Rebuilding an F-head Engine

Page 7: Preventing Oil Leaks

by Eric Lawson

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The Timing Gear Oil Jet

Oil jet locationInstall the oil jet (pointed out in the photo by the red line.) When you install it, ignore the screwdriver slot and use a socket or a wrench. Point the oil jet's hole so its oil stream will hit the fiber gear where its teeth begin to engage those of the steel timing gear.

There were two different oil jets used in the 4F-134 engine. The difference was the size of the oil spray hole. The earlier jet had a .070 inch ( 1.78mm) hole. The later jet had a .040 inch (1.02mm) hole. If you can insert a 1/16 inch drill into the hole, you have an earlier oil jet.

The smaller oil jet was placed into production engines when it was found that some earlier engines showed signs of their #1 rod bearing being starved for oil. The theory behind this change was that a smaller oil jet would divert less oil from the front main and #1 rod bearings. This engine had the smaller oil jet, so I did not have to make a decision about this "problem".

If your engine has the larger oil jet and you feel it necessary, you can find a new jet, or silver solder or braze the hole shut and redrill it to the smaller size. I don't think replacing the old style oil jet is a major concern.

I think an engine's #1 rod bearing would get starved for oil because the engine is worn, and to make up for low oil pressure readings, a higher viscosity oil is used. The heavier oil, when cold, doesn't flow through the narrow oil passages as well and may actually reduce the amount of oil reaching the bearings. The #1 rod bearing is most sensitive to this problem because its oil supply has to travel the longest path. This path also supplies oil to several other places, each of which reduces the oil supply to the #1 rod bearing.

Fixing Distorted Sheet Metal Covers

If you look at the bolt holes in the oil pan and front cover, you may find that the metal is pushed inward around the bolt holes. This happens because, in an attempt to stop oil leaks, the bolts holding these items are over tightened. When the bolts are over tightened, the gasket gets smashed and the oil leak gets worse. Further tightening bends the sheet metal around the bolt holes and makes it impossible to seal the oil leaks.

BoltI was shown an easy way to fix this. Use a bolt the same diameter as the one normally used in the hole you want to straighten. Put the bolt through the hole with the bolt head on the side of the metal that would normally be against the gasket. Put a washer on the bolt and thread a nut onto the bolt. The washer needs to fit flat against the outside of the cover or pan, so make sure the lip on the metal piece isn't in the way of the washer. If the washer is too big, a large nut that will slide over the bolt can be used.

As you tighten the nut, the bolt head will pull the distorted metal against the washer and back into position. This won't take a lot of effort, so don't over tighten the nut. Also, use a wrench on the bolt head to prevent it from turning and scraping metal from the cover.

To check your progress, lay whatever you are straightening, without the gasket, into position on the engine and check for gaps between the sheet metal and the block. When any gaps are less than about 1/4 the thickness of the gasket, the metal's surface is flat enough.

Installing Front Crankshaft Oil Seal in the Timing Gear Cover

Install the front crankshaft oil seal. The open end of the seal (with the lip) should face toward the block. To help prevent oil leaks, coat the metal sides of the seal with gasket sealer. After installing the seal, clean the seal lips with an alcohol soaked cloth and put some engine assembly lube on the seal lips.

In my gasket set, assembled by Crown Automotive, there were two front crankshaft oil seals. At first I thought an extra seal was mistakenly added to the gasket set, but the seals had different inner diameters. One measured 2.645 inch and the other measured 2.690 inch. The surface of the crankshaft pulley that the seal would seal against measured 2.740 inches. On my engine, with the single groove pulley, I used the seal with the 2.690 inch diameter.

It is possible to install the seal without a seal driver, but it will severely test your patience. A seal driver tool makes this job much easier. A piece of steel plate (not sheet metal) that will completely cover the seal will also work. Set the seal in the hole, set the plate on top of the seal, get the seal aligned with the hole and GENTLY tap it in. If the seal gets turned slightly sideways in the hole and will not move further, simply pull it out with your fingers and try again. It will still take a few attempts, but it is still much quicker than not using any driver at all.

Before Installing the Timing Gear Cover

Make sure the crankshaft spacer, oil slinger, crankshaft pulley woodruff key and timing gear oil jet are installed. Verify the oil jet is pointed the correct direction.

Your engine may have a pointer to the timing notch on the crankshaft pulley. If so, have it ready to install as it is held in place by the same bolts that hold the timing cover in place. When the engine is upright and viewed from the front, the second and third 3/8 inch bolts, counting from the lower left corner of the cover, are the ones that hold the timing pointer.

Check that the timing gear gasket's holes align with the holes in the block. I've noticed about half of these gaskets have at least one hole that doesn't line up correctly. If the gasket is paper, soak it in water for a few minutes, set it onto the engine, gently stretch it as needed and thread the bolts into the holes to hold the gasket in place until it dries. Some of the new gasket materials don't respond to the water treatment, so be prepared to use a paper punch to make new holes.

Once everything is ready, coat the gasket with gasket sealer. Also coat the threads of any bolts that go into holes that extend into the crankcase. This last step prevents oil from seeping around the threads of the bolts.

Timing Cover and Crankshaft Pulley

Install the gasket, timing cover, and if needed, the timing mark "pointer". Don't over tighten the bolts holding the timing cover in place. If the gasket looks like it is getting squeezed out from under the timing cover, the bolts are too tight.

Coat the machined surface of the crankshaft pulley with engine assembly lube. This will ensure the seal doesn't get torn when the engine is first started.

Install the crankshaft pulley. Some light tapping might be needed to get the pulley onto the crankshaft far enough for the large nut to be threaded onto the crankshaft. The 1-7/16 inch socket needed for the large nut makes a nice pulley installation tool. Just don't hit the socket so hard that you damage it and be careful not to damage the threads on the crankshaft.

I have noticed the reproduction pulleys don't always fit well onto the crankshaft. If you are having this problem, first try cleaning the inside of the pulley hub with alcohol. Sometimes the anti-rust coating is sticky enough to cause problems. If that doesn't help, either try another pulley or have the inside of the pulley hub machined to the proper size.

To prevent the crankshaft from turning as you tighten the crankshaft pulley nut, place a wooden hammer handle between one of the crankshaft counterweights and the block

The Oil Pickup

Dirty screenClean the oil pickup. Bend the tabs holding the screen cover in place and remove it to completely clean the oil pickup. I am always amazed at what I find caught in the screen -- this time some red, orange and blue RTV gasket maker and some oily semi-solid. There is usually a string that seals the screen cover. If it is there, don't lose it. If it is not there, you can make one out of some oil soaked twine. This seal fits into the back of the groove in the sheet metal screen cover.

Oil pickup location
Reinstall the screen cover and install the oil pickup. When you install the oil pickup, don't forget the gasket that goes between the block and the pickup's flange.

Installing the Oil Pan

Put the rear crankshaft seal packings into the two holes in the rear main bearing cap. The packing will stick out about 1/4 inch (6mm). Sometimes the packing will not easily fit into the holes. Putting water on the packings and twisting it into the hole usually helps with this problem. If that fails, get a different packing set. I've not had any luck with trying to shave off material from the sides of the packings. Whenever I have tried this, I have ended up with an oil leak.

Thrust washerCoat both sides of the oil pan gasket with gasket sealer and lay the gasket into position. Lift the gasket up and place a bead of silicone gasket maker where the front cover gasket will meet the oil pan gasket.

When you install the oil pan, the crankshaft pulley shield goes on the outside of the pan at the front of the engine. The lip of the oil pan interferes with this shield and you will need spacers under each hole of the pulley shield. Two 5/16 inch AN flat washers stacked one atop the other make a suitable spacer.

This summer I lost all of the oil pan mounting bolts. The bolts are 5/16 inch NC, 5/8 inch in length. The 1/2 and 3/4 inch lengths that are commonly available would not work. An industrial hardware supplier had the AN flat washers and these odd length bolts.

Again, watch the gasket as you tighten the bolts. If the gasket looks like it is being squeezed out from under the oil pan, you are over-tightening the bolts. -- Eric Lawson

Continue to Page 8: Vacuum Lines

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Last updated 8 November 1998 by Derek Redmond redmond@cj3b.info
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