Need experienced advice

[kchaazz]

First off, I wasnt really sure where to put this, since there isnt an "Oh $H%T" subforum. Long story short, Im working on a 6G72, SOHC engine. When I went to remove the hydraulic tensioner, one of the two bolts snapped off flush with the block. Now, the hydraulic tensioner bolts to this motor exactly the same way it does on the 4G63, which is to say that it utilizes two 8mm bolts, identical in length and design to the 4G, and also both bolts pass through the aluminum front case before threading into the engine block.
Now, I really, REALLY dont wish to pull the front case off this thing to attempt to remove this broken bolt, and Ive got an idea for an easy fix, however, Id like to run it by everyone who's inclined to take a look before proceeding. Here goes: I am of course aware that there is tremendous force being placed on the two tensioner bolts, however, they are still only 8mm, and since the bolts must pass through the front case to go into the block, and one of the bolts is still good, Id like to try the following:

1. Drill one of the mounting holes in the hydraulic tensioner body to allow a 10mm bolt to pass through

2. Leave the broken 8mm bolt in the block, were going to bolt the tensioner to the aluminum front case by way of the following: Drill and tap the through hole in the front case for 10 x 1.25 and use a 10mm bolt in that hole.

Make sense? Is this a good idea cause it will save a few hours work and shouldnt cause any trouble, or is it a terrible idea??

 

[RobertTheArchitect]

if you are willing to drill into the broken bolt, there is bolt removers that are basically a reversed tap.

what you will have to do is carefully grind down the broken end a little concave, be carefull not to generate too much heat as to not weld the broken bolt to the block. next use an air hammer of something to make a center mark so your drill bit wont slide. bore a whole into the broken bolt maybe 1/4" or 3/8" in. use the bolt remover to back out the broken bolt. finally use a tap to clean the threads before assembly

 

[livedsm4g63]

They are called EZ-Outs.

If your welding is good, weld something on the end. Just an idea.

 

[kchaazz]

Well, thats exactly what I will do if I have to, but Id most certainly have to remove the front case to do that, and Im trying to avoid removing the front case by tapping the front case. Here are some pics to better illustrate:

Clockwise from left, first pic is what you see on the front of this motor. Second pic is of the front case/oil pump, and circled in red is the shouldered hole I intend to drill and tap to 10x1.25 thread. Third pic is the tensioner body, and again circled is the hole on this part I intend to drill to allow a 10mm bolt to pass through

 

[RobertTheArchitect]

you can do what you wish if you are willing to accept the risks, but changing the engineering specs around the timing belt design along with not being able to torque the right grade bolts to spec may lead down the road to a broken timing belt which will blow the engine. If you are willing to accept that risks over a few hours of your time then sure do it

 

[kchaazz]

Indeed, it can be risky, however, a 10mm bolt is far stronger than the 8mm bolt I would be replacing it with. The only down side is the fact that this bolt would no longer be threaded into the block, theoretically diminishing the support of the front case, but once again, this front case is actually braced very well as the thing from top to bottom is literally sandwiched between the block, a 2" thick aluminum girdle, and then the pan is on the bottom.
I really am considering just pulling the thing back apart though, or trying first to remove the broken bolt without pulling it apart, though having over an inch of shoulder to go through before getting to the bolt may make extraction impossible without pulling the case

 

[kchaazz]

Great news, Bogus SVO came over, stuck a chisel in the hole and hit it with a hammer, putting a notch in the end of the broken bolt, then worked the thing out with a screwdriver. Took him 20 minutes. No pulling the motor apart, no drilling/tapping/rigging- Best machinist, broken bolt extractor I know!

 

[brane_97talon]

Awesome man, teamwork makes the dream work!