3B cam B cam (1 Viewer)

[stevebradford]

Hummm... Looks the same to me..

Worn out 3B on the right older but fresher B on the left. Amazingly some of the lobes on my 500,000k 3b are worn down to low humps instead of the perky humps they should be.

 

[GTSSportCoupe]

That B motor looks to be in good shape.

Cam's aren't the only thing that loose their perkiness with age... Poor saggy lobes on that old 3B!

 

[audaciousduo]

WOW! Thats crazy. All that metal floating around has to have wiped all the bearings as well.

 

[stevebradford]

Yeah you would think that, I will let you know.

I got this 3B when she had already been around the block a few times, About 380,000 times to be exact. It was torn out of a 83 BJ60 that i abandoned in a tub full of ice missing a few organs. I swapped it into 1981 Fj40 and daily drove it for another 14 good years. Knowing what I know now I would have saved that 800$ bj60 It was in good shape but thats just what we did back back then.

Anyway back to the motor. Surprisingly considering the cam wear it ran just like any 3B, low on power. It smoked a little on a cold start up and left a couple drips of oil when parked over night out of the crankcase vent tube. I also found two of the rockers had a 1/16 deep pit the valve had dug into it. Got to love these old Toyota diesels just won’t die.

 

[GTSSportCoupe]

I looked up measurements, and the B and 3B should have the same cam lobe height. So that 3B cam is definitely very worn! Is this something typical for high km push rod engines? I guess the mass of pushrod/lifter/rocker/valve/spring results in significant wear over time. I'm used to shim over bucket overhead cam motors; and cam lobe wear is a non issue. One slight advantage for the rubber band technology I guess....

Do you have a micrometer handy?

Standard:
Intake: 45.067-45.157mm
Exhaust: 45.065-45.155mm

Minimum:
Intake: 44.63mm
Exhaust: 44.63mm

 

[stevebradford]

I don’t have a micrometer handy but I might be able to borrow one thanks for tracking down those measurements!

I don’t believe that sort of even wear is typical. Its only on a couple of the lobes also. Possibly due to the valve lash on those worn badly pitted rockers?

The typical wear on the worn out 3b cams I have seen is pitting and removed material from the lobes typically by the edge.

I did notice one difference between the two cams there’s a hole I need to investigate.

 

[GTSSportCoupe]

I don’t have a micrometer handy but I might be able to borrow one thanks for tracking down those measurements!

I don’t believe that sort of even wear is typical. Its only on a couple of the lobes also. Possibly due to the valve lash on those worn badly pitted rockers?

The typical wear on the worn out 3b cams I have seen is pitting and removed material from the lobes typically by the edge.

I did notice one difference between the two cams there’s a hole I need to investigate.

You could probably just use some vernier calipers instead. If you don't have those either I can lend you micrometer/calipers.

It could be that Toyota changed the cam duration but kept the same lift from B to 3B. Meaning the lobes could look more rounded, but might measure the same lift....

That hole must be for improved lubrication? Strange spot...

 

[stevebradford]

Thanks I got some great venereal callipers

When I first noticed the round lobes I thought the same that they were rounder for longer duration on just the intake or exhaust but there was only two rounder lobes.

New theory I’m working on:

Sometime in its History someone did the valve lash and set the gap too tight on two rockers. Leaving not enough free play between the valve and rocker causing the lifter to ride the cam under pressure longer. That’s why two of the rockers were deeply pitted also? I can’t remember what cylinders the pitted rockers operated so there’s no way to be sure that those rockers matched the worn lobes.

Yeah that hole could be for more lubercation but it’s not in the block and has no oil feed. There’s a cover thrust plate that holds the cam into the block that rides there and is splash Lubercated by the gear timing in front of it.

 

[PG45er]

Different engine I know but I've had four 2f's apart for engine work. All four cams were shot with wear like your 3B cam. My research led me to believe a large part of the cause is lack of Zinc in modern gas engine oils as modern engines are either roller cam push rod or overhead cam, zinc not required, and the zinc doesn't play nice with emmisions sh#t. Diesel engine oil had the zinc for longer but has been nearly eliminated from modern diesel engine oils as well so it plays nice with modern diesel emissions. You can get zinc additives but I use racing oil which has the zinc in it for my 2F. I haven't researched but perhaps there is a diesel engine oil designed for the older generation diesels as well??

 

[stevebradford]

All four cams were shot with wear like your 3B cam.

Which type of wear? Or both? I’m used to seeing pitting and removed material near the edges of the lobes like sort of like galling. That sounds like damage caused by your lack of lubercating zinc theory.

For those interested here’s what the first cam bearing in the 3b looks like, explains a few things about the lowish oil pressure.

 

[PG45er]

Both but mostly lobes flattened off.
The 3B does not have roller cam followers, correct?

 

[stevebradford]

Correct just a solid slug like the 2F here’s some more of the usual pitting you can see on the surface that rides the cam on the right lifter.

 

[PG45er]

Most of my lifters were like that as well, sent them away with the cams to get reground, came back like new. One engine has only had the cam break in procedure done but been driving the other for a few years now, not a lot of kilometers but so far so good.

 

[seapotato]

I think you should stop taking them apart.

i bet they all ran fine till you disassembled them.

 

[stevebradford]

i bet they all ran fine till you disassembled them.

Hah they really did!!

This different also high mileage 3B was running just fine with a broken valve spring.

 

[bikersmurf]

I had a cam that looked much like that after only 100k miles. It had five completely round lobes that didn’t have more than 1/8” between the highest and lowest points. It also ran well... although the idle was a bit uneven. I didn’t notice how much power was lost till I’d replaced the cam and woke it up.

The cam bearings weren’t too bad... the lasted another 21 years. They may have even lasted longer had the rod bearing not spun and been beaten into oblivion.

 

[Diesel Cruiserman]

I need to measure my cam, for sure my rocker arms need a little grind to smooth them out. The old adjuster bolt pounded a hole in a few of them.. Old trick we use to do when this would happen is adjust the clearance with a dial indicator.

 

[Diesel Cruiserman]

Found the spec

45.087 mm std intake
45.068 mm std exhaust

my worst was 36.9 best 39.4mm

 

[Diesel Cruiserman]

I can only find a 5 bearing cam for sale in the US, I cannot see why it would not work in the 3 bearing engine. John at Radd had wrote some where that he had issues with ground cams.

 

[stevebradford]

I have seen a 3b ground cam galling badly shortly after brake in at less than 15,000k. Not quite the same hardening of the surface or something..