Spun a Rod Bearing :(

[SrtBrad]

We hardly ever hear about the Viper cars with spun rods. Reason being for the most part is the weight difference between the car and truck.
and i think i like men

 

[NSDQ]

These trucks that sit with low, low miles are asking for all kinds of issues.

That's why I drive the shit out of mine!

 

[rare03srt10]

Im in the process of selling my project SRT10 and been thinkin if i dont sell this thing as a whole soon i may pull the motor and part out. My Srt10 engine has just over 20k miles. Id sell it with bbk throttle body, k&n intake, jmb oil catch can, msd wires, auto tranny, wiring harness, pcm ect for a fair price. PM if u decide to go that route. I can sell without tranny also if u want

 

[caveman]

We hardly ever hear about the Viper cars with spun rods. Reason being for the most part is the weight difference between the car and truck.
and i think i like men

Interesting observations there, Brad

 

[NVR2OLD]

We hardly ever hear about the Viper cars with spun rods. Reason being for the most part is the weight difference between the car and truck.
and i think i like men

There has been quite a few on the Viper Alley site with spun rod bearings with the Gen3 motor also. So it's not the weight difference.

 

[SrtBrad]

There has been quite a few on the Viper Alley site with spun rod bearings with the Gen3 motor also. So it's not the weight difference.

That what i meant to say but Dom just had his mouth full with a brown nose

 

[ICPREY]

Gen III viper guys who track their cars have the same issue if not worse with the G forces and smaller oil pan. Gen III oiling issues

 

[SrtBrad]

Interesting observations there, Brad

Don't you love hackers!

 

[SrtBrad]

There has been quite a few on the Viper Alley site with spun rod bearings with the Gen3 motor also. So it's not the weight difference.

Yes I partially agree but not as frequent as the trucks due to the weight difference. If you factor in performance mods and FI then that's also a whole different story. The Viper motor was engineered for the car's weight primarily. Are you saying that weight is not a factor at all? What kinds of conditions and mods were a factor in the cars that spun rods that you talk of? I might be wrong on the weight issue as I don't have actual numbers and charts to back up my understanding but was explained by a reputable Viper shop that weight is a contributing factor to some spun rods.

 

[NVR2OLD]

Yes I partially agree but not as frequent as the trucks due to the weight difference. If you factor in performance mods and FI then that's also a whole different story. The Viper motor was engineered for the car's weight primarily. Are you saying that weight is not a factor at all? What kinds of conditions and mods were a factor in the cars that spun rods that you talk of? I might be wrong on the weight issue as I don't have actual numbers and charts to back up my understanding but was explained by a reputable Viper shop that weight is a contributing factor to some spun rods.

I'm sure the issue isn't with the weight of our trucks. After talking with alot Viper race tech's and Todd at Arrow racing and Sean at Roe Racing and after I spun a rod bearing this summer. All have said the most commond reason is under heavey load and high rpm the #3 / #5 crank bearings get starved for oil due to the poor oiling system and inherent problem the Gen3 motor has with the lack of lubricating at high rpm. There is a fix for this problem, like mods for the crank journals and oil pump housing and spring. No one has ever mentioned weight.

 

[ICPREY]

More weight=heavier load...I don't think the weight is the main problem for the trucks, but I'm sure it's a contributing factor.

 

[NVR2OLD]

More weight=heavier load...I don't think the weight is the main problem for the trucks, but I'm sure it's a contributing factor.

More on the heavey RPM.

 

[SrtBrad]

I'm sure the issue isn't with the weight of our trucks. After talking with alot Viper race tech's and Todd at Arrow racing and Sean at Roe Racing and after I spun a rod bearing this summer. All have said the most commond reason is under heavey load and high rpm the #3 / #5 crank bearings get starved for oil due to the poor oiling system and inherent problem the Gen3 motor has with the lack of lubricating at high rpm. There is a fix for this problem, like mods for the crank journals and oil pump housing and spring. No one has ever mentioned weight.

Ok lets think about this. Yes I agree the oiling system is of a poor design for high rpm and heavy load driving practices. If the oiling system is poor then technically all the bearings would be vulnerable to spinning. Why is it that most cases of spun rods are #3? My opinion is that the flex of the crank starves our #3 bearings resulting in spun rods. The more weight equates to more load which in turn has more flex on our cranks which equals more chance of spun bearings on out trucks over the cars. What's your opinion? There are other factors involved as well including running lean due to intake issues just to mention another contributing factor.

 

[SrtBrad]

More weight=heavier load...I don't think the weight is the main problem for the trucks, but I'm sure it's a contributing factor.

I agree.

 

[Psycho1122]

My understanding is the stock gearrotor pumps can cavitate at 5300-5500 RPM under hard acceleration. with either of the 2 oil pump designs.

Gear / rotor pumps do not "Cavitate" indepenently. If they suck an "air bubble", they can have a difficult time recovering.

The thread re; Gen III oiling on the Viper Club of America is excellent. The simple, primary issue is Cavitation. (Sucking an air bubble). Either under hard acceleration like SrtBrad stated or high cornering load (G-force). Our trucks are less likely due to deeper oil pan sump and overall less G-Forces. Keeping the oil level at the top end minimum or even just a bit over would be beneficial. I have personally went into a right hand bend with a slight downhill grade at well over a hundred and started braking mid corner. I sloshed enough oil that it came out my valve cover oil cap. Not only did it make a mess, I discovered that my cap o-ring was bad. It is amazing how much the oil moves around and defies gravity in these types of conditions.

Other issues.

1. Due to our intake manifold designs #3 tends to run lean causing premature detonation thus pounding the bearings producing excessive heat and resulting in a spun bearing or worse.

2. Our engines due to the long crankshaft design tend to warp in the middle under extreme torque causing the sandwiching of the middle bearings (#3 and #5) causing oil starvation issues which can also result in a spun bearing or worse.

3. Ring land clearance is so thin that detonation can cause fractures causing small pieces to break off and getting stuck in the piston wall or bearing area causing a spun bearing or worse.

4. Having a reading on later 05 and 06 models with more than 1.0 volts on the knock sensor will produce undesirable hammering on the rods which over time will most likely spin either #3 or #5 rods first. I recommend making sure that the knock sensor voltage reads no more than 0.5 volts. At 1.2 volts the knocks sensor retards the timing by 2 degrees.

5. Having too much timing causing most issues listed above will also result a spun bearing at the least.

Advanced Timing can cause "Pinging". Which is easy to hear and caused by ignition that just too early. Usually does not damage a piston.

Detonation is a monster. Super sonic sound wave caused by fuel mixture self igniting (Usually at the edge of a piston or a sharp edge like a valve relief cut out on piston top). These edges can glow red hot and promote detonation. Our combustion chamber design is not efficient (compare to a narrow angle 4 valve, aluminum, modern motorcycle engine) or flat. Poor quenching of the fuel mixture. You really want to squeeze the fuel mixture towards the center where the plug is (ours is off center).

The best remedie is keep the combustion chamber thermally stable (all aluminum engines like @200F) and give it as cool a charge as possible. An A/F ratio Under 12.6-1 NA is good insurance, I have commented plenty on using an AEM wideband to keep an eye on this. Torries SAFE tunes are smart!!

Ok lets think about this. Yes I agree the oiling system is of a poor design for high rpm and heavy load driving practices. If the oiling system is poor then technically all the bearings would be vulnerable to spinning. Why is it that most cases of spun rods are #3? My opinion is that the flex of the crank starves our #3 bearings resulting in spun rods. The more weight equates to more load which in turn has more flex on our cranks which equals more chance of spun bearings on out trucks over the cars. What's your opinion? There are other factors involved as well including running lean due to intake issues just to mention another contributing factor.

I would not say the design is "poor". But it looks like you can run into a limitation. Especially if you have a Viper car. Thier pan is shallower than ours.
The bearings themselves don't "spin" in the rod big end. However, if they loose the hydro dynamic barrier (from a passing air bubble), now they will get scored against the crank journal and melt away.

I do have a hard time with the crank shaft literally "flexing" in the block to an extent it overcomes the oil's "hydro dynamic barrier" under the flow and pressure from the pump. The blocks are so very ridged in design and have alot of "webbing" cast into them. The cranks themselves are Forged. I would love to see a block diagram of the engines oiling system to see some possible compromise in the oil feeds to the crank and rod journals.

If I had to take a stab at what happened to SrtDub's engine..... He had dreaded Detonation and or Cavitation. Most likely an lean tune combined with limitations mentioned by SrtBrad in the intake (Starved #3 cylinder) caused a lean condition. SrtDub did state that the pistons on cylinders 3+4 were tight on the rods. This would indicate damage from detonation which can collapse the ring lands and stick a piston in the hole. Now the rod's ability to move has been compromised. Maybe to the extent of bending a wrist pin....Boom!! It will happen in an instant with no real warning.

Any chance of a low oil level in the engine?!? Are you running a "Catch Can" to keep hot oil fumes out of the intake!?

Picturs of pistons SrtDub!?!? You did state no FI on the engine correct!?!

Thanks

Cheers!

 

[NVR2OLD]

Psycho1122, Excellent interpretation on whats going on with the spun rod bearings.:rock::rock:

 

[SrtBrad]

Gear / rotor pumps do not "Cavitate" indepenently. If they suck an "air bubble", they can have a difficult time recovering.

The thread re; Gen III oiling on the Viper Club of America is excellent. The simple, primary issue is Cavitation. (Sucking an air bubble). Either under hard acceleration like SrtBrad stated or high cornering load (G-force). Our trucks are less likely due to deeper oil pan sump and overall less G-Forces. Keeping the oil level at the top end minimum or even just a bit over would be beneficial. I have personally went into a right hand bend with a slight downhill grade at well over a hundred and started braking mid corner. I sloshed enough oil that it came out my valve cover oil cap. Not only did it make a mess, I discovered that my cap o-ring was bad. It is amazing how much the oil moves around and defies gravity in these types of conditions.




Advanced Timing can cause "Pinging". Which is easy to hear and caused by ignition that just too early. Usually does not damage a piston.

Detonation is a monster. Super sonic sound wave caused by fuel mixture self igniting (Usually at the edge of a piston or a sharp edge like a valve relief cut out on piston top). These edges can glow red hot and promote detonation. Our combustion chamber design is not efficient (compare to a narrow angle 4 valve, aluminum, modern motorcycle engine) or flat. Poor quenching of the fuel mixture. You really want to squeeze the fuel mixture towards the center where the plug is (ours is off center).

The best remedie is keep the combustion chamber thermally stable (all aluminum engines like @200F) and give it as cool a charge as possible. An A/F ratio Under 12.6-1 NA is good insurance, I have commented plenty on using an AEM wideband to keep an eye on this. Torries SAFE tunes are smart!!



I would not say the design is "poor". But it looks like you can run into a limitation. Especially if you have a Viper car. Thier pan is shallower than ours.
The bearings themselves don't "spin" in the rod big end. However, if they loose the hydro dynamic barrier (from a passing air bubble), now they will get scored against the crank journal and melt away.

I do have a hard time with the crank shaft literally "flexing" in the block to an extent it overcomes the oil's "hydro dynamic barrier" under the flow and pressure from the pump. The blocks are so very ridged in design and have alot of "webbing" cast into them. The cranks themselves are Forged. I would love to see a block diagram of the engines oiling system to see some possible compromise in the oil feeds to the crank and rod journals.

If I had to take a stab at what happened to SrtDub's engine..... He had dreaded Detonation and or Cavitation. Most likely an lean tune combined with limitations mentioned by SrtBrad in the intake (Starved #3 cylinder) caused a lean condition. SrtDub did state that the pistons on cylinders 3+4 were tight on the rods. This would indicate damage from detonation which can collapse the ring lands and stick a piston in the hole. Now the rod's ability to move has been compromised. Maybe to the extent of bending a wrist pin....Boom!! It will happen in an instant with no real warning.

Any chance of a low oil level in the engine?!? Are you running a "Catch Can" to keep hot oil fumes out of the intake!?

Picturs of pistons SrtDub!?!? You did state no FI on the engine correct!?!

Thanks

Cheers!

I am no expert by any means and I'm impressed with your interpretation. This is exactly what type of discussions I like having so we can educate ourselves with the limitations to our engines and drive accordingly. I will respond to your statement a little later. For the most part you have it right but there are further points that have to be addressed to further understand this issue. I will weigh in on this a little later.

Excellent discussion!

 

[SrtBrad]

Gear / rotor pumps do not "Cavitate" indepenently. If they suck an "air bubble", they can have a difficult time recovering.

The thread re; Gen III oiling on the Viper Club of America is excellent. The simple, primary issue is Cavitation. (Sucking an air bubble). Either under hard acceleration like SrtBrad stated or high cornering load (G-force). Our trucks are less likely due to deeper oil pan sump and overall less G-Forces. Keeping the oil level at the top end minimum or even just a bit over would be beneficial. I have personally went into a right hand bend with a slight downhill grade at well over a hundred and started braking mid corner. I sloshed enough oil that it came out my valve cover oil cap. Not only did it make a mess, I discovered that my cap o-ring was bad. It is amazing how much the oil moves around and defies gravity in these types of conditions.

Let's understand where the air bubble comes from. The air bubble that you describe is caused from the oil pump impeller spinning so fast that it creates bubbles inside the system pushing these compressed bubbles through the
relief valve which recirculates back into the pickup right next to the pump inlet causing the oil pump to loose prime. This compressed air is one of the contributing factors to spun rods over a period of time due to the momentary lapse of oil pressure and violent spiking in which the pump has to reprime itself.

There is another type of cavitation that is a different type described above. That issue is usually with the Gen3 Viper cars at the track with wider stickier tires like Hoosiers and usually under hard prolonged cornering/acceleration (about 1.2 G's) in which the oil goes to the side of the oil pan and the pickup sucks in air. This is not so much a concern with the street cars with street tires that don't pull nearly as much G's.

Advanced Timing can cause "Pinging". Which is easy to hear and caused by ignition that just too early. Usually does not damage a piston.

I agree to disagree on this as I have done extensive road tuning without hearing any detonation due to the traffic noise, and a loud motor even with the windows up. I was only able to get volt readings from the knock sensor to adjust the timing accordingly throughout the rpm range. Pinging will damage the piston by cracking the 1st ring land over a period of time. Pinging also pounds the rod bearings bad.

Detonation is a monster. Super sonic sound wave caused by fuel mixture self igniting (Usually at the edge of a piston or a sharp edge like a valve relief cut out on piston top). These edges can glow red hot and promote detonation. Our combustion chamber design is not efficient (compare to a narrow angle 4 valve, aluminum, modern motorcycle engine) or flat. Poor quenching of the fuel mixture. You really want to squeeze the fuel mixture towards the center where the plug is (ours is off center).

Agreed.

The best remedie is keep the combustion chamber thermally stable (all aluminum engines like @200F) and give it as cool a charge as possible. An A/F ratio Under 12.6-1 NA is good insurance, I have commented plenty on using an AEM wideband to keep an eye on this. Torries SAFE tunes are smart!!

Agreed but having the oil temp at 210 is better to burn out any moisture in the oil.

I would not say the design is "poor". But it looks like you can run into a limitation. Especially if you have a Viper car. Thier pan is shallower than ours.
The bearings themselves don't "spin" in the rod big end. However, if they loose the hydro dynamic barrier (from a passing air bubble), now they will get scored against the crank journal and melt away.

Anytime an oil pump can fail within the redline of an engine's operating range is considered a poor design in my book. Sure it's stable at lower RPM's and cornering but why not have a properly designed oiling system that doesn't break down under heavy demand within the engines operating range. Here is what the SRT team did to address the oiling problems from the gen3 and put on the gen4's:
- 180 degree Main Bearings Vs 120
- Larger Oil Pump Volume 120% volume of gen 3 pump
- Revised Oil Gallery Design [larger, bleeds off cavitation-causing air]
- Increased Oil Pickup Tube Diameter (increases pressure in tube during high demand)
- Smoothed radius bends throughout system
- Articulating Oil Pickup (dual directional) swinging oil pickup with correct sweeps
-revised pan baffling (pickup oriented, baffles enclosed by pickup body to prevent slosh-out)
-Narrower Oil Pump Rotor, lower lobe count speeds filling rate, prevents cavitation
-Shuttle Valve Cartridge Relief Valve [no pressure surging]
-Metric Threaded Oil Filter

I do have a hard time with the crank shaft literally "flexing" in the block to an extent it overcomes the oil's "hydro dynamic barrier" under the flow and pressure from the pump. The blocks are so very ridged in design and have alot of "webbing" cast into them. The cranks themselves are Forged. I would love to see a block diagram of the engines oiling system to see some possible compromise in the oil feeds to the crank and rod journals.

All the big builds that I asked about had their blocks "stress relieved" to avoid flex under heavy acceleration/load. Ask your engine builder if they offer this service and why.

If I had to take a stab at what happened to SrtDub's engine..... He had dreaded Detonation and or Cavitation. Most likely an lean tune combined with limitations mentioned by SrtBrad in the intake (Starved #3 cylinder) caused a lean condition. SrtDub did state that the pistons on cylinders 3+4 were tight on the rods. This would indicate damage from detonation which can collapse the ring lands and stick a piston in the hole. Now the rod's ability to move has been compromised. Maybe to the extent of bending a wrist pin....Boom!! It will happen in an instant with no real warning.

Any chance of a low oil level in the engine?!? Are you running a "Catch Can" to keep hot oil fumes out of the intake!?

Picturs of pistons SrtDub!?!? You did state no FI on the engine correct!?!

Thanks

Cheers!

It is very likely and possible that your guess is correct. It could also be from many other factors but most likely your guess is more likely to have occurred. Only way to tell is a tear down and inspection.

A point to consider:
If you drive your gen3 truck hard or do track days and/or dragstrip applications on a regular basis your engine WILL fail eventually due to the oiling limitations over a period of time. It is recommended to refresh your rings rods mains every 100 track hours or every 20,000 miles to have piece of mind. I'm not sure if the Gen4 oiling upgrade is available for our trucks in part or in whole but it's worth checking into.

Corona Cheers back.