Ld-465 max rpm 1800

Have a 66 deuce start and runs great but noticed a majority of the time when driving.
It has no power, exhaust smoke under wot is light haze.
Top speed around 32 mph and rpms wont climb past 1800-1900 even down hill and if I'm going up hill have to down shift and still loss mph, and slightly more smoke.
but after driving awhile it's like a switch
Is flipped and instantly goes from low power/low smoke.
Into a f16 with afterburns lit, pour out smoke like a freight train, rpms take off like a rocket and itll hit 55-60 going up hill like it's nothing

Order new fuel filters,
replaced the fuel pump, newer ip head,
Thinking that possibly the fdc is the issue


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Might be filter related. The fuel system is a return system. Having the truck running for a while could heat up the fuel enough to help it flow through clogged filters. Do you have nothing but diesel in the fuel tank? If the FDC isn't already bypassed, go ahead and do that now to prevent another issue. (Fuel leaking into crankcase oil) The hydraulic head is very reliant on clearances. Heating up could also expand it enough to get a good seal internally of the piston. So you've already replaced the HH? I'd of course recommend the filter swap first.

It's running about 20% used oil
Fdc hasn't been bypassed yet
Hopefully it's just dirty filters but ill find out soon

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How you filtering your oil? That may be what your problems are.

m16ty said:

How you filtering your oil? That may be what your problems are.

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Exactly ! Used motor oil has a tremendous amount of metal particles in it. You need a centrifuge to totally remove them all, but a really good filtration system can really help. Remember the fuel should be cleaned down to at least 6 microns. The old American Bosch service manual said to filter the fuel down to 2 microns ! That would be pretty hard with the filters available now, but that is what the manual said. So if your running dirty engine oil with who knows what in it, that could really plug up that Hydraulic Head .

I doubt its filters. Ive had my truck shut off while driving and up to that point, had no indidcation the filters were getting bad. I say have your injectiors pop tested and adjusted then check valve lash. Id go to the fuel system after checking the air filter. Just my 2 cents .

gimpyrobb said:

I doubt its filters. Ive had my truck shut off while driving and up to that point, had no indidcation the filters were getting bad. I say have your injectiors pop tested and adjusted then check valve lash. Id go to the fuel system after checking the air filter. Just my 2 cents .

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I don't think it could be the injectors or valve adjustment since it is an intermittent problem. Those kind of issues you mentioned Gimp are usually always constant. This definitely sounds like a fuel issue. I'm wondering about the fuel pump now.
"jth3rd" have you checked the fuel pump pressure ? Also the fuel pressure coming out of the booster pump ? This can tell us a lot of what's happening in there. Since your running waste oil, maybe once the engine gets warm enough it is sending warm fuel back to the tank and that is helping loosen up the crud around the fuel pump pick-up screen. Just thinking out loud here.

Valid assessment, could be water in the filters, maybe filters will help.

gimpyrobb said:

Valid assessment, could be water in the filters, maybe filters will help.

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He also failed to mention if he ever drains the primary filter as recommended in the -10 TM.

Who's ready to see the cause

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First photo one filter is bypassed so going to add a modern filter

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I'm going to assume it's a 1966 filter that has never been changed

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jth3rd said:

I'm going to assume it's a 1966 filter that has never been changed

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The stock filter in 1966 was probably a washable one . That looks like a combination of waste oil and not draining the water regularly.
Most people that run waste oil carry extra filters.

Yeah, that's not too bad seen much worse. Did you do both? Does it run any different?

Just drove it after a full maintenance and it's a completely different truck quite, and plenty of power

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In the first picture it looks like your headlight ground wire is broken.

doghead said:

In the first picture it looks like your headlight ground wire is broken.

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Probably so, none of the lights works another project to get too

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Glad it was just the filters and nothing more. Hopefully nothing bad got through to the injection pump. That can really mess up your day !