Concerning a refreshening of Cadillac Allante 4500 engines and other GM aluminum engines ...

I been going over some magazines, old posts and various notes collected over the years, the service manual and have been writing down questions about engine rejuvenating. Some are 4.x related, others are general in nature. My '92 Cadillac is under 100,000 miles, so hopefully none of this will be applicable for another 25 years going by the current rate of driving. The estimated annual mileage she will now get, is around 3,000 miles per year.


All of the A: answers were provided a GM Powertrain / Drivetrain Engineer that worked on the development of the 4.X family of Cadillac engines. We shall call this genetleman "Al" in the notes.

In question is of course, a 4500 Cadillac Allante engine (mine), but the questions and answers
really apply to all production aluminum GM engines.


[align=center]
[/align]

.................................................. ........................


Q: Cleaning
What's the best way to clean this engine? One of Al's posts mentions not removing the lifter valley, which contains the cam bearings. I don't think you can hot-tank a block without damaging the bearings (I could be wrong). Is it best to stick with detergent and water and an assortment of brushes, or is there a solvent that should be used? What should be done (if anything) to protect the surface once its been cleaned? Will the bolted-in lifter valley cause problems getting cleaned or trapping dirt?

A: Cleaning...
use solvent and soap and water. The block should not really need that much cleaning on the inside as I doubt that we are talking about something that is totally encrusted with deposits. "Hot tanking" an aluminum block is not advisable...it will be rendered unusable as the caustic material will attack the aluminum....like it attacks aluminum bearings...that is why they have to be replaced after hot tanking. The re-manufacturing outfits bake the blocks at high temp to carbonize the grease and then power wash them in a cabinet. You really don't need to get this gruesome. Just use mineral spirits and a pressure washer. The bolted in lifter gallery is nothing magic....it is the same oil passages as any cam-in-block pushrod engine has....it is just a bolted in instead of cast-in lifter gallery. No real difference here in terms of trapping any dirt or anything. Just flush well.



Q: Damage
What are the signs of corrosion damage due to poor cooling system maintenance? How do we know when the block (or other components) are too far gone? Can any of these items be repaired?

A: The only real concern for corrosion damage is the water jacket in the block. Due to the construction of the engine with the wet liners, inspection of the block is very easy once the liners are removed...which is a simple hand operation....just pull them out. If there is pitting due to corrosion that threatens to breach the engine case it can be repaired with a high strength epoxy...devcon or JB Weld...after grinding and cleaning.




Q: Lifter galley
Many engine rebuilding articles mention either polishing the lifter valley to aid oil drain-back, or coating it and other internal engine surfaces with Glyptal, or a similar epoxy paint. Is either a good or bad idea? I've read concern that the paint could flake off and clog oil passages. Would polishing be a better idea?

A: Lifter galley....
are you really worried about oil drain down? Quit worrying .. don't paint the inside of the engine or bother to polish the lifter gallery unless you have a lot of time on your hands and nothing to do. It is a waste of time unless you are building an ultra high RPM engine. The oil drains down fine on millions of those engines without polishing so why on earth would that benefit anything??? Some "experts" claim the pointing or coating will trap any stray casting sand and keep it from leaving the cast surface and getting into the oil. I think this is BS but in any case there is no sand involved in the casting of the 4.x blocks (diecast block) so this reasoning doesn't apply, either.



Q: Assembly Lube ...
The manual mentions a standard GM assembly lube. That was 13 years ago. Is anything better on the market, or is the standard stuff OK? How long after the parts are lubed can the block sit assembled without problems?

A: Use the GM EOS as assembly lube. It is still the best thing around. Use a moly grease on the distributor gear packed into the teeth. The EOS can sit in the bearings for a long time without a problem. Your Allante engine has roller followers so the cam is not a replacement item nor something to be worried about in a rebuild.. Just use the EOS on the rollers.
Engine assembly lube needs to be used to protect your engine durring the first few minutes its running to protect the new parts as they start to lap in ,BEARINGS,CAM LOBES, LIFTERS,ROCKER ARMS,AND TIMEING CHAINS/GEARS, DISTRIBUTOR GEARS,ETC. ARE VERY IMPORTANT TO COAT TOTALLY DURRING THE ASSEMBLY PROCESS. first spray the contact surfaces with this ultra penatrateing moly-disulfide lube the carrier in the spray can allow the moly to soak into the metals surface,this stuff has been proven to coat the inside surface of rifle barrels and drastically reduce wear and friction even at temps of over 500 degs(F) and at pressures over 50,000psi,this forms your base layer,moly disulfide greatly increases the load and heat carrying ability of the lubericant and coating the surface with a layer of ultra-fine 20 micron moly before coating things with the lube gets the moly into the metal surfaces (check out the electron microscope photos) next use a good assembly lube that contains moly disulfide and/or zinc dialkyt-dithiophosphate both of which greatly add to the extreme pressure and heat resistance on the bearing or cam lobe surfaces.


Q: Balancing ... Polishing ...
Is there an advantage to static and/or dynamic balancing the rotating assembly? Machine shops can do this for a pretty reasonable price. Does it add anything to engine longevity? If balancing is on the agenda, would it be worth polishing the rods and crank, since any unbalancing would then be corrected by the shop? Does polishing those items have a tangible benefit?

A: Forget polishing the rods or any balancing. The assemblies were manufactured to a very tight balance spec from the factory and the crank is dynamically balanced at the factory to the standard rod/piston weights. Given the ability of most machine shops to balance things I would not bother and they will likely give you back an assembly that is more imbalanced than what you took in. The fact is that most after market balancing is pretty inaccurate. It works OK for most situations where parts are being replaced with parts of a different weight (different pistons, etc) but to re-balance a production assembly would be a total waste of time and probably will create moer problems than solve. The only thing you would gain is a little bit of smoothness..i.e...less engine vibration even if they could improve on the factory balance but it would be doubtful that it would be something that you could even perceive. Polishing the rods is just to remove stress risers to improve the strength and fatigue life. If you were planning on turning the engine 8000 RPM polishing might be a good idea but it is a waste of time for a production engine. The rods are way over designed for the application and have infinite life even well above the production power levels.



Q: Synthetic Lubricants ...
Any advantage using these on a newly redone engine as it will have new seals? I understand they aren't acceptable for breaking the rings in.

A: Synthetic oils ...
Synthetic oils are fine for break-in. That is an old wives tale. GM ships thousands of Corvette engines with Mobil1 and they break in fine. The RWD Northstars for the SRX/STS and XLR were developed with synthetic oil and there is no problem with break-in. Synthetic oil is totally unnecessary in a 4.x engine. No reason at all to use it. Synthetics are used in some applications purely for the high temp stability (above 300 F) to avoid adding an oil cooler - period. Unless you have money burning a hole in your pocket use conventional oil in your 4.x. A Northstar without a oil cooler should run on synthetic oil for this reason.



Q: Fasteners
Can old fasteners be reused? Should they be? Should they be replaced with stock, or with after market higher-quality (ARP) equivalents? Would after market fasteners use the same torque specs?

A: Fasteners ...
You should obtain an intake manifold reseal kit if you freshen your engine or take the intake off. That kit will supply the later intake fasteners and gaskets and upgrade the intake sealing technology. Those are the only fasteners to replace. The 4.x fasteners are all reusable and they are plenty strong for the application. Unless you're going to turn the engine 8000 RPM the rod bolts are fine. You are asking for trouble replacing the stock fasteners because the clamp loads of the after market bolts will not be the same so you will have to develop new torque specs....somehow....or just guess. Not a good idea.



Q: Testing
Should any of the components be tested with Magnafluxing (or some other method)?

A: Testing...why bother. The items like crank, rods, etc. have infinite life in a production engine used in a passenger car. Magna fluxing used parts just tells you the part doesn't have a surface crack. So what. The part can have millions of fatigue cycles and be ready to imminently fail and the magna fluxing will show that it is "fine" as it hasn't started to crack (on the surface) yet. Fatigue life cannot be checked with magna fluxing. Forget about it. Waste of time in this application. (note: will add a paragraph on fatigue life at the end ..)



Q: Thrust Bearing
Should the cam thrust bearing be replaced as a matter of course, or should it just be tested to be within specs?

A: cam thrust bearing..??? The cam thrust load is against the parent metal of the block. There is no "thrust bearing" per se. If the front of the block is chewed up then the block is scrap . . . but I have never seen one do this. There is a little spring loaded thrust button to add some positive load to the end of the cam ... it is a little plastic button with spring loaded ears. It is a cheap piece....just replace it. By the time you "checked" it you could buy 10 new ones.



Q: Timing chain and sprockets ...
Should any of these be replaced as a matter of course or as a preventative?

A: The timing gears are powdered metal and are probably fine. The chain may have a little play in it with a lot of miles and replacing it wouldn't be a bad thing....but personally I would probably not bother as it will run a long long time....and a new one is going to develop the same "slop" very quickly. The timing gears will be "marked" by the chain teeth. This is normal and fine and does not require replacement.



Q: Rockers ...
Al mentions removing the rockers as an assembly with their carrier. Can it be reinstalled without damaging the carrier? Would this have to be done with the heads off so there is no pressure from the push rods against the lifter/cam, or should the rockers and carrier be installed after the head is on the block?

A: Don't remove the rocker arms from the carrier. Just loosen the nuts holding the carrier onto the stud headed head bolts gently doing each nut a increment at a time in sequence. Reinstall the same way. You take the rocker arm carrier off before removing the heads and put it on after installing the heads. Since the carrier goes over the stud headed head bolts it is impossible to remove the heads first. Since this is the say the engine is designed to be assembled it is doubtful that the rocker arms or carrier will be damaged unless you try to completely pull down one of the nuts and not pull them down gradually in sequence.



Q: General ...
- Head porting -- Good idea or bad idea?
- Port matching the intakes to the head -- Good idea or bad idea?
- Decking the head -- Al mentioned 1mm. I've read that some guys are tilting the head so that there is 0 material removed on the valve side and more off the outboard side - this makes valve geometry issues less of a problem. Would 0mm on the valve side and 2mm on the outboard side be OK? Would the intake still seal? If decking were combined with porting, could the C/R remain stock (material removed by porting offset by combustion chamber reduction due to decking)?
- Overall Effects -- Can any/all of these be done without affecting the ECM calibration?

A: General ...
Unless you are really going after the last little bit I doubt that you will find much with the porting or polishing....but, hey, it probably won't hurt anything if you don't get too carried away. I would not angle mill the heads unless you plan on milling the intake face. Since the intake face alignment is critical to avoid warping the block I would be VERY careful here.
Any changes to compression or combustion chamber volume is going to affect the ECM calibration a little. You can probably compensate for compression changes to the spark requirements with changes to the timing setting.



Q: Cylinder Liners ...
What holds them in place? Read over the service manual and can't find a picture that explains what holds them in place in relation to the head. Does the head have mating grooves? Does the block hold the liners in place vertically? The manual mentions using a retainer when installing the pistons into the liners, so I assume that means they move around, but maybe that's to keep them from lifting only.

A: cylinder liners ...
The liners pilot into the bottom of the block/engine case and seal with an o-ring. They butt against the cylinder head at the top and are held in place by the compression of the head when it is torqued down. No grooves or alignment provisions or anything at the top....just the clamp load of the cylinder head. That is fine. We have run boosted 4.x engines at well over 300 HP with no problems with this arrangement so I doubt that you'll see any problems with it. There were millions of the 4.x engines built like that and there were little or no problems ever in that area. The use of a retainer is recommended in the shop manual to keep the liners from falling out of the block when you roll it over on the engine stand to put the pistons and crank in...it really isn't necessary.



Q: Painting
Can the block, intakes, head be painted? Will this have any adverse effects? As many parts are aluminum, would powder-coating be a better choice?

A: You can paint the outside of the block/heads. Any good engine paint that can withstand moderately high temps should work fine.



================================================== ========================



All the comments above apply to rebuilding or freshening a production engine. Obviously, building a full tilt racing engine running at 8,000 rpm may require some different techniques and there are always different opinions on a lot of these items.

I look at a passenger car engine in a passenger car as something that has already been designed and developed just the way it is to do the job at hand. If you start second guessing and modifying you are on your own. After all, these engines run for 100k to 200K at as they are .. Why modify it? what is to gain?

If power is the goal then modifications may help but recalibration of the PCM will be difficult and the likelihood of affecting the calibration is great as the fuel injection is a speed density system that is very sensitive to changes in airflow.

You'll find that it will be very a very easy job to "refresh" your engine. The 4.x engines are very easy to work on actually. The people that have trouble with them are the ones that try to apply the same techniques that they've used for ages on iron engines and don't read the service manual or follow the factory instructions...or try to "re-engineer" them.

In most cases, all you'll need is the complete factory gasket set, rings and bearings. I doubt that you'll find any appreciable wear on the cylinder walls, pistons, or crank.

If the honing pattern on the cylinder walls is still evident it is a sure sign that there is no wear. LEAVE THE CYLINDER WALLS ALONE. Just clean things up and reassemble. Do not hone or do any thing to the cylinder walls....just not necessary and no need to remove any material at this point in the engines life. The rings will seal fine with no honing or anything...trust me.

Get an intake manifold "re-seal" kit . It is more expensive but will supply the later gasket and sealing technology used on the 4.5 and 4.9. The kit includes the newer intake bolts which are required with the later gaskets.

The standard main bearing should be fine. It might be a good idea to order the tighter fit bearing for the #1 main only. This would guard against the "main bearing thump" noted on some engines which is harmless but annoying.

An engine being under 200,000 miles, I would not replace anything except the main, rod bearings, rings, the gaskets or course. All the components should be well within their service life unless some specific wear or problem is noted.

If you have the heads reconditioned I would be very careful to disassemble them first, clean and inspect. Believe it or not, I would expect that all you'll need to do is replace the stem seals, lap the valves gently to clean and check the seating. I WOULD NOT categorically have the guides knurled or seats ground or anything like that. You'll probably find that it is totally unnecessary and probably causes more problems later.

The cam, valve train, etc. should all be fine and reusable. The distributor gear would be the only wear item to check carefully.


By (name respectfully withheld by request ...)


================================================== ===========================


side notes conserning the 4100 / 4500 engines:

Engineering allowed the company to begin increasing displacement and output again. A bored-out (to 92mm) 4.5L (273 in³) 4.5 version was introduced in 1988 with 155hp (116kW) and throttle body injection.

Various versions of this engine were built from this introduction to the end of production in 1992. A high-output LW2 version with multiport fuel injection produced 200hp (149kW) and 270ft·lbf (366N·m) for the Allante.

Outside of the Allante, Cadillac introduced a port fuel injected 4.5L V8 engine in 1990 with 180hp (134kW) across their car line up.

With the head and intake gasket issues resolved in the last couple of years of 4.1L production, the 4.5L V8 experienced considerably less reliability issues than the early 4.1L.

For 1987 & 1988, a more powerful version of the 4.1L engine was introduced in the Cadillac Allante, using a different camshaft profile and roller rocker arms to reduce reciprocating weight, in addition to multiport fuel injection. This engine was rated at 170hp (127kW) @ 4300rpm and 235ft·lbf (319N·m) of torque @ 3200rpm and has proven to be a reliable engine unlike the early 4.1L of the Cadillac line-up.


LIFE CYCLE - to follow later .. below.



.

[IMG]local://upfiles/2893/FAFD061EB38E4C5C91E07EA4BDB84C8E.jpg[/IMG]








.

 

WOW!, a lot of work done here. Thanks, About the only thing I found missing and it took me ten minutes to get to it is the very last step. Adding that can of "Shaler's Resilin" to the oil!
(this was meant as "tongue in cheek" but I watched this done regularly by just about every mechanic I came in contact with in the 30's, 40's, and fifties. (Including my dad.)

 

Just for fun, I went looking for it (also Shaler resin?) .. nothing came up .. spelling?


===============


FATIGUE LIFE ..

Fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading WITHIN LOAD LIMITS.

Without going into technical gobble goop, fatigue life is basically when something fails because you load and unload, or turn it on and off.

Take a paper clip .. bend it once .. its fine .. keep bending it back and forth .. it will fail at some point .. THAT is fatigue life. Each bend is a load. Take a crank, a cam, a piston rod, etc .. all similar situations as the paper clip, except these are designed to load / unload for many more cycles than an engine is likely to see in 1,000,000 miles.

To add a bit of complication for mechanical parts .. speed .. the faster the engine rotates, the higher the load. The higher the load, the shorter the life cycle. Our production engines are meant to normally run in the 2,000 to 3,000 rpm range, occasional runs up to 5,000 to 6,000 rpms. Speed highly accelerates the life cycle. An engine that may go 500,000 miles at 3,000 rpm, may have a difficult time going just 1,000 miles at 8,000 rpms. The paper clip? .. bend it just 30 degrees and count the cycles to failure .. bend it 90 degrees and you will find it fails much faster.

Airplane wing structures, as well as every aircraft component is rated by both FATIGUE LIFE, often stated in "hours" but some items (wings, landing gear, etc ..) by number of take-offs and landings.

One side note .. electronics that survive the first 100 hrs or so of life, will most likely live forever, except when subjected to life cycles. To avoid the life cycles, GM electronics are always on, usually on STANDBY mode. So is your TV and most audio equip at home. The reason that you do not want to disconnect a car battery too many times is exactly that. Each disconnect is a CYCLE, as components get cold and warm up again.

When something is overloaded, mechanical or electronic, the FATIGUE LIFE is often, ONE CYCLE ...


I hope that partially explains it ..

It took a couple semesters of college for the Professors to fully explain it to me, so there is not attempt to do such a job here .. my attempt is only to help the reader visualize the term " FATIGUE LIFE " ...

I invite my friend zinzin (hyperion) to help in explaining this topic, in common terms. His being a airline pilot, goes a long ways to fully comprehend the term and its consequences.





.

 

Don`t know if you guys will see this as it`s an old thread.