2006 Explorer - Timing Chain Question

[Kirka]

.... You can remove the spark plugs and then rotate the crank until all bank 2 (driver side pistons) are equally low in the cylinders by measuring their height thru the spark plug hole. In that position you should be able to rotate the camshaft while avoiding piston/valve interference. Then rotate the driver side camshaft to the approximately correct position relative to the passenger side camshaft. Then tighten the bank 2 camshaft so it won't slip and rotate the crankshaft to TDC and check/adjust for correct timing.

Thanks...

One other q. I am trying to figure out WHY its out of time like this. Since there is no key between the sprocket and the cam, it could have slipped I guess.... or, the would the chain be loose enough to jump if the guide is busted?

 

[2000StreetRod]

incorrect timing

There are a couple of possibilities. The chain will not slip when there is tension on the traction side (the engine is accelerating or running at a constant speed). It will only slip when there is little or no tension on the traction side (the engine is decelerating due to coasting or upshift). With a functional tensioner there is not enough slack in the chain to slip. With a broken tensioner guide there is lots of slack. Enough slack for the chain to contact nearby parts and wear/damage them.

Judging by the valve cover damage I suspect that the guide assembly broke and a piece of it was "grabbed" by the chain and struck the valve cover. The chains are very strong and rarely break. However, pieces of a failed cassette guide can get between the chain and the sprocket allowing the chain links to disengage from the sprocket teeth.

The sprocket retaining bolts are threaded so the traction of the chain tightens them. That's why the rear camshaft sprocket retaining bolt tightens counter-clockwise instead of clockwise.

 

[boominXplorer]

If there is absolutely no guide left intact there is enough slack for the chain to jump the crank sprocket in the front. By looking at yours it looks like it's slipped back about 200 degrees retarded so you can almost bet you have valve damage. I would unbolt and remove the camshaft so all the valves will shut so you can turn the engine over safely. You can try a cylinder leak down test without turning the engine over, you just need the valves closed.

 

[rb142]

I agree that a cylinder leakage test is going to be more useful (and safer) at this point than trying to do a compression test with the starter. Remove the cam or just rotate it carefully as you move cylinder to cylinder to keep the valves closed. Especially if you don't yet have the timing tool set.

Be extra thorough cleaning all of those chain guide bits out of the oil pan (and everywhere else) They get pulled into the oil pump pickup and starve the engine for oil.

Also, check the rear chain guides carefully. If the front broke, the rear is probably not far behind. If it were me, I would replace it all. The time spent pulling the engine out is saved by making it much easier to do the work.

 

[Kirka]

To do either test, I have to remove the spark plugs. Not usually a problem, but last night when I took out the #1 plug (to verify it was TDC).... it was pretty tough to get out. Like the threads were really tight on the plug. Thought I was ruining the head at first, but it came out and the threads looked good afterwards.

Is the plug threads another known issue with this engine? Will it help/hurt any to put a little anti-sieze on the threads when I put them back in?

I will do a compression test after I get the cam in proper time. I will know more tonight after the test.... finger crossed that there is no valve damage.

You guys have been really helpful bouncing ideas around. THANKS

 

[2000StreetRod]

anti-seize

I've installed plugs with and without anti-seize compound. It's my experience that anti-seize prevents the plug from breaking but makes it difficult to remove. I think it hardens from the heat. Most modern quality plugs have a coating that prevents them from seizing. Many plug manufacturers advise against using anti-seize compound.

Removing the camshaft caps without first removing the cam followers must be done carefully. The valve springs will not be uniformly compressed. Because of this the cam will not raise horizontal to the head bearing surfaces and may bind. Installation of the camshaft bearing caps is even more critical when tightening against the valve spring pressure. It is very easy for the camshaft to bind and then a cap breaks. Since there are no camshaft bearing inserts. If you break a cap you need another head.

 

[Kirka]

......
Removing the camshaft caps without first removing the cam followers must be done carefully. ... Since there are no camshaft bearing inserts. If you break a cap you need another head.

OUCH!!! Thanks for the heads up. I guess the cam is "normally" installed before the valves/springs are installed.


Found the torque spec in another post of yours... 53 in lbs, then 12 ft*lbs

 

[2000StreetRod]

installation procedure

As I recall the procedure is to install valves, springs and keepers. Then install camshaft followed by lash adjusters. The last thing is to install the cam followers. A special tool is needed to compress the valve springs enough to remove/install the cam followers and the valve spring keepers.

I just ordered a tool that is supposed to be able to compress the 4.0L SOHC V6valve springs, the modular Ford 2 valve (SOHC) V8 valve springs, and both the exhaust and intake valve springs on the 4 valve (DOHC) V8. I should know in about a week if it works on the DOHC.

 

[Kirka]

Made a little progress last night. With the front cover off, it appears that the main guide is also broken and from what I can tell, the balance shaft guide is also gone.

I tried to drop the block cradle. It will just almost come out. It hits the torsion bar at the back and the rack/pinion unit in the front. I need to get this down so that I can get to the balance shaft guide and verify the timing of the balance shaft.

 

[2000StreetRod]

crankshaft sprocket

Note the position of the crankshaft sprocket if you remove it. Some members have installed it with the face aft instead of forward and had all kinds of problems.

Check the wear on the primary (crankshaft to jackshaft) chain since it has been rubbing against the leaves of the primary tensioner. It doesn't look excessive in the photo.

 

[Kirka]

Update on my progress. Using the timing tool set, I got the LH head back into correct time. Removed all six plugs (they all came out without issue... whew). First I checked the compression on RH Head(1-2-3). Compression on each was 210-212 psi. Next moved to LH head. 4-5-6 were all 0 psi.

Pulled off the head and found this

I have seen other posts where there was valve damage when the engine jumped time. I can confirm that even being 150° out can cause damage. After the head was off, I could hold a light under the head and look into the ports and see light. All exhaust valves were open about 1/8th.

This one will be at my head shop Monday morning to have all six valves and guides replaced.

Here is a view from the piston side of the head. The cam is not holding this open (the rocker fell out when I turn the head over). The valve is bent and touching the head at the red arrow. All three valves are the same way on this head. If I put a light in the intake port, I can see it shining thru from this side of the head also.

 

[2000StreetRod]

bent rods?

I suspect that if the camshaft is more than 30 degrees off (60 degrees crankshaft) there is a high probability of valve damage. I suggest that you check for bent rods since there obviously was a large impact to the pistons.

 

[Kirka]

I had already thought about the bent con rod also. Rather than pulling out the piston and measuring the length of the rod, could I just measure the distance from the top of the block to the top of the piston? I could measure that with a depth mic if I knew what it should measure. Any idea?

If I do pull out the piston, what should the length of the rod be?

Thanks

 

[Kirka]

I did some searching and found this chart with dimensions.

I came up with this.

(Stroke /2) + Con Rod Length + Piston Comp Height - Deck Height
3.32/2 + 5.748 + 1.440 - 8.858 = -0.01in

If I have this figured right, that would be the distance the top of piston (@ TDC) is below the top of the block.

Does that seem right?

 

[2000StreetRod]

Engine specs

Yes, those calculations are correct. I have posted the engine specifications: Engine specifications

I've seen that recess specified somewhere in the shop manual but I'll have to search for it. As I recall it was 0.010 inch.

Edit: Turns out it isn't in the shop manual. I read it in a technical article by Super Six Motorsports: 4.0 SOHC Tech. The article states: "the pistons run .010 in the hole at TDC"

 

[Tech By Trade]

Wow, you are way farther along than I am already. Good work. I am having a hell of a time finding time to work on mine. Finally got the starter and the flex plate bolts off today. Hopefully I can disconnect the bell housing tonight.

 

[Tech By Trade]

Any more news on your job? I finished pulling mine apart last night. All my guides but the ones on the crank to jackshaft chain were shot. My crank/jack chain seemed streched so I ordered up new sprockets to replace that chain too.

 

[Kirka]

Mine is at a stand-still till after the holidays. I have about decided to go ahead and pull the engine and do the chain guides on the RH side too. The last thing I need is to do all this work and then the RH one do the same thing.

My head shop wants $277 to rebuild the head. Includes new springs, valves, regrind seats and resurface. I can get a used head for $100. Are you having to rework yours?

I will eventually replace all the chains/guides. Comes to about $800 in parts....ouch. Best price I have found on the parts is Tascaparts.com.

Are you getting your parts locally?

Thanks

 

[Tech By Trade]

No, everything else survived so far on mine. I did find a ranger 4.0 with low kms for 1500. If I find anything else when i pull the upper pan I will probably just swap that out. If not, I bought around 700 bucks canadian worth of parts from rock auto and white bear yesterday. Should be in under 1000 for everything if nothing else is wrong with it.

 

[Tech By Trade]

Any more updates? Got mine together. I have an intermittent #2 miss. Going to run another comp test this weekend and then if all is good Injectors are next. After that? I am at a loss. May have to take it to a shop.