Truck:
1989 F150 XL 4x4
4.9L Straight Six
155,000 miles

Problem:
While accelerating to pass a semi this morning on my way to work, the engine suddenly idled down casuing me to rapidly loose speed. By the time i was able to pull it off to the side of the road it had completly died. Almost similar to how it'd behave if it ran out of gas, though both of my tanks were over half full. Once on the side of the road, the truck wouldn't restart. When i turned the ignition the starter would engage but it wouldn't turn over the engine. I'm searching my memory to recall what the oil gauge read before the engine quit. I beleive it was reading normal as was the temperature gauge.

Since I am leaving on business this week I didn't have the luxury of skipping work to take care of my beloved truck. I had it towed to my local ford garage. Later that day, a mechanic from the service department called me to give me the news. The reported that there was no compression in any of the cylinders. They theorized that a "fiber" gear on the cam shaft in these "older engines" often gives way preventing the engine from turning. They also thought it my be the result of failed oil pump that broke apart causing a cam shaft failure. My question is; how would a failed cam shaft result in the loss of compression in all six cylinders?

I don't have much confidence in their diagnosis and chose to tow it home with a friends help to work on it myself. They estimated at a minimum it'd cost over $1700 to repair. This is my daily driver but I'll be damned if I'll pay that much for something I can do myself.

So I'm asking my friends here on Ford-trucks.com for some help. What are yoru thoughts as to the problem. Bad cam or some other problem. If it is the cam, how difficult is it to replace with the 300-6 engine? I realize I'm looking at minimum taking apart the front of the engine. Once I get the timing cover off is a swap of the cam realatively straight forward? Your help would be greatly appreciated.

For the mean time it looks like I'll be commuting with my wife. My entire family has been telling me for quite some time that it is time for a new truck but I'm rather attached to my current one. The quicker I can get back on the road the better. Thanks in advance.

 

well it is possible that the cam shaft fiber gears might have deteriorated thus not turning anything. it is fairly simple to replace the gears, you just have to take the radiator, waterpump, fan, belt and grille off to replace it. BUT i would double check your compression just to make sure its that. good luck. hopefully other people on here will pipe in and give you other ideas.

 

Well since the camshaft isn't turning the the valves are not opening and closing. So the diagnosis is probably correct. If you don't like the estimate you can always give it a try yourself. But if you earn say $20 an hour in your normal job remember your time is money too. And then if you goof up there is no warranty, and you then get to do it all over again, or just replace a goofed up engine from the first attempt. Its just another way of looking at the DIY deal. Its a different deal if you are a mechanic.

 

Well yes this could be your cam but I do suppose it could be other things, unless you can give us some more details. First off you should compression test all the cylinders yourself like Travis suggested, that's simple enough. But more importantly we need more details on the noise it makes when you hit the ignition. Is the starter spinning but the motor doesn't sound like it's being turned over? If you really did break your cam gear then the starter should still turn the engine over (cranking the pistons up and down) but you won't be getting any sort of combustion since your valves aren't operation. It should be pretty evident what is going on inside the engine judging but what it sounds like when you crank her over. I wouldn't suggest doing this very much because you could have other problems like a bad oil pump, and god knows you don't want to be cranking dry cylinders.

I guess I'm just saying try to give us as many details as you can. From what you've given us, this could be a PLETHORA of things. And I would just forget about your chat with the techs at Ford, I've learned not to a trust a SINGLE word that mechanic tells me, just for insurance I won't get corn holed (again). I know there's good techs out there but there's no way to differentiate. Good luck brother, sounds like you've got a project on your hands.

 

Take the distributor cap off, and spin the engine. If the rotor does'nt turn, it's the fiber gear.

It's a relatively easy repair. If your compantant with tools/mechanics.

I've seen them come apart and clog oil passages, oil pickups, filters.

Hey, I just noticed. Another Northlander!!!!

I live out in Saginaw.

 

Thanks everyone for your input. Unfortunately, I havn't had much time to do more diagnosis myself. After towing it home I had to pack and right now I'm about ready to hit the road. I'll have to wait until Friday I guess to dig into it deeper. I'll try taking off the distributer cap and seeing if the engine is turning over or not. Thanks for the tip.

So from what everyone is telling me, it may possibly be deteriorated fiber gears on my cam shaft. I still dont' see how that'd result in loss of compression in all six cylinders. Is there a cycle of the cam that would open all six valves? I'd tend to think that a few would be open and a few closed depending on where each cylinder was in the firing/exhaust cycle. I'll have to get a comprssion kit and test it myself.

I wouldn't say I'm a top mechanic, but I am experienced with most other repairs on this truck. You have to be to keep them running as long as we all have without going broke. I recent rebuilt the engine of a V-twin engine in my 84 Harley Davidson so I'm not too frightened to dig into this project. Engine work is however relatively new to me.

If it is the fiber gears on my cam shaft, can I replace the gears alone or will I need to purchase a whole new cam/gear assembly? Or should I replace the whole cam/gear assembly anyway with 155000 miles on her?

Thanks everyone. Feel free to keep on posting your ideas. It is much appreciates.

Fonefiddy.... Saginaw eh? I actually live in Cloquet, so we aren't that far apart. Stay warm....

 

Bad timing gear sounds right, just one thing in the original post sticks out:

"When i turned the ignition the starter would engage but it wouldn't turn over the engine."

That doesn't make sense. I'll assume that's not really the case now as you couldn't attempt a compression test if the engine won't turn over - but was it true then? If so, that's not a good sign...

Or am I reading something wrong?

 

<i>I still dont' see how that'd result in loss of compression in all six cylinders. Is there a cycle of the cam that would open all six valves?</i>

Wouldn't make any difference, if both valve are closed in one or two given cylinders it sill would now have any compression when tested with the timing chain not turning the cam.
With both valves closed no air is taken in, only negative pressure when the piston goes down only to come back up to nothing again.
No air in, no air to compress.

 

"When i turned the ignition the starter would engage but it wouldn't turn over the engine."

I don't have much confidence in my original statement. I'm probably mistaken and I just couldn't hear the engine turn over the starter. To tell you the truth, I can't fully remember at the moment and with me being out of town I can't test that until Friday.

 

What gear in particular would have failed? I'm only aware of the timing gear itself at the end of the cam saft that is wrapped by the timing chain. Unfortunatley I do not have a diagram of the cam assembly avaliable to me at the moment.

If it is the cam gear I imagine I'd need to remove the heads and the pushrods to replace. Is that correct?

 

Looks like the gear unbolts from the front of the cam and you can just replace the gear by itself.

 

No you wouldn't have to pull the heads to replace the timing chain set. Just have to take everything off the front of the motor.
Radiator, fan, alternator, unbolt and lay the power steering pump and ac compressor pump (if it has air) out of the way, water pump and so on.

Not to bad of a job to do, more time consuming than it is "hard" to do.

What happen to the "edit" button?

 

You can only edit a post that you recently created, within about an hour or so...

 

when i rebuilt my motor its a good thing i took some pics. i don't believe that the cam gear is bolted to the cam, it is a pressed on gear same as the gear on the crank. at least the 89 I6 was a pressed on one. not sure if ford decided to change that or not.. here are a couple of pictures to show you.




heres a pic of the front of an I6 you will need to take off the timing cover waterpump, harmonic balancer, belt, fan, radiator, and grille to get to the gears and have room to work.

 

Oh ok I guess I never noticed that before.

I noticed in one post I spelled a word wrong and couldn't fix it.

I thought them I6 had a gear to gear timing setup in em. Nice that way, no chain to stretch out.