'85 F-150 300 engine issues

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Apr 28, 2005 | 07:35 PM

300cidguy

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Joined: Oct 2003

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From: Central Iowa

'85 F-150 300 engine issues

Well, to start off, I bought this truck a year and a half ago. Ran fine, but when I would get up to temp, it had a harsh lifter ticking. I have run Motorcraft 15-w40 Powerstroke oil since I got it. The ticking kept getting louder, only audible from one or two lifters. I was advised to run ATF through the engine for a couple of oil changes by a friend, but over time, the ticking only got worse, and now all of them are rattling. As of late, since this winter, I have been annoyed by low power output, pinging under load, and an intense "Diesel" rattle when engine is running at cruising speeds, and when I level off for my next shift. I try to keep this time of sustained engine speed to a minimum, but I need to fix it. It will "load up" if let idle for a couple of minutes. What I am wondering is if the lifters are all bad, and I am not getting proper valve lift, not allowing the engine to breathe correctly, or if the cam is going flat. I am almost out of John Deere Diesel school, and don't have enough money to put lifters, pushrods, and rocker assemblies in, let alone a cam. I was also wondering what the valve lift specs on an '85 300 are. Any advice would be helpful.

Apr 29, 2005 | 11:30 AM

flatlander_80

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Joined: Apr 2005

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300's are notorious for exhaust manifold leaks and they can sound a lot like a lifter tap. That's where I'd start. Check and/or replace you gaskets. Second, check your timing. Make sure it's good. If that's all good you may have bigger problems than lifters & valves. You said the noise got worse after you put ATF in oil. [Never use ATF,kerosine, or other such remedies, they dilute your oil to a point of doing engine damage. There are commercial additives available that are much safer] What you may have is bad rod bearings. The ATF will disolve any build-up and if they're worn enough they will slap and may even disintegrate. Hopefully, it's something I mentioned before. Good luck!

Apr 29, 2005 | 11:52 AM

sail2244

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Joined: Jul 2003

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From: Meggett SC

It would be really easy to adjust the valve lifters on this engine because all you have to do is to torque 12 nuts to adjust the valves. There is no valve adjustment on this head. The studs comming out of the head are equipped with a shoulder the rocker goes over the stud and one nut is tightened to 17-23 ft-lbs. On older 300's you actually have to adjust the amount you tighten the nuts to obtain a certain gap .125-.175 inches. Allowable valve tappet clearance is .100 to .200 inches so there is a lot of tolerence in the tappet adjustment.

Apr 30, 2005 | 03:26 PM

wrkhrs6

Cross-Country

Joined: Mar 2005

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You don't put the ATF in the oil, you pour it in the carb w/ the engine running @ about 2500-3000 rpm. This softens up the carbon buildup, and lets the rings reseat. It will also clear up the carbon buildup around the plugs. Usually, about a pint is enough. Just pour it slowly. It will SERIOUSLY screw up your bottom end if you put it in the oil.