Driving at highway speed, all was fine...then...loss of power, clattering noises and it dies. Cranks faster than normal and coughs out the intake, with no start.
It has 335K on it.
PO was meticulous about record keeping, and I don't see a timing chain/gear replacement in its past. The PO might still be active on this forum. He knows a LOT about Aerostars.

What's the survey say? Is this probably the timing chain? How can I tell?

 

Sounds about right. Could be the end
But 335k WOW!

 

Pull off a valve cover and crank the engine to see if the rockers move. The passenger side would be easier, but on this van, nothing is really easy.

 

This is the "Grey Ghost" that was owned by Aerocolorado. I'm determined to keep it going...the body and interior are in great shape, and it was running well until today. It's already been decided that I'll get a new engine, if need be.
I should be able to get a camera into the PCV hole to see if the rockers move.
Didn't have such things when I was a kid...now I've got one that I can actually see where the moon don't shine.

 

The stars have aligned, and I'm finally getting around to replacing the timing gears, chain, tensioner and slides on my van.
I've taken out the radiator and fan, and am about to jack it up and lower the oil pan. At least that's what the FSM and other sources say I need to do.
I can't find anything on youtube or in hear or other forums that talk about it much, so I've got questions: Do I need to do that? Can I loosen it and just lower the front to get at everything? Can I do that and re-use the same gasket?

 

What are you trying to do? Remove the oil pan or just drop it enough to remove the timing cover? If that's it, you don't really need to remove the radiator; just the fan and all the driven components like PS pump, alternator, and move the AC compressor. But having the working space without the radiator is nice. (I punctured my radiator while assembling the front parts last time I was working on it, so I wish I had removed it before starting.)

Realize that you will need more access to the oil pan afterward to install a new gasket. This requires lifting the engine off its mounts. It's a lot worse if you have an AWD, with its front axle in the way. You might want to drop that as well.

 

If possible, I'd like to lower the pan enough to get the timing chain done, and put it back up.
Then go camping.
But, if I have to drop it all...at least it's not a rust bucket. Things come apart without much complaining.

 

You do not have to move the pan.

2:18 he pulls the 5 bolts holding the pan to the cover, 3:20 the cover comes off and you can see how the pan stays in place.


Just like a SBF and I suppos lots of others with the front cover/pan interface.

 

When you pull the timing cover off, you will disturb, if not damage, the front part of the oil pan gasket. The 4L v6 uses a one piece gasket that's kind of like a rubber band for most of the pan rails, connected to the big pieces at the ends. You could try using a lot of RTV to seal the area afterward. I don't recall if the 4L v6 timing cover also uses locating dowels like the more recent SBF. These will require you to force the front part of the pan gasket over the little lip that's on the front part of the pan. It is tricky, but it can be done with the pan in place.

 

With the SBF you have to cut the gasket and RTV it up to make the pan seal. Darn site easier than pulling the pan......

 

Yes, that will be easier than dropping the pan, if it actually seals. (In both the 4.0L and the SBF.) I had bad luck in both cases as the oil pan gaskets leaked as well, so I ended up dropping the pan in both cases to replace the gaskets.

 

This 91' 4.0L Aerostar has that set of A/C lines to the rear evaporator...and it looks like they are going to be in the way. I've got the radiator out, and if I evacuate the A/C system, I can take the condenser out, too. This would make all access a lot easier.
Has anyone done a timing chain job on one of these without discharging the A/C?
It's amazing how things were packed around this engine. Makes working on it a bit of a challenge.

 

When I did my timing cover gasket, I had to pull the compressor completely out, and the compressor bracket had to come off also, it sucked

 

I removed the air filter box and laid the compressor in that area without disconnecting its lines. I replaced my timing cover without removing the AC condenser. In fact, I was actually able to do it with the radiator in place. The size of my puller JUST fit in the space between the radiator and harmonic damper. But you might want to remove the radiator for more working space. I don't think you need to remove the condenser.

I first removed the harmonic damper bolt to remove the washer under it. Then I threaded the bolt back in part way and used the puller to push against it to pull off the damper. It turned out that after a bit of pushing on the bolt (and pulling on the damper), the bolt ran out of length. So I had to go buy a longer 12mm fine thread bolt to allow the puller to push it far enough to fully pull the damper off.

 

I got the cover off without dropping the oil pan, the A/C lines, alternator or power steering pump. So far so good...but...

When I turn the crank, the cam sprocket turns and I can bring the crank and cam timing marks in a line...within a half tooth or so, anyway.
I can turn the engine over with a 1/2" rachet and a bit of oomph, but it doesn't offer as much resistance as I expected. Took out a spark plug, and it never builds compression. A borescope shows the piston is moving.

So, it's as if all 6 have no compression. With the chain off, I can spin the crank easily...again, no compression at all. The camshaft turns and feels ok..there is "lumpy" resistance throughout it's rotation.
The van was doing 60 when it died. The starter would crank it, but it spun if fast and there was some firing back though the intake and exhaust.
I'm scratching my head trying to understand how the cam could fail in such a way that none of the cylinders have closed valves.