Low mile case study, 24K 07LC (2025) (1 Viewer)

[2001LC]

Crankshaft TB sprocket. Also had some rust & rubber stuck in teeth, I brushed out.

Assemble when smoothly. Note: Yellow paint indicate torque and done.

I'll note: I do disassemble and assemble (time), the 4.7L 2UZ-fe VVTi engine differently. Than non VVTi.

I set: With the camshaft sprocket timing marks, to the "T".

The harmonic balance (crankshaft pulley) zero line (while line). To the nub on timing cover. Which also has the crankshaft sprocket keep, pointing to square on oil pump housing.

This orients the crankshaft. So that sprocket keep point at square on oil pump housing cover.

Which timing mark (V notch) on CR sprocket, corresponds to CR keep.

 

[GTV]

Hey Paul, I'm doing the timing belt on the Unicorn ('07 VVTI) right now and ran into a bit of an issue...
New belt on and the timing marks all lined up. They look just like your pictures above.

I reinstalled the pulley, pulled the pin on the tensioner and rotated the engine a few revolutions and found that the timing was now off. Strange but ok.

So I took it back apart. I put the cams back on the "T" and the crankshaft to zero (white mark on the plastic cover aligned with notch in pulley).

Extra careful this time, I lined the timing marks back up and reinstalled the tensioner.

I rotated the engine until the belt made a full revolution and the crankshaft was not at zero. I had to turn the crank quite a bit further to get the notch to line up with the white mark on the cover.

I turned the engine around for an additional cycle and the timing marks were even further off.

Not sure where I'm going wrong here. This is my 3rd timing belt job and the 2nd VVTI, I didn't have these problems before.

 

[GTV]

I think I figured out where I went wrong. I should have just made two revolutions of the crank and checked to see if the timing marks on the camshaft gears were lined up. Instead I turned it a lot more and referenced the belt. Lesson learned. It was probably correct to begin with. Oops.

I've spun things around so much that now I need to verify TDC before I go any further. Can I do that easily without removing a valve cover?

 

[Rhetoric]

Pull a spark plug and stick a long wooden dowel in the #1 cyl as you slowly rotate to what you think is TDC.

If you had it all lined up with the belt to start, everything should be in time. Those marks are only good for slipping the belt on. After that you just reference the “hard” marks on the pulleys to verify.

 

[GTV]

Pull a spark plug and stick a long wooden dowel in the #1 cyl as you slowly rotate to what you think is TDC.

If you had it all lined up with the belt to start, everything should be in time. Those marks are only good for slipping the belt on. After that you just reference the “hard” marks on the pulleys to verify.

I'm not 100% confident that it's in time, I moved the crank independently of the cams while trying to figure out where I went wrong. Maybe it still is but I need hard evidence, the stakes are high if it's wrong.

I considered pulling a plug but on a 4 stroke engine the crankshaft needs to make two revolutions for a complete cycle. TDC comes after intake and compression, 360 degrees into the cycle, when the piston is at the top of the bore. In another 360 degrees (after power and exhaust) the piston will again be at the top of the bore. So the piston is at the top twice during a cycle, after compression and exhaust. I need to know TDC after the compression stroke. I could do that by looking at the intake valves but that requires removing a valve cover which I'd like to avoid if at all possible.

 

[Rhetoric]

I'm not 100% confident that it's in time, I moved the crank independently of the cams while trying to figure out where I went wrong. Maybe it still is but I need hard evidence, the stakes are high if it's wrong.

I considered pulling a plug but on a 4 stroke engine the crankshaft needs to make two revolutions for a complete cycle. TDC comes after intake and compression, 360 degrees into the cycle, when the piston is at the top of the bore. In another 360 degrees (after power and exhaust) the piston will again be at the top of the bore. So the piston is at the top twice during a cycle, after compression and exhaust. I need to know TDC after the compression stroke. I could do that by looking at the intake valves but that requires removing a valve cover which I'd like to avoid if at all possible.

Ahhh I see. You moved something independently. Good cause for pause.

A borescope should help you determine which valves are open if you did not want to remove the valve cover. Then watch those hard marks too see where you are at and adjust.

 

[GTV]

Ahhh I see. You moved something independently. Good cause for pause.

A borescope should help you determine which valves are open if you did not want to remove the valve cover. Then watch those hard marks too see where you are at and adjust.

Ok, I’ve thought about this… One could spin the crank and cams independently as much as you like, as long as the timing marks correspond when the belt goes on it will be correct.

Sorry for the thread hijack, follow me for more dumb ways to overthink and waste time

 

[Tentsontop]

Good thread here.

 

[2001LC]

Hey Paul, I'm doing the timing belt on the Unicorn ('07 VVTI) right now and ran into a bit of an issue...
New belt on and the timing marks all lined up. They look just like your pictures above.
View attachment 3863941
View attachment 3863942
View attachment 3863943

I reinstalled the pulley, pulled the pin on the tensioner and rotated the engine a few revolutions and found that the timing was now off. Strange but ok.

So I took it back apart. I put the cams back on the "T" and the crankshaft to zero (white mark on the plastic cover aligned with notch in pulley).

Extra careful this time, I lined the timing marks back up and reinstalled the tensioner.
View attachment 3863962
View attachment 3863963

I rotated the engine until the belt made a full revolution and the crankshaft was not at zero. I had to turn the crank quite a bit further to get the notch to line up with the white mark on the cover.
View attachment 3863964
View attachment 3863965
View attachment 3863966

I turned the engine around for an additional cycle and the timing marks were even further off.

Not sure where I'm going wrong here. This is my 3rd timing belt job and the 2nd VVTI, I didn't have these problems before.

The marks on the belt, will NOT line up, once crankshaft turned. We're only concerned with marks on the crankshaft pulley (harmonic balancer) and camshafts.

We spin the crankshaft smaller sprocket, clockwise 720 degrees (2 revolutions). To get the larger camshaft sprockets to turn 360 degrees (1 revolution).

Each 2 revolutions or crankshaft, all sprocket marks will line up again and again. That is timed.

 

[Zuberg]

@2001LC. Curious if you ever resolved the rough idle issue (i think you had mentioned it in another thread). If resolved m, what was the fix?

 

[2001LC]

Timing marks:

In other threads, I've said; Time (the 3 marks) camshafts to the straight lines (not the "T"s), with crankshaft sprocket "V" notch to the nipple on the oil pump housing.

In this thread I say camshafts sprockets to"T" to and crankshaft sprocket "V" to the square (white nipple on cover) on oil pump housing.

What's the difference in marks. As fare as timing, none. Provide we don't mix sets. In reality either set of marks, can be use. In either VVT or non 4.7L.

But when we use the straight lines. The camshaft are sitting with some of its lobs, riding high, pushing open some valves. With their spring tension from open valve's spring, pushing against camshaft lobe. If we move the camshaft, just the slightest bit. Spring tension, will then move the camshaft abruptly. This can result in interference. According to Toyota. The 4.7L is an Interference engine.
"Interference; is piston top coming in contact with valves face.

In the 4.7L non VVT, we seen many cases, we didn't interfere. We've many instances of non VVT breaking the T-belt under-load, like passing on HWY. New belt and all is good.

I had a non VVt, out of time case, come to me. Where camshaft sprockets bolt, was not torque down. BK2 sprocket spun, shearing the knock pin. Which knock pin, is the timing pin for camshaft to sprocket. It also pegs, sprocket in fixed position on camshaft. BK2 camshaft spun, to multiple out of time position, in relation to crankshafts. First a little more on each start and engine ran. later no start, just cranked and cranked, over and over again. No interference. Camshaft sprocket was found to be ~180 degrees off time.

The concern with the VVT 4.7. Is, it is an interference (make contact with piston to valve) engine. By using the camshaft to "T"s, and crankshaft to nipple on lower T-belt cover (crankshaft sprocket "V" to square) marks. The Camshaft lobs are not riding on high point. So no valve spring tension on camshafts. So no risk camshafts spin on their own, with just the slightest movement.

Once belt on. We can use other set (3 points) of marks to check timing. We have no risk of interference, with belt on. When timing marks line-up. Provided we don't mix and match time marks.

One thing I've not tried. Is have belt off and spin crankshaft on a VVT. Just to see if I get interference. With the spark plugs out. Crankshaft will turn without resistance of compression. If while then turning crankshaft, I felt any resistance. I could stop, and look into cylinder with borescope. See if contact made, which I think would happen. Since we do have cases of interference. With belt break or timed wrong, in the VVT engine.

 

[Rhetoric]

Ok, I’ve thought about this… One could spin the crank and cams independently as much as you like, as long as the timing marks correspond when the belt goes on it will be correct.

Sorry for the thread hijack, follow me for more dumb ways to overthink and waste time

This is definitely true for non-VVTi. But since the VVTi is interference, I would not try to rotate everything independently.

The fact that you have not felt resistance during your rotations indicates, to me, that you must be close. There is some amount of variance before valves make contact with pistons. At least in my experience with interference engine timing belt jobs.

 

[Jack90210]

I have a theory that even mildly sulfated batteries cause all kinds of problems down the road, not the least of which being that they give off hydrogen gas and corrode electrical connectors in the engine compartment.

I top off all of my vehicle batteries weekly with a tender or a charger. Many chargers will tell you how fully charged the battery is when you attach the charger; it's a good way of monitoring battery health -- and in my case, the frequent opening of the hood allowed me to see the crack in the top tank of the factory radiator before any damage was done.

 

[2001LC]

@2001LC. Curious if you ever resolved the rough idle issue (i think you had mentioned it in another thread). If resolved m, what was the fix?

YES and NO.

The NO first. Mid range:

I hadn't noticed before, but at ~2,000 RPM (not loaded). Timing is changing (advancing). I check against other VVT, also not underload (AT in P). While watching timing. They all have some vibration.

Also the VVT actuator may be sticking a tad. Making advance, a little less smooth. They should take care of themselves, with use and proper OF&L.

Yes: Rough idle was correct.

I found and correct, two primary issue. I felt help the most.

• Fuel pressure regulator, failed pressure test. I replaced it. Low mile mile issue we see. The FPR failure, is is likely due to prolonged periods of engine not run. Fuel bled down, exposing needle to air/rust.
• Charcoal canister was saturated (bad). I replaced it. It was very very likely due to overfilling gas tank, repeatedly. It very likely, ran very badly, on hot days for many years.

I had fuel injectors: tested, cleaning and rebuilding and testing again. They were good before (surprising) and exceptional after. Not typical, when engine not run for prolonged periods.

Also:

Cylinder compression balance was off a tad. Which can result in rough idle. Meaning BK1 a bit less even from cylinder to cylinder of 1, 3, 5 & 7 and overall lower than BK2. BK2, having higher readings and more even. But take note: It was second best compression I've seen. Best was, my 320K miles 03LX.

Which neither, have I rechecked, after: Decarbonization (EPR oil flush, 2x cans 44K in full gas tank and doing high RPM runs to cook-off). Each may have had some carbon buildup in cylinder and or in rings/grooves. So they numbers may have changed.
But my 03 w/320K miles, is highest and most even compression, I've ever testing in a 4.7L. Well broken in at 320K miles. Gets best MPG also!

High range, YES. For the most parts. But not 100 %.:

I had notice a wah wah wah at above 4,500 RPM, geared down on HWY high RPM run.

• Some of that sound, was front wheel bearing an axle bearings. I'll be talking about later. Bad service, unrelated to low mile issues.
• Some was AT was overfilled by more than 1 qt. Bad service, unrelated to low mile issues
• Some was bearing in pulleys front of engine and belts. This was age and to some extent low mile related

But sound was still somewhat there, after correcting above. I can only speculate. Others bearings (engine, AT, TC, diffs, rear axle) may needs some breaking in. That sitting prolonged periods may have left minor deposits on them, at points. That deposits should wear with use.

Additionally:

Correcting battery, clamps, fusible link and wire from it to fuse box. Would have given cleaner power to all system, most notable to fuel pump.

 

[GTV]

One thing I've not tried. Is have belt off and spin crankshaft on a VVT. Just to see if I get interference. With the spark plugs out. Crankshaft will turn without resistance of compression. If while then turning crankshaft, I felt any resistance. I could stop, and look into cylinder with borescope. See if contact made, which I think would happen. Since we do have cases of interference. With belt break or timed wrong, in the VVT engine.

The fact that you have not felt resistance during your rotations indicates, to me, that you must be close. There is some amount of variance before valves make contact with pistons. At least in my experience with interference engine timing belt jobs.

I rotated the crank independently of the cams enough that I would have encountered valve contact if it was possible. My guess is that interference would only occur at higher RPM's when VVTi is engaged and the valve timing is retarded.

 

[Rhetoric]

I rotated the crank independently of the cams enough that I would have encountered valve contact if it was possible. My guess is that interference would only occur at higher RPM's when VVTi is engaged and the valve timing is retarded.

That would make sense! My interference engine knowledge is limited to dumb diesels with no variable valve timing. When those hit, it's carnage.

I have made a case before that even the non-VVTi engines *could* have interference under strenuous circumstances, like high RPM or higher temps as parts expand slightly. Which is why I believe that Toyota printed this information. But, as a writer, I can say that documentation isn't always right for versions and versions of a release.

 

[2001LC]

I rotated the crank independently of the cams enough that I would have encountered valve contact if it was possible. My guess is that interference would only occur at higher RPM's when VVTi is engaged and the valve timing is retarded.

Well IDK! Since the VVT cams, only change timing. Advancing (IIRC) cam in relation to crankshaft. They don't/can't change reach of valve or piston.

IDK! Perhaps the "T" marks, have cam in a position. Where, no valve is fully open/extended.