4.0 V6 Cologne timing chain explosion!

[RatCav]

Following on from this thread:

http://www.explorerforum.com/forums/showthread.php?p=3435652

I thought I would start another with a proper title and chronicling the matter at hand.

This my girlfriends UK version of the 1999 Explorer 4.0 SOHC V6 Cologne. It has been fitted with a multipoint LPG system. Regularly serviced and maintained.

Car was running absolutely fine. No knocks or bangs. Car sounded smooth and quiet on tickover, pulled like a train when booted.

I drove it to a dealership for a couple of parts for my Truck (Isuzu Bighorn LWB 3.1 TD) with no hassle, but on the way back I noticed a rumble and vibration between 2500-3000 rpm. Anything before and after that it was hardly noticable, however on tickover the car had a low down rumble and vibration. Changed gears fine and kicked down as it should.

I gave it the once over when home and determined it was bottom end. Spoke to my girlfriends father who is a time served mechanic for a second opinion and he thought it was possibly the gearbox or even flywheel. Not convinced we drove it to a couple of garages and asked for more advice. A gearbox specialist was convinced it was more engine based.

Decision was made to pull the engine out, so I drove it to our workshop.

A few hours later this happened:

Dropped it onto an engine stand, flipped it upside down and removed the lower sump. Found this:

That will be the remains of a guide or tensioner in the sump and most of it sucked up into the oil pickup strainer.

After lots of head scratching and we decided to rebuild it. The car ran fine apart from the vibration and rumble. For the sake of a new timing kit and gasket kit it was worth giving it a try.

 

[RatCav]

Ok. I have spent some more time pulling things apart. So far I have dug this out of the sump and timing case:

Here are some shots of various bits and pieces.

Front:

Exploded tensioned guide:

No other apparent damage:

Balance shaft lacking the plastic for the tensioned guide:

Front cam timing chain tensioned guide seems ok:

Shame about the guide though. All that is left is the small bit of plastic jammed in the gallery which can been seen in the middle of the picture. If you look closely you can also see where the chain has been flapping about and has worn away the metal of the head. I have indicated them in the second picture:

Strangely the rear cam timing chain set was fine.

 

[RatCav]

Now I have a question. The crank is at TDC (Keyway is directly upwards and I set it before taking the crank sensor off with the crank pulley. It can only be a fraction out.

Reading all the documentation the balance shaft should be timed accordingly. From what I gather the sprocket has two marks on it that should line up either side of the 4mm hole. If in that position the indentation on the balance shaft itself should be near horizontal. If you look at my picture. The crank is at TD, but the marks on the balance shaft sprocket is just beyond the 5 o'clock position, and the indentation is almost 180 degress out. (the picture is of the engine the right way up)

I am assuming someone at some point has chained the chains and neglected to time the balance shaft properly. I am assuming that when I fix things I should rotate the balance shaft sprocket until both the lines and indentation are pointing to the right.
Yes/no??

 

[RatCav]

Ok after reviewing the destruction. Time came to start pulling things off. First stage was to start locking things down. The cams were the first stage as I don't want them spinning about. Looked up the "Special Tool" kit. Screw that for a game of soldiers. That is a lot of money for a one off job. Out came the grinder, and drill.

Came up with this for the cams. It mounts on two of the cam cover bolt holes. Then the second piece locks into the notches at the back of the cam shaft. Made two sets, one for either side. When I am done I will take measurements and draw them all up for others benefit.

 

[dezufo]

Nice follow up. I have book marked this so I can keep up with your progress and for future reference.
I like your solution to the special tool.
Good luck with the rest of it.

 

[RatCav]

Yeah .. it is a bit "heath robinson" as they say and could do with a tweak in hindsight, but should do the trick in holding them.

 

[Tech By Trade]

Looks familiar. You should see all the plastic I pulled out of my 07. Welcome to the club.

 

[RatCav]

Yeah .. the more I browse the forum, the more I see this is a common occurrence.

Is there an interval time/mileage for the chains and tensioners?

 

[Tech By Trade]

mine was around 200k kms. Each one is its own ticking time bomb. Welcome to another ford engineering marvel. Make sure you load down the chains before you tighten the jack shaft on each end or you will be out a couple degrees on timing.2000streetrod did his without the otc kit. Good guild in his links on his signature.

 

[RatCav]

Apologies for the delay. Been a bit busy around here lately. Anyway I managed to get down to the workshop this evening for a bit and finally managed to fabricate the rest of my locking tools. Now the crank and cams are both locked down.

LH Cam:

RH Cam:

Now to lock the crank down and still have access to the front sprockets I went for holding it at the rear. First off I made a bracket that bolted to the underside using the bolt holes for the upper sump. I then used a piece of angle and drilled two holes hrough that lined up with the flywheel bolts. This angle rests up against the the bracket:

Underneath:

Side:

Above looking at the flywheel end of the crank. I used a pair of wheel nuts to space the flywheel bolts as they bottomed out before tightening the angle iron to the face of the crank end:

This setup should stop the cams and crank from shifting thus maintaing the timing.

 

[2000StreetRod]

balance shaft timing

Now I have a question. The crank is at TDC (Keyway is directly upwards and I set it before taking the crank sensor off with the crank pulley. It can only be a fraction out.

Reading all the documentation the balance shaft should be timed accordingly. From what I gather the sprocket has two marks on it that should line up either side of the 4mm hole. If in that position the indentation on the balance shaft itself should be near horizontal. If you look at my picture. The crank is at TD, but the marks on the balance shaft sprocket is just beyond the 5 o'clock position, and the indentation is almost 180 degress out. . . I am assuming someone at some point has chained the chains and neglected to time the balance shaft properly. I am assuming that when I fix things I should rotate the balance shaft sprocket until both the lines and indentation are pointing to the right. Yes/no??

Because of the gearing, it can take multiple rotations of the crankshaft to determine if the balance shaft is timed correctly. See: Balance Shaft Timing Procedure When assembling the SOHC V6 the balance shaft is normally timed before the camshafts are timed. I encourage you to follow the normal procedure.

 

[2000StreetRod]

flimsy cranshaft holder

. . . Now to lock the crank down and still have access to the front sprockets I went for holding it at the rear. First off I made a bracket that bolted to the underside using the bolt holes for the upper sump. I then used a piece of angle and drilled two holes hrough that lined up with the flywheel bolts. This angle rests up against the the bracket: . . .
Above looking at the flywheel end of the crank. I used a pair of wheel nuts to space the flywheel bolts as they bottomed out before tightening the angle iron to the face of the crank end: . . . This setup should stop the cams and crank from shifting thus maintaing the timing.

The crankshaft holder in the OTC 6488 timing tool kit is rather flimsy and easily inaccurate. Your improvised tool appears much more robust. How do you plan to keep the timing chain taught in lieu of using the precision tensioner in the timing tool kit?

 

[RatCav]

Because of the gearing, it can take multiple rotations of the crankshaft to determine if the balance shaft is timed correctly. See: Balance Shaft Timing Procedure When assembling the SOHC V6 the balance shaft is normally timed before the camshafts are timed. I encourage you to follow the normal procedure.

Hi StreetRod

So if I remove my locking tools and rotate the crank (carefully) several times I should be able to get back to a stage where the engine is at TDC and the balance shaft is timed?

How do you plan to keep the timing chain taught in lieu of using the precision tensioner in the timing tool kit?

Do you mean the spring loaded tensioners that screw into the side of the heads and tension the guides for the cam chains? If so I plan on using the old ones. I have a few ideas.

1) Mark them when in position. I can then remove them and place in a vice. If I compress them to the mark I can then drill a hole through the sliding part and pin it so it cannot depress more than it should.

2) Mark and remove the tensioner. Place in vice and compress to the mark. Measure overall length. Remove the sliding part completely and insert a piece of bar the right length.

3) Drill an 8mm hole in the end of the sliding part. Drill and tap an M8 hole in the hex head end. Then get a long M8 bolt and feed it through the slider hole and thread it through the other end until it is the right length. I can then lock the bolt with a nut on the hex head end. by using an M8 nut and bolt I should still be able to get a spanner onto the tensioner hex head to tighten it into place. This method has the advantage of (hopefully) missing the spring inside the tensioner. This will be easier to do with the rear one as it doesn't have the large head on it like the front one. I can also adjust its overall length by screwing the M8 bolt in or out. If I only replace one set of chains at a time I only need one of them.

The only issue I have is the front timing chain guide (static outside one) is gone completely. Means the chain is dead straight and tight that side and all the flex is on the tensioned side. My plan to get round that one is to install the new guide, sprockets and chain with the old tensioner. Make sure the guides are bolted down properly, but keep the sprocket bolts loose so they can move. When I install the old tensioner the guides should keep the new chain in the right place and contour. The sprockets should rotate slightly to ensure the chain profile is correct against the guides and tensioner. Once all is well. mark the old tensioner so I can compress it in a vice and get the correct length. Get my adjustable (old) rear tensioner and correct it to the right length and install in the front. That should then hold everything in the right place solid so I can do up the bolts for the front sprockets.

 

[RatCav]

Got a present this morning

One thing I checked was the Crank to Jackshaft chain tensioner had 6 leaves (which it does).

Only thing which confused me was the "Volume Reduction Plug". Its a white Nylon stick about 4 1/2" long.

I haven't seen a reference to this anywhere yet. Is it important to change. Also the tiny grommet that holds it in place is 132 lb-in:

 

[2000StreetRod]

"precision tensioner"

It is likely that if you remove your camshaft and crankshaft holders and rotate the crankshaft to the cylinder 1 TDC a few times eventually the balance shaft marks will align.

The "precision tensioner" included in the timing tool kit is a specific length to make the timing chain taught. The spring in the standard hydraulic tensioner is not strong enough to overcome the pressure on the camshaft lobes exerted by the compressed valve springs. This is not a problem when the engine is running because the rotating jackshaft always keeps the chain between the camshaft sprocket and the jackshaft sprocket in tension on the traction side. Also, on the slack the hydraulic pressure (stronger than the spring) keeps that side of the chain in tension. That's why you can't use the spring pressure extension of the piston as a reference. The timing may be a few degrees off using just the spring pressure.

I eventually used one of my old tensioners as a "precision tensioner". I merely epoxied the fully extended piston in place in the cylinder.

I made the mistake of using the rear tensioner which is shorter than the front tensioner and barely long enough when tensioning the front chain. I torqued the tensioner to about 20 lb-in which was more than enough to achieve a taught chain but not so much to break the plastic guide assembly.

The "pencil" reduces the volume of the oil gallery which reduces the time it takes after engine start to pressurize the front hydraulic tensioner. It was originally part of the 00m12 kit that included intake manifold gaskets and the front hydraulic tensioner.

Be very careful when attempting to extract the old gallery plug. Many members have stripped the head causing significant problems to overcome. After cleaing the plug I made sure the Torx bit was fully seated into the head by tapping on an extension with a small hammer. I applied strong pressure to the socket drive while attempting to loosen the bit.

 

[2000StreetRod]

"precision tensioner"

It is likely that if you remove your camshaft and crankshaft holders and rotate the crankshaft to the cylinder 1 TDC a few times eventually the balance shaft marks will align. Since during factory engine assembly the heads and camshafts are installed after the balance shaft is aligned cylinder 1 should be at TDC on the compression stroke when the balance shaft marks align. However, it probably doesn't matter if cylinder 1 happens to be on the exhaust stroke. Make sure you rotate the crankshaft to the cylinder 1 at TDC on the compression stroke before loosening any jackshaft or camshaft sprocket retaining bolts. The SOHC V6 is an interference engine.

The "precision tensioner" included in the timing tool kit is a specific length to make the timing chain taught. The spring in the standard hydraulic tensioner is not strong enough to overcome the pressure on the camshaft lobes exerted by the compressed valve springs. This is not a problem when the engine is running because the rotating jackshaft always keeps the chain between the camshaft sprocket and the jackshaft sprocket in tension on the traction side. Also, on the slack side the hydraulic pressure (stronger than the spring) keeps that side of the chain in tension. That's why you can't use the spring pressure extension of the piston as a reference. The timing may be a few degrees off using just the spring pressure.

I eventually used one of my old tensioners as a "precision tensioner". I merely epoxied the fully extended piston in place in the cylinder.

I made the mistake of using the rear tensioner which is shorter than the front tensioner and barely long enough when tensioning the front chain. I torqued the tensioner to about 20 lb-in which was more than enough to achieve a taught chain but not so much to break the plastic guide assembly.

The "pencil" reduces the volume of the oil gallery which reduces the time it takes after engine start to pressurize the front hydraulic tensioner. It was originally part of the 00m12 kit that included intake manifold gaskets and the front hydraulic tensioner.

Be very careful when attempting to extract the old gallery plug. Many members have stripped the head causing significant problems to overcome. After cleaning the plug I made sure the Torx bit was fully seated into the head by tapping on an extension with a small hammer. I applied strong pressure to the socket drive while attempting to loosen the plug.

 

[RatCav]

Ahh ... so the simple solution is to just jam the front tensioner so it doesn't compress, and wind it in to 20 lb-in. That should then hold the chain tight enough so you can do up the sprocket bolts.

The trick with the gallery plug is one I always use on things like that. I have an Isuzu Trooper. On the front hub there is a locking plate held in with 3 off 4mm countersunk screws with a tiny pozi slot. Unless you use the tapping technique you strip the pozi slot and you are knackered.

 

[2000StreetRod]

installing new tensioners

Before installing your new tensioners I suggest testing them by compressing the piston with your thumb. Check for good spring pressure and free movement. Also, I suggest oiling them before installation. Some members have installed new aftermarket tensioners that seized immediately after engine start. If the tensioner seizes in the extended piston position the cassette guides breaks. If seized in the piston retracted position the timing chain can slip during deceleration when the traction side becomes slack. There are different torque values for the tensioner with and without the compression ring. If using the compression ring apply thick grease to keep it centered on the barrel during installation. Without the grease it will easily drop off center and then you'll have a significant oil leak no matter how tight you torque.

If the head surface that mates with the sealing face of the tensioner (green arrow) is scratched or pitted I suggest using the compression ring. The red arrow indicates the oil port for the tensioner. There should be a small hole in the end of the piston that allows oil flow thru the piston and helps lubricate the guide assembly.

 

[RatCav]

Yeah, I read about dodgy tensioners somewhere else. First thing I did was take them out and see if they had good springs in and moved freely. I noticed the tiny hole in the end of the piston. I reckoned it was for chain oiling purposes. Cheers for confirming that.

I have that engine assembly manual you kindly provided so will look out for the torque values of everything.

I would of got OEM Ford tensioners, but being in the UK I don't have that luxury. UK Ford doesn't readily support the Explorer, and the parts if they do have them, far exceed the value of the truck. I bought that DNJ kit from Rockauto as they are one of the very few places that have everything and ship to the UK. I did some research and the general opinion is DNJ parts are as good as OEM if not better in some ways. Here is hoping.

 

[2000StreetRod]

tensioner springs

If the DNJ kit tensioner springs are stronger than your old tensioner springs then the DNJ ones are possibly better than OEM. Members are reporting that new OEM springs are very weak. I still had cold start timing chain rattle after installing all OEM timing chain components so I solved the problem with a pre-oiler.