Finally got the 3800 sc Series 2 taken apart, took it to the machine shop to get inspected and the machinist said the thrust bearing was shot and in turn made the front two bearing spin by clogging the oil passages in the bearings. He attributed the issue possibly to the Spec clutch exerting too much pressure and causing the thrust bearing to fail prematurely as there was too much forward play in the crank. Looking at all the components it doesnt seem the engine was in service for too long (the clutch, timing chain and gaskets look brand new for example) and FORTUNATELY the PO stopped it as soon as he lost pressure so the neither the cam bearings or the rod bearings suffered any damage.
1. Has anyone heard of or suffered something similar with this engine? 2. Is there a way to reinforce the crank(i.e. racing bearings or such) so that it can deal with the clutch pressure? 3. Should I just use a lighter clutch instead to avoid this problem? 4. Should I delete the balance shaft and use a high flow oil pump to make more oil available for the crank? 5. What about clearances in general? 6. am i better off getting a short block (so far the machinist quoted me $600 for the work)?
He attributed the issue possibly to the Spec clutch exerting too much pressure and causing the thrust bearing to fail prematurely as there was too much forward play in the crank.
The clutch pressure plate can exert as much pressure as it wants onto the flywheel, it shouldn't load the crank bearings at all. The only time there would be any pressure transferred to the crank would be when the clutch is pressed. I haven't seen anybody else blowing engines even with more agressive clutches.
What caused the engine failure is almost certainly NOT the clutch. I don't have too much experience with 3800 engine failures, so I can't offer any specific opinion on the actual root cause, but "the clutch is too strong" just seems like to me.
1. Has anyone heard of or suffered something similar with this engine?
No, but I could see how it could be possible if a performance clutch with a very high clampling force pressure plate was used and/or the PO "rode" the clutch a lot.
quote
2. Is there a way to reinforce the crank(i.e. racing bearings or such) so that it can deal with the clutch pressure?
There isn't a lot of room inside a 3800 to increase the bearing size. But that's only 1/2 the problem. The other 1/2 is finding a bearing with a larger thrust surface. Something like that would probably need to be custom made, and that is going to cost a lot of money. Again, this assuming there is room on the crank and in the block for machining a larger thrust surface to begin with - which there may not be.
quote
3. Should I just use a lighter clutch instead to avoid this problem?
If the cause of the original failure was due to driver's habits (ie: riding the clutch pedal a lot), then the problem might be able to be solved by just not doing that. But yes, if you can find a performance clutch with the holding power you need that uses a lighter pressure plate spring, that would certainly help.
quote
4. Should I delete the balance shaft and use a high flow oil pump to make more oil available for the crank?
Was lack of oil flow the reason why the thrust bearing failed in the first place? Or was it simply not designed to handle the forces that were placed upon it? If it wasn't designed for the forces then I would say increasing oil pump flow and/or pressure won't fix the issue. 3800 Series 2 and 3 engines already have an awesome oiling system stock as-is, and I haven't seen any "upgrades" be worthwhile or fix any problems.
quote
5. What about clearances in general?
One of the most common 3800 rebuilding mistakes I've heard of that lead to quick engine failures is when builders try to apply Small Block Chevy V8 rebuilding and bearing clearance mentality to a 3800 rebuild. The absolute best thing you can do is set the bearing and other clearances up to FACTORY GM SPECS for the specific 3800 engine you are rebuilding. Do not make any changes except with respect to piston to wall and piston ring gaps, as well as if any aftermarket performance parts you are using specify to use a specific clearance that differs from what the factory says. In the case of piston to wall and factory ring gap specs, this is only a concern if you are using factory pistons and rings - in which case setting up the piston to wall clearance on the loose side of spec is best and doing the same or even exceeding the max ring gap spec for the top compression ring a little would be good advice. Stock pistons locate the top compression ring very close to the top of the piston which exposes them to heat of combustion which can cause top ring overheating and failure. Aftermarket Speed Pro cast pistons feature a redesign where the top compression ring is moved down a bit (compared to a stock piston) to correct this problem. In any case, if aftermarket/performance parts are being used, then I would recommend following the clearance specifications for those specific parts from their manufacturers.
quote
6. am i better off getting a short block (so far the machinist quoted me $600 for the work)?
What's to say if you go buy another used stock short block it isn't going to also have its own share of issues if it has any kind of mileage on it?
-ryan
------------------ OVERKILL IS UNDERRATED Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com
So how did the debris of the bad bearing that had way too much slop move backwards up the oil passage and then moved to plug up the oil passage leading to the other two bearings.
How about instead the bearing after it totally let loose and let all the oil just run out also left the other two bearings after it on the same passage with no oil pressure and that is why they failed? Makes more sense to me but it's just a guess.
So why would the thrust bearing fail? Maybe installed at the factory without the oil passage to be bearing aligned correctly>
well Im not sure which way the oil flows but apparently the thrust bearing sits behind the #2 main and when that wore it pushed the metal towards the #2 and #1 main bearings making them fail. That was their reasoning but im not versed in this engine so I cant really say
well it looks like I will need a crankshaft kit and get everything bored to match. Should I delete the balancer? I keep reading that its not needed and it makes no difference in vibration while saving weight...
well it looks like I will need a crankshaft kit and get everything bored to match. Should I delete the balancer? I keep reading that its not needed and it makes no difference in vibration while saving weight...
"I keep reading that its not needed and it makes no difference in vibration while saving weight"
I find it hard to believe GM spent millions of dollars to designing an engine to accept a balance shaft and then spent millions more on production to install one in every type of this engine they produced when it "makes no difference in vibration"... Who says it makes no difference? And how much of a weight savings is it really to remove it?
A 90 deg V6 engine design does not allow for the engine to run smoothly. The balance shaft was added by GM to counter-act the uneven harmonic vibrations produced by such an engine. Having owned and driven cars equipped with 90 deg V6 engines that did and did not have balance shafts, I can say FOR CERTAIN the ones that did have balance shafts were indeed much smoother feeling than the ones that did not.
If you are doing a Fiero swap using such an engine and are planning on using solid or poly mounts, I think you are going to regret it if you decide to pull the balance shaft out of the engine.
But if you do pull the balance shaft, you need to be aware there are oil passages you will need to plug once it is gone. And what are you going to run for a timing chain? Some aftermarket roller unit that is too tight and wipes out the front cam bearings in short order (common problem with such aftermarket chains).
[This message has been edited by Darth Fiero (edited 08-18-2014).]
This translates to terrible internal engine shake and HP being used to create this vibration. For high rpm engine operation, it is recommended to eliminate or disable the factory balance shaft.
Just how much HP do you gain by removing it and making NO other changes at the same time? Dyno sheets?
But more importantly, have you even been in a Fiero with a 90 deg V6 engine that had solid or poly mounts that had no balance shaft running at idle? Even with the balance shaft in place and working, the 3800 Series 2 isn't the smoothest running engine at idle.
Seeing as how there are many people who complain to me about the 3800 idle vibration as it is, I can't imagine why anyone would want to make it worse when the gains of doing so aren't clear.
But hey, it is your car and you can do what you want. I'm just offering an alternative opinion on the matter.
[This message has been edited by Darth Fiero (edited 08-18-2014).]
Im getting the impression that you think I WANT to do this as if my only goal was to look for more hp. Im just merely asking for input as I have little experience with this engine and Im trying to inform myself the best way possible to end up with something reliable and durable since Im at the point of getting the block machined. You are right on both accounts, I have not been in a Fiero with a functional 3.8 so I have no reference point, my experience is in my other fiero with a 350. Also, its my engine so finally its me that would decide what stays in or comes out. The article simply helped me realize that Im better off keeping the balance shaft as my intention with this build is to use it as a daily driver of sorts so I think you didnt understand my point in posting the article, hope this clears it up. Thanks anyways...
Im getting the impression that you think I WANT to do this as if my only goal was to look for more hp. Im just merely asking for input as I have little experience with this engine and Im trying to inform myself the best way possible to end up with something reliable and durable since Im at the point of getting the block machined. You are right on both accounts, I have not been in a Fiero with a functional 3.8 so I have no reference point, my experience is in my other fiero with a 350. Also, its my engine so finally its me that would decide what stays in or comes out. The article simply helped me realize that Im better off keeping the balance shaft as my intention with this build is to use it as a daily driver of sorts so I think you didnt understand my point in posting the article, hope this clears it up. Thanks anyways...
You asked about the balance shaft removal idea and I gave my two cents about it. You then replied with a link to ZZP's website (which tries to sell the reader on their idea of how it works and why you should remove it) - all the while not telling you the whole story. I've built many 3800 Fiero swaps over the years and I'm saying that you may regret removing it - that is if you spend a lot of time driving your car. You did not say in your post with the ZZP link whether or not you had decided to keep it. But the ZZP article was trying to make a point why you should remove it. So how was I supposed to take it otherwise?
[This message has been edited by Darth Fiero (edited 08-19-2014).]
but if you must know, my concern wasnt to add horsepower by removing the balancer but to make more oil available to the crankshaft since less oil would be displaced upwards to fulfill the balancer needs. That's referenced in #4 in the original post.
but if you must know, my concern wasnt to add horsepower by removing the balancer but to make more oil available to the crankshaft since less oil would be displaced upwards to fulfill the balancer needs. That's referenced in #4 in the original post.
The balance shaft only has 2 bearings (1 at each end). I can't see how blocking the oil flow to it off (after it has been removed) is going to significantly improve the oiling system of the engine. Not that it matters in your case because we still don't know what caused the thrust bearings to fail (ie: overloading or inadequate lubrication).
There are a lot of people running around with 3800 manual transmission swaps (not all of them stock) and we simply haven't heard of very many thrust bearing failures. Not saying that they haven't occurred and just weren't reported on this forum and others, but you would think if it is a big issue we would be hearing more about it.
[This message has been edited by Darth Fiero (edited 08-20-2014).]
Im starting to have serious doubts the block is from a supercharged car. Im not sure how to check it but I will post pics of the bottom. The machinist said it doesnt look like it and that the crank is cast iron instead of the steel crank usually in the SC engine. After closer inspection all the main bearings suffered some damage but the front two suffered the most. The crank can be cut and the block line bored but if its an NA block then could I potentially have the same problem? The block does say "3800 Series 2" "C100" and the casting number which I cant remember but I can call the shop and get. If it turns out to be the case then my options would be to find a SC motor at a junker(already found 2 for under $500), get that reworked at the shop and throw the aluminum heads and other parts on it or try to work out the original block into something that will hold. How can I verify if this is in fact a Supercharger block?
Im starting to have serious doubts the block is from a supercharged car. Im not sure how to check it but I will post pics of the bottom. The machinist said it doesnt look like it and that the crank is cast iron instead of the steel crank usually in the SC engine. After closer inspection all the main bearings suffered some damage but the front two suffered the most. The crank can be cut and the block line bored but if its an NA block then could I potentially have the same problem? The block does say "3800 Series 2" "C100" and the casting number which I cant remember but I can call the shop and get. If it turns out to be the case then my options would be to find a SC motor at a junker(already found 2 for under $500), get that reworked at the shop and throw the aluminum heads and other parts on it or try to work out the original block into something that will hold. How can I verify if this is in fact a Supercharger block?
Well the first problem is it sounds like your mechanic doesn't know these engines very well. THEY ALL HAD CAST CRANKS (SC and N/A). As a matter of fact, the crankshaft was the exact same part number for the SC and N/A engines. The difference was in the connecting rods, pistons, piston pins, and cylinder heads (and even with the heads it was the same casting for N/A, they just had injector holes machined in them). The SC and N/A blocks are the exact same.
The only way you are going to know if you have an SC engine is to check the rods, pistons, and piston pins. You might be able to tell what kind of rods you have by just looking after the oil pan is taken off. We would need to see pictures so we can determine what the rods are, but even then it may be difficult because they look similar (easier to tell when taken out of the engine and placed side by side with N/A rods).
You are right about the crank. Im calling around for other shops cause I'm not confident about these guys although they were recommended by a friend that does top noch head work.. I did confirm that the casting number on the block (24506029) belongs to a 1997-2008 Supercharged engine (as per this article: http://www.enginebuildermag...-3-8l-buick-engine/) and other components seem to indicate the same. We looked also at the rod bearings and they had a 2000 date stamped on them. I'll post pics in a second but Im pretty confident that I dont have mismatched parts other than the aluminum heads obviously not being original equip. After talking to a local custom crank guy I think my best route is to get a crankshaft kit and have the block line bored, check rods for roundness and put it back together with the new bearings as all other parts are healthy. Is there an alternative to the crank sold by Advance or Oreilley's (Crankshaft Rebuilders part 10760P at Advance) or am I safe with that?
to me.
