So its been a while since Ive posted on here b/c all the work Ive done to my 4runner has lasted so long without issue until now. I noticed a big loss in power a few mths ago and I chased a ghost for mths trying to find the problem and the causing item finally Failed today.
So I wanted to share my experience to help any others. I build British cars for a living so I know a bit or two about cars, I also put a lot of miles on my 3.0 auto 4x4 4runner so I know how well it runs and drives. Ive also managed to get 19 mpg with it once; but I avg 17 on hwy before this. and the truck is pure Stock, I try to buy Denso and other factory parts when I can. so heres what happened.

Noticed a big lack in power during a big rain storm in ATL after the new year and change in mpg. I first thought it was just b/c of the horrible rain and traffic in northern ATL but then it continued for the next few weeks.
I then began to hear a very slight tickle sound behind my dash; I thought it was just my tach or speedo cables at first... but then I guess I dont have those. or a heat shield rattle. it was very slight sound and only during accel under load. It then begin and have a slight shutter but only in top gear overdrive; it seemed to be fine as it downshifted from OD. and it seem to be worse in the same pedal location under load... so my first part that I ordered was a new Denso TPS. That seemed to help for the first few drives then it was still the same problem. Then as the shutter and sound behind my dash seem to get worse I started to think my auto trans or torque converter or fluid. So next I did a FULL ATF and filter change; which was a learning experience... b/c it takes 10 Qts!!! holly crap. Still no change. the fluid did look really bad and I should have changed it more often considering I tow a duel axle trailer and cars with it for work... so maybe I just killed my OD or the whole trans.
So... After some searches on here I found that the flex plate can fail. oh fun! that would have really sucked to replace but was kind of glad that it could be that simple and it would give me a chance to pull everything and chase a few oil leaks while I had everything out.
After pulling the bottom cover plate... NO CRACKS in the flex-plate. hmm... so maybe my trans is toast. just for the hell of it Ill go ahead and replace my cap, rotor and plugs... and double check my timing.
well that didnt make any difference either. BUT while I was playing with my timing I noticed my cheap timing light was jumping around a bit more than I thought it should. so I borrowed a friends; which did about the same. I also notice that when I was adjusting the dist I noticed that the rotor had some play in it; which for me is not an issue... b/c my british cars have a spring loaded advance so the rotor will have a bit of movement and spring to it. I should have known better with a 'modern' car.
In the mean time I started to look for another cheap little car for my trips to and from ATL... another Del Sol or a Intragra..... you know something cheap but fun (My real fun car; my '64 Triumph Spitfire I just started a full restore on it so it wasnt ready yet) but I ended up finding and buying a wrecked '01 Tundra acesscab for Cheap! So thats almost fixed ready to replace my 4runner (Im waiting on Summit to get my back ordered parts!!!)

Anyway... Today I got in my 4runner for a trip to town when I heard a really strange knocking sound behind the dash. I popped the hood... I touched and could hear and Feel the knocking under my dist cap. so now Im thinking the new rotor or cap is broken.
I just wiggle the cap a bit and the truck Dies... open cap and check new rotor and cap... all fine. But the rotor moves All over the place. So pulled the distributor and found this!!!!
Just wanted others who might be chasing something like me to just take a quick look at their dist gear.
Has anyone seen this before??? My best guess is that when I bought the truck I was very stupid and bought NEW complete heads from a place in FL called Clear Water Cylinder Heads... Big mistake! I had to rebuild both heads twice before I ended with just replacing everything in the heads. all new valves; seats; guides and Cams. Im guessing now that the cheap soft cams might have damaged the old stock dist gear and then the new harder good cams just wore them out due to the play from before.

Your thoughts? how common is this? I just ordered a used factory dist on ebay so hope to get it back together and running again next week... now my issue is were all that metal went I hope my filter catches it!
Thanks!

 

This is a common problem in the hot rod world when billet roller cams are used in old v8’s. The stock old disti gear is incompatible and can fail.

 

Never had the gear to fail, but have had the entire shaft get play which will cause problems. Every time I do a tune up like new cap and rotor I always check the distributor shaft for play.

 

Yeah, I dont recall what the gear looked like btw when I had the cheap cams vs the new good cams.
If I had kept the old cams I would have a look at that gear to see if they had any wear. this is a main reason why I dont want to buy a new aftermarket dist... as I want the factory dist gear alloy.
If the next one fails again then I know why.

 

As someone else mentioned reminds me of my old mustang days when people would change from a regular hydraulic cam to a roller cam and not change the distributor gear. Definitely think non OEM camshafts can have problems. My experience with a set was less than optimal. 2 lobes worn severely and 1 lobe totally gone.