7MGTE Broken Timing Pulley Guides - Possible Fix??

755hp

Goal - 755hp
Jul 19, 2012
164
0
0
Tri-State Area & MI
andrew_mx83;2055308 said:
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 :)
IMG_20150801_195253971.jpg


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.
Well said, well said....clearly this man has been trained well. Lol

I did not stop to think for one second that the harmonic balancer bottoms out onto the timing pulley. That would make sense (regardless of the #2 timing cover being in between them--there is a hole allowing them to contact) cause the crank bolt is torqued to 195lbft. And with everything aligned on the crankshaft, it would HAVE to place resistance on the torque of 195lbft; as a result, not a damn thing is sliding ANYWHERE.

Sigh....shiet, I missed that one hard.

Alright, next the materials used: Well one of the shop guys attempted the welding at first, so maybe his skills are not up to par?? I don't know. I just took his word for it when he said it was cast iron and couldn't be easily welded (in our shop). But this clears up how Titan Motorsports were able to weld the 2JZ timing pulley guides together (if its the same material); at first, I figured that would have been the best solution. Nonetheless, looking back on it, I prefer the "peening" over material method cause my only concern is the heat from welding warping the timing pulley (slightly) enough where it would be hard to fit back onto the crankshaft again (probably not that much of an issue). However, I'd imagine if the harmonic balancer is suppose to contact/bottom out onto the timing pulley then those welds might need to be sanded down so its flush with its top surface for a proper contact from the harmonic balancer....or maybe the harmonic balancer has a smaller diameter where it contacts slight inside/away from the welds?? Either way, I think the peening over method is better; if anything, its similar to what Toyota did.

But eh man, you shed some light on this subject matter and cleared up some misconceptions....much appreciated.
 

755hp

Goal - 755hp
Jul 19, 2012
164
0
0
Tri-State Area & MI
CyFi6;2055319 said:
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.
Com'on man don't tell me that....you got me thinking some crazy thoughts now. I just got done doing a headgasket job in April where I sent my 7M head off to be resurfaced. Are you telling me....that....no, no, lets not go there. Lol

Furthermore, I had this issue in June 2014 when I was replacing all my seals in the front of the engine (both cams, oil pump drive and front main seals). When I went to replace the front main seal, I found my original timing pulley outer guide off/broken. I replaced it with the one you guys are seeing in the picture....and then I here a noise, checked it and now that one went to shit. So lets just hope the head not being leveled is not the issue here. And seeing as when I did my HG job this past April, I pulled out STOCK HEAD BOLTS. Lol, and seeing as I'm the 4th owner of my Supra and got it completely stock with 105k on the odometer, I don't think anyone has done the HG before me (head was never machined). Its only a guess but given the results/situation, that's what I'm thinking.
 

755hp

Goal - 755hp
Jul 19, 2012
164
0
0
Tri-State Area & MI
akito;2055340 said:
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.
Lol, com'on man, you know I just did a HG job last April from my other thread....and the head was resurfaced of course....let's think positive man, please. Lol
 

CyFi6

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You can still check it with everything together. You just need to get a dial indicator on the front of the crank and find a way to pry the crank in and out of the block. You can carefully pry on the pulley to bring the crank forward, and if you have an R154 transmission which uses a pull type clutch, just press the clutch to pull the crank the other direction. If your thrust bearings are worn significantly it would allow your crankshaft to move in and out which would obviously cause alignment problems with the timing belt.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=71


If you don't have a dial indicator it can be done with feeler gauges though would be more difficult and harder to do accurately.