Was I correct when I read somewhere that part of the mechanical workingness of the VTC assemblies is oil pressure? and the gallies that chug oil up to the top may be clogged or narrowed due to buildup?

Will a flush that helps break down and clean up (though I doubt completely) the gallies within the engine, possibly improve flow to the topmost part of the engine and help decrease the clacking?

Does it have anything else to do with oil pressure? or just the flow?
Im considering a flush and a full synth. I havnt gotten an oil change since I bought the car about 9 mo ago. It supposedly had a fresh full synth within a month before I bought it from the guy. He also claimed that he had put full synth in it ever since it became popular. No idea when that was, but he was the original owner.

What to do?

 

You really need to use the search function...

http://forums.maxima.org/oldthread.php?t=513703

http://forums.maxima.org/oldthread.php?t=382771

http://forums.maxima.org/oldthread.php?t=516665

 

Flow is the result of a pressure gradient, you cant think of them independently.

Are your VTCs noisy or are you just being cautious and trying to prevent a future issue?

 

Is the car clacking? Try the tests in The General Maintainance Sticky above about VTC's. How many miles on the car? If the VTC's clack, it's more about the spring wearing out inside the VTC than oil pressure (after reading many posts here). Or the Timing Chain tensioner.

 

One of the large issues with the VTCs is the lack of properly-sized oil passages (galleys) going to the VTCs. with a decrease in diameter from deposits and gunk, you decrease flow, regardless of pressure. over time, this causes the VTCs to starve for oil and overheat, causing the spring to weaken and eventually complete failure of the VTC assembly.

enlarging the gallies really isn't an option since they're cast into the heads, but cleaning them out during a head rebuild and keeping fresh non-gunking oil in the engine will keep the problem from happening again.

 

The VE just needs cholesterol checkups.

When I said "pressure gradient" instead of just "pressure", the effect that clogging has on it was implied, but I can see how that wasnt very clear.

 

i think i said this before but

using a detergent such as AUTOMATIC TRANNY FLUID (only a little bit though) in the oil to weaken the build up and open the gallies?


and not only one treatment wither... many uses is what im thinking... and money

just a thought

 

Ok so I need stronger springs, or longer springs? I can have springs made to any specification by a supplier of mine. What works best?

I probably wont enlarge the gallies because I plan on swapping the engine later on. But cleaning them out sounds like a plan to me, especially if I do a spring reload for the VTCs at the same time.

And yes to the original question, they WERE clacking very loud and especially at idle when I would stop. Now it doesnt do it so much. Its quieter, and much less often. *shrug* I'm all for taking the engine apart. Fun stuff. And thats not being sarcastic. I love my car.

 

You're a sadist, aren't you? :

 

Replace both upper chain tensioners while your in there. If you pull the engine, replace the lower one as well. The chain guides don't need replacing.

 

There is a rebuild kit for the VTC's. Look in the stickys for this part number. It has the new spring, and a new top for the VTC's with the seals. I believe the part number is 13072-97E00.

 

:attention

no one is going to answer my Q? or have anything to say about it... because i want to know if this would be true

 

if you want that answer, soich.

 

I wouldnt answer that question anyways. I wouldn't think of mixing different chemical chains together. And I never believe advertisements.

Ive seen the rebuild kit for the VTCs, but what I never saw an answer to was, does it come with a replacement spring? or a better one?
I forget who it was that was talking about the assemblies needing a taller or stronger spring, do the Kits come with that better spring?
Is it safe to put a taller or stronger spring in there?

Im at 180k with this engine. Tensioners hmmm... kits for those? or just oe parts? Anyone have a link to a pic so I can recognize it?

 

I think you were looking for this thread:
http://forums.maxima.org/showthread.php?t=513703

I've repaired both, the new one is always stiffer than the old one. Among the old, the one that made less noise was stiffer than the other. The old one gets shorter due to the same wear that decreases its spring rate, I dont think we have a way to know their original height.

If you put it a new spring that is too long or too stiff you may prevent the VTC system from operating because the oil pressure will not be enough to compress it (IIRC its function).

If rebuilds are failing, we may just need to accept this as a regularly worn engine part that needs to be replaced when it no longer functions currectly. Just like injectors, coils, alt, starter, etc...

 

Aaaarghhh!! Do any of you guys read posts?????????


http://forums.maxima.org/showpost.ph...52&postcount=2

Timberjon: Learn how to use the search function,start reading the posts in your threads..The vtc issue has been discussed to death in here,all the info you will ever need on them is in search..