VQ37vhr timing chain

jmroy6

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.



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


Bank 1 and 2 secondary chains time out (compression stroke)



Bank 1 uses punched marks on outside facing sprockets,



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.

__________________
2012 370z GTM SC

Jhill

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.

jmroy6

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.

Ill report back with my findings.

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2012 370z GTM SC

jmroy6

update;

Got the motor completely timed.


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



Bank 1 intake timing mark (secondary chain)



Bank 2 Exhaust timing marks (Secondary chain -oval)



Bank 2 intake sprocket timing mark for secondary chain



bank 1 primary timing chain mark



bank 2 primary timing chain mark


timing chain mark located on crank


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!

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2012 370z GTM SC

Benibiker

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

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2017 Pure Red 6MT 370Z Touring

jmroy6

60k as of now

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2012 370z GTM SC

Quicksilvers

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?

jmroy6

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.

__________________
2012 370z GTM SC

jmroy6

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

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2012 370z GTM SC

Quicksilvers

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?

husam2012

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!

__________________
Creator of the GTR TT Conversion Kit, NA Record Holder (401WHP)
Ecutek Master Tuner (VQ37, VR30, VR38, B58, S55, S58)
BTWTuning

jmroy6

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.

__________________
2012 370z GTM SC

jmroy6

Was the timing off on your motor then?

__________________
2012 370z GTM SC

husam2012

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

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.

__________________
Creator of the GTR TT Conversion Kit, NA Record Holder (401WHP)
Ecutek Master Tuner (VQ37, VR30, VR38, B58, S55, S58)
BTWTuning

b15

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