Grind, rattle, shook, stop

[DRob95]

OK, my son was taking the scout out to the ranch and half way there he heard a grinding noise, than the scout started to rattle and shake, and finally died. We've tried starting it and it seems like it wants to turn over.

So my guess is that it's the timing gear, but how often do these things fail?

It's getting spark to the plugs and gas to the carb. Other than that I have no clue.

It's 1973 IH Scout ii, 345, motorcraft 2150 carb, 727 auto, EZ wire setup.

[74 Scout ii]

if its getting spark it isn't a timing gear the distributor is driven off the cam and mechanical fuel pump is too. more details about the scout might help. will the wheels rear wheels turn ( thinking diff), manual or automatic?

[DRob95]

Originally Posted by 74 Scout ii

if its getting spark it isn't a timing gear the distributor is driven off the cam and mechanical fuel pump is too. more details about the scout might help. will the wheels rear wheels turn ( thinking diff), manual or automatic?

I'm not sure how the rear differential would cause it not to start? It's an automatic 727 tranny.

When we try to start it, it sounds like it wants to turn over, but than we get a small puff of smoke out of the carb. I don't hear any grinding when we try to start it so it's probably not the timing gear. Just my original thought.

Oh, also my son said that the coil fuse blew when he stalled out, so we've replaced the coil and the fuse.

[thehud]

Originally Posted by DRob95

I'm not sure how the rear differential would cause it not to start? It's an automatic 727 tranny.

When we try to start it, it sounds like it wants to turn over, but than we get a small puff of smoke out of the carb. I don't hear any grinding when we try to start it so it's probably not the timing gear. Just my original thought.

Oh, also my son said that the coil fuse blew when he stalled out, so we've replaced the coil and the fuse.

Like it wants to turn over, or it wants to start?

If it is blowing back through the intake then timing is off either by the ignition or by the camshaft. Well that or you have an intake valve or two that is stuck open.

[Dennis Bernth]

The timing gears are pretty stout, and they don't just give out, there has to be a reason. Usually that reason is that the cam bearings are shot, which causes low oil pressure, but also allows the cam to 'bounce' around in the cam bore as the bearings get worse, which stresses the gears. I had an upfront seat (driver's seat actually) view of what happens when a timing gear goes. First off, the top end of the engine was noisy, since it wasn't oiling like it should, and the oil pressure was low. Then the oil pressure would come up to somewhere more normal for a while, then drop back down, but all along the engine was noisy. In my case, after I did the post mortem on the engine I figured that the up and down oil pressure was due to the delaminated cam bearings sliding around and blocking the oil holes, which gave more indicated oil pressure but obviously no oil pressure to the upper end. Eventually it met it's end cruising at 65 mph on the interstate, and it was just like you'd shut the key off; it quit running, no back fires, no noise, no grinding, just quiet. It would crank easily, mainly because it wasn't turning the cam, which I found out when I checked the rotor on the distributor for movement. It turned out that the cam gear had about six or eight teeth knocked off, when it finally got the point that there wasn't anything for the crank gear to grab anymore it quit running. I was able to move the cam gear up and down a good quarter inch, maybe more, the cam bearings were that far gone. I suppose it's possible that yours jumped time on the gears, but if you didn't have any other symptoms like I detailed above I'd look for less disastrous things. My first thought would be to pull the distributor and look at the distributor gear; is it eaten up? If so, I'd shine a light down in the block and I'll bet you DON'T see the bushing that sits in the block that the distributor shaft rides in. Usually they stay right where they are, but on occasion I've had one come out with a distributor. Somebody that doesn't know any better might not put it back in, or maybe it came partially out and fell back into the block; with no bushing, that distributor shaft is going to move around and wear the distributor like crazy, and probably eventually it'll jump time. What type distributor do you have, since it's kind of interesting about the fuse blowing, that shouldn't happen with a mechanical problem......

[DRob95]

Originally Posted by Dennis Bernth

The timing gears are pretty stout, and they don't just give out, there has to be a reason. Usually that reason is that the cam bearings are shot, which causes low oil pressure, but also allows the cam to 'bounce' around in the cam bore as the bearings get worse, which stresses the gears. I had an upfront seat (driver's seat actually) view of what happens when a timing gear goes. First off, the top end of the engine was noisy, since it wasn't oiling like it should, and the oil pressure was low. Then the oil pressure would come up to somewhere more normal for a while, then drop back down, but all along the engine was noisy. In my case, after I did the post mortem on the engine I figured that the up and down oil pressure was due to the delaminated cam bearings sliding around and blocking the oil holes, which gave more indicated oil pressure but obviously no oil pressure to the upper end. Eventually it met it's end cruising at 65 mph on the interstate, and it was just like you'd shut the key off; it quit running, no back fires, no noise, no grinding, just quiet. It would crank easily, mainly because it wasn't turning the cam, which I found out when I checked the rotor on the distributor for movement. It turned out that the cam gear had about six or eight teeth knocked off, when it finally got the point that there wasn't anything for the crank gear to grab anymore it quit running. I was able to move the cam gear up and down a good quarter inch, maybe more, the cam bearings were that far gone. I suppose it's possible that yours jumped time on the gears, but if you didn't have any other symptoms like I detailed above I'd look for less disastrous things. My first thought would be to pull the distributor and look at the distributor gear; is it eaten up? If so, I'd shine a light down in the block and I'll bet you DON'T see the bushing that sits in the block that the distributor shaft rides in. Usually they stay right where they are, but on occasion I've had one come out with a distributor. Somebody that doesn't know any better might not put it back in, or maybe it came partially out and fell back into the block; with no bushing, that distributor shaft is going to move around and wear the distributor like crazy, and probably eventually it'll jump time. What type distributor do you have, since it's kind of interesting about the fuse blowing, that shouldn't happen with a mechanical problem......

That's really insightful..Thanks. I'm not sure what kind of distributor since it came with the engine when we bought it and I can't check at the moment since it's out at the ranch and I'm not going to see it until this weekend.

I did check the points on the distributor and they were firing when we tried starting the engine. We replaced the coil and it was a little hot when trying to start as well.

I'll pull the distributor completely out this weekend and give it a good looking over.

[scoutboy74]

The report of a overheated coil in conjunction with a new wiring harness has me wondering if whoever did the wiring made provision for a ballasted power feed to the coil. If not, it is receiving full battery voltage whenever the engine is running which is hard on breaker points and coils. This wouldn't account for all the noises, but perhaps you have more than one issue at play here.

[DRob95]

Originally Posted by scoutboy74

The report of a overheated coil in conjunction with a new wiring harness has me wondering if whoever did the wiring made provision for a ballasted power feed to the coil. If not, it is receiving full battery voltage whenever the engine is running which is hard on breaker points and coils. This wouldn't account for all the noises, but perhaps you have more than one issue at play here.

This one is definitely new to me. "Ballasted Power Feed?" I did the wiring using the EZ wiring kit and new Dolphin Guages but I never was anywhere about a ballast.

Can you explain this one further? Thanks

[Dennis Bernth]

On the points igntion you need a resistor to cut down the voltage at the coil to keep the points from burning up prematurely. None of the electronic ignitions need them, at least not the 'in line' ones (they have resistance built in to the coil). It's easy enough to add a standard 1.5-2 ohm ballast resistor by mounting it to the coil mount and running the hot wire to it and then to the coil hot post.

[DRob95]

Well not to sound like a complete idiot, but I didn't realize that was what was on top of the coil. We have one of those and have it run to the positive side of the coil.