26 Year Old Spark Plugs

[Polly_3SFE]

I pulled the original spark plugs out of my 1991 Camry 2.0L (3S-FE). They have just over 61K on them. Here's a few pictures of their condition. Looking at NGK's guide to analyzing spark plugs, they don't look bad. I replaced them with new OEM Denso Q16R-U11. At ~$5 for the set, I don't mind replacing every 30K. How do they look to the more experienced eye?

 

[barryh]

In terms of wear they look amazingly good for 61K and fit for further service.

 

[demarpaint]

It looks like they could have easily gone 100K miles.

 

[blupupher]

A '91 with 61,000 miles? That is less than 3,000 miles/year!

Those plugs look fine and could probably have gone another 30,000 miles.

 

[SirTanon]

Considering the mileage, they look great. I'd say that they're still good enough to run, at least from a visual standpoint.

Seems like your engine is pretty easy on plugs.

About 9 months ago, I changed out the plugs in my 2010 Fusion when it hit 215,000 miles. To my shock, the plugs were the factory originals, which meant they also had 215,000 miles on them. So it doesn't surprise me that your plugs look that good @ 61k.

 

[Polly_3SFE]

Yeah, this was my great-grandmother's car. She didn't drive it much. When she passed away 9 years ago, my grandma took over the car and continued garage keeping it. She sold it to me after the new year. I'll be driving the heck out of it.

These last two days I also changed the differential oil, transmission oil (and pan gasket), power steering (just what was on the reservoir), and the coolant. I wanted to give it all new fluids after taking it over. I used Castrol Transmax dex/merc for all three above and Prestone for the new coolant.

 

[nthach]

Those aren't original - those are the newer Denso plugs, originals for that era have the old ND logo and maybe an A on the terminal end, I know this because I yanked the plugs out of my car in 2004 and they were the original Nippondenso PK20R-11 from 1990, Toyota indexed them and they had the ND logo. I think your grandma had the local Toyota dealer do a 30K maintenance on the car at some point. Nippondenso became known simply as Denso in 1997-1998.

Prestone is a no-no for Toyotas in my book, FWIW I have a Lexus of that era that's seen nothing but Toyota red(and pink for top-offs) and the cooling system passages were in pristine shape. Good call on changing the fluids, Camrys of that era and the next 2 after that were well-built cars, not as exciting as their Honda counterparts to drive but it was basically a few steps below the Lexii of that day in fit, finish and built.

 

[69GTX]

Those plugs are probably performing very similar to when they were new. The only issue might have been that the longer they sit in an engine, the harder they might be to pull out without causing other damage in the process, especially those plugs with only 4-5 threads being engaged.

 

[y_p_w]

Originally Posted By: nthach
Those aren't original - those are the newer Denso plugs, originals for that era have the old ND logo and maybe an A on the terminal end, I know this because I yanked the plugs out of my car in 2004 and they were the original Nippondenso PK20R-11 from 1990, Toyota indexed them and they had the ND logo. I think your grandma had the local Toyota dealer do a 30K maintenance on the car at some point. Nippondenso became known simply as Denso in 1997-1998.

Prestone is a no-no for Toyotas in my book, FWIW I have a Lexus of that era that's seen nothing but Toyota red(and pink for top-offs) and the cooling system passages were in pristine shape. Good call on changing the fluids, Camrys of that era and the next 2 after that were well-built cars, not as exciting as their Honda counterparts to drive but it was basically a few steps below the Lexii of that day in fit, finish and built.

Correct. Those are definitely not original plugs from a 1991 model year car. Someone replaced them. My '95 Integra GS-R came with factory plugs that had the ND label on the ceramic and metal base. By maybe '98 I'd bought some Denso plugs that still had the ND logo on the basc, but Denso on the ceramic.

 

[i_hate_autofraud]

They look pretty good!

As a rule on any plug I install, I gap them .001" tighter then spec, as they age,
the gap burns to nominal and later a little over spec, but the plugs don't miss fire unless
you ignore them for years. I drive 15,000 to 20,000 miles a year, I don't want to
pull them out too often.

Old fashioned Champion spark plugs, etc, I may gap .002" tighter if I know
the engine is hard on them.

I use machine shop feeler gauges with .001" increments, requires
some feel for it.

On long life Iridium plugs with 120,000 miles, I could see under the
microscope the Iridium pad on the ground electrode had finally burned off,
gap was .0015" over spec, but still ran good.

At that point, if left in, the ground would burn back faster in late model
engines with lean fuel mixtures and eventually set a code and shorten the
life of all 3 Cat converters on the car! Not worth it!

I also use a dab of anti-seize paste rubbed into the threads, not engine oil,
or the plugs will be hard to get out 5 yrs later and about 10 Ft/Lb torque,
max to install.

 

[ARCOgraphite]

The factory likely would have coloured ink dot on terminal. Would be Nippon Denso. Likely not "hot U" design, NO?
a 16 heat range is HOT HOT HOT. Maybe try a 20. I know denso 16 are sort of in between a 5 and a 6 NGK, IMO.

 

[Polly_3SFE]

Wow, good call. I guess I have mispoken on their age! Was Toyota red coolant around when this car came out? The Toyota service book just calls for a reputable ethylene glycol coolant, which is why I went with Prestone. I would have gone with the red if I knew it was OK for this vehicle.

 

[Polly_3SFE]

The only reason I went with the Denso Q16R-U11 is because that is what the official 1991 Toyota Camry service manual calls for. Maybe I'll try different ones at the next interval though.

 

[y_p_w]

Originally Posted By: Polly_3SFE
The only reason I went with the Denso Q16R-U11 is because that is what the official 1991 Toyota Camry service manual calls for. Maybe I'll try different ones at the next interval though.

Says ND right there in the manual. Can't seem to find an image of the actual plugs without more research, but the box looks like this:

 

[y_p_w]

Originally Posted By: ARCOgraphite
The factory likely would have coloured ink dot on terminal. Would be Nippon Denso. Likely not "hot U" design, NO?
a 16 heat range is HOT HOT HOT. Maybe try a 20. I know denso 16 are sort of in between a 5 and a 6 NGK, IMO.

By that time, standard plugs from ND all had the U-Groove ground electrode. NGK sold plugs with both their V-Power center electrode or standard center electrode. Lots of service manuals listed both NGK versions along with various heat ranges.

I also remember when Accel was selling relabeled ND plugs. It even said U-Groove on the box. It was primarily for domestic applications where the manufacturer rarely specified Japanese plugs. Even when they started using Denso or NGK plugs, the Big 3 would usually specify a relabeled plug with their own brand like AC or Motorcraft.

 

[nthach]

Originally Posted By: Polly_3SFE
Wow, good call. I guess I have mispoken on their age! Was Toyota red coolant around when this car came out? The Toyota service book just calls for a reputable ethylene glycol coolant, which is why I went with Prestone. I would have gone with the red if I knew it was OK for this vehicle.

It was - Toyota really didn't push for it until the mid 1990s officially, but I do have memories as a kid when my dad took me with him to the dealer's parts counter and there was indeed a red Toyota coolant in the 1990s, the dealer had a display as well. Prestone should be OK, no sense in dumping out what's in there unless you're anticipating replacing a hose/thermostat/water pump.

Speaking of which, have you checked the timing belt for any cracks or dry rot?

 

[Polly_3SFE]

Quote:

Says ND right there in the manual. Can't seem to find an image of the actual plugs without more research, but the box looks like this:


Yes, I definitely agree they must have been changed at Toyota at some point. I'll have to ask my grandmother around when. It would have been cool to have the originals!

 

[Polly_3SFE]

Originally Posted By: nthach

Speaking of which, have you checked the timing belt for any cracks or dry rot?


Is it easy to take the cover off? I know the recommended interval is 60K, but I'm betting the belt is in OK condition given the car has seen a pretty easy life so far. I was hoping to put it off until 75K or so.

 

[y_p_w]

Originally Posted By: Polly_3SFE
Originally Posted By: nthach

Speaking of which, have you checked the timing belt for any cracks or dry rot?


Is it easy to take the cover off? I know the recommended interval is 60K, but I'm betting the belt is in OK condition given the car has seen a pretty easy life so far. I was hoping to put it off until 75K or so.


It's 26 years old. If it's on the original timing belt, you're living on borrowed time. Time, ozone, use, and heat age them. I wouldn't worry about a belt that's still in a package, but one that's been used is something different.

Given that it looks like someone has worked on the car, there's a chance the belt was already changed. Personally, I need to get the one in my wife's Civic changed.

 

[slacktide_bitog]

Those aren't the original 1991 plugs. It says Denso on them, with the modern logo. The old plugs would've had the ND logo as shown in ypw's image. Nippondenso changed their name to Denso in 1996.

Originally Posted By: ARCOgraphite
The factory likely would have coloured ink dot on terminal. Would be Nippon Denso. Likely not "hot U" design, NO?
a 16 heat range is HOT HOT HOT. Maybe try a 20. I know denso 16 are sort of in between a 5 and a 6 NGK, IMO.


If he used a 20, they'd foul. The OP's pics prove that 16 is indeed the correct heat range to use