I'm not crazy... 3fe cam gear slipped 10 degrees

[Sand or Foam]

So, this is my first LC and I am sure some of you have seen my post on my 3fe lack of power. I went through all the baseline parts, replaced almost all the fuel injection parts, checked fuel pressure. Timed it and timed again. Compression and leak down test finally(I should have looked here sooner) showed leaky valves so I pulled the head, had it machined with fresh valve seats. Tons of new Toyota gaskets later, there was no change in compression. WTF!
My last hope was the cam gear. They are composite gears and I have seen them fail catastrophically, but never skip a tooth. So maybe the camshaft had been removed and reinstalled off a tooth?? I pulled the timing cover to find the marks perfectly lined up, crap. At that point, I figured what hell, I should look at the cam shaft before I yank this POS out and sell it for scrap metal. The video shows it below(sorry for the poor lighting) but the cam gear is able to rotate about 10-15 degrees on the end of the cam shaft. So my valve timing is super late causing my low compression and the reason why my valves were burnt to s***. And the gears were never unmeshed so the marks stayed where they should. How is that even possible? I thought if a plastic gear slipped at all, it would totally give up and spin all the way around.



Sorry for the rambling, but I am just so glad to have found it. I like to think I am a decent mechanic and this was slowly killing me inside.

Also I wanted to say thanks to all the knowledgeable people that tried to help me track this down. I know I wore some patience and I even think I made @jonheld give up my poor 3fe, who I have seen in other threads really help people out and walk them through trouble shooting. Anyways, just wanted to share in case this ever happens to anyone else.

 

[landcruiser80]

Congrats on finding your problem. Due to all of the other work you have done to it, once you fix this, your cruiser should drive beautifully for a while.

 

[excessive]

so the end of the shaft was worn, allowing it to move? or was the woodruf key missing or damaged?

 

[Sand or Foam]

Congrats on finding your problem. Due to all of the other work you have done to it, once you fix this, your cruiser should drive beautifully for a while.

Thanks! And I hope you're right, after 6 months of working on this truck, I would really like to get in and drive the thing without it randomly dieing on me...

so the end of the shaft was worn, allowing it to move? or was the woodruf key missing or damaged?

It was hard to tell where it is slipping with it still in the car. And the condenser was in the way. I need to get my HVAC buddy to come by and evac the system(full of R12 and functioning!!). Then I can get it out and see whats up.

 

[Sand or Foam]

Fixed video link.

 

[Sand or Foam]

If any one cares, the cam is out and I was able to get a better video of what is happening. The composite gear is rotating on the metal center hub. Any thoughts on how this might have happened? In all my searching I can not find anyone else with this issue in a 3fe...


And for future reference, this is where you need to get the truck to pull the cam out with the engine in an 80.

 

[cruisermatt]

That is REALLY un-good.

Where the actual timing marks on the crank and cam gears lined up?

Besides the obvious need for a new can pulley how's the cam look? Any damage around the pulley mount?

How long did you run it like this?

Since you'll be waiting for a new camshaft pulley to come in from wherever if bare minimum pulling the cylinder head to inspect the pistons and valves. (Edit, just re-read and saw you did a valve job already. I'd still pull it)

 

[cruisermatt]

And what do the plugs look like?

 

[cruisermatt]

My guess is that is a new aftermarket can gear, apparently much weaker composite that the OEM counterpart.

Is there a part number on it?

And if you didn't already realize replace that with a new OEM gear.

 

[Sand or Foam]

My guess is that is a new aftermarket can gear, apparently much weaker composite that the OEM counterpart.

Is there a part number on it?

And if you didn't already realize replace that with a new OEM gear.

The timing marks lined up and I already had the head off because my valve seats were burnt and I thought that was the cause of my low compression. Also threw a ton of other parts at it.
I bought the truck this way, thinking it only needed a tune up. Really wishing I had done a compression test before buying and doing all this work...
Check out this thread on my cam gear: 3FE Valve adjustment question

I had the same question about it being aftermarket too. There are zero markings on the cam gear, so no help there. And C-Dan has a new OEM gear and gaskets heading my way.

 

[cruisermatt]

Ok, good. It's been about a little over a year since I built my motor but I think I have a few pictures of my cam gear. I think it had some markings on it, most OEM parts do. I'll check my build thread.

 

[Sand or Foam]

Ok, good. It's been about a little over a year since I built my motor but I think I have a few pictures of my cam gear. I think it had some markings on it, most OEM parts do. I'll check my build thread.

I would be interested to see what yours looks like. Let me know what you find.

 

[cruisermatt]

Hard to tell, my last phone didn't have that good of a camera, looks like there is something on there. Some Google Image results look like there aren't any markings. But if you're getting a new gear from Dan than you should be fine. How's the camshaft look?

 

[Sand or Foam]

Got my new gear from Dan and dropped that and my cam off at Delta for a regrind. I figured while its out, why not. I also got a chance to talk with Delta about these gears slipping. He said he has seen it, but they usually give up completetly when they do. So we pulled apart my old gear to see what is up.

This is what we found. The gear is cast around the nut shape and it had worn the corners so they became rounded in the composite and could rotate inside the gear.
Close up of the rounded corners:

I am thinking it cracked on the thinnest part where the access holes are and that let it begin to move and round those corners.

Anyway, I am pretty excited to get it back together and back on the road! I think I have all the parts I need, just need a few hours in the garage.

 

[Tools R Us]

One option is to "upgrade" to the earlier 2F metal gear.

 

[Tools R Us]

Are the teeth as worn as they look in the picture? If so, that would cause issues, timing change, play introduced impact wear, cracking, have seen those phenolic gears strip.

 

[george_tlc]

When I first saw this thread I was thinking, "no way gears could slip"... Now I see that the halfwit decision maker for this at toyota went plastic and seeing the failure of the metal insert it's all clear what failed.

I have a gear driven cam and timing in my patrol diesel and couldn't imagine it ever slipping, hence the dismay that the 3fe could slip. Of course the old diesel is all steel, looks like toyota went cheap with plastic - maybe they figured it would quieten things down. Dumb call on their side.

cheers,
george.

 

[FJ40Jim]

Yes, the fiber composite gear is a known weakness. Toyota changed from fiber composite (early F) to all metal (mid F) then to a steel outer gear with elastomer ring (late F & all 2F) then back to the composite. It was done to reduce gear whine.
Upgrade to the F solid steel gears for maximum durability and supercharger whine.

 

[Sand or Foam]

Yes, the fiber composite gear is a known weakness. Toyota changed from fiber composite (early F) to all metal (mid F) then to a steel outer gear with elastomer ring (late F & all 2F) then back to the composite. It was done to reduce gear whine.
Upgrade to the F solid steel gears for maximum durability and supercharger whine.

I get that metal is going to be more durable, but why can't I find other instances of composite gears failing in 3fe's? The only time I did see the cam gear fail was on a rebuilt motor that had a shiny black plastic gear used. And that one lost a whole section of teeth.

I went with a new Toyota composite gear, because I have yet to see any threads on those failing and if this one lasted 200k+, why not stay stock? Not trying to argue, I am just curious as to why everyone seems to always go metal.

 

[george_tlc]

... Not trying to argue, I am just curious as to why everyone seems to always go metal.

As you say, if

I get that metal is going to be more durable, but why can't I find other instances of composite gears failing in 3fe's? The only time I did see the cam gear fail was on a rebuilt motor that had a shiny black plastic gear used. And that one lost a whole section of teeth.

I went with a new Toyota composite gear, because I have yet to see any threads on those failing and if this one lasted 200k+, why not stay stock? Not trying to argue, I am just curious as to why everyone seems to always go metal.

Seems like you answered your own question

The whole point of going to something like a land cruiser is to get durability... not some engineered to be quiet but delicate POS.

cheers,
george.