My wife went and bought a 2003 4.7 ram 1500 for oldest daughter, and ignored me insisting on having a real mechanic look at it. so she drives up and i instantly suspect a head gasket leak. Took it to a shop and of course it does need head gaskets and machining. the shop said we should replace the timing chain set..... there's about 150k on it. is this really necessary? I heard of t-belts breaking but never heard of a chain breaking. anyone with a high mileage 4.7, your input would be greatly appreciated.... probably only have the vehicle a few years as she is a junior in high school and school is 20 miles round trip. thank you!
dodge 4.7 timing chains
- Thread starter joel95ex
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Back in my youth, timing chains on V8s generally slipped somewhere around 100k miles. (They don't break....They jump a few teeth.) Oils have improved, but if you don't know the OCI history...
Plus, a timing set would be cheap, compared to the head gasket replacement. Just sayin'.
Plus, a timing set would be cheap, compared to the head gasket replacement. Just sayin'.
What diagnosis criteria lead to believe the head gasket is bad? The 4.7 are known to get a milkshake on the oil cap if they are short tripped.
My guess is ... since the mechanic has to take off the timing chain set to change the headgaskets, he figured it might be a good idea (or good for his wallet) to replace it all since it has to come off anyways.
My guess is ... since the mechanic has to take off the timing chain set to change the headgaskets, he figured it might be a good idea (or good for his wallet) to replace it all since it has to come off anyways.
I'm guessing it was over heated once.
Originally Posted By: Miller88
What diagnosis criteria lead to believe the head gasket is bad? The 4.7 are known to get a milkshake on the oil cap if they are short tripped.
My guess is ... since the mechanic has to take off the timing chain set to change the headgaskets, he figured it might be a good idea (or good for his wallet) to replace it all since it has to come off anyways.
yes because the shop pretty much doubled the price on the timing set--- its already $3-400 and i think the est had 6-900 for that set----i would but the parts, but still, its 3-400 bucks when the real issue is the heads...
What diagnosis criteria lead to believe the head gasket is bad? The 4.7 are known to get a milkshake on the oil cap if they are short tripped.
My guess is ... since the mechanic has to take off the timing chain set to change the headgaskets, he figured it might be a good idea (or good for his wallet) to replace it all since it has to come off anyways.
yes because the shop pretty much doubled the price on the timing set--- its already $3-400 and i think the est had 6-900 for that set----i would but the parts, but still, its 3-400 bucks when the real issue is the heads...
If the shop wasn't going to charge extra labor, I'd say they have your best interests in their mind. Seems like they just want to make a lot of money from you ...
Its more $$ cause its lots more labor to get all that [censored] off of the front of the engine...its basically a ford 4.6 mod motor copy...x-wife and i had same exact truck bought brand new..all maintenance done by dealer and on time..never abused..no sludge(which they do)..90k overheated for no reason..head gasket..poured some expensive blue stuff in the radiator and straight to the dealer it went on a new one..she didnt trust it and didnt wanna spend $$ on it...was 8 years old..
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The chains stay in place when they do heads...to get the chains off you have to remove everything off of the front of the engine including the big front cover..there is also guides and tensioners to replace also..its not a quick fix at all...
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Originally Posted By: DSparks
The chains stay in place when they do heads...to get the chains off you have to remove everything off of the front of the engine including the big front cover..there is also guides and tensioners to replace also..its not a quick fix at all...
it's an overhead cam engine so all chains come off for head removal
The chains stay in place when they do heads...to get the chains off you have to remove everything off of the front of the engine including the big front cover..there is also guides and tensioners to replace also..its not a quick fix at all...
it's an overhead cam engine so all chains come off for head removal
Timing chains in the old V8s lasted forever as the path was simple. When they went from timing belts to chains they kept a complex path and while timing chains do last a lot longer than belts, they do not last as long as they did 20 or 30 years ago.
They come off the front of the cam and get tied up while the heads are removed...but they stay on the crank...if the guy knows what he is doing...
My 4.7L hasn't sludged up. Hmmmmmmmmmm, news to me!
You're having the heads off... You're already most of the way there. Might as well do it vs. having that grenade thought in the back of your mind all the time
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I doubt the chains are stretched or badly worn, but I would certainly inspect the guides and tensioners. Those are much more often at fault for "timing chain" failures on modern engines than the chains or gears themselves. If it were my 4.7, I'd probably go all the way despite the extra cost. The bottom-ends on those engines are rock solid, so its nowhere near the end of life if its properly repaired.
The Chrysler 4.7 does have one huge difference from the very similar Ford Modular: it has an intermediate sprocket between the crank and the cam sprockets. The intermediate sprocket sits on the front of the block about where a cam-in-block v8 would have its cam gear, and the intermediate gets the 2:1 reduction from crank speed. The two cam chains run at a 1:1 ratio from the intermediate sprocket up to the heads, which lets the sprockets on the cams themselves be smaller than if they had to be twice the circumference of the crank sprocket.
The Chrysler 4.7 does have one huge difference from the very similar Ford Modular: it has an intermediate sprocket between the crank and the cam sprockets. The intermediate sprocket sits on the front of the block about where a cam-in-block v8 would have its cam gear, and the intermediate gets the 2:1 reduction from crank speed. The two cam chains run at a 1:1 ratio from the intermediate sprocket up to the heads, which lets the sprockets on the cams themselves be smaller than if they had to be twice the circumference of the crank sprocket.
Originally Posted By: 4wheeldog
Back in my youth, timing chains on V8s generally slipped somewhere around 100k miles. (They don't break....They jump a few teeth.) Oils have improved, but if you don't know the OCI history...
Yeah, but that was always due to them having a nylon "silent" cam gear. They quit doing that stupidity in the 80s for the most part. All sprockets on a 4.7 are steel, the most wear-prone part of the timing system is the tensioner shoes.
Back in my youth, timing chains on V8s generally slipped somewhere around 100k miles. (They don't break....They jump a few teeth.) Oils have improved, but if you don't know the OCI history...
Yeah, but that was always due to them having a nylon "silent" cam gear. They quit doing that stupidity in the 80s for the most part. All sprockets on a 4.7 are steel, the most wear-prone part of the timing system is the tensioner shoes.
FYI, here's a picture of the timing system on a 4.7. The yellowish pieces are the timing chain tensioner "shoes" that should be inspected if possible:
And YES, standard procedure is to wire-tie the chains in place and leave them around the intermediate sprocket when R&R-ing the cams or heads. But with the heads off, you should be able to get a pretty good look at all of the guides and tensioners except maybe the two on the chain from the crank to the intermediate sprocket.
Just for giggles, this is how completely different a Ford Modular is in front:
And YES, standard procedure is to wire-tie the chains in place and leave them around the intermediate sprocket when R&R-ing the cams or heads. But with the heads off, you should be able to get a pretty good look at all of the guides and tensioners except maybe the two on the chain from the crank to the intermediate sprocket.
Just for giggles, this is how completely different a Ford Modular is in front:
It looks like it's an overhead cam motor. Those chains don't look anywhere near as heavy duty as a pushrod motor chain. A pushrod motor chain is beefy and relatively short and it doesn't have all those different bends to go through like that overhead cam chain has to do. I think you should let them change it, but make sure it's the whole kit like in this picture.
Originally Posted By: Merkava_4
Those chains don't look anywhere near as heavy duty as a pushrod motor chain.
You're thinking old-school pushrod motors like the 440s in my sig, where the chain had to drive the load of the oil pump (one to a few horsepower) and the load of non-roller lifters (sometimes quoted as up to 10 horsepower at maximum RPM).
Even modern pushrod engines have much lighter chains now that the oil pump is driven directly by the crank and roller lifters are used. The timing chain doesn't have to work nearly as hard as it did on an old 60s-80s V8.
Those chains don't look anywhere near as heavy duty as a pushrod motor chain.
You're thinking old-school pushrod motors like the 440s in my sig, where the chain had to drive the load of the oil pump (one to a few horsepower) and the load of non-roller lifters (sometimes quoted as up to 10 horsepower at maximum RPM).
Even modern pushrod engines have much lighter chains now that the oil pump is driven directly by the crank and roller lifters are used. The timing chain doesn't have to work nearly as hard as it did on an old 60s-80s V8.
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