Well, I bought a 90 Q45 in late July just as I learned about NICO. Read the posts about the dreaded chain guide problems, so I simply drove the car home and parked it. I also knew it had a bad #3 injector.
Next, I painted my house. (Insert 3-4 months of no car activity.)
Now, I'm out in the garage dying to get this car on the road. I've wanted one ever since I first saw them at the Seattle Auto Show in the fall of 89. Here's what I've done, and where I'm stuck:
1. Pulled the lower timing covers and found that about 1/3 of the guides were broken off. Couldn't fish out any pieces, so resigned myself to pulling the pan after I got the new guides installed. Ordered parts from Scottsdale (Thanks to NICO for that tip!)
2. Followed the guidelines from Dadealus about replacing the guides, but I heard this funny noise from the left side and figured I was in trouble, so decided I better pull the valve covers and upper timing covers and check out the timing.
3. Scottsdale had sent new chains with my order, so I thought it would be fairly straightforward to change them too. carefully lined things up and installed both chains per the diagrams in the owner's service manual. (I was lucky, it was in the trunk.)
4. Now I start to get nervous. For one thing, when comparing the position of the crank angle sensor with the one shown on page EM-17, mine seems to be a little past the top dead center mark. I think I could loosen the crank angle sensor housing and rotate it enough to compensate for the angle difference, but I am very reluctant to do so unless everything else is alright.
I also looked at the spread between the intake and exhaust cams on the left and fight banks, expecting them to be the same. Not true. The right bank cams are about 90 degrees out of phase, which is what I expected, but the left bank cams seem to be 180 degrees out of phase. Also, by using a wrench on the cast hexagon shoulder of the cams I was able to move the left cam about 10-15 degrees without moving the chains, however attempting a similiar action on the right cam immediately put tension on the chain without budging the cam.
5. I decided to carefully turn the engine through about 120 degrees and see if the left bank timing chains marks were in alignment; they were. I continued turning the engine until I again had all the original timing marks in place. Not a hint of interference was encountered.
I don't want to put the valve and timing chain covers back on until I'm certain I have done things correctly. I think I'm in trouble; I'm an accountant, not a mechanic! Any words of advice would be greatly appreciated.:help
Timing Q45 Chains
I will leave this one up to the experts but to tackle this job you are quite the DIYer.:thumbup
Timing aligment is said to be done incorrectly at times,even by professionals, I concur with your descision to check here, even tho the handcranking seemed to show ok.
I'll leave a more detailed answer up to those more equipped to give it , our online Mechanics.
Fred..
Timing aligment is said to be done incorrectly at times,even by professionals, I concur with your descision to check here, even tho the handcranking seemed to show ok.
I'll leave a more detailed answer up to those more equipped to give it , our online Mechanics.
Fred..
2) Funny noise? Was it a loud clicking or snapping, or a not-so-loud clicking? Both can happen...chains jumping are a lot louder than just having the cams snap under spring load. How did you secure the chains, and do they look like they've jumped at all?
4) Hold off on turning the CAS housing unless you're certain you need to. Unless someone else messed with it, you have to assume the factory setting is dead nuts. Besides, it isn't a life or death critical item...if it's off a little it won't cause an interference problem. That's something you can set later with a timing light. When you were looking at it, were both tension and top legs of the chain taught? If either is slack at all, then it will throw off the reading. It's also possible the pic in the manual is just a reference....making sure you're in the right hemisphere. TDC must be set with the balancer and front cover marks.
I'm a little unclear about what you're saying about moving the chain but not the cam. You're on the driver's side, and the intake cam doesn't move the chain, but the exhaust cam moves the chain? Hazy to me. But best not to turn the cams by themselves! Remember that if you let the cams go, the open-valve springs will rotate the camshafts (the open valves will partly close, and 2 other valves will partly open, bringing equilibrium to the springs). The valves opening might be the ones over a TDC piston and the valves could slam into the TDC piston. If you need to rotate the camshafts, first rotate the crank 45* so the key points upward. This drops all pistons low enough so the valves won't hit them (EM 20).
The cam lobes on right and left banks won't have the same relationship. They're all turning the same direction, but the intake and exhaust sides are different relative to each head. Note the location of the rollers relative to the cam lobes--it all factors in. It might help to draw cross-sections of each head on scratch paper.
Bottom line--if all your timing marks are lined up at the same time, then you should be just fine. *Slowly* turn the crank 2 revolutions with the tensioners in before closing up to ensure there are no interferences. Damn chain likes to jump when you're putting the tensioner in.
4) Hold off on turning the CAS housing unless you're certain you need to. Unless someone else messed with it, you have to assume the factory setting is dead nuts. Besides, it isn't a life or death critical item...if it's off a little it won't cause an interference problem. That's something you can set later with a timing light. When you were looking at it, were both tension and top legs of the chain taught? If either is slack at all, then it will throw off the reading. It's also possible the pic in the manual is just a reference....making sure you're in the right hemisphere. TDC must be set with the balancer and front cover marks.
I'm a little unclear about what you're saying about moving the chain but not the cam. You're on the driver's side, and the intake cam doesn't move the chain, but the exhaust cam moves the chain? Hazy to me. But best not to turn the cams by themselves! Remember that if you let the cams go, the open-valve springs will rotate the camshafts (the open valves will partly close, and 2 other valves will partly open, bringing equilibrium to the springs). The valves opening might be the ones over a TDC piston and the valves could slam into the TDC piston. If you need to rotate the camshafts, first rotate the crank 45* so the key points upward. This drops all pistons low enough so the valves won't hit them (EM 20).
The cam lobes on right and left banks won't have the same relationship. They're all turning the same direction, but the intake and exhaust sides are different relative to each head. Note the location of the rollers relative to the cam lobes--it all factors in. It might help to draw cross-sections of each head on scratch paper.
Bottom line--if all your timing marks are lined up at the same time, then you should be just fine. *Slowly* turn the crank 2 revolutions with the tensioners in before closing up to ensure there are no interferences. Damn chain likes to jump when you're putting the tensioner in.
-
Q451990
- Moderator
- Posts: 11030
- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
Welcome to NICO John! I'd try to take some pictures and post them here (use the member's ride section) for Daedalus and the other guide-experienced to see. That may help a lot.
Living as close as I do to T3 it was much easier and safer to take the trip to Atlanta, but I thought about the DIY route several times. I just couldn't bear the thought of starting that engine up to a "Crunch" and knowing I was responsible...
Good Luck!
Heath
Living as close as I do to T3 it was much easier and safer to take the trip to Atlanta, but I thought about the DIY route several times. I just couldn't bear the thought of starting that engine up to a "Crunch" and knowing I was responsible...
Good Luck!
Heath
Congrats on getting this far, you are obviously talented, and I'll bet you can tell us to the $.01 how much you have spent so far.
I am a banker, and with Daedalus expert help, did a couple of chain guides myself. Are you sure the noise you heard wasn't the chain rattling in the front cover as the tensioner pressurized??? Was the noise on strat up, or just cranking??
Worst case, leave everything open, and see if you can get a local Infiniti dealer mechanic to stop by and give it an eyeball. Probably not more than 15 minutes of looking, and rotating. The guys around here kind of appreciate a do-it-yourselfer, and may give you some preferential treatment.
I am a banker, and with Daedalus expert help, did a couple of chain guides myself. Are you sure the noise you heard wasn't the chain rattling in the front cover as the tensioner pressurized??? Was the noise on strat up, or just cranking??
Worst case, leave everything open, and see if you can get a local Infiniti dealer mechanic to stop by and give it an eyeball. Probably not more than 15 minutes of looking, and rotating. The guys around here kind of appreciate a do-it-yourselfer, and may give you some preferential treatment.
-
John Nordling
- Posts: 68
- Joined: Thu Jul 24, 2003 6:37 pm
First of all, thanks to PalmerWMD for putting my problem in the forum. Thanks also to AZhitman and Heath for the words of encouragement........I need this right now! And, DougQ45, I'll take your idea as a backup plan. I really think that with DAEDALUS' help I can lick this thing.
RESPONSE TO DAEDALUS:
2) Originally, I was only going to replace the guides and tensioners. When I heard the funny noise, I decided to be safe and check things out and replace the chains too as long as I was there. This was over Thanksgiving, and I really think it was a"not-so-loud" clicking. I had wired the chains, but maybe not tight enough. There was no problem with the right side. This was also the point at which I noticed the crank angle sensor seemed to have changed position, futher leading to my desire to be cautious.
When I got the upper timing cover off, I inked both camshaft sprockets where they were in relation to each other. I could not see the mating marks on the old chains until I had them off, but it was easy to line up the mating marks on the new chain on the right side without haveing to move anything. Just got lucky, I guess.
The left side was harder, and kept jumping on me ("loud clicking"). Finally, I was able to line all of the marks up on the left side and found that the inking marks I had made were in the same place as before. That must mean that the chain had not actually jumped time as I feared.
When checking the mating marks, I was careful that the driven side of the chains were under tension.
4) and 5) Let me see if I can clarify what I was trying to convey in my original message.
As I was turning the engine over slowly, it was necessary to stop and get a new position to continue turning the crank. When I paused, the right side would occasionally go slack or tight while making clicking noises, apparantly equalizing the tension on the valve springs. The left chain did not exhibit this same action, and I suspected something was amiss.
Because of this, I tried to move the left side intake cam using the cast-in hex shoulder. I was able to do so through about 10-15 degrees with moderate resistance and without any movement of the cam sprocket. When trying this same thing on the right side, I immediately came up against the tension in the timing chain.
After reading your post, I now think this might be caused by a problem with the variable valve timing mechanism on the left intake cam. Its my understanding that this device works on oil pressure. Is it possible that when the engine is running this situation will correct itself?
I did notice that the exhaust cam sprockets had two marks, 180 degrees apart. However, they were labeled as "RE" and "LE" on one side only, which was in the up position, and that both exhaust cam pegs or locating pins were also in the up position. I considered that the left side exhaust cam might be 180 degress out, but the slotted drive on that cam for the crank angle sensor is an offset type and it was therefore easy to see that it was in the correct position.
I also checked the position of the cam lobes for Number 1 (left bank) and then Number 8 (right bank) cylinders and satisfied myself that the exhaust lobes were properly spaced. As I mentioned in my first post, the relative positions of the intake cams between the left and right banks seems to be different. Maybe this is due to the left side variable valve timing issue noted above. I tried diagrams of a 4-cycle valve train and concluded that I can easily confuse myself!
Bottom line:
a) All timing chain marks are OKb) The engine turns through all four cycles with no interferencec) The crank angle sensor is 10-15 degrees off (just a guess as to how much)d) The left side intake cam can move 10-15 degrees independent of the cam sprocket (again, just a guess as to how much)e) I did check the basic timing by temporarily fitting the lower timing cover and crank pulley, and I double-checked that number one piston was at the top of the cylinder by puttng a screwdriver down the sparkplug hole.
My apologies for being so wordy, I just want to get this right. Have I been studying? You bet. I have copied about two inches of material from previous posts on this site on all kinds of topics. Absolutely invaluable!
RESPONSE TO DAEDALUS:
2) Originally, I was only going to replace the guides and tensioners. When I heard the funny noise, I decided to be safe and check things out and replace the chains too as long as I was there. This was over Thanksgiving, and I really think it was a"not-so-loud" clicking. I had wired the chains, but maybe not tight enough. There was no problem with the right side. This was also the point at which I noticed the crank angle sensor seemed to have changed position, futher leading to my desire to be cautious.
When I got the upper timing cover off, I inked both camshaft sprockets where they were in relation to each other. I could not see the mating marks on the old chains until I had them off, but it was easy to line up the mating marks on the new chain on the right side without haveing to move anything. Just got lucky, I guess.
The left side was harder, and kept jumping on me ("loud clicking"). Finally, I was able to line all of the marks up on the left side and found that the inking marks I had made were in the same place as before. That must mean that the chain had not actually jumped time as I feared.
When checking the mating marks, I was careful that the driven side of the chains were under tension.
4) and 5) Let me see if I can clarify what I was trying to convey in my original message.
As I was turning the engine over slowly, it was necessary to stop and get a new position to continue turning the crank. When I paused, the right side would occasionally go slack or tight while making clicking noises, apparantly equalizing the tension on the valve springs. The left chain did not exhibit this same action, and I suspected something was amiss.
Because of this, I tried to move the left side intake cam using the cast-in hex shoulder. I was able to do so through about 10-15 degrees with moderate resistance and without any movement of the cam sprocket. When trying this same thing on the right side, I immediately came up against the tension in the timing chain.
After reading your post, I now think this might be caused by a problem with the variable valve timing mechanism on the left intake cam. Its my understanding that this device works on oil pressure. Is it possible that when the engine is running this situation will correct itself?
I did notice that the exhaust cam sprockets had two marks, 180 degrees apart. However, they were labeled as "RE" and "LE" on one side only, which was in the up position, and that both exhaust cam pegs or locating pins were also in the up position. I considered that the left side exhaust cam might be 180 degress out, but the slotted drive on that cam for the crank angle sensor is an offset type and it was therefore easy to see that it was in the correct position.
I also checked the position of the cam lobes for Number 1 (left bank) and then Number 8 (right bank) cylinders and satisfied myself that the exhaust lobes were properly spaced. As I mentioned in my first post, the relative positions of the intake cams between the left and right banks seems to be different. Maybe this is due to the left side variable valve timing issue noted above. I tried diagrams of a 4-cycle valve train and concluded that I can easily confuse myself!
Bottom line:
a) All timing chain marks are OKb) The engine turns through all four cycles with no interferencec) The crank angle sensor is 10-15 degrees off (just a guess as to how much)d) The left side intake cam can move 10-15 degrees independent of the cam sprocket (again, just a guess as to how much)e) I did check the basic timing by temporarily fitting the lower timing cover and crank pulley, and I double-checked that number one piston was at the top of the cylinder by puttng a screwdriver down the sparkplug hole.
My apologies for being so wordy, I just want to get this right. Have I been studying? You bet. I have copied about two inches of material from previous posts on this site on all kinds of topics. Absolutely invaluable!
I don't know about adjustability of the VTC/sprocket, but if the car ran fine before you took things apart, and if your chains are timed correctly when you put it back together, then it seems things should run fine when you're done. Again, I see no reason to touch the CAS. 10-15* is a lot; I have to think you would know if your spark was off by that much in either direction. Leave it alone, and check the base timing with a light later. Base timing is 15* BTDC at idle.
Sounds like you're in pretty good shape. Verify again that your tensioners are installed correctly, that the 3 mark pairs are lined up on each chain, and (just for peace of mind) that the crank rotates freely. Then I say go ahead and put it all back together. Remember that the crankshaft torque is critical to oil pressure...270 ft-lbs. Pull the injector fuse, crank the car for 10-15 seconds 4-5 times, replace the fuse, and then fire it up. Before you drive it, change the oil if you haven't already done so.
Sounds like you're in pretty good shape. Verify again that your tensioners are installed correctly, that the 3 mark pairs are lined up on each chain, and (just for peace of mind) that the crank rotates freely. Then I say go ahead and put it all back together. Remember that the crankshaft torque is critical to oil pressure...270 ft-lbs. Pull the injector fuse, crank the car for 10-15 seconds 4-5 times, replace the fuse, and then fire it up. Before you drive it, change the oil if you haven't already done so.
-
Q451990
- Moderator
- Posts: 11030
- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
Q45tech wrote:Be prepared for the horrendous noise that happens till the HLA and tensioners pump up! Run a second turn off run a second turn off 2-3-4 times the noise will stop.
I think this could be avoided by turning the car over w/o the injector fuse and fuel pump fuse installed (to prevent starting) for a few seconds. I tried to get Byron to try it but he forgot before he started the car.
Even a quick spin of the oil pump (to get the tensioners pumped up) while the front cover was off a day earlier, substantially reduced the noise mine made after the guide job. It's also amazing how much oil is moving through that engine. Turning the pump gear one or two times sent a lot of oil through the squirters onto the chains.
I hate the sound of metal to metal...
Heath
P.S. Will you be replacing the oil pump? With all of the crap in the engine it might be a good idea.
-
John Nordling
- Posts: 68
- Joined: Thu Jul 24, 2003 6:37 pm
Well, I'm going to stop worrying and start putting things back on the beast this weekend. I might as well get a new oil pump, as its about the only thing I haven't bought replacement parts for! I don't mind because I want to get 100,000 miles out of this car.
Actually, I may pull the pan first, so I can put things back in what looks like the easiest order. In other words, oil pan followed by lower timing cover followed by upper timing covers followed by the cam covers. Anyone have a suggestion about this?
Thanks for the tips on startup. It may be a while, but I will let you all know how it goes. I'm slow and thorough, but I have time off over the holidays.
Many, many thanks folks!
Actually, I may pull the pan first, so I can put things back in what looks like the easiest order. In other words, oil pan followed by lower timing cover followed by upper timing covers followed by the cam covers. Anyone have a suggestion about this?
Thanks for the tips on startup. It may be a while, but I will let you all know how it goes. I'm slow and thorough, but I have time off over the holidays.
Many, many thanks folks!