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Discussion Starter · #1 · (Edited)
Just wanted to share with the group my experience swapping out the spark plugs. The new plugs (Volvo OEM 30751806) have made a noticeable difference. The engine most definitely runs better and throttle response has improved. I wasn't having any issues and didn't think it would make such a difference, but after 60k miles and almost 5 years the factory plugs did not look so great. So, I highly recommend this DIY job - easy if you've got tools and some patience (you'll need a Torx T27 driver).

See my write up at http://forums.swedespeed.com/showthread.php?116695-T5-Spark-Plug-Change-Write-Up&p=2988801&viewfull=1#post2988801

Here's a pic of my old plugs after 60k miles - yes, they say FoMoCo...

 

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timely post! i definitely want to take this on over the holidays.
i'm at 60k and 7 years on the oem plugs. no issues either but it's good maintenance
 

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I changed mine out this summer and was shocked at how bad the plugs with 60k miles looked. New plugs made a HUGE difference.
 

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what difference did you notice? smoother idle? smoother acceleration? throttle response? car smelled better? ;-)

I changed mine out this summer and was shocked at how bad the plugs with 60k miles looked. New plugs made a HUGE difference.
 

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what difference did you notice? smoother idle? smoother acceleration? throttle response? car smelled better? ;-)
Throttle response was improved dramatically. Between the new plugs an flushing the brake fluid, it is like a new car!
 

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Those don't look as bad as I would have expected. I replace mine every other year before winter, but I have "people" :p .
I guess I could 'borrow' some people...2 years and 36k miles...might be worth it...or not.
 

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Discussion Starter · #8 ·
what difference did you notice? smoother idle? smoother acceleration? throttle response? car smelled better? ;-)
Just got back from a 100-mile drive. Definitively improved throttle response. Not that is was bad before, but a noticeable improvement. Mine had 60k miles and almost 5 years, so going forward I will replace them more often (despite the stated 75k mile interval)
 

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great, thanks! there are days i day dream about a new car, but most days i truly enjoy the c70 and can see myself keeping it for another 50-60k miles. nice to hear little maintenance things like spark plugs can make the car drive even better than it already is

Throttle response was improved dramatically. Between the new plugs an flushing the brake fluid, it is like a new car!
 

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If you do a search, you will find many different opinions regarding brands of plugs but most people say go with Volvo plugs and I have to agree. Some Volvo engines seem to be less fussy than others, but the turbo engines seem to be happiest with factory plugs. I had a 1998 V70 T5M and it only liked Volvo plugs and now I have a 2001 V70 T5M and it is very happy with Volvo plugs too. They are pretty reasonably priced through FCP, Tasca or Lisle so for me it's a pretty easy call. Make sure you check the gap and use a torque wrench. A little dielectric grease on the porcelain helps make the next change easier too.
 

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just did mine today. about 2 hours.

removing the turbo pipe (held on by 2 bolts including a difficult to reach lower passenger side bolt) and strut tower bar, and of course all those t27 bolts on the engine cover (and the reverse steps to finish) took the most time. the actual coil pack and spark plugs removal/install was relatively quick.

tough on my back leaning over the engine though... can see how wrenching for a living can be tough.

like regtor, i had fomoco plugs come out and put oem volvo in.



did a quick drive just to make sure no CEL issues and fill up the tank and the C70 drives fine.

at least for me, there was no dramatic throttle or improvement of any kind... but i will sleep happy with the satisfaction of doing my 1st spark plug change successfully ;-)
 

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My first car was a 1960 Studebaker Lark VIII...nothing but engine under the hood. My first task on this 10 year-old car was to change the plugs and wires(had 33,000 miles in TEN years ). I don't think I even needed to move anything to access the plugs and wires...wide open spaces. Don't think the C70 will be that easy for this old dude. Might ask the dealer to do it @ 40k mile service. I got new front brakes under S&S just last week...I feel I'm a little ahead of the game at this point.
 

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i take it back. after driving it more, i have noticed an increase in smoothness and quicker throttle response when making sudden accelerations to pass. almost rev happy. really makes the car more responsive and leading me to drive more aggressive! ;-)


at least for me, there was no dramatic throttle or improvement of any kind... but i will sleep happy with the satisfaction of doing my 1st spark plug change successfully ;-)
 

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i take it back. after driving it more, i have noticed an increase in smoothness and quicker throttle response when making sudden accelerations to pass. almost rev happy. really makes the car more responsive and leading me to drive more aggressive! ;-)
Our 160hp FIAT 500L makes the C70 feel like it's super-tuned, Polestarred AND has new plugs!!! Still will likely make the change at the 40K mile service in the spring(Dang! Where IS that coupon for service? ) :)
 

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I just replaced mine as well, 8 years, 75K miles.... There were the original Volvo plugs and I replaced them with genuine Volvo Parts.
Honestly the old ones looked pretty good and I didn't notice any difference with the new plugs... but it is good maintenance!
 

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give it a few days and especially pay attention when driving more aggressively. i found it seems to respond better and better

I just replaced mine as well, 8 years, 75K miles.... There were the original Volvo plugs and I replaced them with genuine Volvo Parts.
Honestly the old ones looked pretty good and I didn't notice any difference with the new plugs... but it is good maintenance!
 

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Discussion Starter · #19 ·
Once again, but with a surprise!

I picked up a set of OEM plugs at a great price and decided to put them in. Even though it's only been 25k miles and 2.5 years since I last did them (see my first post above), I figured why not.

It is a bit of a pain to remove the air intake pipe over the engine, but once the clamps are loose and you remove the bolt hoding the rear bracket you can pivot it out of the way to then remove the (silly) plastic cover over the top of the block.



The top of the block was quite dirty so I start vacuuming, and I notice all of the mouse crap... uh-oh

The damn rodents are eating the wiring harness!! They've eaten through the corrugated plastic conduit and started on the wires!!!



This was the worst section, two inches of plastic conduit gone and the wires chewed. This section is on the far right of the block, by the battery, but there was chew damage and eaten conduit in several other spots.

After a lot of careful taping with electrical tape I swapped out the plugs. They looked pretty good, some carbon deposits but generally not as bad as the ones I took out after 58k miles.

New vs. old:



All five old plugs:



Car started right up and no issues, but will have to keep an eye on that harness (maybe I'll price out a new one). In the meantime my battle against rodents continues. Decades ago I put mothballs in my old Skylark when I stored it over the winter and it took a long time to get rid of that smell, but it did seem to work. I've also used Irish Spring bar soap but don't want to put that (or anything else) on top of the engine. So, I'll focus on traps for now...
 

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reg, thanks for the update! I'm putting on new rubber next week(Memorial Day sales!!!) and the 60k mile service will be during the next few weeks(Message is screaming that maintenance is overdue; but I'm only at 58.5k miles after exactly one year since service). Even though new plugs aren't called for until the NEXT service, I think I'll bite the bullet and have the dealer include that swap during the upcoming check-up(unless it's a TON of $$$).
This is the longest(4.5 years) and highest mileage(58.5k miles) of any of our four C70 experiences. Uncharted territory, as they say ;)
BTW, I think our feral cat(s) keep the rodents at bay...alligators, too(haven't seen one of those since we moved in!)
 
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