Oil Cooler line vibration

[Killerbees]

04 Diesel Duramax motor

-12 smooth teflon lines, approx 4 feet length. Measure flow is 4 gpm (idle) to 16 gpm (max rpm). Cooler has only 4 psi drop at 10 gpm.

The hot line has very noticeable vibration, especially idle, feels like an adult toy on low

. The cold line from the cooler, is highly dampened, very little vibs in comparison. There is a noise associated with it, but the noise tends to go away when warm. The internal bypass has been modified, even removed (for complete bypass) and the vibration remains.

Using an oil filter adapter for the cooler flow (derale type).

Is this common? it feels like transmitted noise/diesel clatter. I'm concerned about line longevity. Vehicle in question now over 10K on the cooler. The filter has been changed, no effect.

 

[punisher]

Going to make 2 assumptions:

1) You are running a teflon lined braided steel line ie Aeroquip or Earls.

2) The vibration is a "pulse" in the line itself and not induced by engine vibration.

There is always some vibration/pulse inherent with a gear/gearotor type pump. On gear pumps the pump is constantly loading/unloading as each toothrotated past the output port. I have felt it to some extent on SBC/BBC engines that have a remote filter/bypass delete done on them. Personally I think it is normal pump pulsation, but you will likely get other opinions on this in here (which is a good thing).

 

[Killerbees]

correct assumptions punisher. And if it is a pump side affect, guess there is little I can do.

Is the hose type significant?

 

[oilyriser]

If mufflers can be made for gas flows, it should be possible to make one for oil, though it's much less compressible than exhaust gas. It's probably very tricky to design one for hot motor oil that must never leak.

interesting stuff if you search for:

hydraulic pulse damper

 

[jsharp]

quote:

---

Originally posted by Killerbees:
correct assumptions punisher. And if it is a pump side affect, guess there is little I can do.

Is the hose type significant?

---

The teflon hoses are typically used in applications where you want a "stiff" line such as a brake system. Most of the time synthetic rubber lines with braid reinforcement and an overbraid like Aeroquip AQP are used for oiling, fuel, coolant, etc. I'd guess the rubber lines would help dampen the vibration better than the teflon lines.

 

[TheLoneRanger]

quote:

---

-12 smooth teflon lines, approx 4 feet length.

---

That is a relatively long run for a soft line. Why not use a steel line with flare fittings? And isolate the oil cooler in rubber mounts, to cure the vibration.....Just an idea....

 

[Gary Allan]

I don't know how applicable it would be in this setup, but we used to use convoluted spacers that would soak up shockwaves in our flows. They were effectively accordians and withstood relatively high pressures/vacuums for 1000s of hours of operation in a high mechanical harmonic environment.

Again, I don't know how they would integrate to your system.

 

[Killerbees]

The cooler is on rubber mounts.

To flow 16+ gpm that would be a huge steel line, and I don't know what it would be accomplishing, if anything.

Jsharp, you are probably correct, AQP would be a better dampener.

I'm starting to wonder if I need to worry about it.

 

[jsharp]

Every time I've seen something like this the fix was NOT to convert to a more rigid line, but to use some kind of flexible dampener. A more flexible hose, a bellows isolator or some other kind of flexible coupler like Gary mentioned etc. If the vibration or pulsations are severe enough you'll end up cracking a rigid line.

But if it's just pulsations from the fluid moving through the hose it might not be enough to worry about...

 

[Kestas]

I'd be very worried about the movement from vibration. This is exactly how metal can break from fatigue. Find some way to restrict this vibration.