How to: SOHC V6 Timing Chain Inspection & Repair

[laker82]

Asked around and found a local who mostly builds stock car engines.He did not want to do the lower end but will do the heads. Too many engines ahead of me. First head did have two bent valves so pulling was the right choice.
Found the catastrophic failure that left vehicle dead on side of the road; The rear of the jackshaft has a bolt that holds on the gear to drive the rear chain. That bolt broke. Hope it is still available.
Tork head bolt that holds main chain gear is a E 24 which is larger than a T 60. Did not know that.

 

[Drewmcg]

Asked around and found a local who mostly builds stock car engines.He did not want to do the lower end but will do the heads. Too many engines ahead of me. First head did have two bent valves so pulling was the right choice.
Found the catastrophic failure that left vehicle dead on side of the road; The rear of the jackshaft has a bolt that holds on the gear to drive the rear chain. That bolt broke. Hope it is still available.
Tork head bolt that holds main chain gear is a E 24 which is larger than a T 60. Did not know that.

Thanks, this helped me . . . wish I'd known this a week ago, so I wouldn't need to wait another 5 days to continue this repair! Local O'Reilly's does not stock this socket....

 

[ef2764]

So now what?

What do you do when you have a tap/knock/rattle in your left front valve cover and you pull it off hoping to find your timing chain guides broken and you come up empty handed? It started for me yesterday and after reading the 100's of posts about failing timing guides I figured I'd pull it apart and take a look. No such luck. Anyone have any suggestions? I'm used to pushrod motors that would have lash adjustments or collapsed lifters. My explorer is an 03 with just over 200,000 miles on it and I'm proud to say a very clean engine internally.

On a side note, how far should the plunger of the tensioner be out? My tensioner was bottomed out when I took the valve cover off and the opposite side of the chain was slacked like the tensioner wasn't doing anything. I know this is oil pressure driven somehow but could it have leaked down? Is the spring inside the tensioner supposed to hold the plunger out until you build oil pressure? Again I assume this tensioner is the original but I am the second owner of this vehicle and I can't say for sure.

Open to suggestions here

Thanks

Justin

 

[2000StreetRod]

when tap/knock/rattle?

Welcome to the forum Justin. Does the engine tap/knock/rattle at all engine speeds? Or does it do it just at cold start? It is very hard to locate the source of an internal rattle because sound echoes off the walls of the block. If the sound occurs at mid engine speeds then you might have a failed crankshaft to jackshaft chain tensioner. I suggest pulling the oil pan and checking for fragments in the bottom of the pan and the oil pickup tube screen. If you find the pieces shown below then its your primary tensioner.

 

[laker82]

There is a lot of tension in the chain from the tensioner even not running. When reassembling a dummy tensioner is used, but it is hard to tell the difference from the hydraulic, they are both tight.

 

[laker82]

I would remove the right valve cover next and check that side. It will come out without draining anti-freeze but it is a pain.
That side has the same mileage.

 

[ef2764]

when and how

Does the engine tap/knock/rattle at all engine speeds? Or does it do it just at cold start?
View attachment 85947

It has a very brief rattle at cold start which it always has had. At idle there isn't anything that sounds out of line, when I'm accelerating under load is when I'm hearing it. I replaced the tensioner for the driver's side timing chain hoping that would fix it but that was just a waste of $100. Oil pressure is fine but I like your suggestion to check the pan. That will be my next step.

Thanks

Justin

 

[BobRob]

It has a very brief rattle at cold start which it always has had. At idle there isn't anything that sounds out of line, when I'm accelerating under load is when I'm hearing it. I replaced the tensioner for the driver's side timing chain hoping that would fix it but that was just a waste of $100. Oil pressure is fine but I like your suggestion to check the pan. That will be my next step.

Thanks

Justin

I had very similar symptoms on my 02 with 137,000 at the time. Last spring, I pulled the valve covers to verify the guides were good (which they were) and pulled the front cover and replaced the main tensioner. It wasn't broken but was a weak 3 blade spring. After replacing it with the new, beefier 6 blade tensioner, it has been quiet as can be. That was about 10,000 miles ago.

 

[ef2764]

Pulled the pan

I pulled the lower pan today and low and behold I have chunks of plastic in the sump. I guess the timing cover is next. Wish me luck

J

 

[laker82]

2000StreetRod,
Do you have a rough idea of what percentage of engines with a bad left side also have a bad right side?

 

[Drewmcg]

I pulled the lower pan today and low and behold I have chunks of plastic in the sump. I guess the timing cover is next. Wish me luck

J

The chunks could be from either left or right timing cassette. You might want to do a leak down test on each bank, which would tell you whether its the right (rear) or left (front) cassette. If both banks fail, then s/b the primary tensioner that failed (if the primary chain slipped, then both banks' timing will be off).

My impression from lots of reading here is that the cam timing cassettes fail more often than the primary; and that after Ford beefed up the primary and left tensioners/cassette for at least the late '02 model year builds, the right rear cam timing cassette fails most often.

As Streetrod has stated, if it turns out that one of the front timing chain parts failed, you have the option of leaving the engine in the car for the replacement. But if you leave the upper oil pan/ladder/girdle in, you run the risk of not cleaning out all the plastic bits of the failed part. I think you can remove the upper oil pan on 2wd models with the engine in the car (not sure), but that the front transfer case blocks doing so on 4wd. If you wind up leaving it (upper oil pan) in place, I'd consider running some light oil and maybe a cleaner (e.g., Seafoam Engine Tune) through the new oil for an appropriate interval (15 minutes?) and then draining and pulling the lower oil pan again to see whether you find more broken bits that came unstuck (and to remove and re-clean thoroughly the oil p.u. screen).

 

[Drewmcg]

The above assumes you've slipped a cog or more on one of the timing chains. If not, stethoscope or visual inspection (from top, front cover, or through one of the cam guide tensioner holes) will be required to identify the failed bit.

 

[2000StreetRod]

not many

2000StreetRod,
Do you have a rough idea of what percentage of engines with a bad left side also have a bad right side?

I'd say that its a very low percentage unless the owner has totally neglected the vehicle. It is unlikely that the cassettes would both fail at the same time. Only a negligent or broke owner would ignore the racket and continue to drive the vehicle until the other cassette failed. It is not uncommon to find a 2nd Generation with a failed cassette and a failed primary chain tensioner since a failed primary chain tensioner can be quiet.

 

[ef2764]

The good the bad and the ugly

The good:
I pulled the front cover today. Lo and behold my main tensioner is broken which is where i believe most of the noise is coming from. Mind you this is a 6 leaf tensioner and it broke at the lower pivot.
The bad::thumbdwn:
The pieces in the pan are not from the main tensioner and the left tensioner is still intact
The ugly::thumbdwn::thumbdwn:
I think I have to pull the motor

Does anyone have any pictures of what the balance shaft tensioner should look like? Is there an easy way to inspect the right side rear tensioner without pulling the engine?

Thanks

J

 

[2000StreetRod]

passenger valve cover

You can usually tell if the rear cassette is broken by pulling the passenger valve cover. It usually breaks at the top where the guide post is or near the bottom (see post 2).

Below is a photo of the balance shaft chain tensioner with the block cradle removed.

 

[Drewmcg]

Well, at least your path forward (choice) is clear: either pull the engine and replace all timing chain sets (at least three of the four), or walk away.

It makes no sense to repair the front (primary) tensioner only with a failed rear cam cassette, which will only court disaster. And even if you'd only discovered a failed primary (or left) tensioner/guide/cassette, you'd still be running on borrowed time with that rear cassette.

Just trying to make you feel a bit better here. If you decide to "go for it" and do the whole job, you should have some peace of mind in the end . . . .

 

[ef2764]

Timing the new cams

The more I think about it the more I realize that the jack shaft timing to the crankshaft timing is irrelevant until you set the cam shaft to to jack shaft timing. Correct?

 

[laker82]

Yes, the jackshaft is basically an idler between the crankshaft and the right cam.

 

[Tech By Trade]

Yes, In the OTC timing kit there is a part that locks the crank at tdc on 1, and another that locks the cam at tdc. Once locked you tighten the jackshaft and cam bolts.

 

[ef2764]

The verdict is in

My impression from lots of reading here is that the cam timing cassettes fail more often than the primary; and that after Ford beefed up the primary and left tensioners/cassette for at least the late '02 model year builds, the right rear cam timing cassette fails most often.

So I pulled the right valve cover yesterday. Lo and behold a failed rear tensioner along with my failed primary tensioner. It makes me wonder which one was actually making the noise because I highly doubt they failed at the same time and I've only recently started hearing the rattle.

Anyway motor is coming out today

Thanks for the help

J