jaunty75

Quick question: does replacing the timing chain on a 455 require removal of the oil pan?

I'm trying to decide if this is a job I can tackle myself or if it is beyond my capability.

The situation is that, out of the blue, the engine in my '73 Custom Cruiser will barely run. I parked the car one night last week with it running fine. When I go to start the car the next morning, it started, but it ran VERY roughly, spewing black smoke, making a clattering noise that didn't sound healthy at all, and it would not stay running if I did not keep my foot on the gas.

At first I thought it was just a flooded engine, but it did not smooth out after a few seconds. It sounds and acts like I think an engine that is badly out of time would sound and act. I can't check the timing because it won't stay running unless someone stays in the car with their foot on the gas, but then it isn't at idle, and I'm afraid that, with that clacking noise, I'm potentially doing damage every second I keep the engine running. Plus, the engine is shaking so much that I doubt I could keep a steady aim on the timing mark with a light, anyway.

I don't know what else to check. I recently converted the ignition system to electronic, and I reset the timing after doing so. The engine has run just beautifully since that conversion (about a month ago) until now. I thought at first that the distributor hold-down bolt might have loosened and allowed the distributor to turn, but no, it's nice and tight.

Page 6B-31 of the '73 service manual has a section titled "Timing Chain and Gears (with front cover removed)," and then going back a section to Front Cover removal, step 4, says "drain and remove oil pan." I presume this answers my question, but I wanted to hear from anyone who might have done this.


My other problem is that getting the oil pan out might not be much of a picnic itself. About six months ago I had the car into a local shop that has done some work for me on it (primarily getting my air-conditioning system working again--but this time it was for some front-end work), and while they had it on the lift, they noticed oil seepage around the oil pan gasket, and they offered to replace the gasket. Then, after looking more closely at the situation and what would be involved in getting the pan out (removing starter, exhaust pipes, crossover pipe, flywheel cover, disconnecting engine mounts to allow jacking up the front of the engine), they withdrew their offer to replace the gasket. They told me that there is too much rust around the various bolts that would have to be removed to remove these various things to get at the oil pan, and they were afraid that they would not be able to bolt things back together again afterwards. In other words, it sounds like the bottom end of my car is being held together by rust!


The car has 110,000 miles on it, and the timing chain is original as far as I know.


So the situation is that the car won't run without, apparently, replacing the timing chain. The timing chain can't be replaced without removing the oil pan. The oil pan can't be removed because doing so might render it impossible to put the car back together!

Suggestions?


Thanks.

oldcutlass

The timing cover does not require pan removal, just losening the front few bolts. Tough call on running the engine the way it is without any of us seeing what it's doing. Your assumption on needing a timing set is probably very good.

Oldsmaniac

Are you sure the carb isnt flooding? Black smoke and not running at idle is a good indicator. Dont just assume it is the timing chain. You can check to see if it has jumped time. It is much easier to do timing chain set with oil pan off as the pan and gasket is designed to seal against the timing cover bottom. You will need to loosen front of pan to get timing cover off and then when you are ready to assemble you probably will have oil leaks because you disturbed the original pan gasket.

young olds

ive changed a timing chain with the engine in the car and did not remove the pan, this was on my 68 delta at 16 and had no way to remove engine. i do believe i loosened all the bolts so the pan was a bit lower. I also did a cam swap on my engine on a stand and did not remove the pan, just loosened the pan bolts all the way back.

young olds

to check timing by yourself you can bump it up a little at a time with the engine off and start it after each bump to see if it helps. if not return it to where it was before.

jaunty75

Thanks. I thought of flooding, and I haven't fully ruled it out. But would that account for the wake-the-dead clacking noise? Also, wouldn't you expect the engine to smooth out if I rev it up? It gets no better in this regard.

HOW do I check to see if it has jumped time?

jaunty75

Cool. Thanks.

jaunty75

Thanks. I wondered about this. If true, why does the manual have you go through the seven stages of hell to get at the timing chain?

oldcutlass

Because you may get leaks as Oldsmaniac mentioned in an earlier post. Also the plastic bits from the timing gear are usually wedged in the oil pump pickup screen. While most of the time there is still enough open screen surface area to get good oil flow, it's always nice to clean it out.

jaunty75

Cool. Thanks.

steverw

It might not be easily accessible but you will have to to change the timing cam gear anyway. Try first removing the fuel pump, then theres a window to see the timing chain, not easy but doable, you can feel if theres excessive slop which im sure there is with that milage. And if you have or know someone who has one of those flexible video cable cams (Harbor Freight) you could inspect it even better with it. Maybe the timing gears can be changed without removing the fuel pump, but seems to me that pump arm will be in the way as it runs off the drive on front of the cam, that pump drive will come off anyway to replace the gear. I was able to feel some slop on the other 67 I have this same way and could see it "kind of" from the hole for the pump.

Oldsmaniac

You can bring #1 piston up top dead center on compression stroke and see if timing pointer is pointing to 0 on balancer. Then check to see if rotor is aligned with #1 plug wire on dist cap.

I dont know what to say about clacking, seems odd to me it would do that with a jumped chain or a flooding carb....

jaunty75

Thank you. How do I bring the #1 piston to TDC? (I apologize for all the questions!)

jaunty75

Thanks. I think the fuel pump has to come out. The eccentric is right there in the way of everything.

Octania

Dropping the pan is not THAT big of a deal
rusty xst bolts will snap off, so use your BEST voodoo to prevent that- penetrating lube, HEAT and lots of it, impact not operated at full tilt, etc. Other than that, it's not all that bad. May have to remove motor mounts from engine to access pan bolt in there. Universal SOCKETS will greatly aid this job:

http://www.ebay.com/itm/Snap-On-1-4-...item259600de88

Lift engine as much as you can
turn crank to favorable position to get the pan past front counterweights on crank.

Do the timing cover and set thing
clean out pump pickup
reassemble.

It's not the end of the car, just a damn lot of work best done by someone well versed in getting rusty fasteners apart w/o breaking them.

Oldsmaniac

It may be a 2 person job. With socket on the balancer bolt you should be able to turn the crank. You can also bump the starter. #1 spark plug removed you are looking for the piston to come to the top. On the exhaust stroke one valve will be open when the piston comes up. On the compression stroke both valves will be closed, providing the chain has not jumped time. If the chain has not jumped you should be able to feel pressure or air release out of the spark plug hole while someone is turning the crank bolt with the wrench and the piston is moving up and finger is on the spark plug hole. Do not use finger if bumping starter electrically.

m371961

You can loosen the front half of the pan and get it low enough. Use a lot of silicon squeezed into the gap along the pan when bolting it back up. Pan bolts should come loose easily. The oil seepage you had was most likely from loose pan bolts due to gasket shrinkage/compression.
You can bump the engine with your finger just on top #1 plug hole and feel compression stroke. Put dampner timing mark on 0 and check where rotor points.
You can also turn engine back and forth by hand and see how much the engine turns before the distributor rotor moves.

MDchanic

I would recommend cranking the engine with a timing light on the balancer.
You just reset the timing recently, so you know what it should be. If the chain jumped, then the ignition timing will be off (retarded), because the distributor is driven off of the camshaft.

If the timing is set right, then you can save yourself some time and aggravation for now, but at 110,000, you'll need to do this sooner than later no matter what.

- Eric

jaunty75

Couldn't this also account for the clacking noise? It could be just severe knock? Knocking is, after all, the firing of the spark plug at the wrong time for whatever reason causing the piston to rattle around in its bore, and being out of time due to a slipped timing chain could certainly be a reason for the spark plug to fire at the wrong time. If all 8 spark plugs are firing at the wrong time, and the engine is so out of time that they're firing at the REALLY wrong time, it could sound like someone playing castanets.

oldcutlass

But retarded timing will not cause a knock just very low power because your firing when the piston is past tdc, knock is when you fire before tdc and its forcing the piston back. Some of the noise you may hear are backfires, chain rattling around in the timing cover, etc.
Now it's not to say it can't be a failure of your ignition and I've seen that do really strange things. I would do the mechanical checks suggested above prior to tearing into it.

MDchanic

Well... I wouldn't quite phrase it like that.

Knocking due to detonation is caused by the meeting of two pressure waves in a nearly explosive manner, causing some of the energy of that collision to be transmitted through the cast iron of the head and the water of the coolant, so that you can hear it.
If the spark plugs are firing at idle, but at the wrong time (presumably too late), then they should be firing when the piston is already moving away from them, thus not causing colliding pressure waves.

If the timing chain has slipped, there is a chance that the chain itself could be making noise, due to increased slack from whatever it was that had been holding it in place finally giving way (that last bit of nylon gear teeth, perhaps), which allowed it to skip in the first place, but, aside from less-smooth running, there should be no other noises, especially in your low-compression motor, which should not have allowed the pistons to strike any valves.

If, contrary to the way things are supposed to be, a piston did hit a valve, and bend either the valve or the pushrod, then you could have clatter in the valve train.

OR, you could have a completely different problem form the timing chain.

Best to start by checking the timing - if I recall, the crank timing should be retarded 22° for every tooth that is jumped (I calculated it out once, but it's hazy now).

- Eric

jaunty75

Good point. But how does one know that the timing is retarded? Couldn't it just as easily be advanced by a timing chain problem, or do timing chain problems generally manifest themselves in a particular way?

jaunty75

Good thought. This hadn't occurred to me.

Yes, I realize I need to stop speculating and start checking some things. I won't have a chance to get at the car before Friday, unfortunately.


Thanks to everyone who responded!

MDchanic

The timing chain has to drag the camshaft around in circles.
The camshaft is hard to turn, because it is hard to compress the valve springs.
Therefore, the camshaft will fall behind when it skips a tooth, which will make both cam and ignition timing retarded.

- Eric

jaunty75

Makes sense. Thanks.

oldcutlass

A slipped timing chain by pure physics will retard timing.

Oldsmaniac

The few times I have dealt with timing chain problems the engine would no longer start and while cranking there was no compression only a whine and the starter seemed to have little effort in spinning the engine. Also fuel vapors would be emitting from the carb instead of air being drawn in. I am confused by black smoke and the noise. You may want to pull the mechanical fuel pump and at least look at the lever and as suggested get the cheap Harbor Freight inspection camera thing and look inside at the timing parts.

cjsdad

Not an Olds, but I had a Ford Torino that had a badly worn timing chain and gear. It ran very roughly by the time I took it apart to replace it, but it ran. The trick was getting it to shut off. It dieseled terribly.

A simple way to check if the timing chain and gears need to be replaced is to remove the distributor cap and turn the crankshaft forward, then reverse and see how far the crank rotates before the distributor turns backwards. If the crank turns more than just a few degrees, it needs to be replaced. The timing cover can be removed and replaced without dropping the oil pan, it just takes a little finesse putting it back on. If you find large pieces of the synthetic cam gear teeth are missing you can use a strong light and a grabber to try and pull them out of the pan.

nsnarsk65cutlass

Yes, the timing cover can be removed and installed without removing the oil pan,but if the chain is required the cam gear pieces will be in the pan and eventually get sucked into the oil pickup and cause problems.Pan removal and clean out is best.How rusty can it be?That a shop turned down oil pan r&r there in New Mexico.Try working on salt belt vehicles,just sayin'.

RetroRanger

^^^^this, you know how the old saying goes always check the last thing you worked on well I would start here. Aftermarket e ignitions can be less than reliable and electronics can have a certain percent of infant mortality HEI is probably more reliable than Petronix but any e ignition recently replaced would be suspect in my opinion.

Also like olds maniac stated when my t chain slipped last year the engine turned over but wouldn't start had an ocaisional moment whee it sounded like it might start but mostly was a starter like whine

Still w 110k on an original chain it needs changing....

76 Regency

Hey Jaunty,


I recently did the timing chains and gears on both of my '76 98's and although you CAN do the job without removing the oil pan, I wouldn't recommend it. Like mentioned above, loosening the pan bolts will disturb the pan gasket and you may be causing leaks. This is a good time to replace the pan gasket and while you're in there, the oil pump. The screen should be cleaned out as well. When I did this job on my red 98, the screen was horribly choked with plastic bits from the cam gear. Check out the pics in my post on this job. Aside from the ton of slack that was in the chain, the increased oil flow and tight timing have made an incredible improvement in the performance of the engine.


https://classicoldsmobile.com/forums...placement.html


My cars have dual exhaust which made dropping the pans a bit easier. I also made an engine lift/cradle that I'm able to raise the engine up enough to give plenty of clearance to drop the pan, clean and prep all of the mating surfaces and put it all back together. I used it on both cars and I'm so glad I came up with the idea. It was a ton easier than using a hydraulic hoist.


Good luck!

jaunty75

Update.

I found the time this morning to go out and look at a few things. I realize, as mentioned by RetroRanger, that it's always good to go back and check the thing you most recently worked on. I had visions of the various items installed under the distributor cap being in small pieces or coming loose or something, so I checked that first. Everything looked solid and fine.

So I thought, well, the car's been sitting for six days, and we all know that time both heals all wounds and wounds all heels, so, I thought, why don't I try starting it again. Of course, wouldn't you know it, it started up just fine and ran beautifully. Remember, I tried starting it several times over the course of the day six days ago, and every time it would run rough, spew smoke, etc.



For now, I'm going to pronounce this the winner in the "what's wrong" sweepstakes:

I think it was flooded. Perhaps there's an intermittent problem or the beginnings of a problem in the carburetor.

In any event, I'm relieved to find that I apparently do not have to deal with the timing chain, at least for now. To be honest, I was thinking of selling the car and devoting my time, money, and garage space to my '67 convertible, so look for an ad in the For Sale section sometime soon. Of course, you'll all know about this thread, so you'll all know what you're getting!


Thanks again for all the responses.

johnnyjaws

just take off the fuel pump stick ur finger in there and feel the timing chain if it moves at all its shot its that simpie