Inspect timing chain on 1972 Eldorado without pulling engine

[dochawk]

I have my water pump off (and boy was it ugly).

It's been checked that I inspect or replace the timing chain while I'm at it.

Checking the manual for the timing chain, it seems that for the Eldorado, it begins with "remove the engine"

Is it possible to just inspect the chain without pulling the engine (which is still a bit beyond me).

I have the torque wrench to put the screws back on correctly, but still haven't bought the engine hoist.

[Bobby B]

Rich,
Hi.  Are you getting a " Wobble" or "Wandering" of your timing mark on the damper with the engine running and a timing light on it? You can pull off the distributor cap to expose the rotor. Get a breaker bar on the crankshaft bolt and turn the engine slightly in one direction to put tension on the chain. Now turn it back while looking at the rotor and see if it takes a few degrees before the rotor moves. Remember that the cam is connected by a 2-1 ratio sprocket or gears, so it only turns once to the crank’s two turns (Two crank degrees equal one cam degree). So take this into consideration when calculating how much your "slack" is, in degrees. Usually 5 degrees is acceptable, between 10-15 degrees, time for a change. This is one of the reasons that most cam manufacturers build 2-4 degrees advance into their cams, anticipating wear of the timing chain, which would retard your engine that much during normal wear. Mostly seen when degreeing in a cam with a degree wheel.
Good Luck!
            Bobby

[The Tassie Devil(le)]

You can inspect the chain by pulling the Distributor, and looking down the hole and inspecting the cam gear teeth to see if there is any nylon covering.

Plus, with a long screw driver, or a piece of heavy wire, reach down through the hole and see if you can "waggle" the slack side of the chain.

With a small hook on the piece of wire, see if you can lift the chain up and down from the cam gear.

Any movement here, and you need to go deeper.

Bruce.

[dochawk]

So if I peak down, and all is tight, and the nylon on the chain looks even, I'm good?

This only has 89k miles on it.

If I don't have to disassemble further, it could be drivable again tomorrow!

thanks

[bcroe]

If I saw nylon on that set, I'd replace it NOW before that ancient
piece can fall apart and wreck my engine.  You can pick the time
to do it, or the engine will pick the time for you (at the side of the
road). 

Changing the timing set on a front driver is not a fun or simple
job, just something I have had to do many times to have a reliable
driver.  As far as I'm concerned, 6 degrees of slack at the crank
means the timing set is completely shot.  Bruce Roe

[The Tassie Devil(le)]

The nylon is on the teeth, not the chain.

Here is a picture of a bad cam gear.   And a loose chain.

The last picture is what came out of the oil pump screen.

Surprisingly enough, the car was still running beautifully, and still had good oil pressure.

Bruce.

[Scot Minesinger]

I replaced the timing chain on a 1972 Eldorado without pulling the engine.  The replacement went very well.  If the chain is original, you should replace it.  The cam sprocket is aluminum with a nylon coating and not durable, which is the main reason to replace the timing chain set.

The water pump is off, might as well tend to the timing chain is a little inaccurate, in that you also have to pull distributor, fuel pump and oil pump to do the job.  If you have not done this type of work before it can be done just taking your time and reading.  If you have it is a weekend job, if not several weekends.  It is winter so it is a great time to do it.  The other factor is if you are also completing mechanical restoration work concurrently - media blasting and re-finishing.  If no restoration work, job goes much faster.

The front engine mount often goes bad from an oil leak on front engine cover.  Make sure your mount is good now, if not you have to have yours re-vulcanized - no replacements available.  When front cover is re-installed make sure it is sealed well or you will loose that front engine mount.

Let us know if you want to replace chain set without removing engine and will guide you through it.  It is not too much of a deviation from shop manual.  As I remember you were removing it anyway from other posts - true?

[TJ Hopland]

Its too late in this case but for future reference or others reading and considering this take timing readings before you take anything apart.   If the engine was more or less running good you really want to know where the timing was running.   A timing light, tach/dwell meter, and hand vacuum pump w/gauge are the needed tools. 

Get the base reading then without the vacuum connected then rev it up to the 2500-3000 range where the mechanical advance should all be in.   Then hook up the vacuum and see what that ads.   To get all these readings you will either need a 'dial back' timing light or will have to add marks to the pulley.    To add marks you measure the distance for say 10 degrees on the existing gauge, if its 3/4" you make a new mark 3/4" from the existing notch that will be +10 and another one from there that will be +20.   This means if you are seeing your +20 mark align with 6 on the gauge you are at 26*.     A dial back timing light would have a dial or setting on it that you would set to 20 in this example that electronically delays the flash 20* so again if you see 6 you are at 26.

Reasons you want to do this before you take things apart is say something is amiss with the pulley and gauge?   Lets say you do take before readings.  Car runs great now but for some reason reads base timing is 20* ATDC (after top dead center) which can't be a real setting.   Lets now say same car and you didn't take before readings.   You make your repairs then put the dizzy back in and set it to the spec of 6 BTDC.   You are now 26 off from where it was happily running and are not going to be happy because it either does not run or barely runs now.    What if in the process you find out the distributor has issues and replace it?   Replacement doesn't run as good as the bad one did?   IF you have those readings you can compare and then possibly make adjustments to get them to match or find out you just don't have the right dizzy. 

In the case of finding out the reading is 20 after ideally you would want to try and figure out why before really taking things apart.   On a lot of engines its likely because the balancer slipped.   In that case get it replaced then take readings then proceed with the original repair.    If you can't figure out why its off at least you will know what settings work.     

[TJ Hopland]

Forgot to respond to the original question...     Looking down the dizzy hole is how I do it too.   Based on what I see what happens next.   If its a fairly new to me car and it looks OK I would leave it and get some more miles on it and see what else breaks and how much I like the car.    If its terrible I would replace it in the car and then again drive to see what else and such.

If you like the car and plan on keeping it for a while chances are eventually you are going to want to pull the engine for at least a good cleaning and some new seals and gaskets.  Same with the transmission.   Its not a cheap process and often has a bunch of might as wells but will be worth it in the end.    Doing that too early really stinks because you just don't know the car yet.  Could be other issues with the car.  Could be you really don't like it or drive it.    If you like it and drive it its a lot easier to justify spending the money.    When its out you can get all the crap cleaned out of the pan and oil pickup tube as well as have much better chance things are not going to leak.    Also lets you see a lot more of the engine to either know its good or know it was bad so got addressed as needed.   Good time to replace mounts and clean/detail the engine bay. 

Don't forget when the timing cover is off to get some nuts welded to the inside for those small water pump bolts.   Nuts there will make sure the water pump is leak free and stays that way.  You can't tell from the outside they are there so you don't have to worry about loosing points at a show.    It really stinks to have to pull the timing cover a second time to do that after you have a complete engine installed in the car.

I have not tried it myself but I have been told the 'patch' for when those 1/4-20 water pump threads strip is to get the metric equivalent which is just slightly larger enough that they will sort of hold in damaged threads.   

[dochawk]

In no particular order . . .

1)  Engine wasn't running "well" before this. It was amazing that it ran at all, as some clown had connected there plugs in random order before I bought it . . .vacuum lines are a mess and similarly randomized, I think.  And I have a new delco rebuilt carb, but still have to adjust it--at the moment, 4mpg.  So a quart of fuel per mile, and was losing water at about the same . . .

2)  I guess the question is how much harder it is to do this with the engine in place.  Once this is actually somewhat drivable, my attention will change to swapping the engine in my Miata, which will involve buying an engine hoist.  Given that the hood is already off, and that I'll have that hoist in a couple of months, and will need to lift engine anyway for the mounts, does it make more sense to wait to change the chain until I do this?

3) I see both Cloyes and True Power chains out there, both about $14, but no Delco.  Any reason to prefer either?

4) since the nylon is on the gears, what am i looking for inspecting through the whole the distributor leaves?  Just that it is tight?  debris?  and an even coating on the cam gear that I will see?

5) That sure looks like the water pump in the upper part of the photo on p. 6-118, with associated torques for bolts on 6-117.   No mention of this was made in the section on the water pump.  I assume that I should carefully adhere to these remounting the water pump?

6) At this point, if the job will be easier later as part of another job that has to happen and won't harm me to put it off it's a no-brainer to do it later.  It's much easier to stay motivated with a car that *can* be driven than to pick away at a *someday*.
thanks to all

[TJ Hopland]

A lot of confusion with the firing order with this family of engines (472-500-425-368) is the physical numbering of the cylinders.   Most people would think to look up the firing order but don't think to check the layout.  Having the odd bank on the left side was unusual, kinda like the Fords that were not even odd. 

The issue with the water pump is the 3 different size bolts.   The big and middle size ones are decent sized and thread into the cast iron block so as long as you are not a complete hack you really can't screw them up.  The torque range that will work is pretty wide.    The 3?  small bolts are the issue.  They just thread into the 'tin' timing cover.   Odd design choice since the cover is pretty thin.  A fine thread would have been a better choice because then there would be 1/3 more threads.   Bottom two often are where leaks are for various reasons so are often the ones where someone will just try a little tighter to stop the leak. 

The typical 'mechanic' does not get a torque wrench out for most things,  they just look at the size of the bolt and kinda wing it.   In this case your brain kinda looks at and thinks about the bigger ones so your internal torque setting tends to be a little high for the little ones.    Or like I did one time I did look at the book and then switched on the 'auto pilot'.   Bolts A and B 40 (ftlbs), check.   Bolts C and D, 35, check.   Bolts E and F 120, check.    And as I am trying to crank those little bolts to 120 ft pounds I am thinking that is a little odd for such a small bolt.....  One of those slow motion moments where you know you are about to be in trouble and should have known better.     The little ones are given in inch pounds and clearly noted as that but when you are in a hurry who really reads everything carefully?   I didn't actually look up the numbers for this post, just made em up so don't use them on your car.

Go with the Cloyes.  So far that is a brand that seems to be holding up their quality.   Lots of stories about pretty much all the others having issues with the crank sprocket shattering, hopefully on assembly, not a few miles down the road.    IF you really plan on keeping the car and putting the miles on Cloyes also makes a roller chain that should last forever.  Roller chain is like a bicycle.  Those don't wear like a link belt but cost more.

Yes you are looking down the distributor hole.  You can't see a lot but usually you can see enough to tell if its really bad or not.   Like the others described you may get some things to shove down there to poke at it or try and clean a spot for a better look.   

Doing the chain in the car isn't horrible.  You take the radiator out to get a little room, even better if you can also pull the condenser.  I think in a 72 you just about have room to sit up there then.  Just be sure to catch the pins and stuff a rag in the pan opening so you don't loose a key or bolt in the pan.   Problem comes in getting things sealed up around the pan since the pan was designed to go on after the timing cover but most likely it won't leak any worse than it did before if its 40+ years old anyway.   Working with the engine in a stand is so much easier on the back plus you can roll it around so gravity is on your side holding gaskets in place and keeping oil from running onto your fresh rtv or gaskets.