Detailed Vct Pictures?

[M E S O G L E A]

Does anyone have detailed drawings, pictures, or illustrated parts break down of the VCT system?

All I can find is this and its not very clear.

[The Dan]

Is there something in particular you need to know or are you just wanting to see how it works?

[M E S O G L E A]

Another of my posts refers to noise the front upper portion of the engine is producing.

I thought it was the lifters but after seeing how the cam will move while the gear and VCT housing does not, indicates that something is not correct. I checked for similar cam movement on a spare engine and its quite solid and will not move in relation to the VCT housing.

I'm curious to its internal workings to help me discern what went wrong with it. I plan on tearing off the front of the engine to swap the VCT system starting tomorrow.

[The Dan]

When you are referring to the VCT housing moving seperate to the camshaft, if you are saying that the VCT cam pulley moves while the cam remains still...that is not supposed to happen. Check to make sure you don't have a snapped cam first by removing the cam covers and then check the locking bolts in the back of the VCT cam pulley. There is adjustment there and if the locking bolts have loosened, it will be able to move 10 degrees or so but that's about it.

[M E S O G L E A]

I removed the timing cover to check condition and tension of the belt, which is Nismo and has about 12000Km on it. I also pulled the cam covers to verify the torque on the bearing caps and to look for obvious wear indicators. Everything looks normal.

The cam will move and the gear/VCT does not because it is being held in place by the belt. I tried to reproduce the "failure" on the spare engine (VCT is still attached and cam in the engine) by holding the gear/VCT with a strap wrench and trying to move the cam. It appears to be locked and solid.

I don't know exactly how the VCT mechanism works so I can't fathom what is malfunctioning. Based on the picture, the return spring, helical gear or piston may be broken.

After the swap, I will disassemble and post pictures of the suspected bad VCT.

[Guilt-Toy]

answer old mates question.

[Oblivion]

if the cams moves then there is something wrong with the cam....the VCT doesnt hold the cam in....it only keeps it only tells the computer the degree of the cam, and changes it a small amount through the rpm range.

as Elite man said remove the cam cover and check the cam.

[M E S O G L E A]

With the timing and cam/valve/rocker covers off, I can physically rotate the camshaft (advance/retard a few degrees) while both cam gears, belt, exhaust cam and crank do not rotate.

The engine starts, runs and boosts just fine. I have oil pressure and knock readings are within normal operating parameters.

Based on grinding noise when cold, tapping noise upon VCT actuation when hot and a spare engine not exhibiting the advance/retard movements, unless the intake cam knock pin/keyway broke, I suspect the VCT device is defective.

[Adriano]

Sounds like the cam gear is stuffed, or as 3litre 32 said, the adjusting bolts at the back of the camwheel may be loose.

[M E S O G L E A]

Pulled off the suspected bad VCT unit, the cam is not damaged.

No visual external damage to the VCT and the 4 bolts holding the gear were tight.

The VCT appears to be a sealed unit, but I didn't have much time to look at it because the shop closed.

[Oblivion]

i'd suggest taking it to a mech, before something serious happens.

[M E S O G L E A]

I will finish installing the known good VCT this afternoon.

As for the mechanics, 3 certified ones work at the auto hobby shop where I built the engine and do all the work. They agree with my diagnosis.

I'll try to gain access to the VCT internals. I may call in a favor and have the unit X-rayed.

[M E S O G L E A]

Original VCT was malfunctioning. Known good VCT installed, bad noises stopped and engine runs smoother.

I will cut apart or x-ray the old one and post the pictures in the near future.