I recently was rear ended in my (troublesome) '04 V6 SR5, and picked up a '07 V8 Sport. Unfortunately, there was nooooooo maintenance record included, and the CarFax was a little spotty (mileage indicated was much lower than what the seller was actually informing me). Well, as 4Runners in my price-range were being scooped up left, right and center, I still decided to purchase the vehicle. The owner was mechanically inclined and did his own fluid changes, which seemed fine, and he was forthcoming about it all.

The only issues he brought up as fault for the car was the usual V8 exhaust leak, and how it's a little smokey (white) when it starts for a while.

The mileage per tank is a little worse, 40~60km, but I'm ok with that.

I am still doing my readings up on V8 issues here and there as things pop up, and I am still a little weary about some coolant leakage as my V6 had the headgasket issue and that put a big dent in my wallet. Perhaps some of these things are normal for a V8!

The issues I'm trying to figure out:

- gurgling behind the HVAC controls/glove compartment
- exhaust smelling like gas
- long lasting white smoke from exhaust when starting, up to around 10min
- clunking suspension on passenger side (Eibach Truck lift stage 1)

I vowed to do simple maintenance on my new (to me 4Runner) after the accident, and so I decided to clean the MAF, Throttle body, and check up on the spark plugs to see whether I could get a little better MPG or tackle the gassy smell.

The spark plugs all looked normal except for Cylinder #7 and #8, as pictured. Any ideas as to what could be the cause of these?

I went ahead and cleaned them with a brass brush, and ordered some NGK 4589 and will be replacing them next weekend.

I also burped the radiator a 2nd time, this time by elevating the front-end as the first time did not remedy the gurgling but also did not show any bubbles coming through the radiator kit. No bubbles came through the 2nd time, and I can still hear the gurgling while driving around. Yes, I've read up on heater core stuffs, but the heater works 100%, perhaps a little too strong. The AC is shot though, blinking light (Happened to my V6 and replaced the compressor to fix it), so unsure of the refrigerant levels, so that could potentially fix the gurgling as well ?

Any input would be great!

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The plug insulator looks a little white but not too bad but that does sometimes indicates water in the combustion chamber which could explain the "white smoke", also the rust/corrosion on the body of the plug would concern me as to how water would get in there to corrode it, maybe the previous owner used a pressure washer to clean the engine and forced water in pass the coils.

Do the rest of the plugs have the same rust or just those 2, is the rust what you're referring to as "fouled"?

The 2 plugs shown were the only dirty ones, all others had no grime or rust on them.

We'll see whether the dirty spark plugs return after I swap them out and drive a bit.

I did take the car for a wash once I returned from purchasing it, and I do spray the underside. The previous owner was a surveyer, so he probably drove on forestry roads and such, so there was lots of dirt clumped on the underside. Even then, I live on the rustbelt, so the roads are salted during the winter, hence the good spray underneath. I couldn't see any water getting up to the sparkplug boots from my actions though.

You didn't answer if the rust is what you're calling "fouled"?

This sounds like a blown head gasket to me, especially if those plugs have a white residue on them. How about the oil filler cap? Is there a white/milkshake residue there?

If it has a blown head gasket/s for the 2 plugs shown it would be both heads which is very rare, that is if the 2 plugs shown indeed came out of #7 & #8 cylinders, which are on opposite banks of the V8.

What would you attribute the white smoke to? 10 minutes of white smoke is quite a lot and I agree that blowing both gaskets is rare but something serious has impacted both of those plugs and only those plugs; strange.

Can't say without him doing some further troubleshooting, at this point I would check #7 & #8 cylinders with a bore scope after sitting overnight to see if any coolant is sitting on top of the pistons, also checking the coolant for the presence of exhaust gas.

I can't really judge the comparative condition of the 2 plugs he has shown without seeing all the other plugs!

He also says they're "fouled", I don't see where those 2 plugs are fouled at all, all I see is the rust on the upper part of the plugs which won't affect them firing properly, looking at them they appear to have been firing just fine.

Apologies if 'fouled' was the wrong term to use here, but yes, that's what I meant on the dirty plugs.

Engine runs fine, no hesitations, nice and smooth, no coolant depletions, and gas mileage only slightly less per tank than my former V6 (approx. 420~460km @ 1/4 tank). The V8 getting around 400km by the 1/4 tank mark.

Oil fill cap does not have any froth, and an coolant tester is next on the docket.

Gah, I'm getting anxious at the thought of another head gasket job.

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I agree on replacing the plugs. You didn't get a maintenance doc from the previous owner and those look old, even if they aren't. I don't know why #7 & #8 are rusted like that unless there was a hose leak spraying water on them. (I had that happen on an Olds, where the hose for the heater core sprang a leak and was spraying my distributor, causing it to run extremely rough.)

The white smoke for 10 minutes would be a worry for me, but if there's no residue in the tailpipe then maybe it's just condensation burning off. Replacing the spark plugs and checking them again, say 500 miles, might tell you more.

The gurgle behind the dash I would think is air in the heater core line. I've had a couple of cars do that after changing the antifreeze. I got nothing on the suspension noise. For the exhaust smelling like gas I think you're going to have to take it to a Toyota certified mechanic and let them put the car on an analyzer and see what's up. A half hour's shop fee can go a long way to finding problems.

for the exhaust smelling like gas I had this issue but my mileage went to crap. If I remember correctly Was getting around 350 miles per tank to 150 miles per tank. Ran multiple test and my mechanic at Toyota did test and I had multiple exhaust leaks from manifolds all the way back. But the issue was my front 02 sensors were sensing the air coming in through the manifolds and compensating with more gas.

I had the same smoke after start up and after going 3/4 petal down.

My car is currently down as I’m waiting on Doug thorñey to release more long tube headers in December.

Good to know!

I wonder whether applying some high-temp exhaust leak sealant around the afflicted areas of the manifold would do any good? Even if it is temporary, at least it'd prevent the leak for some time until the sealant has to be applied again.

Funny enough, my mileage this week has been on-par with what got regularly in my V6 (300km/186mi at the half tank mark) after cleaning the plugs, the throttle body, and removing the carbon filter from the airbox.

Just curious, did you disconnect the battery when you pulled the plugs, some do and some don't?

Late to the show, my apologies. I did not see if OP pulled codes or has access to a scanner to view live data such as misfire counts, fuel trim, O2 sensors and the like. In the meantime, corrosion in the plug well means there is likely corrosion in the ignition coil. Moisture will get trapped inside the boot and eat away at the spring and contact surface. You could get lucky and be able to clean them but a safer bet is to replace. On a side note, 4.7 coils tend to form cracks in the plastic housing which could lead to water ingress. Inspect coil housing for cracks. The other question is how water got into 7 and 8. Maybe it was one time event or maybe an ongoing issue? Inspect hood and cowl rubber seals.