My car is growling at me???
09-25-2002, 07:03 AM
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My car is growling at me???
Lately the car has been making a growling noise durig mid to hard right handers. I think that it is just the wheel bearings, but I don't know what else it could be. Does the engine make a noise when the rod bearings are worn out and all of the oil sloshes to one side? 
I sure hope not because I have all of the parts to change my bearings, but I just have to find time to do it. That would suck if it locked up and I was just too lazy to fix it... 
Don't worry, I'm not superstitious! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
I sure hope not because I have all of the parts to change my bearings, but I just have to find time to do it. That would suck if it locked up and I was just too lazy to fix it... Don't worry, I'm not superstitious! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
09-25-2002, 08:42 AM
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[quote]Originally posted by Etkeris:
<strong>Are you serious?? That was the same kind of thing my car was doing right before I spun my #2 RB..
on my '85. I would change them soon if I were you.</strong><hr></blockquote>
That isn't funny dude. I have a few miles. I'll check into it soon.
<strong>Are you serious?? That was the same kind of thing my car was doing right before I spun my #2 RB..
on my '85. I would change them soon if I were you.</strong><hr></blockquote>That isn't funny dude. I have a few miles. I'll check into it soon.
09-25-2002, 08:43 AM
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From Huntley racing....
Huntley Racing had done a lot of research over the years into EXACTLY why 944 cars spin rod bearings. What we found out over several years of searching was that there is much more miss-information that actual facts. First we found that whether in a track car, streetcar or even a weekend show car all 944 based cars including the 968 can spin a rod bearing. Second this has nothing to do with HP or TQ. Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Fifth the Accusump and other systems don't fix this issue (other possible problems yes, but not the common rod bearing failures). Sixth no matter how many baffles you have put in your pan they will not help. I can go on and on but to get to the 'meat' of the matter....
What causes rod-bearing failures is 99% of the time centrifugal force. We found the solution to the mystery in an uncommon place, the Chevy world. It turns out a Chevy motor has the same problem, the 454 big block. Chevy 454 big blocks, which were designed for lower RPM operation, later became popular for drag racers. The drag racers started to turn more and more rpm's in search of more HP, which resulted in a 'new' problem developing, spun rod bearings. It took years to figure out why. The reason turned out to be so basic that the likes of Chevy and Porsche simply 'missed' it.
As a crankshaft rotates it has many forces acting upon it. It is obvious that the pistons push on the rods, which push on the crank and so forth and so on. What was missed was centrifugal force acting on the oil within the crank. High-pressure oil is fed thru the center of the crank to the main and rod bearings. Oil passing thru each journal is forced out of the crank onto the surface of the bearing thru the oil feed, which is nothing more than a hole in the surface of the journal. Where the 'mistake' was made was in the placement of the hole. The single oil feed hole can be drilled at any point 360 deg around on the journal, this is a decision dictated during the production of the crank. When the 944 crank design was made there was no attention given to the placement of this hole and the effect centrifugal force might have on the oil within it. Where the feed was placed just so happens to be one nearly opposite the direction centrifugal force pulls the oil when the crank is in motion. As the RPMs increase the centrifugal force goes up, eventually to the point where the oil pumps pressure simply can't overcome it. When this happens the rod bearings are starved of oil. The reason more track cars have this failure is because they are at high RPMs more often and for longer periods of time. Also track cars tend to have relatively high oil temperatures which thins the oil and causes the oil pressure to drop which lowers the RPM point where oil starvation at the rod bearings occurs. Further the high RPMs and often overfilled oil pans (to supposedly save the rod bearings) cause high windage that aerates the oil, further reducing its lubricating potential. Older motors spin rod bearings more often than newer motors since they have had more high RPM time than new motors and they usually have less oil pressure. Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
Cross-drilling came out several years ago as a remedy for this issue but not because the problem was understood but because the idea was that a second oil feed hole would add more oil. There was a positive benefit from crossdrilling. The new oil feed opposite the original oil feed was not either hurt or helped by centrifugal force due to its position. This meant
that the oil pump could generally keep up with the oiling needs of the rod bearings. Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!! Since we have machined cranks with this technique we have 'NEVER' had a rod bearing failure in any car, ever! We started offering these in 1998.
This subject and its relevance to the 944 world is obvious but it is only one of many possible failures, which can and do occur to these cars. Cars that suffer rod failure generally can trace this to the above mentioned rod bearing problem as the catalyst. Main bearings generally don’t have this problem simply because they are centrally located on the centerline of the crank and have a much smaller ‘arm’ to their outer diameter which makes them far less susceptible to oil starvation from centrifugal force.
So in summary if you have your crank out have the process done. If your motor is still together and you want to avoid spinning a bearing without the Perp drilled crank, keep your oil temps down, limit your RPMs a bit (look at your HP peak and avoid revving past it), run a higher viscosity oil, avoid over filling, and keep the oil fresh.
Derrek Huntley Khajavi
Huntley Racing
************************************************
Do you drive the car hard?? How many miles do you have on it?? Good luck man
Huntley Racing had done a lot of research over the years into EXACTLY why 944 cars spin rod bearings. What we found out over several years of searching was that there is much more miss-information that actual facts. First we found that whether in a track car, streetcar or even a weekend show car all 944 based cars including the 968 can spin a rod bearing. Second this has nothing to do with HP or TQ. Third it has nothing to do with uncovering the oil pick-up (This is a common miss-conception promoted by many many shops). Forth is that extra oil, like a half quart over the dipstick, does nothing. Fifth the Accusump and other systems don't fix this issue (other possible problems yes, but not the common rod bearing failures). Sixth no matter how many baffles you have put in your pan they will not help. I can go on and on but to get to the 'meat' of the matter....
What causes rod-bearing failures is 99% of the time centrifugal force. We found the solution to the mystery in an uncommon place, the Chevy world. It turns out a Chevy motor has the same problem, the 454 big block. Chevy 454 big blocks, which were designed for lower RPM operation, later became popular for drag racers. The drag racers started to turn more and more rpm's in search of more HP, which resulted in a 'new' problem developing, spun rod bearings. It took years to figure out why. The reason turned out to be so basic that the likes of Chevy and Porsche simply 'missed' it.
As a crankshaft rotates it has many forces acting upon it. It is obvious that the pistons push on the rods, which push on the crank and so forth and so on. What was missed was centrifugal force acting on the oil within the crank. High-pressure oil is fed thru the center of the crank to the main and rod bearings. Oil passing thru each journal is forced out of the crank onto the surface of the bearing thru the oil feed, which is nothing more than a hole in the surface of the journal. Where the 'mistake' was made was in the placement of the hole. The single oil feed hole can be drilled at any point 360 deg around on the journal, this is a decision dictated during the production of the crank. When the 944 crank design was made there was no attention given to the placement of this hole and the effect centrifugal force might have on the oil within it. Where the feed was placed just so happens to be one nearly opposite the direction centrifugal force pulls the oil when the crank is in motion. As the RPMs increase the centrifugal force goes up, eventually to the point where the oil pumps pressure simply can't overcome it. When this happens the rod bearings are starved of oil. The reason more track cars have this failure is because they are at high RPMs more often and for longer periods of time. Also track cars tend to have relatively high oil temperatures which thins the oil and causes the oil pressure to drop which lowers the RPM point where oil starvation at the rod bearings occurs. Further the high RPMs and often overfilled oil pans (to supposedly save the rod bearings) cause high windage that aerates the oil, further reducing its lubricating potential. Older motors spin rod bearings more often than newer motors since they have had more high RPM time than new motors and they usually have less oil pressure. Baffles, Accusumps, overfilling etc... do nothing to stop this failure mode.
Cross-drilling came out several years ago as a remedy for this issue but not because the problem was understood but because the idea was that a second oil feed hole would add more oil. There was a positive benefit from crossdrilling. The new oil feed opposite the original oil feed was not either hurt or helped by centrifugal force due to its position. This meant
that the oil pump could generally keep up with the oiling needs of the rod bearings. Huntley Racing however took the cross-drilling to the next level and developed the Perp drilled crank. We perpendicularly bore a new feed into the rod journal, which is actually taking the nemesis, 'centrifugal force' and working with it to help to actually scavenge oil to the rod bearing as the RPMs go up!! Since we have machined cranks with this technique we have 'NEVER' had a rod bearing failure in any car, ever! We started offering these in 1998.
This subject and its relevance to the 944 world is obvious but it is only one of many possible failures, which can and do occur to these cars. Cars that suffer rod failure generally can trace this to the above mentioned rod bearing problem as the catalyst. Main bearings generally don’t have this problem simply because they are centrally located on the centerline of the crank and have a much smaller ‘arm’ to their outer diameter which makes them far less susceptible to oil starvation from centrifugal force.
So in summary if you have your crank out have the process done. If your motor is still together and you want to avoid spinning a bearing without the Perp drilled crank, keep your oil temps down, limit your RPMs a bit (look at your HP peak and avoid revving past it), run a higher viscosity oil, avoid over filling, and keep the oil fresh.
Derrek Huntley Khajavi
Huntley Racing
************************************************
Do you drive the car hard?? How many miles do you have on it?? Good luck man
09-25-2002, 11:24 AM
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Ok, thanks for the info. That does make a whole lot of sense. I wonder why no one ever thought of that before???
Anyway, has anyone had their crank out? Is it really tough? I had planned on pulling the engine and doing some work anyway. Which I need some more advise on too...
Those of you NA guys who have SUCCESSFULLY pulled and reinstalled your engines, could you drop me an email or just post on here??? Thanks!
Anyway, has anyone had their crank out? Is it really tough? I had planned on pulling the engine and doing some work anyway. Which I need some more advise on too...
Those of you NA guys who have SUCCESSFULLY pulled and reinstalled your engines, could you drop me an email or just post on here??? Thanks!
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09-25-2002, 11:52 PM
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I don't own a 944, so there could be something about that engine I'm not aware of, but I've spun lots of rod bearings and been in the car with a lot of damaged or worn out wheel bearings.
You asked "Does the engine make a noise when the rod bearings are worn out and all of the oil sloshes to one side?" I don't know the 944, but the growl in my 931 happened regardless of whether or not oil was covering the bearings.
Diagnosis:
The rod bearing GROWL, and it was a growl, happened on acceleration. Not at a constant speed. The wheel bearing grindy/whiney noise was usually evident on highways. When I changed lanes right, you'd hear it and it would lessen as the car straightened out. When I changed lanes left, you wouldn't hear it. Right corners noise, left corners no noise.
An easy test to reassure yourself is this:
Try a hard left turn and listen for the growl.
Yes/No
Try a hard right turn and listen for the growl.
Yes/No
If No, then Yes, it's probably a wheel bearing.
If Yes, then Yes, could be a really bad set of wheel bearings worn down considerably or, you can start worrying that it's a rod bearing.
If you're interested, and you've determined it's a wheel bearing, you can pinpoint front or back. Assuming a rear wheel bearing, on accel, weight shifts to the back, noise happens. On decel, weight shifts forward, noise disappears.
Or just put it on a hoist and spin the wheels...then listen.
Good luck! Hope it's not your engine.
You asked "Does the engine make a noise when the rod bearings are worn out and all of the oil sloshes to one side?" I don't know the 944, but the growl in my 931 happened regardless of whether or not oil was covering the bearings.
Diagnosis:
The rod bearing GROWL, and it was a growl, happened on acceleration. Not at a constant speed. The wheel bearing grindy/whiney noise was usually evident on highways. When I changed lanes right, you'd hear it and it would lessen as the car straightened out. When I changed lanes left, you wouldn't hear it. Right corners noise, left corners no noise.
An easy test to reassure yourself is this:
Try a hard left turn and listen for the growl.
Yes/No
Try a hard right turn and listen for the growl.
Yes/No
If No, then Yes, it's probably a wheel bearing.
If Yes, then Yes, could be a really bad set of wheel bearings worn down considerably or, you can start worrying that it's a rod bearing.
If you're interested, and you've determined it's a wheel bearing, you can pinpoint front or back. Assuming a rear wheel bearing, on accel, weight shifts to the back, noise happens. On decel, weight shifts forward, noise disappears.
Or just put it on a hoist and spin the wheels...then listen.
Good luck! Hope it's not your engine.
09-26-2002, 03:08 AM
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I can hear it when I am accelerating through a right turn. Now, I'm not as nice as I could be to my car... I usually hear it at 4KRPM and above. It isn't a good sound, and it wasn't there before. I do hope that it is a wheel bearing, but like I said, I am going to do my rod and main bearings as I purchased them a while back. 
09-26-2002, 12:16 PM
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EC,
I still have the same problem with my '91 S2 only it happens when I turn left. If I turn left and accelerate I hear a growling/rumbling noise coming from the rear of the car. I have changed both complete sets of front & rear wheel bearings on both sides. Still have the noise. Also, I just recently had the rod bearings replaced when I had the oil pan pulled for another job. Still have the noise. I have been told by some that it could very likely be the CV joints on one side. There was somebody on the list that had a similar problem and it went away when they changed their CV joints. It is not a trans problem because you would most likely get it in either direction of turn.
When I replaced my rear wheel bearings it was obvious that there was some play there but there was not a ton of wear. I replaced one each (rear wheel bearings) at about 85K & 90K.
My vote is for CV joints.
Good luck,
Max
I still have the same problem with my '91 S2 only it happens when I turn left. If I turn left and accelerate I hear a growling/rumbling noise coming from the rear of the car. I have changed both complete sets of front & rear wheel bearings on both sides. Still have the noise. Also, I just recently had the rod bearings replaced when I had the oil pan pulled for another job. Still have the noise. I have been told by some that it could very likely be the CV joints on one side. There was somebody on the list that had a similar problem and it went away when they changed their CV joints. It is not a trans problem because you would most likely get it in either direction of turn.
When I replaced my rear wheel bearings it was obvious that there was some play there but there was not a ton of wear. I replaced one each (rear wheel bearings) at about 85K & 90K.
My vote is for CV joints.
Good luck,
Max
09-26-2002, 12:35 PM
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I thought the growl that I'm getting was from the test pipe? At least it sounds like it's from that area. I hope it's not the rob bearings. How hard are they to replace?
