VQ37vhr timing chain
 

So when i did the oil galley gaskets, it seems the timing was off on the primary chain (did not remove secondary chains) during assembly. A few symptoms:Car would not start, studdered and immediately died. I did a compression test and only got 100psi per cylinder, this indicated both banks were out of sequence due to improper intake/exhaust timing on compression stroke.

So i disassembled the car again, to check timing. this is what i got.

http://www.the370z.com/members/jmroy...1-img-4437.jpg

Car is set to TDC Compression stroke (cams face up on both banks)

http://www.the370z.com/members/jmroy...8-img-4440.jpg
Bank 1 and 2 secondary chains time out (compression stroke)


http://www.the370z.com/members/jmroy...0-img-4438.jpg
Bank 1 uses punched marks on outside facing sprockets,


http://www.the370z.com/members/jmroy...9-img-4439.jpg
Bank 2 uses the oval marks on outside facing sprockets,

It may be hard to tell from the picture but either bank 1 or bank 2 is off a tooth, in person you can tell the cams are not facing up and out at the same degree for each bank. indication a bank is off a tooth.

This leads me to my question, if both cams are timed out on compression stroke, and cylinder one is at TDC. i should be fine to remove the primary chain (which is not timed/ or aligned with the colored links on both banks & crank). i can realign them to the designated marks on both banks and crank to ensure proper timing since the secondary chains are timed out already? Does that make sense? I don't really want to have to take this apart for the third time, i hoping i can learn from my mistakes and others can too.

this is straight out of the FSM:

Install timing chains (secondary) and camshaft sprockets.
NOTE:
Figure shows bank 1 (rear view).
A : Camshaft sprocket (INT) back face
B : Orange link
C : Dowel groove
D : Matching mark (oval)
E : Matching mark (2 oval: on front face)
F : Matching mark (circle)
G : Camshaft sprocket (EXH) back face
H : Matching mark (2 circle: on front face)
I : Timing chain (secondary)
• Align the matching marks on timing chain (secondary) (orange link) with the ones on intake and exhaust camshaft sprockets (punched), and install them.
NOTE:
• Matching marks for camshaft sprockets (INT) are on the back side of camshaft sprockets (secondary).
• There are two types of matching marks, the circle and oval types. They should be used for the bank 1 and bank 2, respectively.
Bank 1 : Use circle type
Bank 2 : Use oval type
• Shape (orientation of signal plate) of camshaft sprocket (INT) varies depending on the bank position. See the right figure to install.

I believe I understand your question and your answer would be yes you can remove the primary and re time it if a bank is off. If you didn't remove the secondary chains then the intake to exhaust cam timing for each bank should be correct. Not reading the FSM and I don't see it in the pics but there should be some kind of indicator to verify the intake and exhaust cams are in alignment but if you never removed those chains then they would have to be correct. Once those are set you couldn't just have one cam be off you would have to have both intake and exhaust be out of time. So with that said yes you could get the engine back to tdc, remove the primary chain and then re time the engine. If the intake and exhaust cams are in alignment and the primary chain aligns the intaks to the crank then that means your exhaust will be in alignment as well. Hopefully that makes sense, I've not done this particular engine but it's no different in design that others excepte for if the vvel gets screwed.

Thanks. That makes perfect sense, since the secondary chains are correctly timed, i can just align the primary chain up with the appropriate timing marks on both intake sprockets and crank. Upon install, i should be able to see what bank or banks jumped in timing by lining up the colored links to the timing marks.

Getting a second opinion never hurts. :tup:

Ill report back with my findings.

update;

Got the motor completely timed.
http://www.the370z.com/members/jmroy...6-img-4458.jpg

Bank 1 intake & exhaust timing (secondary chain - punch hole)

http://www.the370z.com/members/jmroy...0-img-4438.jpg

Bank 1 intake timing mark (secondary chain)

http://www.the370z.com/members/jmroy...8-img-4448.jpg

Bank 2 Exhaust timing marks (Secondary chain -oval)

http://www.the370z.com/members/jmroy...9-img-4439.jpg

Bank 2 intake sprocket timing mark for secondary chain

http://www.the370z.com/members/jmroy...7-img-4456.jpg

bank 1 primary timing chain mark

http://www.the370z.com/members/jmroy...1-img-4443.jpg

bank 2 primary timing chain mark
http://www.the370z.com/members/jmroy...0-img-4445.jpg

timing chain mark located on crank
http://www.the370z.com/members/jmroy...9-img-4446.jpg

For disassembly on any vq, i will always time out the secondary chains, and not worry about the colored primary chain links lining up for disassembly. upon reassembly you then can line up the colored links with each appropriate timing mark.

hope this helps!

The engine looks very clean inside, how many miles are on it?

60k as of now

Yes thank you nice write up this will help. Your engine does look very clean for just 60K miles. Did your oil galley gaskets begin leaking at 60K miles? Was anything else found leaking? How did your timing chain look?

i started noticing lower oil pressure readings in the fall (58K), so replaced the gaskets and fasteners over winter. a few fasteners backed out on the upper galley causing oil to leak out of the galley. Today the chains looked good, no kinks or abnormal color due to heat, should have plenty of life left before they need to be replaced.

Should be ready to fire up tomorrow, just need to install the blower and a few accessories.

I'm just hoping i don't have bent valves, a leak down/compression test will tell me tomorrow. :ugh:

Yes a compression check will tell you everything. I hope you didn’t bend any valves either or look forward to a rebuild. How much whp and wtq are you currently making?

It's such a coincidence that I went through this just this last week. I had bought a used engine and upon trying to start it, it sounded like it jumped timing and it didn't sound good at all.

I took the cover off, retimed it(Identical procedure to the VR38DETT) so it was a breeze and finally got it running this weekend.

For anybody wondering on how they could go on doing the timing chain or anything timing chain related, you should look for the complete guide on the GTR forum.

It looks very intimidating at first but once you get the hang of it it becomes very simple and straight forward.

Good luck OP!

Currently at 400whp and 340trq, i upgraded to the gtm 1.5 kit over winter so i should be closer to 500whp if everything turns out well motor wise.

Was the timing off on your motor then?

I honestly don't know, but it didn't hurt to retime it in case it was.

I was in such a hurry that i didn't even check if it was off and just retimed it.

In the end, it wasn't the timing that caused my low compression on 2-3 cylinders but the fact that the motor sat for a while. I did the leak down and compression right after putting the cover back on and they were still at 100 PSI/ 80% leak down.

I got a tip from a friend here to start the motor for a few minutes and recheck the leakdown/compression. He said that some engines that have sat get stuck piston rings.

Fortunately after a few minutes of idling the engine it started to idle cleaner and after redoing both tests all cylinders passed with flying colors :happydance::happydance:

Keep in mind that compression test gauges vary from brand to brand as I've tried 3 gauges each ranging from 180-240 compression on the same cylinder. What you need to worry about is just the percentage difference between cylinders.

Do you think this happened over time or it was this way from the factory?

Happened overtime

That's why you do a dry and wet compression test. If an engine has sat or fuel has washed the rings out etc as squirt of oil through the spark plug holes and a retest will give a more realistic result.

Personally although it takes longer a leak down test will give a more accurate representation of an engines condition and how it will run. I've personally seen at least 3 engines that will pass a compression test yet have a misfire at idle due to valve leakage. Off idle the pistons move fast enough to not have a mis and will still build enough to pass a compression test but at idle it will still have a mis.

Concern here would be how did it jump time?

My luck is never ending with this car

So did a cold compression test and here are the results

Cold motor
Cylinder 1 - 165psi
Cylinder 2 - 160psi
Cylinder 3- 168 psi
Cylinder 4 - 165psi
Cylinder 5 - 162psi
Cylinder 6 - 170psi

So i ran the car and pulled it out of the garage Because i wanted to do a warm comp test to compare. The cold readings seemed low/ and wanted to try a different gauge. So anyway as the rpms dropped to about 800. The car just shut off and now i cant even get ignition to turn on. The dash shows both fob key lights, first thought steering wheel lock. Nope, been there done that the fuse is already pulled. Now i dont know what to do. Thoughts?

Both key fob lights? Meaning no fob detected?

Thats correct

http://www.the370z.com/members/jmroy...1-img-4470.jpg

I’ve never been a Nissan tech but have done other brands and all are fairly similar. That to me looks like you have an anti theft issue going on. Any chance you have a second fob to try? If you have a scan tool with the anti theft module accessible (I think Nissan calls it NATS) and if anything in data says anything about anti theft or key invalid etc then somehow your anti theft went screwy. Can try a key re learn, also some years had some issue with the column lock but I’m uncertain the symptom of that wether it be a no start security light, a start but locked column, or a no start no security light (corvettes had a similar issue with a no start due to electric column lock in some years).

Also to give you some relief, I had similar results using a harbor freight compression test kit so don't worry a lot about the numbers but just how close they are to each other.

Good luck!