Sounds good to me. Without the VVT, things become simpler. Because the exhaust camshaft is driven by the intake camshaft, as long as the intake camshaft is locked in the proper position, then that's all that's needed to put the exhaust camshaft sprocket in the proper position. This assumes that the intake camshaft sprocket has not been loosened at any time in the process.
Is the NA engine my engine? If so, I would argue the intake camshaft does not necessarily need to be in the retarded position, although it would be more convenient. This is because the intake sprocket assembly still drives the exhaust sprocket, but the intake camshaft itself sort of floats separately from the sprockets because of the VVT. The intake camshaft can be in the technically correct retarded position for lockdown when the crank is in the wrong position because of that VVT disconnect, and thus timing the exhaust camshaft/sprocket will give a bad result (my problem). So we agree that the crank should be locked.

If the crank is locked in the right place, it forces the intake sprocket to be positioned correctly (assuming tension on the drive side of the chain), and it doesn't matter where the intake camshaft floats inside the VVT mechanism. (No argument that it would be easier to use the camshaft lockdown tool if the the intake camshaft is retarded so the flat is oriented correctly, but if the camshaft doesn't happen to magically fall in that position and it's not convenient to wind it, there's a workaround with shims.) Since the secondary chain sprocket on the intake cam is fixed to the primary chain sprocket, and the primary sprocket is in the right position because the crank is in the right position, it follows that this will force the exhaust sprocket into the right position when the chain is tensioned. As I've posted before, when the crank is locked in the right position and the exhaust camshaft is locked in the right position, then when you use the exhaust sprocket to tension the secondary chain, the primary chain will also be tensioned, and you have the direct connection from the exhaust sprocket all the way back to the crank through the intake sprocket assembly, and the exhaust sprocket can be tightened in that position. My head is starting to hurt, but it's a whole lot simpler in practice than to explain in writing.

 

Hi,guys.Through you guys threads I get two things here:1.Must lock crank and cams.2.It's not oil thin or thick.I want make sure two things before I redo this job:1 After rotate the crank on it's timing position,lock it,and check the intake camshaft flat should face up,if not,may I turn intake cam to right position?or just bypass it do exhaust side, like ttl did. 2 how does jag vvt work? did someone have pics for inside vvt? Sparkenzap did it without remove the timing chain cover, please try remember it and tell me. Appreciate any helps!

 

ttl:
NA means normally aspireated.
If I understand you correctly, I disagree with your statement: (sorry, I have not figured how to use the quote feature)
"If so, I would argue the intake camshaft does not necessarily need to be in the retarded position, although it would be more convenient."
That is because, as you say: " but the intake camshaft itself sort of floats separately from the sprockets because of the VVT"
To get the intake cam in the right position relative to the crank and/or the output cam, the VVT must be in a known, and correct position. In other words, the VVT allows the intake cam, which is locked, to have an offset between it and the other shafts which are also locked. But, it's the relative positions is still indeterminate due to the possible offset of the VVT position.

tomjagxj:
First, let me say again, that my experience with a VVT is limited to an AJ27 engine, which is different from an AJ26, which is what you have, as I remember. But, if you pull the tension to the correct side of the secondary chain, using the exhaust sprocket, as you lock both sprockets, I BELIEVE you will be "unwinding" the VVT. That may very well be the point testpoint and others are trying to make. And what operation are you thinking needs removal of the cover? I believe if you pull with the spanner tool, as shown in the *** pictorial procedure, you can do so without cover removal.

 

This may not be worth discussing any further, but let me go one more iteration because it's fun.

Just to be clear, everything I've said is predicated on the assumption that only the exhaust cam sprocket has been/will be loosened. If the intake sprocket assembly/VVT has been physically disconnected from the intake camshaft, then it will certainly need to be timed properly, which will probably entail winding.

Let's try a mind experiment. Lock down the intake cam in the proper position, flat up. The intake sprocket assembly will now "free wheel" within about a 40 degree limit due to the VVT. We still need to time the exhaust cam properly. Lock it down in the right position, flat up. With the crank locked in the right position, primary chain tensioned, the primary intake sprocket (driven) will be in the right position, and the secondary intake sprocket (drive) will be in the right position (same assembly, no give between them). When the secondary chain is tensioned, the exhaust sprocket will be in the right position. All's good according to your view (if I've interpreted it correctly.)

Taking the experiment one step further, let's remove the intake camshaft and VVT from the system, leaving just the sprocket assembly spinning on its own bearing. Because the crank is locked in the right position, the "intake" sprocket assembly will still convey the proper timing to the exhaust sprocket. This merely illustrates that the position of the intake camshaft is irrelevant to the timing of the exhaust camshaft. Tightening a bolt on the exhaust camshaft has no effect on the intake timing, absolutely or relatively, as long as the chains have been tensioned properly.

I'm in no way trying to suggest that IF the timing of the intake camshaft has been disturbed (ie, something between the sprockets and the shaft has been unbolted), that the absolute or relative position of the shaft is irrelevant. In this case, the position would inarguably be critical for proper retiming of the intake. That shouldn't be an issue for replacing the secondary tensioners, though... only the exhaust cam timing gets disturbed.

 

Man, if you just take the cam saddles off and lift the exhaust cam enough to remove the old tensioners and insert the new ones you don't have to worry about messing with the VVT or the cam timing. As long as you ensure the cam chain stays put and don't loosen the cam sprocket you're good to go. Of course you have to use the right tensioners and bolts, be very careful loosening and tightening the cam saddles evenly, and it's not a bad job at all. If you are doing the promary cam chain tensioners - that's another story, but the secondaries are really not even a big issue to replace.

 

The crank rotates twice for each camshaft rotation, so you need to check the cam flats are up before locking the cam.

In a perfect world, when you get to that position, the intake and exhaust flats will now be aligned and it will be easy to put the locking tool in place. Because I first did the timing without locking the crank, I did not not find this to be the case. The exhaust flat was out of position (advanced) even when the chains were tensioned, so I had to do some shimming so I could loosen the sprocket bolt again and realign the camshaft flat. If yours lines up, then this isn't the problem. If it doesn't line up, then you have the same problem I did.

I wasn't successful turning the intake camshaft itself to get it aligned, and I didn't want to mess with removing parts to be able to "wind" the VVT, so that's why I bypassed it.

 

If you read the first post, you'll see he already retimed the exhaust camshaft with the crankshaft not locked. If he took your advice before doing that, there would be no problem, but now he needs to ensure the timing is right.

 

I think that what test point has been saying in this thread and in my thread is that if you lock the crankshaft, then the intake and exhaust camshaft flats will be aligned and you can lock them down without any trouble. That's probably the case in most projects, but unfortunately Tom and I didn't lock the crank when we first did the procedure. I know that screwed things up for me, and might have screwed things up for Tom.

 

ttl, I know it's a little late to point out the simple way to replace the secondary cam tensioners for you guys, but I thought someone else may benefit and reading you guy's posts just scares the cr@p out of some of us DIYers. Best of luck !

 

Fair enough. Fact of the matter is that it scared the cr@p out of me when I realized what I had done to myself! Moral of the story, use your method, or make sure you lock the crankshaft before using the other method. Then it should go smooth and worry free either way.

So for all the someone else's out there, I concur with Jimmy that these posts should NOT stop you from changing out your tensioners! Go for it!

 

Agreed on the basics.

 

Well, to circle back around, the lift the saddle method is not perfect either, at least according to JagScott, who broke his cam because he apparently had it lined up on a cam lobe as he tightened it. For me, the Jag written procedure seems straightforward, and having the tools gives me confidence I can deal with other problems that come up, like head gaskets and such.

 

I learned a lot from you guys,thanks! I still got something can't understand. Didn't lock crank can make timing mess, but between two sprockets(intake and exhaust cams),the chain "tight side" is always tight when engine running,if tensioner working, there should no noise come from chain.My car's noise is from chain hit that tensioner,the car runs smoothly and seems not timing issue.Any suggestion?

 

If mistiming can cause that chain noise, can anyone explain to me? Thanks a lot!

 

A valid question! I original answer was addressing the engine overheat, which can happen from timing error. Then the thread went a different direction.
So, back to your problem. What kind of noise is your engine making? I assume you removed the VVT bush (the thing that feeds oil into the front of it through the solenoid). Are you sure it went back together right? You said you used short bolts. Did they tighten down without bottoming out? In other words, was the tensioner tight? Any other symptoms?
I, for one, am sorry about forgetting your original question.

 

Sorry, nothing to offer on that here. Are you confident saying the noise isn't from a different source than the chain?

Am with Ross though on the possibility that overheating is a timing issue.

 

That's OK Sparkenzap.The noise sound like the chain contact the tensioner.when started it ,got 50 second sound,then gone,but after the car getting hot(about 10 minutes),noise come back,in that 10 minutes,even I accelerated 5000 rpm,no sound,everything is ok.After noise back,rpm up noise down,idle is the worst,but you can't hear inside car with fan on or turn signal.The tensioner was tight(14N.M OR 10 FT.LB). About the VVT bush,I didn't notice it move or not,I just focus on tight the exhaust cam bolt and don't let sprocket move.I really don't know how jag VVT working,so I asked the question"how does jag vvt work? did someone have pics for inside vvt? ".I read some inf about vvt,in my mind,it seems has two parts,outside and inside,outside part has sprocket turn with chain,inside part has something can turn 60 degree with intake cam depend rpm,and then intake cam turn with sprocket.Am I right? If I'm right,even their position mess up,it just effect timing,not the chain(tight side still tight).If I'm wrong,please tell me how it effect the chain(like tight side loose).Thanks again! By the way,who use 10w40 instead of 5w30?

 

Everything you said sounds right. The vvt is as you describe. The movement is controlled by oil pressure. On the AJ26 engine (early V8) the vvt moves to one of two positions (it is not proportional). think of a v shaped chamber formed beteen the two parts. More pressure opens the chamber, and a spring returns it.

 

Thank you sparkenzap!would you tell me what chamber's position when engine stop(we face the car in front of it),left or right?the spring already returns it,right?I changed oil(10w40) today,much better! but still has noise after 20 mins.Now I'm sure the VVT didn't cause the noise,something else!

 

the "rest" position is non advanced.