Topic: timing belt tensioner? (Read 3510 times)

cavell · « **on:** 17 July 2017, 14:31:58 »

my 02 L81 3.0 has a new timing belt cast alum bracket with the 2 new rollers. the 1st design is EB? the 2nd is 01? i cannot make out my cast mark but it looks to be 6B? but, the previous tech reused the right/lower roller with the fixed middle hub. it is supposed to be the HEX style that you can rotate to adjust the cam timing on cams 3/4. is it imperative that i replace the roller with the correct offset design? maybe thats why the timing went off and bent the valves on this motor? i did order a new offset roller to be safe. $30 no big deal. ebay is great. i did find a local seller with a new timing kit with cast bracket, 3rd roller and belt for $60. maybe i should buy it and resell it for more. they go for $120-150

Kevin Wood · « **Reply #1 on:** 17 July 2017, 17:28:18 »

UK engines had moved on to the 3.2 by then, so our experience might not be directly relevant, but by 02 they had gone to using a fixed idler for the lower right roller.

It doesn't actually matter which one you fit. Adjustable idlers will still work with the later engines. It is important that you replace it, however, as it's the bearings in the idlers that are the main cause of cam belt failures.

As to the castings, I think I'm right in saying that the latest ones, as would be on an 02 engine (here, at least) were marked "01", so it's possible it has been fitted with the incorrect one in the past.

I think I'd be inclined to try the 01 casting first with either lower idler and see if it times up OK, with plenty of travel left in the spring tensioner and plenty of clearance between the idlers and pullies. If that doesn't work you can always swap the two new idlers onto the existing casting and re-use it.

cavell · « **Reply #2 on:** 17 July 2017, 18:22:07 »

i think ALL the online videos show the adjustment procedure for the timing belt with 2 hex rollers. they use the upper roller to tweak bank 1 cams and use the lower roller to tweak bank 2 cams. i cannot find a procedure that adjusts 1 roller only.

i think saturn used the 3.0 motor in the L300 sedan prior to 2002? perhaps it had a single hex setup?

do you have a link to the 1 hex adjustment procedure?

the way it is explained to me is all motors have tolerances. some have stock heads, some may have milled heads, some blocks are 54 deg +.1 deg and some are 54 deg -.1 deg. you install the timing belt and the cam sprocket teeth line up fine. you are not off 1 tooth which would be noticeable.

than you use the hex adjuster to fine tune the cam alignment marks. and turning the hex will move BOTH cam banks?
so why did they go to a double hex design?
the roller with the 1/2 moon graduated mark is for adjusting tension, not for aligning the cam marks.

Kevin Wood · « **Reply #3 on:** 17 July 2017, 18:45:06 »

With the fixed idler at the bottom right position, you can't adjust the relationship between cams 3 and 4 and the crank. You adjust cams 1 and 2 using the adjustable idler on the aluminium casting. In my experience, cams 3 and 4 always end up spot on with the fixed idler, so I guess they just figured out it was unnecessary.

I adopt a slightly different procedure when installing the belt, in that I find it helps to turn the crank back about 1 tooth on initial fitting (so the locking tool is vertical rather than resting on the water pump pulley). This gives you enough slack to get the belt over the crank, fixed roller and cams 3 and 4 without getting an extra tooth in that run. Then run the belt over the other sprockets and, when you come to get it finally over the spring tensioner, you can take out the extra tooth of slack by rotating the crank forward to the locked position making sure the belt doesn't slip on the crank pulley.

I don't believe we've got a guide for the fixed idler procedure.

cavell · « **Reply #4 on:** 17 July 2017, 20:03:07 »

Well, I do have 2 new rollers/bearings and 1 old roller. It would be good to have all new rollers.

Nick W · « **Reply #5 on:** 17 July 2017, 22:42:59 »

Quote from: cavell on 17 July 2017, 20:03:07

Well, I do have 2 new rollers/bearings and 1 old roller. It would be good to have all new rollers.

If you're not changing ALL of them, there's no point in doing the job. Put the covers back on, drive it till one of the rollers throws the belt, and bin the car.

cavell · « **Reply #6 on:** 17 July 2017, 23:39:22 »

Cast alum bracket/2 rollers is 2 weeks old. Are you saying replace them? Former owner changed timing belt, bracket, rollers, drove it for 2 weeks and it jumped time. Bent valves. Have not figured out why timing went.

Kevin Wood · « **Reply #7 on:** 18 July 2017, 08:22:54 »

It'll be fine to use the 2 week old rollers if they are not damaged. Worth changing the lower right hand tensioner though.

I'd have a careful look at how the belt runs. I suspect the wrong casting may be the reason it's failed. Maybe post a few pictures of the current setup?

cam.in.head · « **Reply #8 on:** 18 July 2017, 08:26:06 »

id be interested in what you find,especially re the right or wrong casting.what are the differences and why do we change them anyway ?

cavell · « **Reply #9 on:** 18 July 2017, 16:55:51 »

i cannot post pics. but, the old casting has the hex roller directly above the water pump centerline. now it is about 1" to the right. the distance between the roller and the cam sprocket is about 8mm.

Shackeng · « **Reply #10 on:** 19 July 2017, 18:45:07 »

Quote from: cavell on 17 July 2017, 23:39:22

Cast alum bracket/2 rollers is 2 weeks old. Are you saying replace them? Former owner changed timing belt, bracket, rollers, drove it for 2 weeks and it jumped time. Bent valves. Have not figured out why timing went.

No he's just being Nick.

cavell · « **Reply #11 on:** 19 July 2017, 20:30:42 »

got new roller today. it does not come with a spacer. though the fixed roller has a spacer. is the fixed spacer the correct one for use with the roller? well, i did pull the vue out of a bin. thats trash bin? you brits talk funny

Kevin Wood · « **Reply #12 on:** 19 July 2017, 23:20:02 »

I'm pretty sure I found the spacers to be the same between the two types.

cavell · « **Reply #13 on:** 25 July 2017, 03:17:57 »

it is running. my kid with identical vue was over yesterday and i changed a wheel bearing. her vue motor makes the same sort of clatter/tap noise. is it noisy fuel injectors? cam/lifter clatter? motor does not exactly purr. hmm, i hope it checks out ok in the next few days.

Doctor Gollum · « **Reply #14 on:** 25 July 2017, 04:21:58 »

Quote from: cavell on 25 July 2017, 03:17:57

it is running. my kid with identical vue was over yesterday and i changed a wheel bearing. her vue motor makes the same sort of clatter/tap noise. is it noisy fuel injectors? cam/lifter clatter? motor does not exactly purr. hmm, i hope it checks out ok in the next few days.

Lifter treatment

cavell · « **Reply #15 on:** 25 July 2017, 14:52:35 »

motor was not running when i got it. pulled heads. bent intake valves. cyl 3 had a major amount of black carbon crud. 1/16" layer on exh valves faces. cyls1-5 looked normal. almost no buildup. front head or 2-4-6 looked ok. talking combustion chamber appearance. i also noticed the front bank O2 sensor had a white buildup while the rear head sensor had a normal black sort of sooty look. coolant leakage? cracked block? cracked head? no i did not have heads pressure tested since it was a bad timing belt that was my main issue.

Kevin Wood · « **Reply #16 on:** 25 July 2017, 15:32:48 »

If it's just been rebuilt then expect the lifters to be noisy. They can take 20 minutes' running or more to quieten down.

Marks DTM Calib · « **Reply #17 on:** 25 July 2017, 15:54:17 »

After the valve replacement did you check the valve seat seals with a bit of liquid in the combustion bowls?

Also, the fact that one of the cylinders was showing fouling may suggest a weak spark and poor combustion.

As Kevin said, it can take a while for the lifters to fill following head work.

cavell · « **Reply #18 on:** 25 July 2017, 17:10:00 »

thats true. what happens in cylinder? fuel is injected and spark ignites it. too much fuel and/or weak spark can work together or independently to cause the issue. does cyl also have good compression? i cant really verify ring condition unless i do a leak down test. i got vue as a flip. fix obvious issues. i didnt feel like putting in a rebuilt motor.

Marks DTM Calib · « **Reply #19 on:** 25 July 2017, 17:46:56 »

So from personal experience of this power plant (not that I know much.....

)...

The blocks are pretty bulletproof and the heads plus block don't suffer overheating issues.
I am yet to see a cam belt failure result in only 12V to be damaged......
As per all petrol engines, they are sensitive to poor or failing coils packs, not as noticeable as many engines due to the six cylinders so can be a possible. (early engines had DIS and its common on reassembly for the leads to be connected wrongly but later are coil per plug)
To much fuel is very unlikely (given the operating method of the engine).

cavell · « **Reply #20 on:** 26 July 2017, 00:11:01 »

Started vue this afternoon. It purrs now. Clatter sound is gone. With 100% new exhaust, vue is so quiet. So, how do you verify weak spark on cyl #3? I have no misfire codes. But combustion chamber looked bad when I pulled head. Should I just try another coil to be safe?

Marks DTM Calib · « **Reply #21 on:** 26 July 2017, 08:21:58 »

You need a test plug to try the coil whilst its disconnected from the plugs, at atmospheric pressure you should be able to get a spark of 35mm+. You could rig something up to do this also, if its 20-30mm max the coil pack is getting tired.

cavell · « **Reply #22 on:** 26 July 2017, 13:43:59 »

my vue use the 3+ coil pack for each bank. i do not know what the test procedure is for these types of coil packs. another tech says my heavy carbon/crud residue is probably due to bad rings on that cyl.

Kevin Wood · « **Reply #23 on:** 26 July 2017, 14:19:58 »

It's very rare to get any bottom end problems / wear at all on these engines, unless the piston ring top groove has been crimped by valve to piston contact. Does it burn any oil? I'd expect consumption to be considerable if there's sufficient getting by the rings to cause a noticeable issue in the combustion chamber.

Might be worth pulling the plugs after a decent run to see if there are still signs of a problem there?

cavell · « **Reply #24 on:** 26 July 2017, 15:04:46 »

i bought the vue for parts really. new exhaust and tires. i wanted to see if i could fix the heads actually and move on. i only plan on driving it to verify it is fixed. 1-2 weeks than its gone

Marks DTM Calib · « **Reply #25 on:** 26 July 2017, 15:19:39 »

Quote from: cavell on 26 July 2017, 13:43:59

my vue use the 3+ coil pack for each bank. i do not know what the test procedure is for these types of coil packs. another tech says my heavy carbon/crud residue is probably due to bad rings on that cyl.

Heavy crud might be but, a carbon coating is generally poor combustion.

Plus this power plant has little issue with rings etc.

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Author Topic: timing belt tensioner? (Read 3510 times)