The solution to chain rattle

[KAL]

Interesting information. Thanks Greg.

Once the group buy is complete and inhave received the kit I will definitely add my 2 cents with a detailed write up

[jjrichar]

Hi all, I'm new to Audizine, but have been following this thread with interest for a while.

I have a '04 4.2L Allroad (BAS engine) with the startup rattle, which to me sounds like it is coming from both the chains and one of the cam adjusters. It's been there for a while, and after doing a bunch of reading on the problem, I only recently started to get concerned. The engine in my car is virtually identical to the setup in the BBK engine, which is what is in the S4.

I did a mod to the car recently that seems to have made a difference. Some may be interested. While I don't think it is as good as the oil accumulator solution, it's a lot cheaper, and will take you about an hour to do.

Before doing any reading on the problem, I did a bit of testing. I removed the fuel pump fuse and cranked over the engine for about 10 seconds, replaced the fuse, and then cranked the engine over. Started perfectly. No noise and sounded like a brand new engine.

I live in Australia (right hand drive cars), so the fuse panel and driver are on the same side. I'm not sure if this is the case for left hand drive cars. If it is on the opposite side, this mod is going to be a little more involved.

I removed the panel below the steering wheel, removed the fuse panel, and identified the wires going to each side of the fuel pump fuse (visually and from the wiring diagram). One is yellow (goes from the fuse to the pump), and the other is red/green (from the fuel pump relay to the fuse). Basically I just cut into one of these wires and put a simple switch in here. It doesn't matter which wire you cut into, I cut into the red/green wire because it was the most convenient. I just added wiring length to each side, and then put the switch to the lower left of the steering column.

When starting the car, now I just turn the switch off, so the fuel pump gets no power. I crank over the engine for about 8 secs then stop cranking. I then turn on my installed switch, which allows the fuel pump to work, and then crank the engine. Starts with no rattle at all.

Is this the perfect solution. No. What are the problems?
1. This solution requires there to be no residual fuel pressure in the fuel rail. After being left overnight, this is going to be the case. However if the car has recently been driven, there will be some residual pressure, and the engine will want to start even with the fuel pump switch off. Depending on the severity of your rattle, this may be no problem, as you may only get it when you do a start up first thing in the morning.
2. I'm sure this is putting more wear on the starter, and may lead to premature failure. That being said, I'm prepared to deal with this over the possible alternative.
3. You can't start the car as quickly.

Advantages:
1. Rattle gone.
2. Even without the rattle, when the car started first thing in the morning, it had a real raw sound about it. As an enthusiast, this always made me cringe a bit. After doing this mod, this no longer happens either. Priming the engine with oil prior to start is clearly a good thing to do.

Personally I think the oil pre-charge accumulator is a great idea, and I plan to do this in the future. Fitting it is clearly an issue. I spoke to Paul at Gruven parts that makes the aluminium oil filter housing cover that would fit the engine (I saw a picture earlier in the thread). I wanted to know what thickness it was at the top of it to see if a thread could be put in here. He replied that it was more than 1/2 inch, and they would tap the hole for me for a small cost. To me this sounds like a great solution.

A bit of background info on the tensioners in the engine. Not having seen one before, I chased down an Audi "master technician" as they are called, and got into his head about it. They are very different to what I imagined. I've stripped to individual parts and rebuilt an engine the same as what is in my other car, a BMW. The tensioners in the BMW have a spring that applies pressure until oil pressure is built up. A simple solution that works very well. The Audi setup is apparently very different. Instead of a spring, there is a ratchet mechanism. When the engine is going, the oil applies pressure to the tensioner. When the car is shutoff, this ratchet mechanism holds the tensioner in place until the next start. The problem is this ratchet fails, and when the engine stops, it allows the chain to go loose, rather than hold the tension. Interestingly, its the guides that fail eventually, causing major engine damage, but its the tensioners that create the slack chain, that then slaps against the guide and eventually makes it break.

I know there are people on the thread who don't believe this is the cause, but personally, guides are made nylon in loads of engines, and few have problems like this. A tensioner that doesn't tension and allows a chain to slap against a guide in my opinion will break a guide earlier than one that doesn't have the chain slapping against it, even if it is just for a short time on startup. Stopping the chain slapping is I think the best thing you can do to stop the guide breaking.

[IslandHydro]

Hi all, I'm new to Audizine, but have been following this thread with interest for a while.
<snip>
I did a mod to the car recently that seems to have made a difference. Some may be interested. While I don't think it is as good as the oil accumulator solution, it's a lot cheaper, and will take you about an hour to do.
<snip>

Sometimes the simplest solutions are best, even if they aren't the most effective overall. Your idea has a second potential benefit - theft protection!

[bioluminescent]

jjrichar- your solution is very clever. Lately I have been priming my engine before cold start by turning the key a bit without letting the engine turn. I would say 90% of the time this works. I haven't tried it in true cold weather yet though, as it is spring/summer here and I've only been doing it for a month or so. Every so often the car starts accidentally in this process. Your system is clearly doing the same thing, only more effectively.

[CoolHeadS4]

Wouldn't it be better to cut the ignition circuit? I have no clue which circuit wire we would have to install the switch in though.

Would there be a possibility to flood the engine doing so?

[Steelman]

jjrichar- your solution is very clever. Lately I have been priming my engine before cold start by turning the key a bit without letting the engine turn. I would say 90% of the time this works. I haven't tried it in true cold weather yet though, as it is spring/summer here and I've only been doing it for a month or so. Every so often the car starts accidentally in this process. Your system is clearly doing the same thing, only more effectively.

X2. I've found this is key as well. If I wait an extra 5-10 seconds before actually starting the car 9/10 times there's no rattle. Haven't tried it in cold weather yet either.

[IslandHydro]

X2. I've found this is key as well. If I wait an extra 5-10 seconds before actually starting the car 9/10 times there's no rattle. Haven't tried it in cold weather yet either.

I don't understand this ^ method: if the engine isn't turning over - then oil isn't being pumped. The fuel pump is (I think) electric - so it pumps, but the oil pump is mechanically driven by the engine. Am I missing something? Jjrichar's idea allows the engine to turn over, without starting by removing fuel, and does pump oil.

[Brettannica]

I don't understand this ^ method: if the engine isn't turning over - then oil isn't being pumped. The fuel pump is (I think) electric - so it pumps, but the oil pump is mechanically driven by the engine. Am I missing something? Jjrichar's idea allows the engine to turn over, without starting by removing fuel, and does pump oil.

The engine is turning over priming the oil,the fuel pump is simply disengaged from the process, then jj engages the fuel pump and starts the car.
Simple

[CoolHeadS4]

What jj explain is clear. It's the method Bioluminescent explain that is not clear when he stipulate that the engine is not turning.

[IslandHydro]

The engine is turning over priming the oil,the fuel pump is simply disengaged from the process, then jj engages the fuel pump and starts the car.
Simple

I was talking about bioluminescent's post (and followup by steelman) where he wasn't cranking the engine.

[cheetah993]

I was talking about bioluminescent's post (and followup by steelman) where he wasn't cranking the engine.

He is cranking it, just not long enough for it to start. At least that was the impression I got from it.

[bioluminescent]

He is cranking it, just not long enough for it to start. At least that was the impression I got from it.

This. Maybe I shouldn't be referring to the engine as turning. I crank the engine without letting it start and then I start it a few seconds later and no chain rattle. I think of it as priming, though I'm not sure that is technically what's going on, but it really works. jjrichar is doing the same exact thing, but his system is much better because a lot of time when I do this I start the engine accidentally. His way does not allow for the engine to start until you hit the switch again. Again though, I haven't been able to test this in frigid weather.

[Steelman]

I should clairify my post above. The point I was trying to make was I never jump in my car and just start it up, it's not a Honda. I make it a point to turn the switch on, wait 4-5 seconds while the systems come online then turn the engine over and for some odd reason I tend to not get the rattle near as much. Is it "priming" the engine, no because the engine is not turning over.

[Latosa]

Guys this is a good idea ,but since my accusump system was put in service and this was a YEAR AGO I can't imagine my self cranking the car twice for a year on a daily basis wich is my car is for .Again who ever wants some help I'm open help with this mod.since I think I'm the only one from few people running this setup on a daily basis for a year now maintenance free and no chain rattle.

[jjrichar]

Here's a bit of background to the mod I did. Like I said above, one of the issues was that residual fuel pressure will try and kick the engine over even when the fuel pump is off. I wanted to find a solution that didn't have this problem.

I spoke to a number of people about the problem and what to do about it. My discussion with experts also touched on some stuff discussed above.

Idea 1: Stopping ignition while you crank over the engine (ie. don't have the spark plugs working): This is a bad idea. If you crank over the engine it's going to inject fuel into the cylinders/exhaust without it being burnt. When you do then start the engine with the ignition working, all this fuel is going to ignite. BAD. Backfires, flames shooting out of the exhaust, etc. I was advised by many an expert not to do this.

Idea 2: Stopping the fuel injectors from working while you crank over the engine: This would have been the perfect solution, as no fuel will ever get into the engine. Old fuel injection engines had a single common wire that powered the injectors. Putting a switch in here would have been very easy. Unfortunately, your modern Audi V8 is not like this. Each individual injector is powered by separate wires directly from the ECU. They don't go through a fuse prior to getting to the injectors. This solution would require 8 separate switches on the wires from the ECU. Not an easy task. I was advised by a fuel injection expert that the wires to the injectors were very fine tolerance, and cutting into these and inserting switches was likely to result in the injectors not firing correctly. Put simply, it might work, but it was going to be a difficult task, and there was a real risk of me rendering the engine unusable.

Hence idea 3, turning off the fuel pump, was the one adopted. Like I said above, it doesn't take very long, and will cost less than $10 in parts from your local electronic hobby shop. Like I said above, it's not the perfect solution, and I plan to go down the accusump road.

With regard to "priming" by just turning on the ignition without starting for about 5 secs prior to start, here's my understanding of system and how it works. When you initially turn the key, thé fuel pump isn't going. I measured the voltage going to the pump, and nothing happens until the engine actually starts to turn over. My assumption is the ECU gives a signal to the fuel pump relay when it gets a signal from the crank position sensor to say the engine is turning over. No fuel pressure is going to be in the fuel rail (except for residual) until the engine actually starts to turn. It should also be clear that turning the key without actually cranking over the engine (ie turning the oil pump) is not going to prime the oil pressure in the cam adjusters/chain tensioners.

I just received an email from Paul at Gruvenparts, and he said that it would cost $50 extra to put a 1/2" NPT threaded hole in. This would bring the cost of the cover to about $170. It should then be quite a simple job of fitting the accusump to the top of the OFH using the hoses that accusump can supply. For me this is a good solution that doesn't require me to find third party parts to join to the oil pressure sensor point or something like this. Accusump were keen to have a look at the OFH cover from Gruvenparts as they think this is a good solution.

I'll keep people posted as I get more info.

[Brettannica]

I was talking about bioluminescent's post (and followup by steelman) where he wasn't cranking the engine.

Gotcha island. My bad.

[IslandHydro]

Gotcha island. My bad.

No worries, it's all good

[jjrichar]

Sometimes the bleeding obvious doesn't just jump into your head.

I was thinking about the problem of having residual fuel pressure in the lines for a consequent start when I have the fuel pump switch turned off when cranking the engine. Very simple solution.

When you turn off the car after it has been going, don't turn the ignition off. Turn the fuel pump off first. The engine will run normally for about three seconds, and then start to stutter due to low fuel pressure. Immediately this starts to happen, turn the ignition off. The residual pressure has now been removed. If you try to start the car straight away, it won't start due to the lack of fuel pressure. Perfect.

I think the rattle from my car is probably on the worse end of the spectrum from what I've read. I would get some rattle on start after about 1 hour from previous operation. The problem was the residual fuel pressure was still plenty to start the engine, even though the fuel pump was turned off. Using the method above, I can always crank over the engine without risk of starting to initially build up the oil pressure.

Like I said in an earlier post, one of the things I really like about this is the sound (apart from the lack of rattle) the engine makes on start. It just sounds so much better.

On the accusump subject, I am still going down this path. I'm just waiting for some hydraulic connections to finish it off. I've mounted the accusump and fitted most of the electrics. I only just thought of the solution above this afternoon. I'm not sure I would have done the accusump thing if I'd already had this solution. I definitely think it's a better solution, but the cost difference is significant.

[IslandHydro]

On the accusump subject, I am still going down this path. I'm just waiting for some hydraulic connections to finish it off. I've mounted the accusump and fitted most of the electrics. I only just thought of the solution above this afternoon. I'm not sure I would have done the accusump thing if I'd already had this solution. I definitely think it's a better solution, but the cost difference is significant.

Couple questions: How long are you cranking with the fuel pump off before you go ahead and switch it on? Where did you mount the accusump? Pics? Interested to hear what it (accusump) does for your worse than average rattle!

Thanks

[jjrichar]

I crank the engine for a different time depending on how long the car has been left. If it's been running inside the last couple of hours, I might give it two seconds prior to stopping, turning the fuel pump on and then starting. If it's been left overnight I give it eight seconds. That's probably complete overkill, but I know that's it plenty to prime everything.

When I was looking at the accusump install, I emptied the oil filter housing prior to removing the oil pressure switch at the rear. When I put everything back together, and the car has been sitting there for the entire day, the eight second crank was plenty to fill the whole OFH and pressurise all the tensioners etc. The start made no noise. This told me that the eight second crank was plenty for normal cold starts. That being said, I'd rather overdo it than not.

With regard to the install, I've mounted it on top of the intake manifold. I made a mount from sheet aluminium and it sits about 2 cm above the manifold itself. There is a gap of about 1 cm from the top of the accusump to the inner padding of the bonnet (hood). The wiring for the switch went in through the cabin air filter housing on the passenger side, and then routed to the driver's side behind the center console.

I'll put up some pics, results and basic DIY after I get the hyd connectors and everything is put together.

[Omerta]

I love the fuel cutout switch idea that jjrichar has rigged up. The biggest flaw would be accidently hitting the switch while driving which is added risk... an interlock could prevent that from happening.

Prelube pump seems like it could be a cheaper solution but it would add an additional step to the startup process but it would not be impossible to automate.

The accumulators are pretty bulky... especially when you are looking at increased capacity. The added benefit of the accumulator would be if you put your car out on the track fairly often. I look after OE on large industrial gas turbines - our systems use both accumulators, prelube and jacking pumps... mainly due to the overall mass. On large diesels that I was a technician on we only had heaters and prelube pumps on the timer prior to startup.

I get mad chain rattle at cold temperatures (I've started it at -30°C) but otherwise its every once in awhile during a cold start. I'm glad I came across this thread... I didn't realize it was a part that had a high failure rate - thinking the guides were metal. Hence the prelube option in cold weather would be ideal for me.

[Omerta]

Also, when you guys were installing the accumulator. Is there a reason why the pressure switch on the oil filter was ignored (#11)?



Looks like a good spot to keep the length of tubing short and have the accumulator high on the engine (mount it above the intake manifold).

I'm doing some more research and favoring the accumulator over using a prelube in the sump. There is not a ton of selection out there for accumulators though.

[jjrichar]

For those who are interested, I've started a new thread in this forum about my Accusump installation and first impressions. Some who are following this thread may be interested.

http://www.audizine.com/forum/showth...st-impressions

[0000 V8]

Also, when you guys were installing the accumulator. Is there a reason why the pressure switch on the oil filter was ignored (#11)?



Looks like a good spot to keep the length of tubing short and have the accumulator high on the engine (mount it above the intake manifold).

I'm doing some more research and favoring the accumulator over using a prelube in the sump. There is not a ton of selection out there for accumulators though.

This is the exact location I used for my Accusump install, and I dont really understand why people are needing to use the aluminium cap (or spend $50 on getting Gruven to tap it when you can do it yourself). I built an adapter and even made my own threads on some of the parts. It works fantastic. I have some pics in my build thread.

[Omerta]

I'm playing with the idea of designing a kit for this. Hydraulic accumulators are more cost effective if I can find one with the right dimensions. Is there interest in this kit and how much would it be worth to you?

[speedshopmike]

what's the point of a kit?
all components needed are available.
i've now had my early b6 a while.
it had pretty gnarly1st start rattle, and even some on restarts if the oil wasn't entirely warmed up still.
canton, did you build a run of the housings?

[0000 V8]

what's the point of a kit?

I tend to agree. All the parts you need are out there. If one can not figure out what exactly they need, they probably shouldnt be doing the install.

[Omerta]

what's the point of a kit?
all components needed are available.
i've now had my early b6 a while.
it had pretty gnarly1st start rattle, and even some on restarts if the oil wasn't entirely warmed up still.
canton, did you build a run of the housings?

Standardizes and gets rid of the guess work. But this is why I asked, some value their time differently.

[tboo72]

Ive tried to read most of this huge thread but Im confused on one part: Accusump says the electric valve can be hooked up to the ignition on to provide pre-oiling. Does this mean the Accusump system will be on continuously while the engine is running? If so is that ok?

[jjrichar]

Have a read of my post on the installation (link above). It explains how it all works.

In a nutshell, if you have the switch on, the valve will be open, and the accusump will have oil flow in and out of it as oil pressure changes. No problem, as this is what it is designed to do (it's designed for racing applications to constantly supplement the normal oil system). The only possible issue with leaving the switch constantly on is the valve is energised the whole time the car is on, which may reduce its lifespan.

If you turn the switch off, it just holds the pressure the engine was supplying at the time you turned it off. Normally this is done momentarily after maximum oil pressure is supplied from the pump. This will normally occur straight away on a cold start, or when the engine gets to approximately 2000 RPM when warm.

When canton say "hooked to the ignition", what they mean is connected to a circuit that only has power connected when the ignition is turned on. This way, with the switch turned on, the valve opens when you turn the key to start the car, and it turns off when you shut down the car.

[Latosa]

Ive tried to read most of this huge thread but Im confused on one part: Accusump says the electric valve can be hooked up to the ignition on to provide pre-oiling. Does this mean the Accusump system will be on continuously while the engine is running? If so is that ok?

My system been running for a year and half now and is been conected to ignition switch form day one.Remember accusump is built for this use, it works as pre-oiling on cold start or every start and it works as a oil damper during engine operation.It supplies positive pressure to oil pump pressure side under hard acceleration ,or if you do road racing prevents oil pressure loss during hard turns.

ZERO RATTLES SINCE PUT ON SERVICE ONE YEAR AND HALF ,MAITENANCE FREE TOO!JUST IN CASE MY CAR IS A DAILY DRIVER I PUT 25 TO 30 MILES DAILY .

[nonchalant_Gee]

I love this thread buying this kit very soon even though I don't have a rattle

[tboo72]

My system been running for a year and half now and is been conected to ignition switch form day one.Remember accusump is built for this use, it works as pre-oiling on cold start or every start and it works as a oil damper during engine operation.It supplies positive pressure to oil pump pressure side under hard acceleration ,or if you do road racing prevents oil pressure loss during hard turns.

ZERO RATTLES SINCE PUT ON SERVICE ONE YEAR AND HALF ,MAITENANCE FREE TOO!JUST IN CASE MY CAR IS A DAILY DRIVER I PUT 25 TO 30 MILES DAILY .

How does having the sump affect doing an oil change?

[Omerta]

How does having the sump affect doing an oil change?

You're essentially increasing the oil capacity of the engine by the size of the sump. Unless the sump is setup to keep the valve open when the ignition is energized (some have argued it wears it out).

When you do an oil change, and its wired to come on as the ignition is energized you must turn the ignition on and allow the oil in the sump to drain out through the system. Then shut off the ignition and change your oil, the first start after a change will not be charged.

[Latosa]

You're essentially increasing the oil capacity of the engine by the size of the sump. Unless the sump is setup to keep the valve open when the ignition is energized (some have argued it wears it out).

When you do an oil change, and its wired to come on as the ignition is energized you must turn the ignition on and allow the oil in the sump to drain out through the system. Then shut off the ignition and change your oil, the first start after a change will not be charged.

well explained ! what I also do is pour oil in the filter bolw right before starting the engine .

[tboo72]

You're essentially increasing the oil capacity of the engine by the size of the sump. Unless the sump is setup to keep the valve open when the ignition is energized (some have argued it wears it out).

When you do an oil change, and its wired to come on as the ignition is energized you must turn the ignition on and allow the oil in the sump to drain out through the system. Then shut off the ignition and change your oil, the first start after a change will not be charged.

So if I have a 1 qt sump, do I have to add another quart of oil past the 9.5 quarts that are in the engine already? Also, anybody run into heat issues mounting it on top the engine?

Thanks

[Omerta]

So if I get a 1 qt sump, do I have to add another quart of oil past the 9.5 quarts that are in the engine already? Also, anybody run into heat issues mounting it on top the engine?

Thanks

Depends on the method that its installed.

Option A:
Valve set to open when ignition is energized (As a racing sump would be) I would not add another quart as the entire purpose of the sump is to give a 1qt buffer to maintain constant pressure regardless of and reductions in pressure from the pump (high and sustained g-force turns).

Option B:
Set on an electronic switch that is manually activated prior to start and turned off once the engine has been running thus providing only startup protection. In this case, I would add an extra quart because under normal operations there technically would be 1qt less in the active circulating oil.

If neither of those are what you plan to do, fill me in and I'll make some suggestions of methodology.

[tboo72]

Depends on the method that its installed.

Option A:
Valve set to open when ignition is energized (As a racing sump would be) I would not add another quart as the entire purpose of the sump is to give a 1qt buffer to maintain constant pressure regardless of and reductions in pressure from the pump (high and sustained g-force turns).

Option B:
Set on an electronic switch that is manually activated prior to start and turned off once the engine has been running thus providing only startup protection. In this case, I would add an extra quart because under normal operations there technically would be 1qt less in the active circulating oil.

If neither of those are what you plan to do, fill me in and I'll make some suggestions of methodology.

Thanks for the response. Option A seems easier & less of a hassle. Why do some choose option B?

[Omerta]

Thanks for the response. Option A seems easier & less of a hassle. Why do some choose option B?

Option B is cheaper and it has been argued that Option A will wear out the seals on the sump piston sooner. If I were to install it on my car, I'd go with option A.

[tboo72]

Option B is cheaper and it has been argued that Option A will wear out the seals on the sump piston sooner. If I were to install it on my car, I'd go with option A.

Ah, makes sense