Chain guide replacement - Possible jumped timing chain

[Q451990]

Not sure if it's still available but it's worth a try.

zerothread?id=154482

[trw2k]

Jeez you guys are amazing the way you help.I am downloading the 94 manual at the moment.

The "slipping" is from the tension the valve springs put on the cam lobes causing the camshaft to spin when the chain has enough slack to allow it.

What you said in this quote is what I was thinking. I did not have the middle tie in place just the lower tie. The lower guide was worn away and when I took the upper guide away it created slack that then allowed the camsprokets to rotate forward enough to take out the slack in the upper part of the chain but created a lot more slack to the lower part of the chain. I am thinking that when I intall the new guides that the cams might rotate backward when I install the upper guide. I am not sure I am saying this clearly.

I did not follow the procedure as you stated anlasak. I may get to know this car a little more intimately than I would like because of it....

I just ordered the parts..should be here in a week or so.

[trw2k]

Anlasak, the 94 manual works for the 90 Q45?I also found on the forum someone mentioning this website but the service manual for the 1990 cost 69.95. I was just quoted 130.00 from another source so I like your price the best.

http://www.books4cars.com/resu....y=59

(not sure if that will make a link)

[Raxephon]

Its pretty much the same as my '91 hardcopy.(Just in pdf form)

[trw2k]

Thats great thanks!

[gniknave]

The lower guide was worn away and when I took the upper guide away it created slack that then allowed the camsprokets to rotate forward enough to take out the slack in the upper part of the chain but created a lot more slack to the lower part of the chain. I am thinking that when I intall the new guides that the cams might rotate backward when I install the upper guide. I am not sure I am saying this clearly.

Ouch. I do understand what you're saying by the cams rotating backward when you install the new upper guide. If that doesn't work (you might want to say some prayers), then you might want to consider taking up some yoga to relax you through doing the job the long way...

[Raxephon]

Ouch. I do understand what you're saying by the cams rotating backward when you install the new upper guide. If that doesn't work (you might want to say some prayers), then you might want to consider taking up some yoga to relax you through doing the job the long way...

Ummm, why not pull the driverside valvecover and be able to visually inspect it for sure to see that the timing marks line up when you turn the crank 120DEG from TDC?

Wiseman say, " Prayers good for soul, but will not pay for motor"



Besides, if it hasn't already been done, she's probably due for a Valvecover re-sealing anyway.

[trw2k]

Yeah I really don't want to get it back together only to take it apart again. Is it possible to just pull the camsprocket cover on the drivers side and see if the alignment marks line up? Or should I take the whole valve cover and the camsprocket cover off?

[Raxephon]

Is it possible to just pull the camsprocket cover on the drivers side and see if the alignment marks line up?

Not really. When you turn the crank 120 DEG past TDC, (the position at which the timing marks on the cam sprockets and chain line up on the left bank), they are at their highest point, in relation to the angle of the block, inside the valvecover.

And thats with the upper timing cover off.

Attachment: Top picture is @ TDC, Bottom picture is 120 DEG past TDC. Red outline is valvecover area(roughly)

[trw2k]

Thanks, that is what I am going to do then. I wanted to look for pieces of debris from the guide there anyway. Changing the guides out is looking like an easier and easier job compared to checking the timing. I guess a little more precaution on my part would have eliminated the need. **Take note future chain guide replacers!**

[trw2k]

Ok, so I have removed the valve cover thanks to Jeff Williamsand this thread zerothread?id=107690RTV is pretty tough stuff.

I can see the alignment marks (pictures) and it looks like the chain did skip one tooth. The gold links should be directly above the alignment marks..right?

[trw2k]

The alignment mark on the crankshaft also looks like it off by a tooth but I fastened the tie when I first began and so I doubt this has moved. Could the chain have been put on a tooth off? Is there another way to check the timing?

The chain guide kit should arrive Monday or Tuesday Scottsdale http://www.trademotion.com/par...=3221 .

[Raxephon]

The gold links should be directly above the alignment marks..right?

Yes, but they're actually silver, only the bottom one, (crankshaft), is gold.

[PopPop]

It should not slip at all if you :

1. Set at TDC2. R&R Passenger-side guides only3. Rotate crankshaft 120 DEG.4. R&R Driverside guides.

The "slipping" is from the tension the valve springs put on the cam lobes causing the camshaft to spin when the chain has enough slack to allow it.

How are these guys suppose to rotate engine anlasak with wire ties tight on chain links? It also works better if you place wire ties on chain roller bearing surface than around outer link surface! Plus you didn't specify the direction to rotate the crank! You know that makes all the difference for people that don't know!

[trw2k]

Thanks anlasak, you are right. Everything is so tarnished it just looks gold.

[trw2k]

Yeah, I didn't exactly follow the procedure precisely. I discovered a lot of loose rubber hose fittings and one really kinked on as a result though..(looking at the bright side)...

[PopPop]

The alignment mark on the crankshaft also looks like it off by a tooth but I fastened the tie when I first began and so I doubt this has moved. Could the chain have been put on a tooth off? Is there another way to check the timing?

The chain guide kit should arrive Monday or Tuesday Scottsdale http://www.trademotion.com/par...=3221 .

It could have jumped time while driving because of the lost of tension on these chains! Now here goes the million dollar question! How are you going to put in new parts with all those wire ties in the way? The new parts are bigger and you have too rotate tension side guides around the chain! Just take your time and be careful! I myself don't like the red RTV that Infiniti uses! I prefer the gray!

[trw2k]

Thanks PopPop. Never having done this obviously I figured I would get the new parts, mark the timing chains and the sprockets so I know where they are now and then take off the ties and replace the guides. It looks like if I turned the crank with the new guides in the crankshaft and camshaft marks would be where they are supposed to be. It does look like the entire chain has jumped ahead one tooth. I think the chain has jumped off the sprockets before I ever began this process..while the car was running and actually jumped back into place. It would explain the way this car would run/not startand then run absolutely perfectly from time to time.

[Raxephon]

How are these guys suppose to rotate engine anlasak with wire ties tight on chain links? It also works better if you place wire ties on chain roller bearing surface than around outer link surface!

1.Set Crankshaft at TDC on Compression Stroke 2. Remove Lower Timing Cover 3. Remove tensioner on Right Bank 4. Remove old guides 5. Install new guides 6. Install tensioner on right bank 7. Rotate crankshaft clockwise 120 Degrees (towards driverside) 8. Remove tensioner on Left Bank 9. Remove guides 10. Install new guides 11. Install tensioner on left bank

At no point should you need tie straps if you have things set correctly.

When the motor is set at TDC (compression stroke) there is not enough tension from the valve springs to rotate the cams on the right bank, (Passengerside), when there is slack in the chain. But there is on the left bank, (Driverside), at TDC.

Once you rotate the crankshaft 120 DEG clockwise, ( to your right when facing the engine from the front), it relieves the excess tension from the springs on the left bank,(driverside), but increases the tension on the right bank, (passengerside).

[trw2k]

Anlasak, This thread of yours zerothread?id=140310 (I believe) confirms my timing chain jumped a tooth. I borrowed your picture to add here to illustrate. I have 8 plates between the camshaft sprokets on the rightside (passengers side) and 9 plates on the left side (Drivers side). It looks like the exhaust cam on the left side moved forward a tooth. I will post a picture later. I was looking at the notches in the camshaft that line up across from each other when at TDC that allow you to remove the cylinder head bolts and I notice the drivers side exhaust cam looked off. I remembered that thread and went back and sure enough there are 9 plates on that side and 8 on the other. Cool. Thanks

[JedCoop]

Yeah, I didn't exactly follow the procedure precisely. I discovered a lot of loose rubber hose fittings and one really kinked on as a result though..(looking at the bright side)...

The kinked hose in the picture is not the factory hose and should be replaced.

The factory hose is molded in a "U: shape and by now usually very brittle. The first time I pulled the plenum on my car it only creacked a little so I just cut off the 3/8ths inch of hose that was cracked. I just pulled the plenum again last weekend and had to replace the hose completely.

While replacing that hose I also replaced all the other ventilation hoses on both sides of the engine and on the TB.

Given that someone has done a sloppy job changing hoses on your car in its past, I'd consider inspecting them all, and replace what is practical even if it looks "OK". A vacuum leak can cause a lot of hard to diagnose badness.

Here is a list of hoses:zerothread?id=26426but the diagrams don't seem to work anymore and here is another list too:http://infiniti.home.insightbb...s.htmBut the parts diagrams pointed to from Q45.org don't work anymore, either!

Not sure which is the right part number to order.

Maybe someone can post a working pointer to the parts diagrams?

[Raxephon]

Anlasak, This thread of yours zerothread?id=140310 (I believe) confirms my timing chain jumped a tooth. I borrowed your picture to add here to illustrate. I have 8 plates between the camshaft sprokets on the rightside (passengers side) and 9 plates on the left side (Drivers side). It looks like the exhaust cam on the left side moved forward a tooth. I will post a picture later. I was looking at the notches in the camshaft that line up across from each other when at TDC that allow you to remove the cylinder head bolts and I notice the drivers side exhaust cam looked off. I remembered that thread and went back and sure enough there are 9 plates on that side and 8 on the other. Cool. Thanks

You're welcome.

Anything to keep a Q on the road

Just don't try to set the timing chain on the left bank without rotating the crankshaft 120 degrees clockwise from TDC, otherwise you run the risk of it skipping before you get the tensioner installed.

The kinked hose in the picture is not the factory hose and should be replaced.

The factory hose is molded in a "U: shape and by now usually very brittle. The first time I pulled the plenum on my car it only creacked a little so I just cut off the 3/8ths inch of hose that was cracked. I just pulled the plenum again last weekend and had to replace the hose completely.

While replacing that hose I also replaced all the other ventilation hoses on both sides of the engine and on the TB.

Given that someone has done a sloppy job changing hoses on your car in its past, I'd consider inspecting them all, and replace what is practical even if it looks "OK". A vacuum leak can cause a lot of hard to diagnose badness.

Here is a list of hoses:zerothread?id=26426but the diagrams don't seem to work anymore and here is another list too:http://infiniti.home.insightbb...s.htmBut the parts diagrams pointed to from Q45.org don't work anymore, either!

Not sure which is the right part number to order.

Maybe someone can post a working pointer to the parts diagrams?

Ask and ye shall receive

[JedCoop]

Ask and ye shall receive

Thanks anlasak... this forum is great!

the hose is labelled "11826+C" on the first diagram.

[Raxephon]

Thanks anlasak... this forum is great!

the hose is labelled "11826+C" on the first diagram.

The parts catalog is showing part number 11826-60U04 for "11826+C"

[trw2k]

anlasakmaxnixgniknaveQ451990PopPopJedCoop

Thanks you all so much! You all rock big time! It had jumped two links on the drivers exhaust side and it is now on the road and running as smooth as ever. I got all the parts out of the pan and oil pump and now it has smooth starts, more power and is very quiet.

Analask, I definately would not have known this for sure had it not been for your post on the number of teeth between the marks. When I adjusted the cam back two links the numbers matched what you had counted between the teeth and the cam indents were lined up as per the pictures here. SO thanks for that post!

Honestly, even with all this help I really doubted that I had actually diagnosed the skipped teeth correctly. I really thought that there was a fifty fifty chance I would get this back together and it would not run at all and I would be taking it apart again this weekend. Having taken both rocker arm covers off I was also curious to see if I could remember how to put it all back together. When I first got this car I took one look at the octupus like engine and immediately thought that I would definately not ever be working on this engine. It is suprising to me how, nut by nut, it all comes apart and is not that big of a mystery in the end.

You all saved me a lot of money.

THANKS!

[Raxephon]

Congratulations!

I'm glad you got your Q back together and running properly.

These cars are just too nice a vehicle to end up in a wrecking yard.