Replacing Leaking Cam-Hub Outer O-Rings (Seals)
Part Two
Part One - Main Article
Tools (Cam Pullers)
Cam Hub Diagram & Dimensions
KARL MAXON'S NOTES
Some time back, I was looking for a puller to be able to remove the cam pulley hub on the V6 engine. This was to replace the small o-rings behind the hub which were leaking quite a bit (also useful in case the intake valve clearances need adjusting).
The front was a breeze with a normal harmonic balance puller. I bought an inexpensive Lisle brand model 45500 puller (from generic discount tool outlet) and used 50 mm bolts for the front cam pulley because the puller is (was-more later) 1 inch thick. I bought a short (1 inch long) bolt to replace the very long center bolt that came with the puller (5/8" dia 18tpi grade 8).
For those familiar with the 164, the rear cam pulley has very little room to work with between the pulley nut and the right firewall (approx. 2 1/2 inches). So, in order to get in the tight space, I ultimately made a puller to fit: I took the Lisle puller noted above to a machine shop, and for a small fee they milled the thickness to exactly 1/2 inch total thickness - flat on both sides (it comes rounded on one side). The center bolt was ground down by the shop also so that the total thread length matched the thickness of the puller (and so total bolt length was approx. 1 inch long). I then used 40 mm bolts (7mm dia like stock - 8.8 grade) to allow the pulley to be "spaced out" after fitting it in the tight space.
The end of the cam fits right inside the center bolt hole so the puller bolts cam be put in easily, starting with the bolt farthest from the front of the car (without the center bolt in place, otherwise your fingers can't get to the back bolt). You have to leave a space between the puller and the hub of approx. 1/4 inch, so that there are enough threads for the center bolt to start with. I then inserted the center bolt (takes nimble fingers), then the final two puller bolts can be put in. Use a large wrench to start pulling, while using a suitable tool to hold the pulley from turning by accident. The reason the puller needs to be spaced/gap'd out a bit is that if the puller is tight up against the hub, only a few threads are available to start the center bolt, which is not enough given that the puller appears to be a cast iron variety.
With careful patience, the hub popped loose, and removal of the puller bolts and then the hub was as easy as could be. In order to have room to work with, I moved the dog bone (undid front bolt after loosening the bone and swung it out of way), the back pulley timing belt cover (went in and out easily because of the tabs on the bottom of the cover), and rubber fuel line. I moved the few electric lines out of the way also. I also had the right inner fender removed, and used a large 1 5/8" socket to turn the engine to top dead center, and marked pulleys and hubs for reference just in case. Everything else stayed in place!
Note that I had responses to inquiries regarding the pulley hub removal ranging from "undo the motor mounts, jack up the engine and use a regular or factory puller"(response from Alfa dealers), to "we don't do that until the heads or engine is out of the car"(various shops and Alfa dealers), and "you need to drop the sub-frame with engine"(1 shop and an Alfa dealer).
My 164L is a 1991 with 106,000 miles on it. I understand that later single cam V6's have a one piece pulley to rectify the leaking o-ring, but I haven't confirmed this. The o-ring is a tiny round rubber-band sized piece that costs approx. 50 cents. That's all that keeps the oil from leaking from inside the pulley, as the outside has the normal large oil seal in the cylinder head.
I tried locating a factory puller but they are no longer available, and from the descriptions I could get, it doesn't fit the tight space of the rear area, hence the jacking up of the engine for routine valve adjustments I suppose. I used the factory pulley tool to hold the pulley from turning while removing the cam pulley large nut (Alfa part number 18200 51000 00 00), and a Proto brand "torque adapter" 7/8" size, with 3/8" drive - its 2 inches long (part number 5128, I got from a Proto dealer) - to torque the cam pulley large nut back down with a torque wrench (I used a regular 22mm wrench to remove the nut - 7/8" is just over 22mm). The factory manual procedure is to torque down them center nut, then tighten the pulley small bolts. I did the entire procedure with the timing belt in place, and it took less than 2 hours start to finish, even being super careful (timing belt still on &endash; so didn't want to end up pulling everything!!!).
Since replacement there has been no real oil leaks from the O-rings. The cam seals appear fine for now, and I see no detectable leak. When I had the distributor off recently, I replaced the O-rings there as well, and now the top-end appears to be nice and dry all around. The leaky cam O-rings were getting oil all over the timing belt, and as I had just replaced it I wanted to help ensure increased reliability and longevity. Time will tell on that end!
-------Also look to see if the oil pump pulley seals are leaking (visually from oil wetness). I don't know of any way to remove this pulley with motor in the car, but if you still see some wetness after replacing your o-rings this may be the cause. The big cam seals should be OK, so you may not want to wrestle with trying to get them out, and may want to wait until you do a complete timing belt replacement or motor out/heads off to do that.
You should be able to replace the o-rings without pulling the cam covers/air box etc. if you're very very careful and use white-out and scribe marks at TDC on the pulleys. You may need to remove the belt covers to have enough room to manuever with the fingers, but maybe not, as the factory manual shows the cover being left on (just small caps are removed to pop the cam hubs off) for routine maintence/valve adj/intake cam removal without removing the timing belt. Just take your time and be methodical.
I recommend reviewing ALL sections regarding valve adjustments, engine teardown, and timing belt procedures (including TSB's) on the CarDisc CD ROM prior to commencing, to see how factory removes those hubs. They're available at www.cardisc.com I believe. The "91-93" disc should work for you as it has the 3.0V6 in it. If you already have the manuals, etc, it sounds like you're set. I also HIGHLY recommend the factory cam pulley holding/turning tool and are really long 22mm open or box end wrench to get the cam pulley nut off!
Note that clearance is hampered mostly by the thermostat housing on the front cam pulley, and by the fender well and A/C tube on the rear cam pulley. Again if all you're doing is removing is removing the hubs, you should be fine.
-------A procedure deliberately left out of the article is the use of "heat". All shops I spoke to needed to use a small propane torch to heat the hub right around the end of the cam as well as the nuts to get them off (hence find a really long 22mm wrench combined with the factory tool). Use LOTS of industrial foil AND asbestos wrap used on racing applications around exhaust pipes and the brake master cylinders to cover EVERYTHING remotely susceptible to heat damage, and ESPECIALLY move the fuel lines out of the way and keep all heat/flame away from all volitile compounds, and have an extinguisher at hand.
-------I wrestled for quite awhile before finally doing like all the shops recommended (applying heat) and voila, the nuts pop'd right off (also using liquid wrench/WD 40). I then wrestled with trying to get the hubs off with the puller, then finally again leaving the puller ON the hub (to keep the pressure on the hub) applied some heat to the hub (through the slots in the puller) and again, the voila, the hub pop'd right loose. PROCEED AT YOUR OWN RISK using open flame/heat as described above. Several shops told me - that if the nuts and hubs come off without lots of anguish, they weren't on there tight enough to begin with!
When the hubs pop loose you'll think something broke (like the puller) as it goes "POP/CRACK" - at least both of mine did...
Click here to see Karl Maxon's harmonic balance puller
MATTHEW DOOHER'S NOTES
To replace the cam hub O-rings: I followed the detailed instructions provided by Karl Maxon to do this job. I also made use of detailed pictures and measurements provided by him to create a puller and a cam pulley holding tool. The job was so very easy. I can't believe I put up with leaking seals for so long. Leaving the old cam belt on at this stage and having the engine at TDC meant that I would know if I made any mistakes or slipped a tooth etc. The only mistake I made was to take off both hubs at the same time. By doing this when you attempt to undo the other hub nut the cam belt moves a little and of course the pulley on the first shaft is free to turn because it is no longer keyed to the shaft. To put it another way, the free cam shaft stays where it is and the one you are working on rotates as does the crank shaft.
Once again, Thanks Karl great advice and thanks to Alfa Bill and IAP for various bits at half the price of my local dealers.
Just remember don't take both hubs off at once! Other than that you will wonder why you put the job off so long
No I didn't use heat to get the big nut off I did however use a 3/4 drive socket set with a 600mm long breaker bar. My home built cam pulley holding tool is also this long. Thinking back it took quite some force to release the nut. I had one person on each tool. (make sure the person owning the car is the one holding the cam pulley holding tool!)
As for the popping off of the hubs they did pop off true. I was using a 12 inch shifting spanner to tighten the centre bolt on the puller and it did get quite tight. But nowhere near needing heat.
My puller was made from a solid piece of 1/2 inch plate so there was no buckling and it certainly wasn't tight enough to strip the 7mm bolts. So I would say try it with no heat and if you need it then worry about it.
Click here to see Matthew Dooher's harmonic balance puller
CHECKING FOR TOP DEAD CENTER (TDC) - SEE TSB 91-03, 91-04
You can ignore the mark on the timing wheel and instead align the front crank pulley notch with its marker, about 10 o'clock, while being certain that the cam markers are pointing inward, toward each other, at about the 1 o'clock and 11 o'clock positions (I never found these with the cam belt covers on - Ed). Also, you may like to confirm that the flywheel is at the vertical line.
Mark this position of TDC precisely or you will need to remove the cam covers to confirm that the notches on the middle of the cams are aligned. This method is more fool proof, yet is not necessary if you are extremely careful in your marking and the cams are correctly aligned to begin with.
THE DOG BONE (IF you need to remove it):
How to remove it: The dog bone has two opposite threads on it, one is right-handed the other left-handed. Take a good look at thread, the right handed screw slanted to right( the normal one ). The left-handed thread slanted to left. If you are not sure, use a right-handed thread screw to compare them you will see what I mean slanted to right or left. Release these two nuts on dog bone ( the length adjustment bolt ) one at time by using two open-ended wrenches. One wrench on center of dog bone to keep it from turning, the other wrench at nut to loosen it. Watch out when loosening the left-handed nut, you turn the opposite direction of right-handed nut to loosen it.
Now, loosen the ( vertical ) screw that secure dog bone to body first. Don't remove it yet. Then loosen the horizontal bolt that secure the dog bone to engine block. Now you should be able to remove both screws if dog bone is not in too great tension. If both screws seem to be quite tight, use the open-ended wrench to adjust length of dog bone by turn center of dog done. You have to get two nuts on dog bone out of the way( toward center ) to adjust it. After you release tension it should be easy to remove both screws that secure dog bone to engine and body. Now adjust the dog bone to shorten it so you can remove it from the tight space.
How to put it back: opposite of above procedure, the dog bone should be shorten to make it easy to get into tight space. Then lengthen it...
Dog bone adjustment: I need to put a little bit tension( or compression ) there. By no tension I mean after I put it back and before tighten the vertical screw on car body, I can insert and remove the screw with no resistance. Now, at no tension position, I tighten both screws that secure the dog bone to body and engine block. Now adjust the length of dog bone by using open ended wrench turning at center of dog bone. You can either shorten it ( under tension ) or extended it( under compression ). I think about two turns of dog bone should be enough, remember because the two threads one dog bone are opposite, each one turn change length by two pitches of thread.
After adjustment is done. use one open-ended wrench prevent dog done from turning, tighten two nuts on dog bone one at a time by use another open-ended wrench.