Correlation = Causation?

Just installed a lo-pro front bumper and did the "viper cut" at the same time. Engine "whir" is noticeably louder when driving now. Is this a result of exposing more of the engine after cutting/reshaping the wheel wells? I don't think there's any issue, just wondering if correlation does in fact equal causation here.

 

Doubt it's the viper cut, more likely the bumper is more metal than was there before and the noise is resonating off that.

It doesn't help that the engine sounds like someone shaking a paint can full of bolts under normal circumstances.

 

Lol that is true. If Toyotas weren't so reliable, there would be thousands of extra threads asking about why the engine is making a certain sound. At least people just assume it's fine because of the name.

Didn't consider the metal resonating the sound. Thanks for your input!

 

There have been a couple of threads about it. They use solid lifters instead of hydraulic lifters in the 1GR, which causes lot of the noise.

 

I would imagine the Viper cut would make the 4runner less Aerodynamic? So maybe you would get some increased noise coming from that part of the vehicle.

 

What is the purpose of a “Viper cut”?

 

Another good possibility.

Slightly increased approach angle at the corners, plus 10 cool points and plus 100 horsepower. I just liked the look paired with the lo pro bumper.

Mine isn't as extreme as I've seen on others here:

 

I always that it was to give clearance for tires bigger than 285’s.

 

It may help but I had 285’s without the Viper cut. Maybe it adds cool factor.

Makes sense that it helps approach angle. That would be on hell of an obstacle. I would certainly drive around it.

 

Shh, my 265s will hear you.

I agree. It wasn’t my primary reason for doing it. I would do the same. I guess my primary reason was just aesthetics.

 

I thought they use a shim bucket style.
As long as I dont have to adjust them, I am fine regardless.

 

I knew I read it somewhere, and figured it was a logical explanation. But, this is what I'm finding:

"
For valve actuation, the VVTi 1GR-FE engine used shimless type valve lifters. The early version of the Toyota 1GR-FE engine is not provided with hydraulic lifters, so you must control the valve clearances once in 60,000 miles (100,000 km) of mileage.

The dual VVTi 1GR-FE engine used roller rocker arms with built-in needle bearings that reduced the friction that occurred between the camshafts and the roller rocker arms. This version of the engine has hydraulic lash adjusters. Through the use of oil pressure and spring force, the lash adjuster maintained a constant zero valve clearance."

It doesn't really specify when they stopped using solid lifters. So, I guess I might be wrong.

 

My 97 Tacoma with the 3.4 V6 was supposed to have the valve lash adjusted every 60k? miles using shims. After 21 years and 260,000 miles, I never had them adjusted. Dealership actually told me not to bother.

I’m not sure I understand where the lifters are located on an overhead cam engine.

 

That's a good point! Don't we just have rockers driven by the cams? Now I'm even more confused.

 

Yeah, I see that we have roller rockers. But, it states that earlier versions of the 1GR had solid lifters. But, where do we have lifters? Do they sit on top of the valves themselves?

 

What was redesigned about it? Anything I can find about it suggests that it has been exactly the same since 2010 in the 4Runner. The Tacoma had the single VVTI version from 2005 to 2015, while the 4Runner got the dual VVTI version starting in 2010 and ending never, apparently.

The fourth generation 4Runner used the single VVTI version.

 

This is still confusing though. If it's really a dual overhead cam engine, it shouldn't need rockers. But, if it is one cam on each head, that would make more sense. I guess I would need to look at disassembled pictures of the one GR in order to really understand.

 

I’m not buying that there are lifters between the valves and rocker arms. We need a picture.

 

Thank you, I will check it out.

 

The video really helped! I was completely clueless, thanks.

 

Great write up.. Makes sense..I think allot of Japanese engines had shimmed/shimless buckets for the valve lifters.
I dont think you are wrong.
My 2001 CR-V needed overhead camshafts to be checked due to clearance needed.
Its not the same as the overhead valve V8 motors like Chevy-Ford did back in the 60's..Those were horrible and needed to be adjusted allot.