Noisy Idle

[IsaacHayes]

On mine, the replacement sprokets were a worse cast than factory, and looser with the new chain. The original ones were not worn enough (or really at all) to cause any issue. I just did the chain and new guide on my 3100. This was at ~180k miles or something.

[60dgrzbelow0]

if we are replacing the chain and top sprocket -- do we really need to replace the lower? I know it's recommended given the miles -- but it is the chain that's stretched... I've always wondered about the real need to replace the gears if they aren't VERY worn...

consider that the cam/lifters/everything else is stretched/worn...

The Short Answer: Absolutely!

The Detailed Answer:

Timing Chain Sets are exactly that... "Sets". The Timing Chain on the GM Stock TS unfortunately works by seriously hard friction (unlike that of the "TRUE" Roller Timing Set) that is caused by the flat "V" designed metal plates of the "V" shaped inner portion of the Timing Chain working by grabbing and grinding away on the inner teeth of both the large and the small gears. Because the smaller gear has less teeth and less overall surface area to distribute these forces, the torque energy coming from the driving force of the crankshaft will, over such a long period of use, seriously wear down and alter the shape and perfection of the small nose crank gear.

You have only to look at the comparison images between the stock GM Timing Set Gears and the Cloyes True Roller Set on the link I mentioned above to verify what this damage looks like...and in my case...those images are of a used GM Timing Set from an engine with under 100,000 miles!

Add to this the fact that there is very poor lubrication getting thrown centrifugally outward from the lead camshaft journal between the back of the inner large upper gear race to lubricate both gears and the timing chain. In the case of your engine running for over 144,000 miles, the smaller gear on the crankshaft will actually show very deep, striated gouges into the metal insides of each gear tooth. Putting a brand new upper cam gear and brand new timing chain in sync with such a damaged lower crank gear is a recipe for inviting serious problems when these multiple, unmatched mechanical interfaces meet.

The last issue has to do with the very big difference in sensor readings you might wind up getting that may confuse the ECM while trying to figure out why the lower block Crankshaft Sensor, the 24X S/S vane Cam Sensor behind the HB and the Camshaft Sensor located in the top, front of the engine can't seem to get in sync with each other and reconcile to keep the engine running smoothly at different RPM levels. God forbid that you start getting odd codes and misfires from this unfortunate set of mis-reads caused by the imperfections in not having an entire matched Timing Chain Set.

Forgive the question, Please ... But what is the real impediment to doing this job properly and completely?

[cold_surfer]

I'm curious on the 1993 F-body how long a chain/gear swap would take. Is this a 3 hour job or 8 hours riddled with bolts going into coolant areas? Messy job or clean? I've replaced chains and belts on 6+ cars, for reference. 231, toyota camry, WV cab, jeep 4cyl, 305, 350. The 207 bird is very clean FLorida car with recent water pump.

[cold_surfer]

60dg,

sounds like from your post the timing chain is as important as the Toyota camry 4cyl belt replacement for the timing. It was like getting a new engine in that car when getting a new not-stretched, belt. Same with the VW.

Thanks for the accurate input... I appreciate it !!!

[cold_surfer]

so what is the best bang-for-the-buck chain set? $35 vs. $100. is the cloyes really overkill if we are still running stock...

[60dgrzbelow0]

I'm curious on the 1993 F-body how long a chain/gear swap would take. Is this a 3 hour job or 8 hours riddled with bolts going into coolant areas? Messy job or clean? I've replaced chains and belts on 6+ cars, for reference. 231, Toyota Camry, WV cab, jeep 4cyl, 305, 350. The 207 bird is very clean Florida car with recent water pump.

The Short Answer is: 4-6 Hours

The more complete explanation is:

You can get this job done in a very straightforward manner with instructions from the Haynes 4th Generation F-Body Manual (Pages 2A5, 2A6, 2A7). But the amount of time this will take (4-6 hours?) depends upon on being well organized prior to doing any tear down, and prior to re-assembly, taking the time needed to clean all the mating surfaces on the assemblies using gaskets as clean as Kleenex. Having everything on this list will help:

New Timing Cover Gaskets
New Water Pump Gaskets
New 50/50 Anti-Freeze
A Drum of "Purple Power" (For Soaking Timing Cover to Remove All Traces of Old Gaskets)
A BIG Coleman Cooler (For Soaking the TC & Metric Mounting Bolts (Cleaning/De-Greasing)
A Three Prong Puller (W/ Square Flat Tines to Remove Small Gear on the Crank)
A "Y" Shaped Harmonic Damper Puller
A Tube of ARP Non-Hardening Bolt Sealer (For Bolts Penetrating into the Water jacket)
Black RTV Sealer (For Worn/Corroded areas on the Engine Block Water & TC Locations)
A Tube of Bolt Threadlocker (For the Three Bolts Holding on the Large TS Gear)
Gasket Adhesive Spray
A Small Torque Wrench
A Metric Wrench Set and Metric Sockets (Also... A Small Metal Straight Edge)
A Pan/Receptacle to Capture the Waste Anti-Freeze
A Large Flashlight

...but there is more...

Like the Bad Joke about the Podiatrist treating the patient with an in-grown toe nail... and winds up amputating a Leg... You'll have to seriously consider replacing some other components and parts once you have taken apart the front of the engine and carefully replaced the Old Timing Set with the new one. The below list shows the things that should also be replaced at same time:

A New Water Pump
A New PTFE Timing Cover Seal
A New "Speedi-Sleeve" Kit for the Harmonic Balancer
A New Serpentine Belt
A New Serpentine Belt Tensioner
A New 24X Cam Sensor (this one is ONLY exposed when the HB is removed...)

Since you are going to have all these components either off the vehicle or within easy access, it makes good sense to replace the items on this second list to ensure that engine oil or water does not leak out all over your latest repair. In the long run, it will be better to reconcile yourself to these added expenses, and perhaps avoid having to do something like...changing that old, remounted Water Pump just a week after you buttoned everything up.

It may be possible to either borrow or rent some of the tools from an Auto Parts Store and save some expense there when making your parts purchases. The Torque Values for re-assembly can also be found on this 60* Site.

As for the choice of timing sets, the Cloyes "True Roller" TS costs two or three times as much as the GM "GI" version, but it does offer a bit of a HP bump because of the big reduction in friction and the power needed to overcome it. But if performance is no consideration, a brand new stock TS will be better than anything in the engine after 144,000 miles of use.

[60dgrzbelow0]

60dg,

sounds like from your post the timing chain is as important as the Toyota camry 4cyl belt replacement for the timing. It was like getting a new engine in that car when getting a new not-stretched, belt. Same with the VW.

Thanks for the accurate input... I appreciate it !!!

Glad to help!

[cold_surfer]

I noticed the gear puller was ground FLAT on the "L" (Square Flat Tines) to make them more like flat teeth instead of a rounded spoon. Is this due to clearance issues on the back side of the gear (btweeen gear and block) or is that just the one that you happened to have ? Is that recommended or required?

Did you modify a gear puller to be like that?

[60dgrzbelow0]

OEM 27011 Three Prong Puller

I noticed the gear puller was ground FLAT on the "L" (Square Flat Tines) to make them more like flat teeth instead of a rounded spoon. Is this due to clearance issues on the back side of the gear (between gear and block) or is that just the one that you happened to have ? Is that recommended or required? Did you modify a gear puller to be like that?

I couldn't for my life remember where I lucked out and bought this damned thing, so I went out in the garage, got the tool from the tool box, took as many numbers off of it as I could, then did the "Google" research on it and found all the information you will need to get the same one. It is made by the OEM Tool Company and is marked as "OEM27011". I found the tool being sold on eBay and copped their images and made a composite photo to show you exactly what it all looks like . See Attached Image....

I could not locate it in the local stores nearby, but now that you know exactly what it is and who makes it you can call around and see if anybody has this weird puller. I did discover that OEM has their own web site and will probably charge dearly for it...but I can tell you..with only a narrow 3mm space between the back of the crank gear and the face of the lower engine block...without this little baby...it will be very hard to get the damned gear off! Here is the site:

http://www.oem-tools.com/index.php?cPath=22

In a worst case scenario...consult with John (Forced Firebird) I seem to recall this similar thread came up on another forum and he showed us all how to modify the average three prong puller to work correctly (with pics of it being used). I hope you can get exact one...It works as smooth as glass. Oh...one more thing...the nose (point fulcrum) of this little puller would slip easily inside much too far into the crankshaft bolt hole, so I looked at my Harmonic Balancer puller and glommed the conical button from that set to slip into the beveled front of the crank bolt hole first and then stuck the nose of the OEM puller inside with a glob of Moly-D Grease...and that did the trick (See Attached Photo of Button of it in use)

Hope this helps...

--==Bob==--

[cold_surfer]

just curious if the factory heats up the gear and it is easier removed with torch heat?

deep creep penetrating oil help?

I was taught on my 77 231 to use hammer/chisel to shatter the cast iron gear and remove it that way. guess that's the last resort.

[60dgrzbelow0]

The contact between the outer race of the crankshaft and the inner race of the small cam gear is an interference fit. Ergo you could try to soak the area between them for a thousand years and it would have absolutely no effect. As for your 1977 experiences, things have changed a great deal in this regard when it comes to sealing up engines from oil leaks:

So before doing anything as exotic and even dangerous as what you are suggesting, think about the heat transference involved using a blow torch in that area. Just behind that small gear is the soft, fragile front engine oil seal made of PTFE (Poly-Tetra-Flouro-Ethylene AKA TEFLON). If that seal were to begin to melt or catch fire when exposed to so much concentrated heat, it could combust at the low temperature of 900 * F and will then instantly turn into a cloud of Phosgene Gas right there in your face. One little whiff of that stuff ...and you could die quicker than you can say, "Timmy Fell Down the Well!"

But besides that little problem, the concentrated heat from the torch might also badly affect the bearings in the front your engine. If they are of the Tri-Metal variety, like the Clevite 77s, there is a possibility that the heat can moving rapidly down the crankshaft and transfer into the bearing surfaces there and either warp or even melt the soft lead or Babbitt bearing material and defeat its integrity.

Cast Iron and Steel expand or contract at the rate of about 1/64 Millionths of an inch for every one (1) degree increase/decrease of the metal's temperature. This may not seem like much of a change, but you could wind up making the small crankshaft gear cherry red to expand it away from the crank nose and have no way of stopping the crank and the front of the engine block from getting too damned HOT as well. You could end up doing more harm than good...including warping portions of the engine block that are already pre-stressed with torque on the bolts holding the Main Bearing Caps into the engine block saddles...or even boiling the oil in the adjacent oil galleries and God knows what else!

Trust me, Brother...with the proper tool (OEM Puller) and a light smear of Molybdenum-Di-Sulphide Grease on the crankshaft area in front of the small gear... With just a few turns on the tool...that small gear will come (pop) free easily and drop into the palm of your hand ...like a crisp Oreo Cookie into a Glass of Cold Milk...and you'll live to enjoy it!

[cold_surfer]

come to think of it -- the 231 only lasted 4 months after the chain switch (when we shattered the iron gear without heat but with a big hammer and chisel). What happened was the timing chain cover gasket got twisted on re-install since we used tacky gasket holder and it made a small opening that would pee out oil (only when engine was running and just a tiny amount at a time). never saw the oil leak until it was 2.5qts low, rod bearings were under lubed, and it spun a bearing in tune with a knocking rod. sold the engine for $300 more than I paid for a W-350 and did an engine swap. it was my first timing chain was a v-6 25 years ago -- all the ones afterward were 4 or 8 cyl. never did the chisel routine on a 4cyl. live and learn...

how do you properly "space" the sprocket from the block on re-install?

[60dgrzbelow0]

... live and learn... How do you properly "space" the sprocket from the block on re-install?

When you install the new crankshaft gear, it just has to be pushed on as far in as it will go, right up to the point where the crankshaft flairs (flares?) into and meets the front portion of the front main journal. When it is finally on this far, there will be a space of about 3mms between the back edge of the gear and the front face of the engine block. There are three possible methods to use for installing the crank gear:

(1) For the motor mounted on an Engine Stand, you can just use a section of galvanized muffler pipe of around 2.25" in diameter and then cover it with a length of 2"X4" that you can hit it on with a mallet. With a light smear of Moly-D...the small crank gear will make it all the way in with just a few hard thumps...no sweat.

(2) For the ITV installation, some mechanics prefer to just grease up the inner shaft of the Harmonic Balancer and using a few hardened steel washers to act as thrust bearings with some Moly-D in between, they slip the washers onto the Crank Bolt and slip the HB on the crankshaft with the small gear ahead of it...then tighten it down slowly with a medium sized breaker bar. Be mindful that the 9.8 Crank Bolt is pretty damned tough Hombre...but it isn't Superman ...and so using a small (Ladies Compact) mirror to eyeball the proximity between the back of the small gear and the engine block until its finally all the way in will prevent you from over doing the job and breaking the Crank Bolt off inside the crankshaft. Keep in mind that you will have to immediately use a the Harmonic Balancer Puller to remove the HB ...so that later you can install the Timing Case Manifold and Water Pump and then re-install the HB for the last time.

(3) The last way may be the easiest because it involves using the factory tool ...a Kent-Moore item # J-38612...It's elegant, simple in design...and generally...as scarce as Hen's Teeth. It consists of longer version of the 9.8 crank bolt with strong hex head and a floating larger hardened thrust washer. The bolt/washer portion slips inside the second part of the tool set: A hollow section that sports a female key way to slip along over the crankshaft Woodruff Key. The thrust washer rides on the outside of the hollow part and when turn with a large socket and bar, the bolt drives the whole unit against the front of the small gear. It works very well in driving the gear all the way on in short order.