Sounds like maybe he let it start up without first pumping-up the hydraulic tensioners. SOP with Nissan timing chains is to pull the fuel pump fuse and crank dry for about 30 seconds to build hydraulic pressure, then reinsert the fuse and let it start. I'd say VQ's jump 1~3 teeth about half the time when you fail to do that, usually on the back or righthand bank.

Teach your mechanic another trick with keeping the chains in place before the guides are in, use a string of 3~4 zip ties around the main chain until everything is in place. That way the valve spring tension can't make the cam chains force a slippage.

VStar650CL wrote: ↑

Wed Jun 09, 2021 7:48 am

Sounds like maybe he let it start up without first pumping-up the hydraulic tensioners. SOP with Nissan timing chains is to pull the fuel pump fuse and crank dry for about 30 seconds to build hydraulic pressure, then reinsert the fuse and let it start. I'd say VQ's jump 1~3 teeth about half the time when you fail to do that, usually on the back or righthand bank.

Teach your mechanic another trick with keeping the chains in place before the guides are in, use a string of 3~4 zip ties around the main chain until everything is in place. That way the valve spring tension can't make the cam chains force a slippage.

Interesting comments.

Is it too late to save this motor?

What would have to be done?

Thanks for your input!~

.

If it just jumped on the front bank then the cover has to come back off to put the front cam chain back where it belongs. What concerns me is the zero compression on #4, it may have jumped far enough to doink a valve. If that's the case you're into a much bigger repair. So before you tear the cover back off, I'd pull the front valve cover and check free height on the valve springs. If you find one on #4 that's substantially lower than the others when free, then that valve is bent and not seating.

VStar650CL wrote: ↑

Wed Jun 09, 2021 3:37 pm

If it just jumped on the front bank then the cover has to come back off to put the front cam chain back where it belongs. What concerns me is the zero compression on #4, it may have jumped far enough to doink a valve. If that's the case you're into a much bigger repair. So before you tear the cover back off, I'd pull the front valve cover and check free height on the valve springs. If you find one on #4 that's substantially lower than the others when free, then that valve is bent and not seating.

Thanks very much Vstar !

I forgot to Mention, we have an unusual amount of Blow-by coming from the front area as well (not too much from the back). EXCESS EXHAUST was minimized through the use of Catch can system. *THE CAR smokes like crazy. See Film..

https://i.imgur.com/uNqqd34.mp4


?

Holed piston most likely. Somebody play Taps, please.

VStar650CL wrote: ↑

Fri Jun 11, 2021 6:47 am

Holed piston most likely. Somebody play Taps, please.

(sigh)

The Dayum Piston has a Hole....How did this happen?

Should i bother with the 'Check Free Height' test?

(Uggh)





.

When a valve hits a piston, one of them gives. Usually it's the valve, but not always.

VStar650CL wrote: ↑

Fri Jun 11, 2021 9:15 am

When a valve hits a piston, one of them gives. Usually it's the valve, but not always.

Vstar...i appreciate your insight.

Would it be worth it to check the 'Free Height on the Valve Springs?' (as you suggested before)?





?

Not if there's a hole in the bucket or a valve cocked sideways. It sounds to me like you have slightly-bent valves on #2 and #6 and either badly-bent ones or a piston-hole on #4. The huge blowby leads me to suspect the latter. Crashing everything on one bank while the other remains healthy isn't unusual, it happens when one cam chain jumps but the other cam and the main chain keep time.

I'm not very musical, someone please play Taps.

VStar650CL wrote: ↑

Fri Jun 11, 2021 2:58 pm

Not if there's a hole in the bucket or a valve cocked sideways. It sounds to me like you have slightly-bent valves on #2 and #6 and either badly-bent ones or a piston-hole on #4. The huge blowby leads me to suspect the latter. Crashing everything on one bank while the other remains healthy isn't unusual, it happens when one cam chain jumps but the other cam and the main chain keep time.

I'm not very musical, someone please play Taps.

Ok...for future reference,...what went wrong?

How can i avoid this in the future?

?

What did your guy find under the timing cover? It's clear that the front bank cam chain either snapped or jumped a bunch of teeth. The main chain can provoke that with back-and-forth motion when the guides wear out, but the cam chain also has to be "stretched" to allow it to jump. Chain stretch isn't really stretch, it's link-by-link wear that adds up to what seems like a longer chain. So did the engine have top-end oiling problems? Vis the main chain guides and tensioner, VQ's usually give plenty of warning when the guides are worn out. They start making a "mad bumblebee" noise that gets louder and louder as the remaining plastic gets thinner. The sound actually comes from the metal chain links gradually grinding into the metal frames of the worn-out guides. Were you getting any of that? If you still have the old chains and plan to replace the motor, you might want to do a complete autopsy and post some pics.

VStar650CL wrote: ↑

Fri Jun 11, 2021 5:56 pm

What did your guy find under the timing cover? It's clear that the front bank cam chain either snapped or jumped a bunch of teeth. The main chain can provoke that with back-and-forth motion when the guides wear out, but the cam chain also has to be "stretched" to allow it to jump. Chain stretch isn't really stretch, it's link-by-link wear that adds up to what seems like a longer chain. So did the engine have top-end oiling problems? Vis the main chain guides and tensioner, VQ's usually give plenty of warning when the guides are worn out. They start making a "mad bumblebee" noise that gets louder and louder as the remaining plastic gets thinner. The sound actually comes from the metal chain links gradually grinding into the metal frames of the worn-out guides. Were you getting any of that? If you still have the old chains and plan to replace the motor, you might want to do a complete autopsy and post some pics.

-
TIMING CHAIN JOB
No...when initially done, he found 'nothing' unusual except the chain was worn (expected w/ 160k) and guides were also worn (but nothing out of the ordinary).

OIL ISSUES
No....none prior to timing chain job (other than the usual consumption through friction, typical for the 3.5vq)

RATTLE NOISE
We discovered a rattle noise after changing variable valve Solenoids (car kept stalling out; at stop lights). When the noise was pointed out, i suggested Timing Chain or Guides was causing the problem

RECENT HISTORY
About 6 mths ago, the car was overheating and it was discovered that the Gasket head was leaking. We made the mistake of trying 'Engine Block Treatment' which stopped the car from over-heating, but ruined the radiator (and who knows what else) it clogged up. After replacing the Radiator. There was never an evidence of Water/Oil mixing...so gasket leak wasn't too bad.

SHAVED HEADS
While i had the motor out, i had the heads shaved. (i wonder if the Guy who did the heads, screwed with the Valves????)

FRONT VALUE CAM CHAIN
What if i fix this...will the car run better???

Thanks for your Valuable input...appreciate it~






.

Balkins wrote: ↑

Sat Jun 12, 2021 6:00 am

RATTLE NOISE
We discovered a rattle noise after changing variable valve Solenoids (car kept stalling out; at stop lights). When the noise was pointed out, i suggested Timing Chain or Guides was causing the problem

The mad bumblebee isn't really a rattle, it's a definite buzz. Rattling makes me think there was probably an issue with oil pressure to the timing cover that was causing weak tension, allowing the chains to slap. This could have resulted from local sludge buildup or a baked o-ring inside the timing cover in the wake of your overheating episode. The passages into the cover are small, so any amount of clogging or any leaking seal will compromise pressure to both the tensioner and the phasers. Slapping chains generate tremendous back-and-forth inertia with changes in engine speed and phaser position, so at some point an acceleration or deceleration probably caught the cam and main chains with disparate inertial loads and forcibly jumped the cam chain.

VStar650CL wrote: ↑

Sat Jun 12, 2021 6:37 am

Balkins wrote: ↑

Sat Jun 12, 2021 6:00 am

RATTLE NOISE
We discovered a rattle noise after changing variable valve Solenoids (car kept stalling out; at stop lights). When the noise was pointed out, i suggested Timing Chain or Guides was causing the problem

The mad bumblebee isn't really a rattle, it's a definite buzz. Rattling makes me think there was probably an issue with oil pressure to the timing cover that was causing weak tension, allowing the chains to slap. This could have resulted from local sludge buildup or a baked o-ring inside the timing cover in the wake of your overheating episode. The passages into the cover are small, so any amount of clogging or any leaking seal will compromise pressure to both the tensioner and the phasers. Slapping chains generate tremendous back-and-forth inertia with changes in engine speed and phaser position, so at some point an acceleration or deceleration probably caught the cam and main chains with disparate inertial loads and forcibly jumped the cam chain.

I'm impressed with your knowledge...thanks very much~

Guess i'll start calling local junk yards...see what i can sell this thing for...~


.

You're most welcome. There are tons of good used VQ's out there in the $1000 range if the rest of the car is worth saving.

VStar650CL wrote: ↑

Sat Jun 12, 2021 7:47 am

You're most welcome. There are tons of good used VQ's out there in the $1000 range if the rest of the car is worth saving.

Ya Know...i'm not sure what's going on...but the USED CAR MARKET is Booming~
I'll have to research it...and see if putting a rebuilt motor is best.

Everything else on the car works great!

Balkins wrote: ↑

Sat Jun 12, 2021 8:51 am

Ya Know...i'm not sure what's going on...but the USED CAR MARKET is Booming~
I'll have to research it...and see if putting a rebuilt motor is best.

The boom won't last, it's mainly because new car inventory is shrinking rapidly because of semiconductor shortages. Can't build cars without car computers, and it's hitting everybody. We're down 100 new units from normal at our dealership and still shrinking. That makes used cars more valuable too, because everyone is hungry for trades to have something on the lot. The shortage will be around till at least the fall, but I don't think it will last far beyond that.

VStar650CL wrote: ↑

Sat Jun 12, 2021 10:01 am

Balkins wrote: ↑

Sat Jun 12, 2021 8:51 am

Ya Know...i'm not sure what's going on...but the USED CAR MARKET is Booming~
I'll have to research it...and see if putting a rebuilt motor is best.

The boom won't last, it's mainly because new car inventory is shrinking rapidly because of semiconductor shortages. Can't build cars without car computers, and it's hitting everybody. We're down 100 new units from normal at our dealership and still shrinking. That makes used cars more valuable too, because everyone is hungry for trades to have something on the lot. The shortage will be around till at least the fall, but I don't think it will last far beyond that.

What makes you think the SC market will change by the Fall (everything i've read says Next Yr 2022)???

...got some insight you can share?

.

Balkins wrote: ↑

Sun Jun 13, 2021 4:13 am

What makes you think the SC market will change by the Fall (everything i've read says Next Yr 2022)???

...got some insight you can share?

I use a ton of small-bore microcontrollers in my side business, plus all manner of other electronic components. Fresh delivery for most of the backed-up componentry looks like Oct~Nov from most major silicon sources. They're all balls to the wall and putting on extra capacity in places (like here) where COVID is effectively over, so I expect a good deal of those deliveries will actually be early. It will take a little time for that to migrate upstream to the car factories, but only a little. The whole industry is used to coping with quick-turn supply issues, this is just more widespread than the average shortage.

Based on that, I think things will likely be normalizing by late fall or early winter. For now the only sector that seems to be getting worse is wire-wound (things like spark coils and power resistors) because probably half of that comes out of India, but there's a lot of idle winding equipment here and in the EU and I don't think that shortage will last long either.

Its Really Dumbfounding; "How dependent we are" on foreign biz to make production.

I'm building a DT computer, as you know, prices have skyrocketed for all Cards

OH well...

Balkins wrote: ↑

Mon Jun 14, 2021 6:44 am

Its Really Dumbfounding; "How dependent we are" on foreign biz to make production.

I'm building a DT computer, as you know, prices have skyrocketed for all Cards

OH well...

I think we've become terminally stupid as a country. Thank 5 straight administrations of "Big Business Elitist" government with one exception, and now we're dumb enough to return to what we know doesn't work. Even Bush the elder was no friend of small business, while $100M "mom and pop" industries flourished all over Taiwan, Korea, India and others. Reagan was the last one to really understand it, along with (since this ain't the Politics section) he who shall remain nameless. Somehow nothing has changed a bit.

VStar650CL wrote: ↑

Mon Jun 14, 2021 7:06 am

Balkins wrote: ↑

Mon Jun 14, 2021 6:44 am

Its Really Dumbfounding; "How dependent we are" on foreign biz to make production.

I'm building a DT computer, as you know, prices have skyrocketed for all Cards

OH well...

I think we've become terminally stupid as a country. Thank 5 straight administrations of "Big Business Elitist" government with one exception, and now we're dumb enough to return to what we know doesn't work. Even Bush the elder was no friend of small business, while $100M "mom and pop" industries flourished all over Taiwan, Korea, India and others. Reagan was the last one to really understand it, along with (since this ain't the Politics section) he who shall remain nameless. Somehow nothing has changed a bit.

VSTAR...sent you a PM...did you get it?

~Balkins

Yep, replied to you yesterday after work. Or did you send another one after that? Don't see anything unread in my inbox.