Guys,

I got a 1999 4Runner that I've had since new. It now has 90,000 miles, and it still runs like a dream -- silky smooth operation at all speeds. I've always had the fluids changed (oil, transmission fluid, coolant, etc.) regularly at frequent intervals.

But, I never had the spark plugs replaced. How critical do you feel that spark plugs need to be replaced at this point it time, given that my 4Runner is running perfectly silently and smoothly at all speeds and still getting good fuel efficiency?

The reason I ask is because in the previous cars that I have owned, those cars have run rough as ˟˟˟˟˟ after a tune up!

How about the need to replace PCV valve, 02 sensors, and fuel filter?

 

If it's running fine, let it be. Unless it starts skipping, I wouldn't mess with the plugs. I changed the plugs in mine, and did a little tune-up, and now it runs really rough. It wants to skip and it just doesn't sound good at all. Chances are the plugs are gonna give ya trouble, since they've been in there so long. If it runs good, then just leave it like it is....just my .02

 

What do you mean when you say "the plugs are gonna give ya trouble"?

Do you mean that they are going to be hard to unplug?

 

um, thats regular maintenance, changing plugs, pcv valve, air filter, etc. they are components that have a short life span and will wear out quickly. its recommended to change the spark plugs at ever 30k. u will enjoy improved fuel efficiency and engine operation and definitely an increase in reliability and longevity of the engine.

 

You can do it yourself for less than $30. I say, why not replace them? I'm assuming you have the 3.4; spark plugs are part of the standard 90k service.

The timing belt should also be replaced at 90k on the 3.4. If it breaks while you're driving, it won't damage your truck, but it will leave you stranded!

 

Do you guys not think that it will run rougher when one changes the spark plugs?

I've had that experience in my past cars. Also, 93ToyKid in the above post indicates the same problem.

 

Why would it run rough if you get new OEM plugs and ensure they are gapped correctly? That sounds like an urban legend to me.

 

dont know nothin about a tune up but in the taco i have when i got a tune-up at the stealership they charged 65.00 just to change the plugs....does that constitute a tune-up? on the 4runner i'm driving now i changed the plugs myself and it only cost about 20.00 for the cost of the plugs......and the stealership wanted to charge extra for what they called injector cleaner......can't i just add that stuff into the fuel every second fill-up??? so far it (my 4runner) runs great........

 

another added bonus of changing the spark plugs is lower strain on your ignition system, which would now require less of a jolt to jump that huge spark plug gap that has developed over 90k miles of wear.
If you've had ill effects after a tune-up in the past, I hate to say it, but I question the methods or materialls. Tune-ups are "good" things. They renew wear items back to stock specs.

 

Use OEM plugs and gap them correctly and it shouldn't be a problem. I think part of the running rougher may due to having the plugs gapped incorrectly. Another reason may be that the plug wires get damaged when removing them from the original sparkplugs.

If I had 90,000 miles on the original plugs, I would probably change them.

When I bought my truck, it had 110,000 miles on it and I think the plugs were the original ones. I have since changed them and I didn't experience any ill effects. I couldn't tell that it ran any better either, but its good knowing that I have new plugs and how many miles are actually on them.

 

Good deal?

My bud from a dealership can do the following for 175.00

oil change/filter
pcv
rear/front differ. fluid change
new coolant
plugs/wires
lube all that needs lubed
transmission fluid change
fuel filter change

and.. I think thats it. My runner has 56K miles on it right now.

 

Actually from a dealer thats a pretty good number...

Although you could save money buy doing everything yourself. If its a transmission flush they usually run 100+ anyway.

I would have figured a dealer would charge 300+ for that stuff.

 

If that includes the parts/oil, then yeah, that's a good deal. Especially at a dealer. If you bought all the stuff yourself and did it, it will be easily over $120.00 or more by my guess.

I like doing things myself, because I know they were done and done right, but that's not bad at all.

 

I just did a coolant flush myself and it is rather time consuming. To do it right, you will need the following:

Prestone dex-cool $9.43
Prestone Super Flush $2.50
Distilled water (x2) $1.16
5-gal drinking water container (for used coolant) $5.60
TOTAL: $20 or so

Just follow the directions on the Super Flush container.

In addition, I changed out the upper and lower radiator hoses ($33.00 at the dealer), added Redline Water Wetter ($11), and replaced the thermostat with a 170* from NAPA ($10). With the Water Wetter, you can run a greater ratio of water to coolant and not harm anything, all while reducing temps. Water Wetter has other benefits like eliminating hot spots and reducing the chances of detonation...of course I am installing the supercharger, so your needs might be different.

All the other stuff is cake, but time consuming. Wallmart seems to have the best prices on supplies.

 

Well, I should have clarified....my friend who works at a dealer will be able to slide me in to get this done....

 

Be proactive, not reactive...always cheaper in the long run.

It is called maintenance for a reason. Do it.

 

although I prefer doing things myself I do like the dealers A/T and coolant flushes. Since they have machines that push the old crap out as its replacing the new stuff.

How does that prestone flush work? Put it in and let it circulate then drain it? Whats the procedure?

I changed my coolant in a 92 ford ranger but putting in water running it, draining it, more water, drain, more water, drain, more water drain...until it finally came out clear again. Then added the new stuff, now that was a pita.

 

You add the bottle of Prestone Flush, fill with hose water, turn the heater on high, start the vehicle, let it run for 10 minutes after full operating temp, let it cool, then drain. The next step is to just fill with water, and do the 10 minute thing again.

After that you are good to go for coolant/distilled water (and water wetter if you wish).

Hope that helps.

 

Drain. Fill w/ water. Take loose the top radiator hose from the radiator and secure it with zip ties down towards the ground. Hot water will come out of this, so don't be near it! Put the hose in the top of the radiator and leave it on. Crank the engine, run it until it gets hot and then the radiator and engine will get flushed w/ water, cleaning it out w/o all that fill and drain crap. Connect back up the hose, fill it up w/ coolant, check the levels hot and you are done. Did mine in like an hour start to finish.

 

This only happens on junky first gens!