. Of course you have to take off the bling cover to the engine first. Then to get to the 4 pass sides, you are there with no worries. On the drivers side, I just unhooked the large electric plastic hose from the connectors - but I did not take off the mounting plate in the way of the 3rd plug back. The 4th plug back took a 2" extension and a 2" universal extension - if you have two 2 X 2's" or two 2 X 3's you should be alright. The longer extensions will get in your way.
Hint: When removing the coil, turn and wiggle with minimal force - pulling straight up did not do it. This was something that made me nervous after seeing how much those cost. Just a little wiggling and you can hear the pop from the rubber gasket.
IMHO - I did not use any compounds or lubricants - never have - the factory does not either from my understanding as I removed my NGK's and replaced them with Denso's. I am sure Toyota uses whatever brand won the bid that year between the 2. Easy job - and good for another 120K. Cheers

 

[Nottajeep]

air flow hoses on pasenger side

Can anyone tell me if the bottom of this hose connects to something? When I removed the air chamber box on the passenger side, this hose fell off and the bottom end of the hose is somewhat rotted, which tells me it never was connected to anything. I'm on break until I hear back from someone that knows what's up. Thanks!

Thingies in the way must be removed to access the plugs as necessary.

 

[Wellcraft19]

Does this help?

Ran down to the garage to check, but I have the engine cover on right now (and not eager to pull it after dinner and a few beers).

So to be honest, hard for me to tell. The image is from 2006 when I pulled everything to replace the starter contacts on a 1999 LC100.
Looks like hose passes by the power steering pump, but then...

Sorry for the long beer break, but pretty sure you do not mind an extended one...

BTW, the long hose (upper one in my picture) originates at the power steering pump, and goes to top of intake manifold. Think it has to do with the "variable" power steering (more power at low rpm = lower vacuum in the manifold).

 

[Nottajeep]

P/S Air Hose- (short curvy hose)

Thanks Wellcraft! I looked closer to your pic and found the nipple I needed.

Ran down to the garage to check, but I have the engine cover on right now (and not eager to pull it after dinner and a few beers).

So to be honest, hard for me to tell. The image is from 2006 when I pulled everything to replace the starter contacts on a 1999 LC100.
Looks like hose passes by the power steering pump, but then...

Sorry for the long beer break, but pretty sure you do not mind an extended one...

BTW, the long hose (upper one in my picture) originates at the power steering pump, and goes to top of intake manifold. Think it has to do with the "variable" power steering (more power at low rpm = lower vacuum in the manifold).

 

[SHAGGY101]

spark plug trick

Hey guys, a toyota mechanic showed me a trick to do while changing spark plugs. In order to prevent a shrouding effect caused by the spark plug and the expanding gases as the air flows from the intake to the exhaust, you should index the prong on your spark plug so that it allows a clear flow from the intake to the exhaust. I hope the pics are self explanatory but if you have any questions please feel free to ask. He said that this could increase engine performance as much as 5 hp. Whether or not you will see this much is another thing, but it does not hurt to do this anyway.

Pic 1: mark where the prog is on top of the plug on both sides
Pic 2: torque down the spark plug to the specified torque (I believe 12 ft-lbs?)
Pic 3: then turn tighten the plug until it is indexed correctly

 

[Nottajeep]

This might be possible on the front two plugs, but those back two plugs are way too much of a PITA to do this. Let me know if you notice any difference.

Hey guys, a toyota mechanic showed me a trick to do while changing spark plugs. In order to prevent a shrouding effect caused by the spark plug and the expanding gases as the air flows from the intake to the exhaust, you should index the prong on your spark plug so that it allows a clear flow from the intake to the exhaust. I hope the pics are self explanatory but if you have any questions please feel free to ask. He said that this could increase engine performance as much as 5 hp. Whether or not you will see this much is another thing, but it does not hurt to do this anyway.

Pic 1: mark where the prog is on top of the plug on both sides
Pic 2: torque down the spark plug to the specified torque (I believe 12 ft-lbs?)
Pic 3: then turn tighten the plug until it is indexed correctly

 

[SHAGGY101]

This might be possible on the front two plugs, but those back two plugs are way too much of a PITA to do this. Let me know if you notice any difference.

I was able to do this on all of the plugs. The PS was no problem. It was the last 2 on the DS that were a PITA. I used a mirror and a light to check the indexing (just like the dentist does to your teeth) and different extension sizes to snake my way in there. I did not have to use a swivel socket.

I could not tell a difference. It would take a lot more than 5 hp to feel anything here at 7582 ft!

 

[OregonLC]

Assuming there is a single optimal plug orientation, how does one know what direction the gases are actually flowing? The horizontal alignment assumes a linear flow from inlet to outlet. I think that's actually the least likely flow. There's got to be a significant swirl action going on, no? And how much extra stress does one put on the head by over-torquing the plug to get the specific alignment?

Not trying to put down the theory, it just seems like there's more downside than up.

 

[SHAGGY101]

Assuming there is a single optimal plug orientation, how does one know what direction the gases are actually flowing? The horizontal alignment assumes a linear flow from inlet to outlet. I think that's actually the least likely flow. There's got to be a significant swirl action going on, no? And how much extra stress does one put on the head by over-torquing the plug to get the specific alignment?

Not trying to put down the theory, it just seems like there's more downside than up.

It is assumed that since there is a very short time between the intake, compression, combustion, and exhaust strokes that the air can be assumed and idealized as flowing along a linear path from the intake to the exhaust port. There are a lot of assumptions going on, just kind of a cool school of thought. As far as the extra stress on the head goes, the crush seals around the plugs take most of it so that there is not much more than the factory specified amount acting on the head.

 

[OregonLC]

It is assumed that since there is a very short time between the intake, compression, combustion, and exhaust strokes that the air can be assumed and idealized as flowing along a linear path from the intake to the exhaust port. There are a lot of assumptions going on, just kind of a cool school of thought. As far as the extra stress on the head goes, the crush seals around the plugs take most of it so that there is not much more than the factory specified amount acting on the head.

Regardless of the time, the flow is anything but linear. There's a lot of mixing, compressing, burning, and expanding going on. One must assume that for power to be created a substantial percent of the volume must follow (and push!) the cylinder down.

Either way, are we even certain that flowing through the gap of the plug is better than flowing parallel to the ground electrode? Is one less drag? Does one remove more waste gases? Does one result in a cooler/hotter plug? There's just a lot of finite math going on in there that we could debate all day and never get to the bottom of!

Here's another theory where they index the gap toward the center (as well as drill the electrode!). How to drill and index your spark plugs for better performance/economy. | eHow.com

Same theory here FORDMUSCLE.com web-magazine - How To Index Spark Plugs

To me, this theory (exposing the gap to allow for a more linear flame front) has more merit than improved air flow. As you mentioned, the timing is very short so it seems that gap orientation may be essentially 'advancing' the timing a tiny bit. If nothing else, it may provide a more complete combustion event. But again, that assumes a completely homogenous air/fuel mixture (as well as a million other variables, I'm sure). Interesting debate nonetheless!

 

[SHAGGY101]

Regardless of the time, the flow is anything but linear. There's a lot of mixing, compressing, burning, and expanding going on. One must assume that for power to be created a substantial percent of the volume must follow (and push!) the cylinder down.

Either way, are we even certain that flowing through the gap of the plug is better than flowing parallel to the ground electrode? Is one less drag? Does one remove more waste gases? Does one result in a cooler/hotter plug? There's just a lot of finite math going on in there that we could debate all day and never get to the bottom of!

Here's another theory where they index the gap toward the center (as well as drill the electrode!). How to drill and index your spark plugs for better performance/economy. | eHow.com

Same theory here FORDMUSCLE.com web-magazine - How To Index Spark Plugs

To me, this theory (exposing the gap to allow for a more linear flame front) has more merit than improved air flow. As you mentioned, the timing is very short so it seems that gap orientation may be essentially 'advancing' the timing a tiny bit. If nothing else, it may provide a more complete combustion event. But again, that assumes a completely homogenous air/fuel mixture (as well as a million other variables, I'm sure). Interesting debate nonetheless!

When looking at the actual area the spark plug takes up in the cylinder, there is most likely no flow restriction (see picture). This indexing could most likely provide a more complete and uniform burn if anything. We could theorize that there could be a residual swirling effect of the air after it has entered the chamber. When the spark plug is matched up with the "swirl" (most likely in line with the intake and exhaust ports) then it would aid in that more thorough and uniform burn. This would also be determinant of the positioning of the plugs in the chamber (I am not sure of the 100's)

 

[Wellcraft19]

Jason,
A tad late to look at the forum again (Christmas time...) but glad the photo did help you.

/// Per-Ola

 

[BOLANDMARC]

Since were on spark plugs and positioning all I can think of with the indexing is the spark plug thread is a set length and to face the electrode in a certain direction does that meanthat the plug doesn't get tightened down all the way?
but now a question on my 105 is it possible to replace the original spark plug leads with aftermarket high performance leads, read maybe less expensive and more available!
mines a 2002 4.5litre six 105 series with the coil pack ( I think thats what their known as)

 

[moooooooo]

why not just get something like these?
Bosch Automotive Aftermarket - Spark plugs - Bosch Super 4

then you dont have to worry about indexing them.

 

[LXstatic]

Anyone have experience with these plugs? - E3.56 Spark Plugs | E3 Spark Plugs

 

[04UZJ100]

Anyone have experience with these plugs? - E3.56 Spark Plugs | E3 Spark Plugs

Yes. Everyone who tries a plug othet than OEM always has issues. Stick with OEM. What more do you want from a premium stock component that has a minimum design life of 120k?

 

[LXstatic]

Yes. Everyone who tries a plug othet than OEM always has issues. Stick with OEM. What more do you want from a premium stock component that has a minimum design life of 120k?

I was just curious as to whether their claims of increased MPG were worth the change of plug from OEM, that's all. Seems gimmicky...

 

[ptrsn]

#7 wasnt that bad