Hey, guys. I'm new here.

I acquired a 1983 D150 with 200,000 original miles on the 225 slant. Still has Lean Burn system. As soon as I brought it home I started having problems with it. This may be a long post, so I will try to keep it organized for easy reading.

First issue:
Odd, intermittent tapping coming from rocker area. It only happens when fully warmed up, and it will tap a few times then stop. Then a few minutes later it will repeat.

What I have done to try to remedy the issue:
Installed aftermarket mechanical oil pressure gauge. It reads 40 at hot idle, and stays around that point when accelerating. Usually drops to 15 - 20 when stopped at a red light.

Pulled valve cover, and noticed everything was black and gunked up. Pulled rocker assembly, cleaned it up nicely, re-greased it, installed everything back in original locations, and torqued to Haynes manual specs. This only made the tapping louder.

I then changed the oil (for the second time), using 4 quarts of 10w30, 1 quart of Marvel Mystery Oil, and a Napa Gold filter. This made the tapping stop completely! for 2 days..... After 40 miles of driving, it started again.


Second Issue:
When taking off from a dead stop, it takes about 3 seconds for it to actually move. The gas pedal is a little stiff as well. I have no idea what that could possibly be. Carb? Trans? Rear gears?

The engine sounds like it has plenty of life left in it while driving, and it will get up and go if I mash the gas. Idles pretty smooth too once warm. My main concern right now is the tapping. I really don't want to tear the engine open to get to the lifters, as time and money are a concern right now. Any suggestions for something else I can try first?

The tapping under the valve cover is likely the result of the crud inside the engine messing with the hydraulic lifters. I would put the engine on a reasonable oil-filter change frequency (4000 to 5000) miles and hope for the best. There are a couple of engine flush formulas available in this forum,,,

Concerning the truck not pulling away,,, is it an auto tranny? If so it also probably needs fluid maintenance,,consider a fluid and filter change.
I would look at changing out all fluids, diff, brake fluid, antifreeze,,,,
For the stiff throttle,, spray the pivot points on the linkage and carb with light oil.

Dadtruck has nailed it. Noise is probably a sticky lifter. Keep running marvel mystery oil.

The hesitation on aceleration could be one of a number of things. If you have a lean burn system then your best bet is to either immediately replace it with a standard electronic ignition and non-computer controlled carb (or both, depending on what variety of lean-burn system you have). If you don't want to swap it all out then you ned to buy a factory service manual for your specific truck and cros your fingers that it isn't a bad computer. Proper vacuum routing is critical on lean-burn engines as is the integrity of all vacuum diaphragms (choke pulloff, brake booster, and computer).

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Casually looking for a Clifford hyperpak intake for cheap.

This problem plagued my 84 D100 for a few years. The engine was so gunked up the rockers and pushrods were black! I took the pushrods out and soaked them in solvent, then ran a wire through the pushrods. No more ticking after that.

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If it was easy, everybody would be doing it.

Thanks for the feedback, guys!

The problem has changed from only tapping when warm, to only tapping when cold. So i'd say the MMO treatment is definitely doing something.

I'm going to remove the lean burn as soon as possible and convert to electronic ignition. I'll replace the carb too while i'm at it. What would be the best non lean burn carb to swap to? (keeping cost in mind too) I don't mind staying single barrel, but going 2 barrel with an adapter plate would be nice too.


It is an auto transmission. The fluid didn't appear bad when I looked at it, but i'll change it just to be safe.

As for the push rods, mine were full of junk too. I soaked them and blew them out with air, and oil flow improved after all that.

The two barrel adpeter on a one barrel manifold is a bad idea. Chrysler engineers designed a two barrel intake manifold for a reason- the single hole for the one barrel carb is too small to flow the CFM of a two barrel carb.

That being said, a one barrel carb is plenty for a street driven truck. I would go with the best condition one barrel carb you can find that has the correct ports to math up with your emissions equipment and a vacuum advance distributor. Your best bet will be a Holley 1945 carb from the late 70s or early 80s. Try and find a NOS one or a good original condition used unit. Avoid parts store remanufactured carbs.

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Casually looking for a Clifford hyperpak intake for cheap.

Had the same ticking with my '86. Old mechanic said to put a 1/2 cup of transmission fluid in with the next couple of oil changes. Problem solved.

I am currently doing a similar swap on my truck. Got a like new 1945 Holley for a 1974 Dodge truck 225 with a lifetime warranty for under $200 from National Carburetors. I tried for a BBS, they did not have them in stock.

http://www.nationalcarburetors.com/look ... num=nd1378

You can get a NOS distributor from Old Car Parts NorthWest. They are currently trying to sell the bulk of their inventory on ebay. Below is a link to their store.

http://www.ebay.com/usr/oldcarpartsnw?_ ... 7675.l2559

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86 D100 short bed A833, lean burn deleted.
07 Honda Accord EX-L V6
03 Toyota Highlander - 305k and still going strong
13 Toyota Highlander - 151k