4.0 SOHC new timing parts, running on one side.

[booblinker]

I got an 01 Ex cab 4.0 4x4 for $100. Story is, it had new timing parts put in, ran perfect for a little while(not sure how long) now it will start but runs on one side only. Where do I start? I'm assuming compression test would be the best place to start. Are these interference motors? If one head is bad should I buy new timing parts and a reman head, or drop a grand and put a good used motor in it?

 

[booblinker]

 

[adsm08]

IIRC 01 was a split year where both versions of the 4.0 were available. But given the nature of the question I assume this is a SOHC.

First I would pull the valve cover quick and see what things look like. You an see the timing guides, and if one is broken, just by pulling the valve cover.

This engine is not interference, so I wouldn't worry about valves having bent. Just a broken timing guide.

Bear in mind though, if the rear set is being serviced the engine must come out, because the one bolt is accessed through a hole that falls inside the area covered by the transmission bell housing.

 

[RonD]

Nice truck for $100

I thought 4.0l SOHC was an interference engine?
9.7:1 ratio is hard to get to on non-interference

4.0l OHV was non-interference, 9.0:1

I would do the compression test just because no disassembly is required unless you count spark plugs, lol.

But do remove all spark plugs first
Then test 1 cylinder at a time
You need good crank speed for compression test, can't get that with 6 compression strokes slowing you down.

 

[adsm08]

I have never seen a SOHC engine bend a valve, and I googled it. First thing that came back said it isn't.

It may be that if timed wrong it will hit but when the chain goes the valves pull back far enough to not hit.


http://www.underhoodservice.com/exploring-service-needs-on-the-ford-4-0l-v6-engine/

 

[RonD]

That underhood service article is good but is incorrect on the non-interference part, but always comes up as gospel, lol.

Post #3 here has pics: http://www.explorerforum.com/forums/showthread.php?t=404301

On another forum I helped a guy with low compression on one side, same issue valves bent, because cam slipped, he said there were marks on the pistons on that side

 

[adsm08]

That's interesting because I have run across at least two that had chain guides break while running where we just threw timing sets in them and they ran fine, no bent valve.

 

[RonD]

I think on passenger side cam there is no pin or "keeper" that locks gear to cam, so it can slip enough to cause the contact.
Cassettes falling apart would cause the rattling but not sure if it would change cam timing enough.

From that one picture and from what I have read and heard first hand I would have to say the valves share the same space as the pistons, so interference engine.
All 3 pistons have the same marks so not an individual valve or rocker issue.
Looks like all the exhaust valves on that bank were still open at end of exhaust stroke so contacted pistons.
Not sure maybe 10-15deg cam slip???

 

[RonD]

Also just found this one: http://www.ford-trucks.com/forums/1304141-is-4-0l-sohc-v6-an-interference-engine.html

Post #10

 

[adsm08]

Yeah, I saw that one picture too. It's hard to argue that isn't an interference engine after seeing that.

I know a broken timing guide will let the cam neutral since it lets the tension off. I'm thinking it gets the valves out of the way. I know on the 5.4 once the cam neutrals you can careful move the crank around without valve damage. But then the 5.4 can have the valves about 50* out.

 

[booblinker]

Kind of feeling like I may have been lied to. There are missing electrical parts on the drivers side of the motor, lots of parts including all ignition all look original. There are timing parts in the bed though. Guess I will pull the plugs and check compression sometime this week.

 

[booblinker]

turned the motor over with the starter,no bad noises, but sounded like it turned to easy.

 

[RonD]

Were spark plugs in or out?

If in was there any loping?

"Too easy" like low compression?

 

[booblinker]

Plugs were still in, didn't lope, sounded smooth. I did have a freshly charged 850 CCA battery and the starter looks new. Bought a borescope to hook to my phone to look at the pistons.

 

[booblinker]

Trike project is one brake cable from being done, street bike is back together just need to sync the carbs. Just need to finish my flooring project and the Ranger will be first in line.