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YOUR RESEARCHHours to replace chain guides, vs engine pull...
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large non-removable ims bearing
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Reported cause
One clue that I have about the engine is that it was the large non-removable IMS bearing.
Leading evidence: 'large non-removable ims bearing' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'large non-removable ims bearing' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check here' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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My 8 year old OBD II did very little, and at $150 this tool proved to be worth it.
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Performed · outcome unconfirmed
Cam deviations were within spec when I had them checked last year, but I know the guides are shedding plastic, so this is something that I need to do sooner or later.
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Performed · outcome unconfirmed
The chain guides can be replaced after the engine is out.
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Engine was replaced at some point, but I have no info on whether the engine was a new replacement or a used engine.
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Cam deviations were within spec when I had them checked last year, but I know the guides are shedding plastic, so this is something that I need to do sooner or later.
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Suggestion
The guys that do this with the motor in the car have done it several times and know how to "skip" steps or do the repair a little differently then it was designed to get done.
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Suggestion
Maybe you can also replace 2 of the larger guides (one on each bank) but to get the other two you will need to remove the transmission and the front consul (oil pump).
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Suggestion
Industry standard is 3% growth is the limit due to the geometry of the chain will no longer be a good match for the sprockets .If a chain has worn to 3% growth in length, the sprockets should be replaced also..
small "single roller" chains anytime i had the opportunity
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So on the 5 chain engines I would suggest replacing the cam pads and probably the small "single roller" chains anytime I had the opportunity to be in the vicinity..They can be replaced without "splitting the cases"..
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My new inde says it's 14 hours labor to replace the chains/chain guides on my 03. He also says it's 10.7 hours to r&i the engine/trans. I think that the 14 hours includes another 10.7 on the engine r&i. 3.3 hours for chains/guides once the engine is out seems reasonable to me.
What do you guys think? Am I smoking crack on this?
Given the miles and just the age of our cars, they'll all need top end rebuilding? Usually when I read posts about major engine work it's bottom end, but if the bottom end is healthy, no scoring, surely at some point the nylon chain guides have to be replaced, with the chains also? When doing that, there must be a long list of while you're in there. Nothing worse than missing something.
I wish to hell my Indy had told me to get my oil filler tube replaced when the alternator was. Grrr.
The chain guides can be replaced after the engine is out.
The chains cannot be replaced unless you split the case since there is no master link.
14 hours seem doable for removing the engine and replacing the chain guides. It's a very different picture if you need to replace the chains on a 3-chain engine.
Well, if your chains are worn out and need replacement, and the heads have to come off anyway, you might as well give them a valve job. And because you are splitting the case, you have to replace all the one time used fasteners, Tensioners, AOS, RMS, FMS, water pump, thermostat, IMS. You will also find plenty of worn out coolant hoses, coolant tank, and breather hoses / vacuum lines.
The only other things you would have to check, inspect, and consider are the rings and condition of the pistons / bores.
Yea you're smoking crack !! J/K
If the chains are worn out ( long chains) you will have the whole engine apart anyway, so , the "while you're in theres" would be a complete overhaul/refresh of the engine....
The chains don't actually stretch, they wear at the pins and pivots which makes them longer...there are actually chain gauges that can measure the wear...a 3% wear is the industry standard on chain wear, but on the M96 on my personal engines I use 1- 1.5% ,,, most shops/builders just replace them without measuring them " just for the hell of it" ....there are no service intervals on chain replacements..so it does make since to just replace them when doing an overhaul/refresh..
Why are you tearing in to the engine anyway? Just to replace the chain guides? Did you find a lot of chain guide debris in the sump?
You can't really measure the chains while in the engine...you need to have a fairly long straight section to measure...How many miles/hours are on the chains??
Original chains, 139K miles on the engine. Last oil change I started seeing what texsquirrel and I think are super fine black chain guide filings. In a few days I'm going to pull the oil filter and see what's up, it's been about 1K since the oil change.
I'm also due for a IMS bearing, and my RMS is leaking a tiny bit. So goal here is to figure out what I can afford to do right now.
well, at 140,000 miles, I would say the chains have seen their days. But, I totally understand that there are budget constraints in real life. Knowing that replacing chains, at these miles, really leads to a total engine rebuild, and dropping the engine to replace a bunch of stuff right now will still run you into $4K-$5K, maybe you should change the oil more often, drive the car less, and save up for a rebuild.
Is it accurate to say that 3.4 and 3.6 have different issues regarding chains and the plastic tensioners? If so, how does the recomended service differ amd when?
My 99 3.4, at 113k miles, had minimal wear to the main guides, but a lot of wear on the variocam pads. I changed the variocam chains and pads (and main guides because I had them), and this eliminated ALL startup chain noise. I had replaced all tensioners previously, but do not believe they actually needed it. My engine just needed the variocam pads changed, which would have cost very little since I did the engine removal, work, and installation myself in the garage.
If anybody has the details, now would be a good time to discuss the difference between the 3.4 and 3.6 as relates to the thread topic.
As a 3.6 owner, I never focused on the chains nor worried about the plastic bits that wear in the 5 chain system of the 3.4 because my understanding is the 3.6 doesn't suffer from it. Nor have I worried about replacing the timing chains at a pre-determined interval. Maybe I should worry about it or maybe not. Dunno
Bet the 3.4 owners would like to know as well. Certainly is a good topic for discussion and education.
So let's play the "what-if" game for a second.
What if you have a 3.4 or a 3.6 that you or previous owners have properly serviced. Let's say you have no bore scoring as a result and aren't necessarily looking to rebuild the engine because you don't need too. Instead, you are looking to keep it running as long as you can but realize that the Porsche Maintenance Schedule doesn't go out a couple of hundred thousand miles with recomendations on the 3.4 and 3.6 as it relates to the chains and bits.
So what can go wrong, what should you look for, what can you do to prevent any breakage and problems. In essence, what service amd procedures should be performed and when as it pertains to the 5 and 3 chain systems.
Porsche M96 Timing chains 101:
As a general rule, timing chain systems are designed to last the life of the engine ( unlike timing belt systems) . They can be single roller, dual-roller ( or even triple roller or quadruple roller ect) as necessary for strength.Obviously dual rollers are twice as strong and wear resistant than single rollers...They can even be Hyvo design for quieter operation..
Typical life span for Porsche M96 timing chains range from 100k miles to 300k miles depending on the service intervals and average running RPM..
Timing chains don't actually stretch, they wear at the pins and pivots to grow longer. Industry standard is 3% growth is the limit due to the geometry of the chain will no longer be a good match for the sprockets .If a chain has worn to 3% growth in length, the sprockets should be replaced also..
Wear from abrasives and stress are what causes the length to grow....
So the more frequent the oil is changed the less abrasives and the less wear on the chains.
Rpm is the stresser, at low RPM under 2k , the valve springs resist rotation of the cams on the lift side of the lobe, then when the cam goes over the nose of the lobe on the closed side the springs accelerate the rotation of the cams..Because there are 3 cylinders acting on 1 chain this resistance and then acceleration causes a harmonic stress. The engine is actually happier above 2k RPM and the chains are less stressed..From 2k Rpm to 5.5k Rpm is the sweet spot, above 5.5k Rpm the stress starts to rise again due to harmonics and centrifugal forces..So the amount of hours spent below 2k and above 5.5k RPm play a big factor in the life of the timing chains..
Both 5 chain and 3 chain M96 have two long dual-roller chains and a shorter chain that is either a dual roller (early engines up to 2001) or dual Hyvo ( 2001 +)
The 5 chain engines have two more very short "single roller " chains that connect between intake and exhaust cams and also a set of Cam pads that theses chains run on.. Since these are " single roller" chains they are twice as likely to wear due to abrasive oil or harmonic stresses so the "life span" would be expected to be 50k miles to 150K miles depending on maintenance history and average RPM in use..
So on the 5 chain engines I would suggest replacing the cam pads and probably the small "single roller" chains anytime I had the opportunity to be in the vicinity..They can be replaced without "splitting the cases"..
As far as measuring the chain wear, it can be done with the chains laid out and measured using the proper gauge/procedure..but nobody does this,, right ??
There could be a directive designed and a spec provided to get a fairly accurate measurement in situ by installing a new chain and measuring the distance of the stroke of the tensioner and compare that to the measurement of installing a chain that is worn to the 3% limit and get a measurement of the tensioner stroke distance...
Then you could say that measurement X = like new chain, and that measurement Y= 3% wear limit, and even create a special tool for the measurement and market it...but the reality is that no one would buy it/use it ( like special tool 9599 for chain tension ) and just use the "while you're in there" protocol and just replace them.....thats the age we live in...
Porschetech is one of a few I don�t fact check here. Thanks, I�m very, very appreciative of his kindness to share. Can you please provide any guidance on helping a 3 chain longevity?
Sure, three chain engines can benefit from starting the engine and driving off immediately keeping the RPM above 2k rpm and below 3k rpm unit the engine is warmed up. This is good for timing chain wear and also good for cylinder protection. Warming up quick to get off "cold start mode" helps protect cylinders and keeping the RPMs between 2k-3k helps warm up faster and keeps chain harmonics in the sweet spot..
Under normal driving conditions keep RPM between 2k and 5.5k RPMs will keep chain harmonics in the sweet spot, avoiding prolonged idle periods ,and using quality synthetic oil with frequent changes will give the longest chain life...
This is instinctively the way I drive my car normally every day anyway unless I want to hear the Banshee Scream up to 7200 rpm Red-Line, which I also do frequently for a few seconds...( just got back from doing it
)
It's amazing to me how so many people think it's a good idea to let a cold car idle to warm up while they drink coffee or whatever. Starting to hear more and more recommendations to do what he says here and drive off gently but immediately if you care about your engine.
My neighbors all seem to start their cars then go back in the house. As if by warming up the car some magic happens that can't happen when you are driving. What a waste of fuel.
Plus, why spew pollutants.
OP here, amazing how this thread went from a discussion on how many hours it takes to do the chain guides to a discussion on how to warm up our cars. Got to love the internet!
Yes I would, also like I mentioned earlier the 5 chain engines have two "single roller" chains and sliding pads that will need attention/maintenance half way through the life of the other "dual roller" chains..
But that can be done without "splitting the cases" ..
A little bit old of a thread, but I am finding brown plastic bits in the oil filter that I am assumimg to be the chain guides. I have a 99 C4. Engine was replaced at some point, but I have no info on whether the engine was a new replacement or a used engine. I have put on 70 000 on the car since we bought it 5 years ago, though. One clue that I have about the engine is that it was the large non-removable IMS bearing.
Anyway - question is: what be be replaced in my 3.4 engine in terms of the plastic guides and chains without taking the engine out?
Only the variocam pads. Honestly i wouldnt attempt a variocam pad/chain swap with the motor in the car. The guys that do this with the motor in the car have done it several times and know how to "skip" steps or do the repair a little differently then it was designed to get done.
First thing u need to do is grab a scanner and get cam deviations.
Search for my thread on variocam pad replacement and it will show u what i was able to do with the motor out.
I am not doing it myself. I will get a shop to do it. Trying to find one. The 3 I have asked so far will take the enigine out and want $12 - $15 000 canadian to do it by taking the engine out, and another said they can do it with the engine in the car and want $5000 canadian. I big difference, so I'd like to educate myself to see if it is too good to be true. With brown plastic bits in the filter, I would assume I should replace ALL the chain guides and chains. Cam deviations were within spec when I had them checked last year, but I know the guides are shedding plastic, so this is something that I need to do sooner or later.
I will look up your threads, thanks.
Holy $hit 12-15k ......r they splitting the motor? Its takes me 8 hrs of labor to remove and install a motor.....r they charging u $1k/hr. Even $5k is insane.
Keep in mind that is in Canadian dollars. But I am MORE than willing to drive to get this done if I can save a $1000 or more. I am open to suggestions. I am in Edmonton, Alberta, Canada.
There is no way to replace all the guides and chains without splitting the case.
you can only replace the two short chains and guides between the cam shafts on each head with the engine in or out of the car.
Maybe you can also replace 2 of the larger guides (one on each bank) but to get the other two you will need to remove the transmission and the front consul (oil pump). One thing for sure, you cannot replace the large chains and crank to IMS chain (and guid) without splitting the case.
The exchange rate is not that different. They must be quoting splitting the engine case which i would not do unless u were commiting to a full rebuild.
With the motor out and not splitting the case u can swap out the 2 small cam chains, the variocam pads and the two long chain pads only on each side. This is maybe a 16-20hr job and parts shoild be $3-500. I would expect this job to be in the $3-5k range for a good shop.
What u can not change is the 2 long cam gear chains themselves, ims chain pads or chain.
Sorry i dont know anything about your area, maybe someone here can help?
https://rennlist.com/forums/rennlist-canada-98/
I do not which pads are shedding plastic, but from what I am reading, I should put my money on the variocam pads, it seams. So these ones are possible to change with the motor in, ok.
I just got a Quote to replace both banks Cam Adjuster with Pads = 18 hours labor @225 / hour. (Seattle Labor rate at best Indy on East Side).
Necessary due to Cam Deviation check showing -9 Bank 1 and -5 bank 2. This is a 108000 mile 2000 C4. The Adjusters with Pads are $1480 each. They are not dropping the engine. Just removing my TechArt Headers - bumper - ect. Doing both sides saves $1000 verses doing one and the other a year or so later.
Not happy with a $8400 repair cost but I have had this C 4 for 13 years and made many other "investments" it her... so this is my Keeper.
Just another Note - I wanted to learn more about the health of this engine - so I did some research and bought a FOXWELL NT530 Scanner. Surprised to see it really can display Cam Deviation and many more Porches ECU and other system details. My 8 year old OBD II did very little, and at $150 this tool proved to be worth it.
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