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Fiddling with Rambler's since 1995

Rambler American Restoration

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Replacing An Oil Pump In A `68 American

Recently, I purchased a `68 Rambler American. I got a good solid car that ran for $24. The big problem with the car was that the oil pump was bad. I've changed oil pumps before and its never been that big of a deal. The only catch with changing oil pumps on I6 (at least of the 199/232/258 variety -- I can't speak about the earlier ones) AMC's is that removing the oil pan with the motor in the car is difficult. You can do it, but you need to lift the engine as high as you can get in the engine bay, unbolt the crossmember and pry it down as far as it will go (I'm told this is not as easy as it sounds). Since I didn't know how long the car was run with no oil pressure, I assumed (correctly) that the main and rod bearings on the car were shot with the crankshaft probably needing some attention as well. I went ahead and pulled the motor. Assuming you don't need machine work done on the crank, you should be able to do this in two days.

To pull the motor, you will need the following:

  • Jack stands
  • A large floor jack
  • An engine hoist (sometimes called a cherry picker) -- you can rent these for about $20 a day. Make sure you get a chain to attach to the engine.
  • An engine stand -- you can also rent these but they only cost about $60. If renting one for a few days comes close to this, you may want to consider purchasing one. They break down for storage.
  • Standard assortment of socket wrenches, box wrenches, and screw drivers. You will also need an assortment of extensions. I used one 12", two 6", and one 3". A universal joint is needed to unbolt the transmission if you are going to leave it in the car.
  • An oil drain pan
  • A pan to collect the antifreeze. Make sure it can hold at least 3 gallons of liquid. If it doesn't, get a bucket to dump the antifreeze into when the pan gets full.
  • A grease pencil or marker to mark the hood hinges
  • An impact wrench to remove the flywheel/flex plate bolts.

Pulling the motor (note: This is the Reader's Digest version of motor removal. Consult your service manual before you start.):

  1. Mark around the hood hinges to facilitate alignment later. Unbolt the hood (front bolt first) and set it out of the way.
  2. Put the car up on jack stands and drain the oil from the engine and transmission. If the car has an automatic transmission, remove the transmission cooler lines as well. Locate the water jacket drain plug and spray it with penetrating oil..
  3. Drain the radiator and then remove the plug from the water jacket. This will drain most of the coolant.
  4. If you are removing the transmission with the engine, disconnect any shift and clutch linkage, and remove the driveshaft and transmission crossmember.
  5. Take the car off of the jack stands and support the transmission with a floor jack.
  6. Disconnect all belts, hoses, wiring, throttle linkage, etc.
  7. Remove the carburetor, radiator, and fan.
  8. Attach the lift chain to the engine and attach to the engine hoist.
  9. If you are leaving the transmission in the car, put the car back on the jack stands and unbolt the transmission bell housing from the engine. On automatic cars, remove the flex plate to converter bolts.
  10. Remove the bolts holding the front motor mounts to the engine
  11. Remove the engine and flywheel/flex plate and mount on the engine stand. Turn the engine upside down.

Changing the pump:

You will need at least the following to change the oil pump:

  • A new oil pump and pickup. Your oil pump pickup tube is likely to be incompatible with the new pump. The pump had a design change in the late `70's. Both style pumps where used until the mid `80's and will interchange with the correct style pickup tube. The new style is the only one commonly available. Consult Rambler Dan's AMC parts list for part numbers.
  • Gaskets for the oil pan. Now would also be a good time to plan replacing the rear main seal and timing chain set. It will only cost about $50 to do it now.
  • Gasket sealer ( I prefer the spray type).
  • A carburetor gasket.
  • An accurate torque wrench that includes the 20 to 100 ft. lbs. range.
  • Either a micrometer or Plasti-Gauge.
  • A good gasket scraper. I also use Permatex Gasket Remover. You spray the stuff on and it dissolves any glue used before.
  • A rubber mallet
  • A bunch of shop rags
  • Assembly lube.
  • Permatex #2.
  • Feeler gauges.

Here is the procedure for oil pump replacement

  1. Turn the engine upside down.
  2. Remove all of the oil pan bolts and remove the pan. Pay attention to where all of the bolts came from since 3 sizes are used. If the pan is stuck to the block, gently tap with the mallet until it comes free. If you hit it to hard, you can deform the pan and cause an oil leak.
  3. Stuff a bunch of shop rags in the engine to prevent getting parts of the old gasket in the engine and remove the remains of the gasket. Clean the oil pan as well. Take care not to gouge the gasket mating surfaces.
  4. Remove the two bolts from the oil pump and remove the pump. You may need to use the mallet to break the seal between the pump and the block. Clean the remains of the gasket from the block.
  5. Remove the shop rags from the engine.
  6. Remove the main bearing cap from the thrust bearing (#3 from the front) and inspect the bearing journal and the bearing. They should be smooth and evenly worn. The bearing should also have a dull gray color to it. If you see copper, you will have to have the crank machined. If the bearing and journal look okay, clean all oil from them and check the bearing clearances. Your service manual will have the proper methods and specs to check. If the clearances are out of spec, remove the timing chain cover, timing chain, the remaining bearing caps (make sure to keep them in order) and the crankshaft. Take the crankshaft to a machine shop and have it checked thoroughly to make sure the journals are in good shape. Have them supply the proper size bearings and double check to make sure you have the correct size bearings when you pick it up. (To have the crank machined, new bearings, a timing chain, cover gaskets, turn the flywheel, and have the oil pan and timing cover hot tanked, it cost about $250.).
  7. If the crank and bearings are okay, and you are replacing the rear main seal, remove the timing chain cover and chain, unbolt the bearing caps, and remove the crankshaft (trust me, its MUCH easier with the crank removed). While it is out, inspect it carefully for wear in the front and rear seal areas. If you have a micrometer, check the journals for wear.
  8. Remove the old rear seal. I needed to use a square drive screw driver to drive it out of the block. Clean the area the seal fits into.
  9. Install the new seal and the crankshaft and torque the main bearing caps to spec. Pry the crank forward and backwards several times and check the clearance between the thrust bearing and the crank. Your service manual will have this measurement in it. If it is out of spec, consult a machine shop.
  10. Remove the bearing caps and give each bearing and the rear seal a good coating of assembly lube. Put a thin coat of Permatex #2 on the ends of the rear main seal and reinstall the bearing caps.
  11. Regardless of weather or not you remove the crankshaft, re-torque the bearing caps. This could save you from a rebuild due to a spun bearing. If any bolts don't seem to be holding well (the wrench will have a springy feel to it instead of a solid one), replace the bolt. If a fatigued bolt breaks, it can cause major damage to the engine.
  12. Reinstall the timing chain and cover (if removed).
  13. Reinstall the harmonic damper (if removed). Lightly coat the end of the crank and the snout on the damper with assembly lube.
  14. Install the new pickup tube on the oil pump and install the gasket and oil pump. If the pump doesn't seat, rotate the shaft on the pump so the slot in the shaft lines up with the tang on the distributor. Install the bolts and torque to specs.
  15. Install the oil pan.
  16. Now, the fun part -- getting the engine right side up. Originally, I had planned on some help doing this. With the head on it, an I6 is very top-heavy. I ended up just reattaching the engine lift chain to the hoist and slowly lifting it with the hoist. One word of warning here, be careful not to raise the hoist to fast. If the engine snaps upright, the chain can break.
  17. With the engine back on the hoist, reinstall the flex plate or flywheel and reinstall in the car.

Last Updated 01/04/04 06:28:43 PM