Coil pack preventative replacement? (3 Viewers)

[shtbrwn86]

Dealer replaced coil packs on cylinders 3 and 8 (90k ago). The rest are original to the car with 262k. I know a lot of you carry a few spares just in case, but I was wondering if it makes sense to replace at least #7 and #5 preventatively since those look to be the most challenging to replace in the field. There's also an oil leak in that area that I want to try and identify.

While we are talking OCD PM, does it make sense to replace the other 6 now given the miles? Or just the difficult ones and carry a couple spares for the others?

 

[sr5pickup]

How did the ones you pulled look? I pulled some from a 01 2uz with 199k and while they were all good, no codes or misfiring they all had cracks and splits in the body, assuming from age and numerous heat cycles so I replaced them all. At that mileage you might want to pull the rest and inspect them. You could always replace a couple at a time and keep the old as spares.

 

[JunkCrzr89]

I preventatively replaced all of them at 200k miles. Most had brittle boots and cracked shafts. Kept the 1 decent one as a spare in the glove box.

 

[JunkCrzr89]

There's also an oil leak in that area that I want to try and identify.

Likely spark plug tube seals in the valve cover.

 

[shtbrwn86]

Likely spark plug tube seals in the valve cover.

The annoying part about this is the dealer replaced the valve cover gasket and spark plug seals about 50k ago. But like a lot of other stuff on this rig, they didn't seem to do a great job so I end up coming back and re-doing stuff.

 

[shtbrwn86]

How did the ones you pulled look? I pulled some from a 01 2uz with 199k and while they were all good, no codes or misfiring they all had cracks and splits in the body, assuming from age and numerous heat cycles so I replaced them all. At that mileage you might want to pull the rest and inspect them. You could always replace a couple at a time and keep the old as spares.

Haven't pulled any yet. Dealer did the work for the prior owner due to CEL. Probably best to pull and replace all of them and keep the ones that aren't cracked as spares.

 

[Bisho]

I replaced a few due to cracks at 265k ish miles, but kept them as spares. I replaced the rubber boots and seals on the rest. I do have OBD fusion to help read codes. 10k later I did have one go bad, and it was crack free. I replaced it with a spare until a new replacement arrived. I now have the four new ones on the passenger side, so odds are if one goes bad it should be easy to replace. I guess I’m not in a hurry to spent the money on the rest, as I have 3 spares.

 

[SWCruiser]

I would just replace and be done with it. It all depends how convenient or inconvenient a failed one would be. My truck is driven in the Tri-state and it's a pain in the ass if you have car trouble. I also would hate to have isssues while on vacation. My cost basis relates to how much would I be willing to pay if I had a breakdown while on vacation with the cruiser. 2-3 days downtime is worth a lot to me. A lot of guys don't like to replace until it breaks down but I do t like to gamble with my free time.

 

[JunkCrzr89]

The annoying part about this is the dealer replaced the valve cover gasket and spark plug seals about 50k ago. But like a lot of other stuff on this rig, they didn't seem to do a great job so I end up coming back and re-doing stuff.

I’d be annoyed about it, too. Lot of talk over the years recommending people buy Cruisers with impeccable dealer maintenance history, but as you and many others have experienced, dealer service is often half-ass, incomplete, or just plain $hitty. The massive number of corrections that @2001LC has had to make following dealer services over recent years is a testament to how crappy of a job a lot of today’s Toyota techs do, unfortunately.

 

[Tres Toys]

My experience with our three 100's over many years is to just carry an OBD II scanner, a spare OEM coil or two, a decent set of tools including a flashlight. Its a failure mode that is not going to leave you dead in the water and it is a pretty much a one banana job that I have schooled one of my kids in dealing with. Some of the OEM coils seem to last a very very long time. I don't recall seeing much for physical indications of failure on the ones I have replaced. But it all boils down to personal preference, driving locations/weather, the drivers comfort in dealing with issues on the fly and budget. I prefer to let money trickle out on an 'as needed' basis when the consequences are low and the cost of a full set of OEM coils is fairly high. You just have to figure what you think works best for your situation and run with it, then adjust as needed.
Best of Luck

 

[abuck99]

If you change your plugs early (@50-75k intervals,) and replace the boots and seal on the coil packs at timing belt change intervals they should last the life of the truck.

Where they fail is from heat, heat from poorly performing plugs that demand more energy from the coil to create more spark from the plug- this shortens coil life. Excessive heat within the coil will eventually cause a split along the molding seam in the body of the coil- at that point the coil is compromised. When replacing spark plugs at TB change interval, replacing the boots and seal is a good practice.

Coil Boot Kit: Denso 671-8184 ( this kit has gone up in price since I did mine but still worth doing)

 

[JunkCrzr89]

If you change your plugs early (@50-75k intervals,) and replace the boots and seal on the coil packs at timing belt change intervals they should last the life of the truck.

Where they fail is from heat, heat from poorly performing plugs that demand more energy from the coil to create more spark from the plug- this shortens coil life. Excessive heat within the coil will eventually cause a split along the molding seam in the body of the coil- at that point the coil is compromised. When replacing spark plugs at TB change interval, replacing the boots and seal is a good practice.

Coil Boot Kit: Denso 671-8184 ( this kit has gone up in price since I did mine but still worth doing)

Swimming in oil because of leaky tube seals is also a problem.

 

[SteveH]

Denso coil boot kit here: 1999 LEXUS LX470 4.7L V8 Spark Plug / Ignition Coil Boot | RockAuto - https://www.rockauto.com/en/catalog/lexus,1999,lx470,4.7l+v8,1356094,ignition,spark+plug+/+ignition+coil+boot,10150

 

[kwon-offroad]

Denso coil boot kit here: 1999 LEXUS LX470 4.7L V8 Spark Plug / Ignition Coil Boot | RockAuto - https://www.rockauto.com/en/catalog/lexus,1999,lx470,4.7l+v8,1356094,ignition,spark+plug+/+ignition+coil+boot,10150

Interesting that Rock Auto doesn't show this boot kit if searched under a later model (2006) but if you drop down through this link it does show applicable from 1998-2015. The replacement (and superseding PN) coil pack is the same across the series so is it safe to assume this will fit a 2006?