4G64 Timing question.. and WOW how lucky am I?!

[Regedit024]

so i noticed there seemed to be quite a bit of slop in my timing belt a few days ago. i know on imports most people say oem is better but i went with the cloyes set, both belts, both tensioners, was $45 with tax and shipping. i rolled it around to the marks pulled the covers off and this is what i found!!

15201

now, keep in mind i only decided to change the belts because the one i could see with the top cover off seemed warn and loose!
amazingly the only gear on the timing belt that was off was the oil pump and it was only by one tooth, but talk about a ticking time bomb! i have no way to know how long the balance shaft belt has been broken, but im guessing since before i even got the truck.

so here are my questions.. what are the chances that anything was damaged internally by the lack of a balancer on that side of the engine for who knows how long?

and..

as you can see in the picture i dont have the spring type tensioner with the pin, i have the cam type.. how tight should these belts be?

[royster]

Jeeso-flip, what a mess!

I'm not sure any damage would have been done by the "b" belt shaft not operating...the more knowledgeable people can chime in on that one.

Be absolutely sure to clean the whole front of the engine up, I MEAN anal~retentive, so no particles take ferris wheel rides on your new belts.

I am unfamiliar with the cam-type tensioner...it looks like the pulley is actually on the tensioner itself. Never saw that before.

[geezer101]

Having a balance shaft belt blow on you won't cause any immediate damage to the balance shafts or bearings but if a balance shaft belt blows and goes through the timing belt path it can result in the timing belt jumping, and in turn valve train damage. My G63B runs a spring loaded timing belt tensioner . Timing belt should have 7-9mm of deflection from its path towards the edge of the oil pump housing (the long side of the belt towards the straight edge of the die cast metal) I'm going off the Haynes engine manual specs. Heed Roysters' warning on getting it clean - anything that can contaminate the belt will reduce its serviceable life. Also check the condition of your tensioner pulleys while you're fishing in there. Would be a shame to get a new belt on it only to find the pulley bearings are junk...

[royster]

Another helpful hint is to remove the grille and radiator for the belt exchange: it doesn't take that much longer, and your accessibility/view of the front of the engine will likely prove 'worth it'. Remember, also, the timing mark on the head is a metal bump, and not the top of the head.

15202

While your radiator is out, back-flush it upside-down and see if you find Jimmy Hoffa. Likely you have lots of gunk inside and on the cooling fins outside.

[DroppedMitsu]

You should be fine with the broken balance shaft belt, I doubt it hurt anything, heck a lot of people even get rid of the balance shaft belt. And I would definitely recommend changing all pulleys

[Regedit024]

thanks a lot guys for the info, and the tips.. i DID have the cam lined up on the edge of the head, went back reconfigured and everything works out way better, all the marks line up very well. two new pulleys and 2 new belts, and i did take out the radiator and the shroud, i learned that lesson long ago, the hard way, as in fan clutch into the radiator hard way ;)

havent really had time to finish up on the belt install, im still having a hard time finding concrete information on how tight i should make these belts, heck i cant even find the firing order for this engine. im starting to wonder if this is even the engine that came in the truck, anyone see anything in the pic that would make them doubt that this is a 4g64?

[geezer101]

Well, it's definitely a 4G6x engine - no mistake on that. What does the number on the block say? As for belt tension allow 7-9mm of deflection on the long side of the belt towards the oil pump housing edge (the die cast outer edge). Don't forget to check the belt tension after running it for a while.

[royster]

From my own build thread, I had the same question. Here is the reply:


The factory service manual doesn't state how much pressure to apply to the tensioner itself, just says "apply pressure" and then tighten the bottom adjustment bolt before tightening the top one. It doesn't need too much, just enough to seat the belt in the cam gear enough. Usually letting a new spring in the tensioner apply the pressure is enough.

Robert

[royster]

Also, you need to assure the oil-pump-side balance shaft is properly positioned: there is a "screwdriver test" to make sure it's correctly positioned. This procedure is mentioned in the service manual. If this hasn't come to your attention, you need to stop and look into it: the balance shaft can be off even though the mark aligns, because (if memory serves me well) there are two rotations-to-one on that shaft. The screwdriver test lets you know the proper positioning. Holler if you need more info on this.

http://www.mightyram50.net/vbulletin/showthread.php/2974-90-2-4-oil-pump-replacement?p=26684&viewfull=1#post26684

"Here comes another crucial point that is missing from my manual: the nut that holds the mysterious Silent Shaft. And the conspiring bolt that protects the Cave of Ali Bubba…he’s the redneck version of the Arabic story. Facing the engine, there is a bolt on the right-hand side, back there near the starter. This bolt is how you access the Silent Shaft secret society".

15212

"Remove the bolt, and try to get a phillips screwdriver into that hole. Dinner and drinks might work, with a few personal complements thrown in, but since the timing belt is off, it’s perfectly okay to turn the oil pump gear and get that shaft to turn. Get a feel for it: regardless of your heterosexual inclinations, you’ll be handling The Shaft a bit more during this operation. It’s okay: everybody does it, but no one talks about it. That's one reason it’s CALLED a Silent Shaft, based on secret society principles.

Place that bolt in the cardboard holder in that designated single spot.

Turn the shaft until the screwdriver goes all the way in, and when you turn the oil pump gear back and forth, you can feel it bump against the screwdriver. Leave the screwdriver in there, for now".