May have found the reason for the spun bearing...
Pro Wrench
Joined: Jan 2011
Posts: 1,869
Likes: 44
From: Philly
Great thread. I'm interested in the outcome.
I loved my 01 A6 2.7T. Drove it for many years performing routine maintance along the way never had any major issues. In fact I dumped about 7k upgrading to a stage 3 (bigger turbos, fueling, stronger clutch...) loved that car. I recently picked up an 04 A4 USP to drive while my Rover is under the shade tree. That car goes to AWE Tuning on Monday for a stage 2 bump. Audi FTW!
Keep the thread updated this is great material.
I loved my 01 A6 2.7T. Drove it for many years performing routine maintance along the way never had any major issues. In fact I dumped about 7k upgrading to a stage 3 (bigger turbos, fueling, stronger clutch...) loved that car. I recently picked up an 04 A4 USP to drive while my Rover is under the shade tree. That car goes to AWE Tuning on Monday for a stage 2 bump. Audi FTW!
Keep the thread updated this is great material.
Last edited by coors; Mar 25, 2014 at 06:26 AM.
Baja
Joined: Feb 2011
Posts: 9,298
Likes: 318
From: Boston Strong
deck the block, of course why would you not?
everyone runs to have their heads decked when doing head gaskets, but you're re-installing them on what is inevitably has to be a warped block; it's been heated and cooled a million times.
the idea is to start off with true surfaces, as long as you're mach. doesn't do something crazy you can adjust with head gaskets. But you just don't go machining chamfers off for the sake of removing them.
you must remember, block has limits. if you machine the block too much, now you have changed the push rod length and geometry.
decking you're block and heads will raise you're compression, if you stay with LR limits then you should be able to run stock thickness Cometic gasket and still have increased compression.
you size the head gasket to the head and the block not the other way around.
(I would not try to duplicate the ARP studs, just buy them. also I would have my mach. try and re-seat those liners before I pinned them and had the block decked. no sense in pinning a liner that is bottomed out.)
theirs my wisdom
everyone runs to have their heads decked when doing head gaskets, but you're re-installing them on what is inevitably has to be a warped block; it's been heated and cooled a million times.
the idea is to start off with true surfaces, as long as you're mach. doesn't do something crazy you can adjust with head gaskets. But you just don't go machining chamfers off for the sake of removing them.
you must remember, block has limits. if you machine the block too much, now you have changed the push rod length and geometry.
decking you're block and heads will raise you're compression, if you stay with LR limits then you should be able to run stock thickness Cometic gasket and still have increased compression.
you size the head gasket to the head and the block not the other way around.
(I would not try to duplicate the ARP studs, just buy them. also I would have my mach. try and re-seat those liners before I pinned them and had the block decked. no sense in pinning a liner that is bottomed out.)
theirs my wisdom
Thread Starter
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Mudding
Joined: Mar 2014
Posts: 157
Likes: 3
Exactly.
Good point about the pushrod (and possibly the intake's fitment) changing due to machining the block too far. Often over looked until too late.
Yes, I'll be using legit ARP head studs.
NO liners had moved, so if there's material to machine off to get the liners flush, I won't need to pin them.
Good point about the pushrod (and possibly the intake's fitment) changing due to machining the block too far. Often over looked until too late.
Yes, I'll be using legit ARP head studs.
NO liners had moved, so if there's material to machine off to get the liners flush, I won't need to pin them.
Last edited by ImQuattro; Mar 25, 2014 at 09:58 AM.
Rock Crawling
Joined: Mar 2013
Posts: 452
Likes: 26
From: Oregon, north of Salem
drowssap "everyone runs to have their heads decked when doing head gaskets, but you're re-installing them on what is inevitably has to be a warped block; it's been heated and cooled a million times."
______________________
Ain't so. The only major reason to shave down the heads,is to true up flat surfaces, IF they are warped; often they are not. If warped to extreme, one cannot even true them up enough to salvage them, and it is necessary to get replacement "good" heads. So, to shave down heads that are not warped, is sheer foolishness and a waste, of both money and of good head metal. VERY SELDOM, will blocks warp, and that is almost the only reason to shave down, "deck" the block top surface. When top hat liners are installed, the surface is decked, to get top of top hats even with top deck, but the amount of metal removed from he block itself is extremely small; maybe none. I have rebuilt a ton of engines, and not yet seen a block top surface warped.
______________________
Ain't so. The only major reason to shave down the heads,is to true up flat surfaces, IF they are warped; often they are not. If warped to extreme, one cannot even true them up enough to salvage them, and it is necessary to get replacement "good" heads. So, to shave down heads that are not warped, is sheer foolishness and a waste, of both money and of good head metal. VERY SELDOM, will blocks warp, and that is almost the only reason to shave down, "deck" the block top surface. When top hat liners are installed, the surface is decked, to get top of top hats even with top deck, but the amount of metal removed from he block itself is extremely small; maybe none. I have rebuilt a ton of engines, and not yet seen a block top surface warped.
Rock Crawling
Joined: Mar 2013
Posts: 452
Likes: 26
From: Oregon, north of Salem
Dane, "The bearings always confused me, with the under/over sized stuff. Anyways, this it?
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Yes, easily understood how one could get confused about such an issue. Camshaft bearings, Main bearings, and connecting rod, often called "rod," bearings, are oversized to conform to camshaft or crankshaft journals that have been turned down to smaller diameters, necessitated by damage of those journal sections, damage such as being egg shaped, out of round, or scored up, etc. Now, these oversized (thicker) bearings are not called oversized, but are called undersized, as the mating surfaces on cam/crank are undersized, from original size. If you are not confused yet, I don't understand why?
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Yes, easily understood how one could get confused about such an issue. Camshaft bearings, Main bearings, and connecting rod, often called "rod," bearings, are oversized to conform to camshaft or crankshaft journals that have been turned down to smaller diameters, necessitated by damage of those journal sections, damage such as being egg shaped, out of round, or scored up, etc. Now, these oversized (thicker) bearings are not called oversized, but are called undersized, as the mating surfaces on cam/crank are undersized, from original size. If you are not confused yet, I don't understand why?
Rock Crawling
Joined: Mar 2013
Posts: 452
Likes: 26
From: Oregon, north of Salem
As many know, the chamfer at the top prevents the liner from sealing against the head & head gasket."
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Yes, this is true, the chamfer gives a sharp edge at the top of each liners.
You: "It was just one of the many terrible designs in the motors."
____________________
chamfer was done for good reason, or so the engineers thought: To prevent the top ring of each piston from forming a wear ridge at top of sleeve, as seen so often on earlier engine designs with no chamfer at top of sleeves.
You: "This allows two things to happen (both simultaneously sometimes) the chamfer doesn't extend high enough to be sealed by the crushed head gasket and then doesn't put pressure on the sleeve. This can allow the sleeve to move which then can act like a hole punch to the head gasket resulting in head gasket failure. Also because of this non-seal, combustion pressure/heat can leak down past the chamfer into the water jacket (think steaming the milk of a cappuccino) which leads to near instantaneous overheat situation. This can be recognized by symptoms like, blowing hoses, reservoirs, radiators etc -all the weaker points in the cooling system. Typically the 15psi that the cap retains on the system should vent (which will appear like an overheat) but my theory is it can only vent so much and therefor that pressure builds up to vent elsewhere. "
_________________________
It isn't that the chamfer doesn't extend high enough to be sealed by head gasket, it does, but the problem is that the chamfer makes for a sharp edge at top of sleeve, which CUTS into the head gasket fire ring should the sleeve move upward. Combustion gasses moving past this sharp edge at top of liner CANNOT GET INTO THE WATER JACKET, UNLESS SAID WATER JACKET IS CRACKED, and if this cracking has taken place, you are not going to be able to block the gasses trying to move into water jacket, or block the coolant trying to move from the waster jacket, through the cracks, into the combustion chambers (remember how often the "steam cleaning" of pistons happens?) Simply machining the deck down to allow a slight bit of flat surface, rather than sharp edge at top of each liner, it won't suddenly allow your liners to function like top hat liners, which have considerably more top surface to bear against the head gasket.
You: "Yes, I'm aware that decking the block raises the compression ratio, I haven't figured out how much needs removed or how much that changes the ratio. Higher is ok with me, it already require premium"
_________________________
I have "been there; done that," on this engine, 3.9 L. version in Range Rover. Raising compression ratio, as you are planning to do, makes for serious pre-detonation, "pinging," which could easily lead to serious damage to piston tops. In consideration, in the aforementioned engine, I installed lower compression ration pistons, available from Rover, so that I could run low octane, cheap gasoline without problems, and it worked beautifully.
You: " might as well get the power from it. (I know someone will point out that lower octane fuel contains more power -to which I'll say, yes, but due to no EGR (which lowers combustion temps by diluting the fuel/air mix in the cylinder), higher fuel octane is needed to control pre-detonation. Which results in a better burn and thus more power blah blah blah.
Either way, I'm by no means an expert, just doing a lot of reading, studying, and researching and since I'm not doing flanged liners, I want to do the next best thing to make this motor last as long as possible.
My Audi's have lasted way past 200k miles before needing anything beyond routine preventative maintenance. Due to excellent engine design IMO, so doing head gaskets on a Rover every 60k isn't "routine maint", it's a design flaw."
_____________________________
Some would argue that it isn't a "design flaw," for these engines never experienced problems with cracked blocks when they were 3.5 L. versions; only when Rover bored them out to 3.9/4.0/4.6 diameter bore, did the too thin aluminum walls behind the liners begin cracking when overheated. Rather than a design flaw, it was more one of evolutionary growth taken to extreme, which Rover should have recognized, but did not, or more likely, simply ignored it.
You: "When the cometic MLS gaskets arrive, I'll compare them to the used and new composite gaskets and report back.
I've only used MLS head gaskets on all the high power turbo Audis I've built in the past due to their better sealing capabilities.
________________________
Yes, this is true, the chamfer gives a sharp edge at the top of each liners.
You: "It was just one of the many terrible designs in the motors."
____________________
chamfer was done for good reason, or so the engineers thought: To prevent the top ring of each piston from forming a wear ridge at top of sleeve, as seen so often on earlier engine designs with no chamfer at top of sleeves.
You: "This allows two things to happen (both simultaneously sometimes) the chamfer doesn't extend high enough to be sealed by the crushed head gasket and then doesn't put pressure on the sleeve. This can allow the sleeve to move which then can act like a hole punch to the head gasket resulting in head gasket failure. Also because of this non-seal, combustion pressure/heat can leak down past the chamfer into the water jacket (think steaming the milk of a cappuccino) which leads to near instantaneous overheat situation. This can be recognized by symptoms like, blowing hoses, reservoirs, radiators etc -all the weaker points in the cooling system. Typically the 15psi that the cap retains on the system should vent (which will appear like an overheat) but my theory is it can only vent so much and therefor that pressure builds up to vent elsewhere. "
_________________________
It isn't that the chamfer doesn't extend high enough to be sealed by head gasket, it does, but the problem is that the chamfer makes for a sharp edge at top of sleeve, which CUTS into the head gasket fire ring should the sleeve move upward. Combustion gasses moving past this sharp edge at top of liner CANNOT GET INTO THE WATER JACKET, UNLESS SAID WATER JACKET IS CRACKED, and if this cracking has taken place, you are not going to be able to block the gasses trying to move into water jacket, or block the coolant trying to move from the waster jacket, through the cracks, into the combustion chambers (remember how often the "steam cleaning" of pistons happens?) Simply machining the deck down to allow a slight bit of flat surface, rather than sharp edge at top of each liner, it won't suddenly allow your liners to function like top hat liners, which have considerably more top surface to bear against the head gasket.
You: "Yes, I'm aware that decking the block raises the compression ratio, I haven't figured out how much needs removed or how much that changes the ratio. Higher is ok with me, it already require premium"
_________________________
I have "been there; done that," on this engine, 3.9 L. version in Range Rover. Raising compression ratio, as you are planning to do, makes for serious pre-detonation, "pinging," which could easily lead to serious damage to piston tops. In consideration, in the aforementioned engine, I installed lower compression ration pistons, available from Rover, so that I could run low octane, cheap gasoline without problems, and it worked beautifully.
You: " might as well get the power from it. (I know someone will point out that lower octane fuel contains more power -to which I'll say, yes, but due to no EGR (which lowers combustion temps by diluting the fuel/air mix in the cylinder), higher fuel octane is needed to control pre-detonation. Which results in a better burn and thus more power blah blah blah.
Either way, I'm by no means an expert, just doing a lot of reading, studying, and researching and since I'm not doing flanged liners, I want to do the next best thing to make this motor last as long as possible.
My Audi's have lasted way past 200k miles before needing anything beyond routine preventative maintenance. Due to excellent engine design IMO, so doing head gaskets on a Rover every 60k isn't "routine maint", it's a design flaw."
_____________________________
Some would argue that it isn't a "design flaw," for these engines never experienced problems with cracked blocks when they were 3.5 L. versions; only when Rover bored them out to 3.9/4.0/4.6 diameter bore, did the too thin aluminum walls behind the liners begin cracking when overheated. Rather than a design flaw, it was more one of evolutionary growth taken to extreme, which Rover should have recognized, but did not, or more likely, simply ignored it.
You: "When the cometic MLS gaskets arrive, I'll compare them to the used and new composite gaskets and report back.
I've only used MLS head gaskets on all the high power turbo Audis I've built in the past due to their better sealing capabilities.
Thanks; I am always anxious to see what others have to say about the Cometic MLS, comparatively speaking, and I am sure that many other Rover enthusiasts are too.
Baja
Joined: Feb 2011
Posts: 9,298
Likes: 318
From: Boston Strong
"I have rebuilt a ton of engines, and not yet seen a block top surface warped."
then you sir have never proper machined an engine and the TONS of them that you HAVE are done are wrong.
All i can say is you must be talking out your BUTT, because you're mouth has to know better. (with all you're experience rebuilding TONS on engine.)
don't bother responding, i'm done you you supposed expertise.
then you sir have never proper machined an engine and the TONS of them that you HAVE are done are wrong.
All i can say is you must be talking out your BUTT, because you're mouth has to know better. (with all you're experience rebuilding TONS on engine.)
don't bother responding, i'm done you you supposed expertise.
Last edited by drowssap; Mar 27, 2014 at 11:27 AM.
Thread Starter
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Mudding
Joined: Mar 2014
Posts: 157
Likes: 3
As a note, I would point out that the liners do NOT extend up to the surface of the deck, therefore, unless the HG really crushes down into the cylinder, the chamfered edge does not seal against the fire ring of the HG.
The liners are all about a 1/16th of an inch below the deck surface.
I don't have the block in hand yet (at machineshop) to measure the actual difference exactly, but going from memory 1/16" is about right.
The liners are all about a 1/16th of an inch below the deck surface.
I don't have the block in hand yet (at machineshop) to measure the actual difference exactly, but going from memory 1/16" is about right.
Thread Starter
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Mudding
Joined: Mar 2014
Posts: 157
Likes: 3
OE head gaskets are .053" thick, and measure .050" after being installed and torqued & heat cycled.
This will be interesting with the .040" Cometic gaskets.
Hindsight tells me I should have waited to order them until the machine shop has totaled up the removed material.
This will be interesting with the .040" Cometic gaskets.
Hindsight tells me I should have waited to order them until the machine shop has totaled up the removed material.
