Chain guide broke

I had a rattling noise develop randomly one day and couldn't discover what is was until I used the stethoscope method and had a noise come from the front of the passenger side valve cover. Today I opened it up and discovered a few broken plastic pieces broken. It has to be chain guide is my thought and was wondering if you guys have ever had this happen or heard of it happening. thanks

I've heard the guides on the 4.6 and 5.4 were prone to breaking
How many miles you at?

The guy I bought this from a long time ago rebuilt the motor with new forged rods/pistons and most everything internally was replaced but I'm thinking he maybe re used the chain guides and tensioners so I'd imagine they have some mileage. The rest of the motor is new/fully built.

Yes, happened to me. Stock 3V timing gear, but 26124 springs and 127300 cams. I saw no tension on either chain, but thankfully timing hadn't jumped.

Pankerton96 said:

I had a rattling noise develop randomly one day and couldn't discover what is was until I used the stethoscope method and had a noise come from the front of the passenger side valve cover. Today I opened it up and discovered a few broken plastic pieces broken. It has to be chain guide is my thought and was wondering if you guys have ever had this happen or heard of it happening. thanks

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It's happened plenty of times. The old style ratcheting metal tensioners can lock open and put stress on the guides, breaking them.

Yeah thankfully mine didn't either. Any tips for replacement? And how long did it take you?

I know the reputation of MMR is not always stellar. But does anyone have an experience with their billet aluminum chain guides?

http://www.modularmotorsportsracing...in_page=product_info&cPath=13&products_id=568

I am agonizing over plastic or cast tensioners.... seems like the billet arms and the 2V Tensioner would be the way to go... The bigger issue for me is, how does anybody degree cams with plastic tensioners?

I have read from Billy and Lito that they will cause variation in ICL measurements. Taking them on and off is a no go with that gasket that wants to tear is you look at it wrong... what do people recommend when decreeing cams, cast or plastic??

I would run exactly what the factory has in there. I wonder what the tensioner failure rate is on completely stock vehicles. 1/100,000. 1/1,000,000.

Once you start changing stuff: my 26113 springs (the lightest comp offers,) are as much as I'd give this stuff. Of course, luck needs to be on your side.

These are only my opinions having an engineering background and now having looked at the timing tension system with my own eyes on my own engine.

Pankerton96 said:

I had a rattling noise develop randomly one day and couldn't discover what is was until I used the stethoscope method and had a noise come from the front of the passenger side valve cover. Today I opened it up and discovered a few broken plastic pieces broken. It has to be chain guide is my thought and was wondering if you guys have ever had this happen or heard of it happening. thanks

Click to expand...

I had a tensioner that was leaking bad and it made the chain loose and broke it's cam chain guide on the right side at 75k miles. So I installed the frpp camshaft drive kit and haven't had any problems since. MMR only has a aluminum tensioner arms not chain guides I think.

Yup my guide and tensioner both failed taking out my motor at 180k

BruceH said:

It's happened plenty of times. The old style ratcheting metal tensioners can lock open and put stress on the guides, breaking them.

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Yep, I still use them on my car that will see minimal miles, but the motor in my kids car has the plastic ones since he will be putting on the miles.

I see so many people on FB recommend the old style, BECAUSE they ratchet and keep tension, and here were like "psh, dont do it, they ratchet and break shit"

but thats FB for ya

FB is about the worst thing that has ever happened to communal knowledge about automobiles. It's terminal. Maybe there'll be a cycle and people will go back to books, and then forums again.

Yeah, literally every day, same groups. "Who uses a 2step", "has anyone ever (insert the first mod anyone ever does to car car)" like he's literally the first guy in the world to think of new mufflers, or a throttle body spacer.

One guy bought early 3v plugs and pulled out his, had later plug design
"Will these work? It's what part guy gave me"
Jesus they are SO freaking different it's not even funny, let alone the threads are bigger on old style and wouldn't fit if you tried. But everyone there responding "don't you'll break your pistons" like he could actually torque them down

Cars are particularly afflicted because everyone has one and everyone wants to half ass modify it at the least, especially Mustangs since they are enthusiast vehicles and are dirt cheap and ratted out to hell.

But.. this goes on with everything. Politics. It's an endless echo chamber of the same questions and arguing and it's been happening for almost a decade now. Bizarre. Who knew that a social media platform would bring out the monkey in all of us? I guess we should have.

I've been running the metal 2V tensioners for about 25,000 miles and no issues so far. Seems like they are both prone to locking up so take your pick.

So besides taking the front cover off, how difficult are they to swap out?

Pull cover. If the new ones are clipped shut you may get away with just removing the old tensioner and installing new one. But make marks on the chain and gears to be sure they didn't slip a tooth when you pull the tensioner out

If you pull the old ones off, I'd re-prime the system with a pump sprayer after putting the new ones on. You don't want to jump a tooth due to the tensioners not being fully pumped up. That may just be true for the metal ones though.