Howdy all. I was recently driving in my 1973 FJ40 On the freeway when I heard a knock. I promptly shut the motor off. Got it home started tearing stuff apart and got the timing gear cover off and noticed a broken timing gear. The crank gear easily was spinning against the bare spot on the timing gear. So I put a gear tool in to see if the cam would spin and it spins past the bare spot freely and once lined up with the crank spins together well. Was wondering if I can simply put a new timing gear on and re-time time it, or if there was something more serious that caused the timing gear to break. Like i stated both the cam and crank spin freely. Also i inspected all the push rods and they are all straight, and oil was relatively clean when i drained it.
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I would fit a new/used timing gear to it, and do a compression test. That should tell you something, especially if you ever took one in the past for comparison.
- Thread starter
- #4
Yes, the motor had great compression and oil pressure
Was that an OEM gear or an aftermarket Chinese unit? I've heard bad stuff about the Chinese stuff, specifically very fast or uneven wear. I'd source a good used OEM one of it was me
Was that an OEM gear or an aftermarket Chinese unit? I've heard bad stuff about the Chinese stuff, specifically very fast or uneven wear. I'd source a good used OEM one of it was me
- Thread starter
- #7
Unknown, however it was fiber glass and I’ve heard the oem ones were aluminum? Not sure if that’s correct though
Living in the Past
SILVER Star
Early were a carbon fiber type material. Heard of steel but not aluminum timing gears from Toyota.
not correct, who'd you hear that the OEM was Aluminium?
this is what happens with a foreign, non-OEM, gear
Oooh that’s going to ruin your day.
it was a parts rig I bought way back in 2012.
middlecalf
SILVER Star
Those are different failures, no? The op’s is in the teeth, the last is in the web. Other posts about the web failures, but this teeth failure seems different.
Some F engines definitely had composite gears - I have seen them in junkyards (teeth stripped). I believe you can fit a later metal gear, and should do that.
Living in the Past
SILVER Star
When I rebuild my 68 F145 it had a steel gear. By the time I bought it in 74 the engine had been rebuilt already. Very poorly done but did have a steel timing gear which makes me wonder now if timing gear failure was the cause. Certainly wasn't because they were doing a quality job. Rod caps did not have cotter pins in the castle nuts. The three plates used to lock flywheel bolts were there but no tabs were folded over. One loosened and locked the clutch up within six months. Rod cap didn't loosen up for over a year. Being older now I know I should have passed on this cruiser. Had a receiver that weighted forty pounds welded on. Still had all original single circuit brakes that the original owner had tapped into in the back line and had a plug to operate hydraulic brakes on a trailer. It's no wonder the engine needed to be rebuild so soon. Thinking the improved oil system of the last year of the F155 might of helped but still not up to what they must have been towing.
I don't believe you can simply pull the old one off and put on the new on. Fairly certain you have to pull the cam to press on and press off the cam gear. That involves pulling the rocker assembly, push rods, dizzy and lifters. Not a lot more work from where you're at now.
That's how I did mine. However with the cam out I found excessive wear and a few lobes were out of spec. I sent it to Delta cams along with the lifters for resurfacing. I also had an RV grind done to it.
- Thread starter
- #16
Yes the cams gotta come out. About to start that now haha, I’ll update what i find once it’s yanked. I’ll proably be replacing it with an oem Toyota Steel gear, just found oem part number. I’d assume i should replace the crank gear as well?
1911
chupacabra
It's always a good idea to replace both at the same time, if possible.
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1. The problem with spitting teeth at freeway speed is not knowing if one or more valves were left floating open when the pistons came up TDC, potentially impacting. I’d want to pull plugs and use a stethoscope camera to look-see if the top of any of the pistons look like carbon was disturbed.
2. Don’t be surprised if you have a new, different knock when you’re done. Sometimes replacement gears do that. I had one that took over 10k on the odometer to settle down.
2. Don’t be surprised if you have a new, different knock when you’re done. Sometimes replacement gears do that. I had one that took over 10k on the odometer to settle down.
- Thread starter
- #20
I’ve heard some pretty bad things about the new non oem ones, would you suggest going with the new reproduction or going with oem
