One of the worst oil leaks you can have is the timing chain cover seal. When the seal is worn out or improperly installed, the engine fan can blow your oil everywhere, giving the impression that you have many leaks instead of only one. This is an involved job, but it really takes only patience to complete.
First, you must disconnect anything on the firewall that will inhibit your motor from vertical movement of about 3 inches. This would include your throttle linkage, but not your oil feed line. Remove your air cleaners. Put the front end of your car up on jack stands. The best place for them is 4″-6″ behind the engine mounts.
Drain your radiator and remove it from the car. Next, loosen your generator and remove the belt. Now replace your engine mount bolts with ones that are at least 4″ long. These bolts are 3/8″ diameter SAE fine thread. Do this one at a time. The idea here is to keep the mount from sliding on the frame. When you put in the longer bolts, just go in about 1/2″. Using a 12″ long 2 x 4 under the oil pan, begin jacking up the motor. You need to have the crank bolt clear the front radiator support enough to get a socket on it. This crank nut is 1 11/16″. Use an air gun to get this nut off, but be sure to flatten the lock tab back
Once the crank nut is off, slide the washer (lock tab) off. Inspect it now to be sure it has a locating tab on the back of it and also to be sure it has enough meat on it to be re-used. If not, take no chances, get a new one. Now pry off the pulley. You can do this easily if you have a puller. Sometimes it will come off by tapping it on the outside edge with a rubber or plastic hammer.
Place an oil drip pan under the timing chain area. (The cover still has a little oil in it). Remove all bolts from the cover. You will notice that some have a 7/16″ head and others have a 1/2″ head.
Once all the bolts are out, you can use a screwdriver to gently prise off the cover. Clean and inspect the cover for cracks. Inspect the crank nut for cracks also. Clean and inspect all bolts and washers. You should have oval shaped washers and they should be flat. Clean and inspect your pulley and harmonic balancer.
The harmonic balancer should be able to sing “God Save The King” with little or no prompting. If not, replace immediately…you probably have a Japanese part where it shouldn’t be. Remove the old seal and the old gasket. Replace the seal by gently tapping it into place with a rubber hammer or large socket with close to the same outside diameter as the seal. Of course, a ‘seal set’ works best for this job if you have one.
Wipe down the engine block. Clean the threads on the end of the crank shaft carefully with a fine wire brush. Install your new gasket onto the cover (use “Aviation Form-A-Gasket”). Check all holes for old gunk and brush on a thin coat of sealer onto the block. Coat your new seal with grease and gently slide it over the end of the crank shaft taking every precaution not to scrape the seal against the shaft. You must now align the seal. Put some light oil around the shaft and slide the harmonic balancer-pulley assembly back onto the shaft. Gently tap it back into place while guiding it into the new seal. Try to put very little pressure on the seal. Now, start replacing the bolts. If your cover had no lock washers, it’s a good idea to use some now. Use “internal” tooth lock washers. That way your bolts won’t be too short to do the job. After all the bolts are started, ‘snug’ them up. Use a criss-cross pattern as illustrated.
After they are all in place, tighten them up. Lift up at the bottom of the cover to keep pressure off the seal.
If you don’t know what ‘tight’ means, use a torque wrench. Settings should be 10-12 lbs. for the smaller bolts (1/4″) and 15-18 lbs. for the larger bolts.
So you’re done (almost). Your new seal is in place. If you followed the instructions it will give you years of good service (50,000 miles at least). If you didn’t follow the instructions you will know right away because the new seal will leak worse than the old one.
Let’s finish up with a few good tips. Your crank nut will go on next, but don’t forget the lock tab washer. Be sure and clean the threads on the nut. Use a pick if you must, but get the treads clean. It’s very important that the nut goes on all the way back. I like to use a little red “Locktite” at this stage on the
threads of the crank. Be sure you have checked the ‘key’ in the crank for tightness and the ‘key way’ in the pulley for wear before assembly.
Note: it is not uncommon for this key way to be worn out and no longer fully functional. Call me if this is the case with your car and we will talk. The crank nut should be tightened to 125-135 lbs.
Obviously re-assembly is straight forward. If you used the long bolts as suggested, lower your motor down til it is 1/4″ above the frame and replace the long bolts with the stock ones. This little bit of space will give you maneuvering room to locate the engine mount bolts. Don’t forget to add oil (maybe it’s time to change the filter too) and of course water. This job takes about 3 hours in our shop with no problems. If you can do it in 4-5 hours you’re very good, and of course..ready to move on to the next leak. I’ll tell you how to
fix that one next time.
Welcome to Tech Tips. This is where we give you advice on technical issues based on our many years of experience rebuilding, restoring and maintaining classic British cars.
Oil leaks – Part two.