7MGTE Broken Timing Pulley Guides - Possible Fix??

[755hp]

What's happening guys. Alright so this is just straight BS! I heard a grinding noise coming from the front of my 7M (sounded like it might have been the belts); then I listen closer and it was coming from inside the timing cover. So, I pulled off the timing cover to find that my belt was slid forward as if the guides on the timing pulley were not there.

I then proceeded to pull apart my timing belt, harmonic balance, etc and....sure enough, my 7MGTE timing pulley outter guide/ring broke off....again.

I had this issue with the original part (June 2014). I replaced it LAST YEAR with a brand new part from Toyota for $63. Along with doing a massive headgasket job in April 2015, I installed a Gates Racing timing belt as well as a new tensioner. And here it is the timing pulley guide broke off a year later and chewed up my brand new Gates Racing timing belt as a result. It left belt shaving (outter side) all around the timing cover areas and even wore a groove into the inner side of the second timing cover. You can see the path of where the belt ran along the inner side of the second timing cover:


Broken 7M Timing Pulley guide/ring:


How it should be/seat:



And so, I've come to a conclusion....I am tired of this life.

As a result, I'm thinking to weld on the guide/ring to the timing pulley as a possible fix. Cause honestly, I don't feel like spending another $63 (now $66) for another brand new Toyota timing pulley and then it breaks in the near future again. I'm thinking to go to my school's engineering machine shop and have them place 4 tack-welds 90deg apart from one another around the outter side of where the ring guide seats (it will be away from the threads and notch for the crankshaft):

I've seen a similar thing done to the 2JZ engine's crank timing pulley. This is a photo of a Modified 2JZ Timing Pulley done by Titan Motorsport where they placed welds as shown to combat against pretty much the same issue. I'm guessing I can apply this to the 7M, no??

Question: The only thing I'm worried about (but not sure) is will the heat from the welds warp the timing pulley a bit and then it won't slide/fit onto the crankshaft anymore?? What do you guys think?? Or should I just shell out another $63, oh wait, $66 for a brand new one....that will probably break any damn way, again??

Let me know what you guys think of this idea; I'm sure I'm not the only one who has had to deal with this issue, so here's a thread with a possible solution/thought.

Thanks guys, much appreciated

- 755hp

 

[SeeUSmile]

far out.... first time I've seen this. Only thing that comes to mind for me is the pull-type clutch factor from the gearbox perhaps ? but don't know how everyone else is doing fine with it :S

 

[akito]

This literally happened to me last week. Idk if you're on the FB page but I posted this and my fix (another OEM gear pulley) This definitely raised concerns for me because I bought an OEM one from the dealer, although I paid $80 for mine -__- I installed a new gates belt and the pulley. IDK if there's an aftermarket reinforced unit I hope mine doesn't go out annually...

 

[3p141592654]

Could it be the Gates belt? Seems like you have that in common, and I haven't heard this being an issue before.

 

[755hp]

Alright guys, so I've found my solution to this whole thing today.

So I went to my school's engineering machine shop and told/showed one of the shop guys what had happened to my crank timing pulley. I told him that I'd like to weld the guide/ring onto the timing pulley. And so the guy agreed and said first, I need to fit the guide/ring onto the timing pulley and then he'll weld it. And so, I took some sand paper to the inner side of the guide/ring to take off a bit of material just so it would fit onto the timing pulley again. After fitting it up, the guy ask if I was ready and I agreed.

Okay, so you'll the BS that happens next.

So the guy gets his welding suit/gear ready, aligns himself to weld and starts....then he stops. What happened?? He says the damn thing is CAST IRON and thus, it is hard/difficult to weld. I could have sworn this part was steel; cast iron for our crank timing pulleys?? If I were Toyota, I would have had this part CNC'd from a block of forged steel. But then again, that's probably not feasible in an application for high number of parts; and even so, it would be damn expensive in manufacturing costs. Sigh, nonetheless, okay, so I try to accept the part is Cast Iron and a bit/tip/notch of the material has just melted away (except for the guide/ring which was steel apparently) so plan B; he suggests to take a center punch to it to try and fold the edges over so it will keep it from coming off. And so, I begin with the center punch on a steel table however, the part kept moving around. Here's where it gets good....I then placed my timing pulley in some vise-grips to keep it from moving around....bad idea. As I took the center punch to the edges, the shock traveled through the part and dented the other inner guide/ring. So now I have two loose guides/rings and one is dented from shock.

I am tired of this life.

As a result, one can only conclude the following...


Sigh, take care

- 755hp

 

[akito]

Could it be the Gates belt? Seems like you have that in common, and I haven't heard this being an issue before.

No, because this is my first time using a gate's belt on this motor. The belt I used when I built this block in 08 as an OEM timing belt. The belt i'm using now is a Gates replacement of the OEM unit, not a Gates performance blue belt like 755hp's belt.

755hp - Was your last unit an OEM unit from Toyota?

 

[Suprapowaz!(2)]

Mine separated like that when I was disassembling my motor. I'll have to buy a new one.

 

[3p141592654]

Seems like something is causing this. A brand new pulley that separates in less than a year is not normal.

 

[755hp]

755hp - Was your last unit an OEM unit from Toyota?

If you mean my timing belt, then yea, I believe it was (I'm the 4th owner of my Supra; car was completely stock when I got it); definitely not a performance belt of any sort.

 

[cinderMK3]

Is it possible the tension pully slightly off causing it to ride along that lip eventually leading to failure? I know its only one bolt holding it level, maybe a worn edge of it?
Or weak bearing?

 

[755hp]

Is it possible the tension pully slightly off causing it to ride along that lip eventually leading to failure? I know its only one bolt holding it level, maybe a worn edge of it?
Or weak bearing?

Don't think so, its a brand new belt and tension; just installed in April.

 

[akito]

If you mean my timing belt, then yea, I believe it was (I'm the 4th owner of my Supra; car was completely stock when I got it); definitely not a performance belt of any sort.

\

Sorry I didn't clarify, I meant to ask if your replacement gear puller was an OEM unit from Toyota.

 

[755hp]

\

Sorry I didn't clarify, I meant to ask if your replacement gear puller was an OEM unit from Toyota.

Ohh, okay. Ohh yea, for sure; got it from ToyotaPartsZone or VillageToyotaParts last year in June (can't remember which one).

 

[755hp]

Alright guys, so after that unexpected failure of trying to fix the first guide/ring and having the second one come loose in the process, I pretty much just gave up on Monday (emotion/frustration), stayed in my house the whole week, board as hell searching for engineering jobs, playing video games and watching porn as I didn't have a running a car to go/do anything else; I was about to buy a new one but then....I realized I'm broke (cause I finished my pocket on a Spec Stage 2 clutch which finally came in today). After feeling mentally exhausted trying to deal with the whole situation (after all, I replaced this thing LAST YEAR), I decided on Thursday night to give it one more try on Friday in the shop. And so, I did and....I got it!!

So, to pick up where I left off, basically, the second guide/ring came loose as I was hitting the other guide/ring from the top with a center punch/hammer (the second guide/ring was siting on top the vise grips which took the shock). As a result, I now needed to fix BOTH guide/rings. And so today (Friday), I went to my school's engineering machine shop again and asked to use one of the "flatblade/tip" chisels along with a hammer to hit/fold the material over on the inner guide/ring of the timing pulley. The shop assistant then suggested I place the timing pulley horizontally in the vise grips and hit/hammer it from the side; and so, I did. Having a very thin flatblade/edge chisel really is key here cause, there is not much material (lip/edge) to place/set the chisel on the pulley in order to strike/fold over the material onto the guide/ring. Here are some photos of the finished result for the inner guide/ring:

**Keep in mind, you want to use brass jaws on the vise grips in order to hold the timing pulley and place it horizontally (vise gripping it from the front face to the back/top side or face before the outer guide sits; this reduces the shock from leaving dents on the timing pulley when striking/folding over the edges** I tell you this so you refrain from being a bum and f**king your part like I did last Monday (steel jaws, held vertically instead) which left me in this very situation with the second guide/ring. Heed these words as I speak them to you....as they are the truest of them all.







Although my issue (originally) was with the outer guide/ring, the inner one is now seated on tighter than Toyota's press/fitment when manufactured; however, I had a thought about that which I'll get into below. First, here are some photos of the outer guide/ring (top side). You'll see where I began (lol) cause, there are too many marks/strikes on one side as oppose to where the shop guy placed the marks to finish the fitment in a 360deg pattern (he felt only a few were needed; same points where Toyota applied notches):





As a result, the top side was completed (now both sides) and the guides/rings were tight/reinforced stronger than what Toyota had originally placed together. NOW....that brings me to another thought. If you look at the last two photos, you'll see some dimensions written on the top side of the Timing Pulley. That was placed there from the shop guy as he took a micrometer to the inside of the timing pulley to measure its diameter. The resulting measurement/numbers are what you're looking at; inches on top, millimeters on the bottom. He raises a good point here... The reason he took these measurements is to compare them to the crankshaft dimensions (which of course did not get measured as it was still in the car at home; mics were not taken out of the shop). However, he was really concerned that my belt had a tendency to wanna walk/come forward with such force that it would break the outer guide/ring.

He then asked me, how I took off my timing pulley; basically, he asked if I used a puller to remove the timing pulley. And as you'll learn now, I told him "no, I didn't". I explained to him that for some reason, my harmonic-balancer and timing pulley always came off easily by using (with a bit of force) my hands and no puller. As a result, he then explained that there is a reason a puller is needed to remove and press these components on (at least the timing pulley). The tolerance between the timing pulley and crankshaft are so tight/minimal that it requires a bit of a press fit. This would keep it from walking/sliding forward or backward. And, in a case the timing pulley DID walk/slide in either direction, the belt would want to follow; this is because the timing pulley has the guides on both sides catching/pulling the belt with it. However, if the timing pulley walked too far, it would place too much force on the guides stressing them to a point of breaking.

This would make sense....theoretically seeing as my timing pulley didn't ever need to use a puller to remove it....in other words, it can slide with minimal force than usual allowing the timing belt to walk where the pulley slides. Possibly not good, right?? But yet, there is quite a bit of tension on the belt (perpendicular to the crankshaft....liking a bending-moment) so how and where would the timing pulley get enough force to wanna walk/slide given the tensile force/load on it, right??

My Thoughts: Here's where I had a thought to add to this... What if Toyota was so "brilliant", brilliant enough to design the timing pulley guides in such a way that after a certain amount of stress/force is applied to them from the belt, they break off. And if they break off, that should then signal you have a problem with the alignment of your timing belt/gears---look into the source and fix the main issue then replace the timing pulley. Otherwise, IF the guide/rings were fitted so tightly to the point they would NEVER come off, how would one ever know the alignment of their timing belt/gears are off?? How would you ever know....the guides are ALWAYS strong, they are ALWAYS there to protect the belt and they ALWAYS keep it in place....how would you know?? Until....the alignment gets REALLY bad to the point where the belt wants to snap due to bad alignment partially at the top (coming off cam gears only and rubbing against cover), right?? And here it is, I just tightly reinforced the guides/rings and have not corrected the main issue that may have caused this in the first place... Think about it....before you start looking at me like I'm crazy, think about it....Lol.

Who knows....who knows. I might be thinking a bit too deep on the subject matter. But I'd like to think that Toyota IS "brilliant" in their engineering/design of their cars and that the quality/fitment of these 7MGTE 6M timing pulley guides/rings ARE loosely fitted, on purpose....not by bad manufacturing/assembly/design.

In any case, I took the car out of a test run, drove around my college campus, drove on the highway and even ran side by side hitting it here/there with a Nissan GTR (as well as an E92 M3 behind us, Lol) and yet....she's holding up great so far (with no grinding noise from the timing pulley either of course). Hey man, look....the timing of an engine is no f**kin joke; get it wrong and your shit will easily become a bomb in milliseconds (e.g. your exhaust valve doesn't open after combustion stroke....ptsss). I'm not suggesting everyone try this as solution; its what I reason'd and tried for myself. Thus, proceed at your own risk/choice....I take no responsibility for bums and the following consequences.

And so, this is just my 2-cents on the whole subject matter and my concluding "SOLUTION" (purpose of this thread) to a "7MGTE Broken Timing Pulley Guides"; this is "my" version of a "possible fix". Lol

Long live the boost'd one, take care

- 755hp

 

[SeeUSmile]

dam photos are taking long to load. I shall follow up on it after. Glad to hear you got around the problem

 

[3p141592654]

Mine came off without a tool and that was in 2006. Many miles since then. But I think you have the right idea. You are looking for something that is out of alignment. Look at the crank snout for any damage to keyway, or indication of movement of the pulley.

 

[GC89]

I wouldn't feel comfortable stressing the pulley like that with all those punch marks. Also welding cast shouldn't be an issue for an experienced welder unless toyota used some very inferior alloys.

The best solution obviously would be to have a billet one cnc'd. I would also look for anything that could be causing alignment issues. make sure to not only check the crank for signs excess wear, but also the cam pulleys and oil pump drive pulley.

I haven't seen this as a wide spread problem and believe even Duane and some of the other high power guys are on stock units. If anyone would have found the issue and addressed it, he would have.

 

[andrew_mx83]

C'mon, do you really think that Toyota would just leave the pulley to free float on the crankshaft and have some magical way of moving back and forward to align the belt? The T belt pulley bottoms out on the #1 main bearing journal, and the serpentine belt pulley bottoms out on the T belt pulley. The crank bolt pulls the whole lot up tight so none of it can move back and forward. The only way that could have happened is if your crank bolt wasnt installed or wasnt tight. Or, excessive thrust bearing wear i guess.
Look, i even took a picture in case you dont belive me

Oh, and FYI, the pulley is sintered metal, not cast iron. Similar in that it is a powdered metal but they are formed under pressure and much stronger/better tolerances than castings. All oem's use sintered metal pulleys on their timing belts, and they go for millions of miles with no wear. No need to go cnc'ing up big billets here. The obvious trap would be to cnc it out of aluminium, then you get pulleys that wear away fairly quickly like those good old hks cam pulleys
You can also TIG to these pulleys without much problem, but peening it over as you have done it is the way to go.
The rings do come off from time to time, it happens. Ive seen a couple. Usually due to poor handling IMO, knock that lip around too much and you'll disturb the peen marks and maybe even the press fit.


Dont stress too much about the sliding fit of the pulley on the crank, unless its sloppy. Ive pulled apart dozens -some are a tight, almost press fit and some are loose sliding fits. The trick is to apply a smear of oil of grease to the inside of the pulley bore on installation, then you dont have a hard time getting it off in the future as they dont rust together. As you can see from the pic above, none of it is going anywhere so the fit here is purely to keep it all concentric and not critical that its some super duper press fit.

 

[CyFi6]

A much more likely cause of this issue in my opinion is a cylinder head or cylinder block being resurfaced off-flat, or at an angle. Any longitudinal tilt of the cylinder head is going to cause the belt to ride to one side.

One possible solution is to add a washer with the inner diameter equal to that of the crankshaft, and an outer diameter equal to that of the outer diameter of the ring. When placed between the timing gear and the harmonic balancer, the washer would be sandwiched tightly, preventing the ring from being able to come loose. The harmonic balancer would need to be machined (engine side) by the same amount as the thickness of the added washer in order to retain the proper belt alignment on the harmonic balancer. This of course only solves the outer ring issue, the inside one could still potentially come loose.

Like Andrew said, everything is tightly sandwiched in there by the crank bolt, there's no way it is going to slide along the shaft in use. I pulled mine off with hand tools as well.

 

[akito]

Both mine crank pulley and timing gear came off easily. Crank keyway is in perfect condition. Although what you said 755hp makes sense but I think everything is fitted without much tolerance for the belt to start moving and in terms causing the ring to break off of the pulley.

"A much more likely cause of this issue in my opinion is a cylinder head or cylinder block being resurfaced off-flat, or at an angle. Any longitudinal tilt of the cylinder head is going to cause the belt to ride to one side" -- CyFi6

^^ this makes sense and i've heard it's possible but idk if there's any documentations.