Truck took a few tries to start, now have knock/tapping noise?

[mrrsm]

The recommended Metric Oil Pressure Adapter suggested by @ littleblazer is made by Accel Auto-Meter Competition Instruments Part# 2268 and will require a careful pre-fitting with the Analog Oil Pressure Gauge Kits that have the better Copper Pressure Fitting Non-Flare design rather than using the ones with the Opaque Nylon Oil Line.

I realize that it is tiresome to imagine the Motor Mounts as being Right at The Top of The Circus of Central Casting as the cause and origin of the repeated Flex Plate failures… but if you do decde to change them out along with a brand new Transmission Mount… the best choice will be the GM OEM Part # 15062381 … and could cost a pretty penny, too at around $85.00 a piece.

Also... Your Proof of Flex-Plate Failure images show just how much Motor Oil has been leaking out of the Rear Engine PTFE Seal... and the need to hand polish away the offending Crank Journal rough spots for the replacement needed. The oil drops collecting on the Fasteners should encourage you that you do not have any Oil Consumption Problems from Burning or mis-direction into the Air Chamber via the PCV Hose...and that is all Good News.

As far as the method you have been using to tighten down the Torque Converter Bolts... instead of going through the Starter Motor Cavity to do this... Pull the Black Plastic Plug located in the underside rear of the Crankcase Oil Pan Flange...rotate the Flex-Plate by Hand to align the Three 120 Degree separated Torque Converter Bolt Holes with that unplugged opening...and afterwards, insert a 15 MM Deep Socket through that opening and with just a Dab of Loc-Tight on their threads, tighten them ALL down evenly first... then continue rotating the Flex-Plate and use a Torque Wrench to finish them off. The Mild Steel of the Flex Plate is easily crushed and distorted into ovals by trying to use Too Much Torque on those Ultra Hard 10.9 (Grade 8) Short Bolts. You can also use an H-10 Hex Socket if the OEM cleaned up TC Bolts are still in there... or stick with the 15MM Deep Socket as they will both work on the same Factory Bolts. It goes without saying that this is a laborious PITA as you well know... but this amount of attention to these details might pay off and solve the issue.

 

[littleblazer]

Motor mounts aren't all that bad to do I've learned

 

[mrrsm]

Paul... I have yet to find a decent Step-By-Step on the doing of what seems on the face of it to be a trivial job... but if you take the time to write that up in a separate How To Thread... I will be the very first to read and appreciate your experience with the task.

 

[littleblazer]

Paul... I have yet to find a decent Step-By-Step on the doing of what seems on the face of it to be a trivial job... but if you take the time to write that up in a separate How To Thread... I will be the very first to read and appreciate your experience with the task.

Problem was I didn't take any pictures... there is a write up on here somewhere and that's what I followed. It really isn't too bad. If you can pull the strut assembly you're 80% there. After that separate the upper control arm and then just support the block by the pan with a jack and a 4x4. Loosen the top mount nut jack up the block to loosen it/break it free. Then pull the three bolts on the frame for the mount and route it out. Its one of those you'll know when you see it deals.

 

[Mooseman]

Not a write-up but does have some info:
Motor Mount Replacement Issues

And using my Google Foo, found this write-up that I will add to the FAQ's.
https://gmtnation.com/forums/thread...trailblazer-the-relatively-painless-way.9833/

I knew there was one but I missed it when I was building the FAQ's.

 

[Capote]

The recommended Metric Oil Pressure Adapter suggested by @ littleblazer is made by Accel Auto-Meter Competition Instruments Part# 2268 and will require a careful pre-fitting with the Analog Oil Pressure Gauge Kits that have the better Copper Pressure Fitting Non-Flare design rather than using the ones with the Opaque Nylon Oil Line.

I realize that it is tiresome to imagine the Motor Mounts as being Right at The Top of The Circus of Central Casting as the cause and origin of the repeated Flex Plate failures… but if you do decde to change them out along with a brand new Transmission Mount… the best choice will be the GM OEM Part # 15062381 … and could cost a pretty penny, too at around $85.00 a piece.

Also... Your Proof of Flex-Plate Failure images show just how much Motor Oil has been leaking out of the Rear Engine PTFE Seal... and the need to hand polish away the offending Crank Journal rough spots for the replacement needed. The oil drops collecting on the Fasteners should encourage you that you do not have any Oil Consumption Problems from Burning or mis-direction into the Air Chamber via the PCV Hose...and that is all Good News.

As far as the method you have been using to tighten down the Torque Converter Bolts... instead of going through the Starter Motor Cavity to do this... Pull the Black Plastic Plug located in the underside rear of the Crankcase Oil Pan Flange...rotate the Flex-Plate by Hand to align the Three 120 Degree separated Torque Converter Bolt Holes with that unplugged opening...and afterwards, insert a 15 MM Deep Socket through that opening and with just a Dab of Loc-Tight on their threads, tighten them ALL down evenly first... then continue rotating the Flex-Plate and use a Torque Wrench to finish them off. The Mild Steel of the Flex Plate is easily crushed and distorted into ovals by trying to use Too Much Torque on those Ultra Hard 10.9 (Grade 8) Short Bolts. You can also use an H-10 Hex Socket if the OEM cleaned up TC Bolts are still in there... or stick with the 15MM Deep Socket as they will both work on the same Factory Bolts. It goes without saying that this is a laborious PITA as you well know... but this amount of attention to these details might pay off and solve the issue.

Yeah I'll be using Genuine GM motor mounts and a Genuine GM trans mount. Pricey, but they're the only ones that have proper resonance and work properly. My other motor already has an adapter for an Oil Pressure gauge fitted, so one less thing to do with that guy. I'm not gonna have this current motor in much longer, so not really worried about about installing an oil pressure gauge with this one.
I wasn't going through the starter motor cavity, I was using that hole with the black plug and rotating the flexplate manually to test all the bolts. That's how I've always done it, can't imagine trying to do that on our trucks. Its almost impossible to reach the starter as it is without all sorts of extensions or without removing the driver's side front wheel completely.

@littleblazer Easiest way I've seen is to lift the motor up with a jack after you've loosened the engine from the mounts. I know one side has some trouble going in when installing the new mounts; and said mount may need to have a stud ground down or cut a bit down to fit. That's if you cannot lift the engine up anymore to get the clearance needed to install it.

 

[littleblazer]

Yeah I'll be using Genuine GM motor mounts and a Genuine GM trans mount. Pricey, but they're the only ones that have proper resonance and work properly. My other motor already has an adapter for an Oil Pressure gauge fitted, so one less thing to do with that guy. I'm not gonna have this current motor in much longer, so not really worried about about installing an oil pressure gauge with this one.
I wasn't going through the starter motor cavity, I was using that hole with the black plug and rotating the flexplate manually to test all the bolts. That's how I've always done it, can't imagine trying to do that on our trucks. Its almost impossible to reach the starter as it is without all sorts of extensions or without removing the driver's side front wheel completely.

@littleblazer Easiest way I've seen is to lift the motor up with a jack after you've loosened the engine from the mounts. I know one side has some trouble going in when installing the new mounts; and said mount may need to have a stud ground down or cut a bit down to fit. That's if you cannot lift the engine up anymore to get the clearance needed to install it.

Yea, that's how I did mine. Just one side at a time. Time was ~2 hours

 

[mrrsm]

You peaked my curiosity about the possible causes of the Rear Main Seal leaking and three sites came up with some surprises that might catch your interest:

This first one comes from the GM Engine Builders folks and on pages 2 and 3.. they describe a problem with leaking around the rear crankshaft seal on the GM 4.2Lengine covering your 2007. Apparently the "In House Fix" they came up with involves an obscure modification using what they describe as a "cup" and shows images and describes the full installations "Do-s and Don't-s". They also address the subject of a marred end of the Crankshaft Flange and the need to "sand it down", etc... So FWIW... this PDF has the Dope on the problems they identified:

http://www.enginebuildermag.com/wp-...alIssue/02_01_2008/3555GM1pdf_00000005694.pdf

This next one might prove VERY Helpful to you.. as long as you can figure out all of the dimensions of the Crankshaft Flange using very accurate measurements that may be quite different on your particular 2007 Motor and because of the sheer size of the OD and thickness of that Flange... the Micrometer will have to be quite large. If you DO find the right Speedi (Micro) Sleeve hidden in this PDF to affect this repair... THIS will turn out to your BEST Crankshaft Repair Option:

http://www.skf.com/binary/21-128020/11337_2-EN-SKF-Speedi-Sleeve.pdf

...and this last one involves describing all of the Flaming Hoops of Fire that the GM Dealerships have to Jump through to get anything done on warranty work deemed necessary enough to get VERY involved and consequently... very expensive for the Dealership if they can't pass along the costs for these repairs to the customers on legitimate and necessary warranty work.

https://gm.oemdtc.com/6241/99-00-89...n-2017-and-prior-gm-passenger-cars-and-trucks

 

[Capote]

It's an '04 engine brother. I'm not worried about the rear main seal on this one, it's leaking because it wasn't properly seated. My main focus is just to replace the flexplate up until work can be started on the Turbo motor. That motor will have all new internals.

 

[Sparky]

I replaced my starter on my 02 from the top when it went bad. Popped the hood, reached down, and went to work.

Helps I have skinny arms lol.

 

[Capote]

I replaced my starter on my 02 from the top when it went bad. Popped the hood, reached down, and went to work.

Helps I have skinny arms lol.

Can't reach it at all. The bumper sticking so far out doesn't help, makes it awkward leaning over the truck to do anything.

Replacing the flexplate Sunday at Brandon's house. I may try to drive it there, not sure yet. I drove with my other one cracked to all hell a whole week to work before I realized what it was.

 

[Sparky]

Ah, you don't do it from the bumper side. I reached in over the driver side fender.

I'd be scared of it coming free and launching itself. I've seen pictures of flywheel damage if they break apart. Blown up bellhousings, torn through floorboards, cowls shredded...

 

[mrrsm]

When the 4L60E is finally removed... it might be wise to slide off the Torque Converter from the Transmission TC Pump and examine the “O” Rings on the Shaft for tearing damage ... and perhaps even eliminate the TC issue as playing any part altogether by getting a new one if possible... while things are all apart and the Getting is Good.

 

[Capote]

Ah, you don't do it from the bumper side. I reached in over the driver side fender.

I'd be scared of it coming free and launching itself. I've seen pictures of flywheel damage if they break apart. Blown up bellhousings, torn through floorboards, cowls shredded...

Hard to reach anything low in the engine bay no matter what side you're one. I haven't decided how i'm gonna get it there 100% yet.

When the 4L60E is finally removed... it might be wise to slide off the Torque Converter from the Transmission TC Pump and examine the “O” Rings on the Shaft for tearing damage ... and perhaps even eliminate the TC issue as playing any part altogether by getting a new one if possible... while things are all apart and the Getting is Good.

We've already planned on removing the transmission pump and replacing the bearings.

 

[Capote]

I was totally wrong, I was seeing a chipped portion of the crank that connects to the flexplate. I forgot it had a distinct knick in it from my original broken flexplate doing some damage to it. Wasted a lot of time dropping the transmission. This thread can be closed, will not be driving the truck until I swap my other 4.2 motor in.

 

[Blckshdw]

As requested