3FE Discouraging tale (valves, oil galley, and knocking)

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roadstr6 said:
This thread has scared me away from ever owning a 3FE truck.
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3Fe with only 130k should never have these issues. I think it goes to show neglect is worse then high mileage. Truly think if I had started with a small rebuild of the top of the engine it would solve all other issues. With severe neglect I think most people would suggest this. I've replaced a lot of stuff that made no difference. Changes occurred when I adjust the valves so most likely all the issues could be right there. Finally found a line mechanic at a dealership that has experience with these trucks and it's in his hands right now. One of the hardest things is to either research and gain the knowledge needed to fix the engine or find someone local that already has that knowledge and you can trust. I ran into the issue of finding a shop that had the knowledge but not trustworthy, then I had a mechanic that I trusted a lot but didn't have the knowledge.
 
lt1fire said:
So the hotter the car gets this problem starts? Is it overheating at all? Your 80 should get to operating temperature in no time at all so the two hours and then it starts to hiccup means something is heat soaking and then failing.

Does it cut off when it goes bad?
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No overheating. Heat soaked yes. Never had the issue this acute but always had power loss issue. Seemed to sort of hold its own, now it gets progressively worse to the point I have no power. Heat soaked valves that will not stay in place, maybe could cause a similar issue? I'm not sure. Never touched anything on the tranny, fluid always looked correct color and level. Then again multiple people have mentioned the torque converter. @mtweller Could there be a possibility that an engine problem has stressed the tranny to the point of failure as well?
 
roadstr6 said:
This thread has scared me away from ever owning a 3FE truck.
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Lol, right. I lived mine great motors but like all early yota EFIs.... they are smart engines compared to a Carb but not really smart enough to tell you what's wrong with them.

Tracking down the issue on the 88 rally car was similar to this. Took forever going through the FSM and checking everything.


TheWhitefox said:
No overheating. Heat soaked yes. Never had the issue this acute but always had power loss issue. Seemed to sort of hold its own, now it gets progressively worse to the point I have no power. Heat soaked valves that will not stay in place, maybe could cause a similar issue? I'm not sure. Never touched anything on the tranny, fluid always looked correct color and level. Then again multiple people have mentioned the torque converter. @mtweller Could there be a possibility that an engine problem has stressed the tranny to the point of failure as well?
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While I dont really think the issue is fuel related. Have you hooked up a fuel pressure gauge to see what it is doing when you have these lack of power or no start issues?
 
If you are going to trouble shoot this yourself grab one. Perform every test in there that is even remotely similar in symptoms. Perform them all again when the heat soak starts.


It's all just a process of elimination. Like @mtweller said it may even be multiple things.
 
Don't dis the 3fe too bad, I had mine running 70+(with 35s) to Tennesee and back at GSMTR, 7 hours each way and it does great.
Granted it gets much better gas mileage at 65, but no problems. BTW, mine has 250,000 miles.
I would bet its a torque converter issue, also. Is there a trans cooler on it?
 
dbenke said:
Don't dis the 3fe too bad, I had mine running 70+(with 35s) to Tennesee and back at GSMTR, 7 hours each way and it does great.
Granted it gets much better gas mileage at 65, but no problems. BTW, mine has 250,000 miles.
I would bet its a torque converter issue, also. Is there a trans cooler on it?
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No trans cooler 🤔. Could a valve issue/lack of power cause strain on the converter eventually leading it to fail?
 
dbenke said:
Don't dis the 3fe too bad, I had mine running 70+(with 35s) to Tennesee and back at GSMTR, 7 hours each way and it does great.
Granted it gets much better gas mileage at 65, but no problems. BTW, mine has 250,000 miles.
I would bet its a torque converter issue, also. Is there a trans cooler on it?
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For curiousity sake, Question for you? Can you tell me what RPM equals 70mph in overdrive gear, straight and level on the highway for your rig. I know in my busted rig its exactly 2200rpm.
 
Mine is a little higher, around 24 to 2500
 
dbenke said:
Mine is a little higher, around 24 to 2500
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Interesting. I've been running 93 because of the knock, Wondering if that would make that much difference.
 
I want to say mine is around or slightly above 2200 (91 80 series with 33s). @dbenke doesn’t the 62 have different ratio for diffs?
 
It runs 4.11s. I was thinking about going to 4.56s, though
 
AJR said:
I want to say mine is around or slightly above 2200 (91 80 series with 33s). @dbenke doesn’t the 62 have different ratio for diffs?
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Mine is a 91 as well with 33s, good to know its 2200rpm for you as well. 4.56 would definitely make an improvement in most driving conditions, want to do the same!
 
RPM will vary slightly vehicle to vehicle even with the same specs just due to the fact that his tires might be closer to a true 33 than yours, etc...

In an 80 series cruiser it should be right at 2100 for 70mph with 33's. Of course your speedo is off with the bigger tires, so if it is reading 70 it is at about 74

If you even need to know this is pretty good calculator

Engine RPM Calculator

www.csgnetwork.com
 
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Does the truck not start after it "gets hotter" or will it just not drive?
 
lt1fire said:
Does the truck not start after it "gets hotter" or will it just not drive?
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It will start, idle is a little rougher, if you can get it to a cruising speed 35, 45 etc it can do a okay job at holding it, it will what a call "idle accelerate" but trying to make it go was when it was very very noticeable, worse was when she was hot 3 hours in, 1 hour after the first rest, and I dropped into 2nd and it would chug chug chug, rpms slightly surging truck throwing you forward and aft. I let off and sort of idle accelerated through second, slowly slowly getting up to speed still experiencing these symptoms just not as severe since I closed the throttle. Happened in all gears and not at the gear change only after it dropped in and you opened the throttle to accelerate it would get worse the more the throttle opened. You would experience this in the slightest at first just cruising at 65, slight rocking forward and aft every once in awhile, becoming more and more steady, rpms increasing and increasing to hold the same speed. Almost as if the front brakes would grab for a half second and let go. But it rolled fine in neutral, changed all the gears at the normal time, reverse with no issue, put in park and open the throttle, no issue, except for ever increasing valve noise along the drive.

In the first year I had the truck before any of the valve adjustments I drove it to ATL from Raleigh, NC and back with no issues and all over town as a daily driver. Seems like this has developed and worsened since my ownership. But I'm the first one in 20 years to put a couple thousand miles on it in a year. Previous owner had it for 16 years and only put 20k on it! Then a used car dealer had it for 18mths, drove it a few hundred miles then sold it to me.
 
ok so to hold the same speed, say 70 on your speedo, your rpms are at 2200 but then to stay at 70mph your rpms start to increase??

certainly sounds like a slipping converter
 
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lt1fire said:
ok so to hold the same speed, say 70 on your speedo, your rpms are at 2200 but then to stay at 70mph your rpms start to increase??

certainly sounds like a slipping converter
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Maybe loss of power is the valves moving and this is a separate new issue? Makes sense. Especially considering "heat soaked" etc.
lt1fire said:
RPM will vary slightly vehicle to vehicle even with the same specs just due to the fact that his tires might be closer to a true 33 than yours, etc...

In an 80 series cruiser it should be right at 2100 for 70mph with 33's. Of course your speedo is off with the bigger tires, so if it is reading 70 it is at about 74

If you even need to know this is pretty good calculator

Engine RPM Calculator

www.csgnetwork.com
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This is amazing, had no idea.
 
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