4.0 sohc camshaft 'walking' ??

[Sutherbb36]

Can't find any other threads with this issue

I have an 03 ranger I bought that had bad timing casettes and needed a rebuild. Rebuilt the whole thing with all new parts, replaced all the valves etc etc

Get everything back together and fire it up only to hear a ratting noise coming from passenger side. Runs fine for a minute. Engine then dies, won't start. Check compression. Uh uh.

pull motor back out and find cam shaft has come apart at the end piece (See pic) this allowed the cam to 'walk'

Ok I thought, must have missed the cam being bad on assembly. Bought a new used cam and get it all back together and runs good for a few minutes, same noise from passenger side. Then wants to die. Pull valve cover off and cam has walked again??? Wtf is going on


(Pic of cam)

https://i.imgur.com/gfWT8mn.png

 

[chefduane]

Get a hold of 2000 Street Rod. The guy is a wiz with Ex internals.

 

[Stick4503]

I would say that your head has excessive wear in the cam bearing area. These heads do not have bearings as you know, so once they are out of spec the head is trash

 

[Sutherbb36]

I would say that your head has excessive wear in the cam bearing area. These heads do not have bearings as you know, so once they are out of spec the head is trash

Hmm

there was not much side to side play when we put the good cam in it.

 

[Sutherbb36]

Get a hold of 2000 Street Rod. The guy is a wiz with Ex internals.

I tagged him thanks

 

[2000StreetRod]

Thrust cap?

One of the head camshaft bearings and its associated camshaft bearing cap acts as a thrust bearing keeping the camshaft in place axially. On the driver side it is the front bearing/cap. Notice in the photo below how much wider the front cam cap is compared to the other three caps.

On the passenger side the thrust cap is at the rear.

Check that the wide cap is at the rear. If it is then pull the cap and check for wear. As Stick4503 posted, there are no camshaft bearing inserts which is another instance of Ford/Cologne "cheaping out" the design. The SOHC V6 was designed to be a higher rev engine than the OHV. Just because the camshaft only rotates half the speed of the crankshaft is no excuse not to use bearing inserts. I think each head is line bored with the caps in place and to provide the proper clearance tolerance for the mating camshaft. If the camshaft journal, head bearing or cap bearing is worn past allowable tolerance the most reliable option is to replace the entire head with camshaft.

 

[Sutherbb36]

One of the head camshaft bearings and its associated camshaft bearing cap acts as a thrust bearing keeping the camshaft in place axially. On the driver side it is the front bearing/cap. Notice in the photo below how much wider the front cam cap is compared to the other three caps.
View attachment 90516

On the passenger side the thrust cap is at the rear.
View attachment 90515
Check that the wide cap is at the rear. If it is then pull the cap and check for wear. As Stick4503 posted, there are no camshaft bearing inserts which is another instance of Ford/Cologne "cheaping out" the design. The SOHC V6 was designed to be a higher rev engine than the OHV. Just because the camshaft only rotates half the speed of the crankshaft is no excuse not to use bearing inserts. I think each head is line bored with the caps in place and to provide the proper clearance tolerance for the mating camshaft. If the camshaft journal, head bearing or cap bearing is worn past allowable tolerance the most reliable option is to replace the entire head with camshaft.

Do you happen to know the normal "end play" or axial movement allowable?

 

[2000StreetRod]

end play

Do you happen to know the normal "end play" or axial movement allowable?

According to my shop manual:

Camshaft
End play mm (inch): 0.075-0.185 (0.0003-0.007)
Journal to bearing clearance mm (inch): 0.04-0.095 (0.002-0.004),
service limit: 0.152 (0.006), Tighten camshaft bearing cap bolts to 15 Nm (11 lb-ft) when measuring journal clearance.

 

[Sutherbb36]

According to my shop manual:

Camshaft
End play mm (inch): 0.075-0.185 (0.0003-0.007)
Journal to bearing clearance mm (inch): 0.04-0.095 (0.002-0.004),
service limit: 0.152 (0.006), Tighten camshaft bearing cap bolts to 15 Nm (11 lb-ft) when measuring journal clearance.

Thank you.

As far as I can tell the head is still well within spec.

I reused the original cam on the first try and then bought a used cam on the second. I still think it's the cam. I'm going to try a new Ford cam and see if that doesn't fix the issue. If that doesn't work, it looks like a new head is the fix.

After extensive practice we have gotten pretty good at pulling the engine out. Hopefully this will be the last time, however.

 

[boominXplorer]

Make sure the cam gear your using looks like the one in the pic. The left cam uses a 1/2" shorter gear in depth and could of been switched.

 

[Sutherbb36]

Alright, Jesus tap dancing Christ.

So pulled the motor out for the 3rd time. replaced the cam with a brand new one from Ford. Upon inspection it seems like they are built a little different from the original ones. IE not pressed together, but built as one solid piece.

Checked the end play on the new cam and it was well within spec as well as the head. Get everything installed and torqued and get the motor in.

Run it without issue for 10-15 minutes while I try to diagnose a miss in cylinder 3 (left hand side). Looks like dead wire. Replaced it. Still misses. Coil has good spark. It's pretty new anyway. Pulled the plug. Looks fine. Swapped the plug with another cylinder. Still Misses. Weird.

Then after maybe a total of 15 minutes of engine running time we hear a noise like something came loose in the motor and is rolling around. Then a noise from right hand side and motor cuts out. WTF

Pulled right hand valve cover and rear chain has broke......

Our only guess at this point is that from previously running the vehicle with cam issues and rubbing against block and valve cover that the chain 'link' came undone????

this will the 4th time pulling this motor and I am about fed up

 

[Sutherbb36]

I want to followup this thread in case someone else out there does this same thing.

So what was causing the cam walking issue was we had the jackshaft spacer on backwards.

It's the little piece in between the jackshaft and jackshaft sprocket.

After the 3rd failed cam, the last one being the brand new Ford cam along with chain/cassette failure. we pulled everything off and out and realized our mistake. ( should have done this after failure one, but we honestly couldn't think of what could be causing it because the part is so random)

It's definitely been a learning experience but I have to say, we definitely know these motors really well now, ha. We can also pull the motor and put it back in about half a work day.