2005 V6 valvetrain... wtf?

subaruspy

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Having a rough day, folks. Hours after completing the body work (they clipped a deer last fall) on my girls' ragtop and getting it legal, The Bad Noise started coming from the engine, and the tow truck just dropped it off.

The clatter is top end, driver's side, so I'm hoping "not too bad, bent rod, broken spring, just hope we don't have a valve in the cylinder really messing things up".

Only I'm looking around online (having never touched this motor and can't find the Haynes manual I picked up when we got the car last summer) and can't make out whether this is a push rod or an OHC engine. Would some kind soul please enlighten me before I start pulling it apart?
 
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subaruspy

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Thanks. I don't know if I'd call a jackshaft and three timing chains "clever", but at least that rules out push rods. So with one cam over, it'll be driving the valves via rockers. Is there any "usual" failure in these things that results in an uholy racket from under the valve cover?
 

subaruspy

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Okay, as these things go it looks like good news - the port side tensioner guide went to pieces. I'm guessing that "broken plastic thing" is a relatively common failure in these engines.

Next question: Since it's my first time inside this thing, can anyone direct me to a good and free shop manual for this year and engine?
 

Bullitt95

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Okay, as these things go it looks like good news - the port side tensioner guide went to pieces. I'm guessing that "broken plastic thing" is a relatively common failure in these engines.

Next question: Since it's my first time inside this thing, can anyone direct me to a good and free shop manual for this year and engine?

The Cologne 4.0L V6 used in 05-10 Mustangs is a SOHC engine with a balancer shaft and an additional rear timing chain (stupid idea). These engines are generally robust and can last up to 300k miles, with the only common failure point being the plastic thermostat housing.
A broken timing chain guide is usually caused by a failed tensioner causing the chain to slap against the guide. The cure is to replace the whole kit (chains, guides, and tensioners).
 
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MustangIIMatt

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The effin short version of fixing your problem is as follows:

Drop the transmission (doesn't have to be removed completely, but it does have to be lowered).

Remove the engine (not enough room to work between back of engine and firewall).

Remove valve covers and timing covers.

Set engine to TDC and remove timing chains and guides.

Install new chains and guides using the following tool to time everything (there are no marks, which is typical on engines engineered by Germans, including this one).

Amazon product
View: https://www.amazon.com/DPTOOL-CAMSHAFT-Explorer-Mustang-Mountaineer/dp/B07RPSLK3V/ref=sr_1_1_sspa?keywords=4.0+ford+timing+tool+kit&qid=1653948703&sprefix=4.0+Ford+%2Caps%2C127&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQkhSTVk4RlRUOU5FJmVuY3J5cHRlZElkPUEwMzEzMDUzMzFPVUlCSTNIQUUyNSZlbmNyeXB0ZWRBZElkPUEwMjI1NDcwMjhSWElHWUJLTk05VCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=


Re-assemble engine.

Install engine.

Put transmission back where you found it.

Amazon product
View: https://www.amazon.com/Ford-Mustang-Haynes-Repair-Manual/dp/1620921871/ref=sr_1_3?crid=WUUDSDB2QXSB&keywords=Haynes+manual+ford+mustang&qid=1653948825&sprefix=haynes+manual+ford+mustan%2Caps%2C103&sr=8-3


That book has the procedure in detail, and for a Haynes manual, it's surprisingly accurate.

with the only common failure point being the plastic thermostat housing

And the timing chain guides, and the head gaskets after awhile. That said... the 2005-2010 Mustang with the 4.0 is still an absolute GEM to drive, and actually is reasonably reliable. It was the first six-cylinder engine that performed worth a damn Ford ever used in the Mustang. The 3.7 that replaced it was superior in every way, but the 4.0 made an absolute mockery of the 3.8 and 3.9 V6s that preceeded it, and every inline six and the 2.8 Cologne that was its ancestor.
 
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subaruspy

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I get it. But this time around we're not pulling the engine, just doing the front end.

We already had the Haynes manual, but it was mislaid in a big turn-the-house-upside-down over the winter while we were putting down new floors, so we just went out and bought a second copy, which is very annoying.

We're aware of the OTC 6488 tool (and the knockoffs e.g. the one you linked to), but weren't yet sure we wanted/needed it. Also, summer is very short here, so time is of the essence and we don't have the luxury of shopping for best price that might come with a six-week delay (like that one).

But what really has me astonished is the lack of positive engagement between any of these sprockets and shafts (except for the crank). Two sprockets just screwed to the jackshaft without splines or anything else to keep them from rotating out of time with each other but a hug and a prayer? And this engine is supposed to be reliable?
 

KRUISR

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But what really has me astonished is the lack of positive engagement between any of these sprockets and shafts (except for the crank). Two sprockets just screwed to the jackshaft without splines or anything else to keep them from rotating out of time with each other but a hug and a prayer? And this engine is supposed to be reliable?
You should look up the history and cam issues with the 96-99 Taurus SHO 3.4L 32V V8.
 

MustangIIMatt

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But what really has me astonished is the lack of positive engagement between any of these sprockets and shafts (except for the crank). Two sprockets just screwed to the jackshaft without splines or anything else to keep them from rotating out of time with each other but a hug and a prayer? And this engine is supposed to be reliable?
That's the industry standard way of doing it these days.

You should look up the history and cam issues with the 96-99 Taurus SHO 3.4L 32V V8.
Not even remotely related here. That was Ford and Yamaha trying to do something silly by pressing a ball into the end of the cams. Modern engines use either a slightly rough surface and an insane amount of torque, or just the torque to achieve sufficient clamping force.
 
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MustangIIMatt

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I get it. But this time around we're not pulling the engine, just doing the front end.

You're probably going to find out the hard way that your rear guides are broken too while doing this. They're made of the same plastic that gets brittle over time and that rear chain sees a lot less oil.
 

subaruspy

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That's the industry standard way of doing it these days.

Modern engines use either a slightly rough surface and an insane amount of torque, or just the torque to achieve sufficient clamping force.
That's funny, the Subaru EJ25S I just did head gaskets on - a year newer than this Mustang - has notches milled in the ends of the camshafts that positively engage the timing sprockets, just like they always have, no fooling around. So much for the modern, industry-standard way.
 

subaruspy

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You're probably going to find out the hard way that your rear guides are broken too while doing this. They're made of the same plastic that gets brittle over time and that rear chain sees a lot less oil.
I don't doubt you for a minute. And my circumstances make that a tough call we're going to have to make asafp.

Talk to me about chains and tensioners. They seem nice and tight after 225K km. Re-use?
 

MustangIIMatt

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That's funny, the Subaru EJ25S I just did head gaskets on - a year newer than this Mustang - has notches milled in the ends of the camshafts that positively engage the timing sprockets, just like they always have, no fooling around. So much for the modern, industry-standard way.
GM, BMW, Ford, Volkswagen, and Honda all have the "new" way of doing it on at least some of their engines. My favorite is the BMW N20 where everything floats but the oil pump/balance shaft, THAT pulley gets pinned. :rlaugh:
 

MustangIIMatt

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I don't doubt you for a minute. And my circumstances make that a tough call we're going to have to make asafp.

Talk to me about chains and tensioners. They seem nice and tight after 225K km. Re-use?
As cheap as a whole kit is (SKP has a kit with a year warranty on it for $68 on RockAuto), it hard to justify cheaping out on it, especially when it all has to come out anyway. I've actually used that SKP kit on a 4.0 I did in someone's driveway and carport on a side job, it's not bad.
 

subaruspy

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GM, BMW, Ford, Volkswagen, and Honda all have the "new" way of doing it on at least some of their engines. My favorite is the BMW N20 where everything floats but the oil pump/balance shaft, THAT pulley gets pinned.

Remind me to never buy any of those.
 

subaruspy

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As cheap as a whole kit is (SKP has a kit with a year warranty on it for $68 on RockAuto), it hard to justify cheaping out on it, especially when it all has to come out anyway. I've actually used that SKP kit on a 4.0 I did in someone's driveway and carport on a side job, it's not bad.
I noticed that one. Seems crazy cheap for all those parts. I don't consider the warranty to mean anything, since all the value is in the effort, not the pieces. So the quality of that kit's alright?
 

MustangIIMatt

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Remind me to never buy any of those.
It really is the direction things are going. On the one hand, it simplifies things on the assembly line. On the other, it means dealerships/shops/mechanics/owners have to buy, rent, or borrow special tools to install them, and some of the torque requirements are nuts (the aforementioned N20 crank bolt gets torqued to 100Nm+270° of rotation, which is over 500 ft/lbs when finished).
 

MustangIIMatt

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I noticed that one. Seems crazy cheap for all those parts. I don't consider the warranty to mean anything, since all the value is in the effort, not the pieces. So the quality of that kit's alright?
Yeah, it wasn't any better or worse than what I deal with on the daily at the shop, and it fit perfectly.
 

subaruspy

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It really is the direction things are going. On the one hand, it simplifies things on the assembly line. On the other, it means dealerships/shops/mechanics/owners have to buy, rent, or borrow special tools to install them, and some of the torque requirements are nuts (the aforementioned N20 crank bolt gets torqued to 100Nm+270° of rotation, which is over 500 ft/lbs when finished).
I wouldn't have the first clue how to do that.