C4 Sparkplugs Revisited - Again

[milehigreg]

Changed the plugs on my 89 coupe this weekend, Stock L-98. I have read the previous thread on this subject but none of the numbers match up so here goes. The previous thread says owners manual calls out FR3CLS, but the plugs I removed were R45TS. The plugs I got from ZIP are FR5LS. The old plugs were actually rusting on the steel parts. I don't think I have ever seen rusted plugs on an operating vehicle before. Also the new plugs will place the tip at least 3/8" further into the combustion chamber and yes, there are not tapered but have the washers. Finally, the plugs that came out were in pretty good shape. None were obviously fouled. Gaps were right at .035. The odd numbered cylinders were perfect, nice gray color. The even numbered cylinders seemed a bit oily. Is this typical from one side to the other? Shine the light of the CAC on this please!!

 

[G Winter]

If your engine has the aluminum heads , which I think it does , the R45TS are the wrong plugs. If it has iron heads they would be right. The aluminum heads require a much longer reach. If you have the aluminum heads I would advise getting a thread chaser and cleaning the threads befor you try insalling the new plugs. When I purchased my 90 which has the alum.heads they also had the wrong plugs in it. :eyerole

 

[Vettefan87]

My brother changed the plugs in his 1973 TA and a month later they were already rusting. I dont know what kind of damage that would do to the threads, and yes you do have aluminum heads unless someone changed them, but I doubt that happened.

 

[ProEMTPFF]

His is a '89 so he has the aluminum heads.

 

[vetteboy86]

The only thing that was rusted was the actual iron nut part on the plug. It was just from some condensation on the part. Around these parts that is not uncommon.

Craig

 

[Vettefan87]

Yeah that is what I figured since he said the steel parts of the plug, the only steel part is the nut right?

 

[Edmond]

Did you guys put some anti seize before you put the plug in? I think we're in the same weather and haven't had any problems.

 

[Vettefan87]

I can't remember if the shop that put my motor back in did that or not, since when they put it in I bought all new spark plugs and wires for the third time ad .

 

[milehigreg]

I spoke to our friends at Zip and they confirmed that the R45TS were for 85 and 86 which were iron head L98s. I did not chase out the threads. # 2 was the only one that was a little tight coming out and going back in. Yes, I did use anti seize. I have only fooled around with cars in Arizona and Colorado. My car spent most of its life in Illinois so if you Hoosiers have seen rusted nuts it must not be too uncommon. Anybody have a take on the plugs being a little oily on only the passenger side?

 

[Edmond]

Anybody have a take on the plugs being a little oily on only the passenger side?

Could it be the piston rings letting some oil slip in there? Is the exhaust coming out dark?

 

[Vettefan87]

Were the electrodes oily or the threads on the plugs??

 

[milehigreg]

I like the way you guys are thinking. I have only had the car about a month so I don't know if it consumes oil. The mufflers and tips were installed new by the dealer and are discoloerd yet. It doesn't smoke. There did seem to be more oil on the threads than the electrodes. Where are you headed with that thought? Oil coming from outside in? I checked the Corvette specs book which calls out the FR3CLS as the correct plug. The wrong plug was installed. Wonder what else.....

 

[Vettefan87]

Maybe since that side is a PITA to change the previous owner put a little oil on the threads to make it easier to get out? But other then that the valve seals are notorious for wearing out and the motor will puff so to say for the first few seconds of start up, that is all I can think of.

 

[*89x2*]

Changed the plugs on my 89 coupe this weekend, Stock L-98. I have read the previous thread on this subject but none of the numbers match up so here goes.

I still have my original 1989 Corvette spark plugs that I pulled and placed in boxes out in the garage - If it were not so dang cold, I'd go look :ugh

 

[Edmond]

Maybe since that side is a PITA to change the previous owner put a little oil on the threads to make it easier to get out? But other then that the valve seals are notorious for wearing out and the motor will puff so to say for the first few seconds of start up, that is all I can think of.

And not to mention the age of the car!

It's a 16 year old car, the age is going to start catching up to it. But I don't understand why it would only be on one side. I don't think that oil could leak on the threads from the outside, it is sealed very well.

As for the owner using oil to lube it, that could be. Stranger things have happened!:L

 

[G Winter]

Where does the pvc hose go to on these cars. Maybe that could feed one side if it was bad .
BTW I did use antiseize , The local shop says they never bother with it on aluminum heads and no trouble... wonder if they ever have to replace plugs in those cars again :eyerole

 

[AdvancedAutoCC]

Where does the pvc hose go to on these cars. Maybe that could feed one side if it was bad .
BTW I did use antiseize , The local shop says they never bother with it on aluminum heads and no trouble... wonder if they ever have to replace plugs in those cars again :eyerole

RUN, do not walk away from this shop! ANYBODY who doesn't use antiseize on aluminum head plug changes is begging for trouble, or is little more than a backyard hack.

On a side note.... I started my plug/wire change on my shop Vette last night, and whoever did the last "tuneup", replaced the wires with Taylor cheapies that were (and I kid you not), so long the excess was wrapped around the master cylinder on one side and the blower fan on the other. :L This, and the distributor was clocked wrong (obvious by this point the motor's been out). BUT...when I pulled the plugs, they were brand new NGK Iridium plugs, installed with antiseize...go figure. :confused

 

[oldvet]

I like the way you guys are thinking. I have only had the car about a month so I don't know if it consumes oil. The mufflers and tips were installed new by the dealer and are discoloerd yet. It doesn't smoke. There did seem to be more oil on the threads than the electrodes. Where are you headed with that thought? Oil coming from outside in? I checked the Corvette specs book which calls out the FR3CLS as the correct plug. The wrong plug was installed. Wonder what else.....

My owners manual say ACtype FR5LS with .035 gap, for 89/L98 with Alu Heads