The ol' Tahoe is down for the count - coolant in cylinder(s)

The instance of poor quality converter rebuilds is not a new one.
Proper jigs and fixtures are the key to producing quality parts...

When you get the converter out.....IF you can get access to a lathe that can swing it....grab the converter by the hub and gently clamp it..

Rotate the converter slowly by hand and observe the pilot on the front of the converter.

Also watch the entire outer rim of the converter for run out.

Before installing the replacement.....check it for run out as well

This sort of crap just sucks....

What brand of rebuilt .?????????

Rebuilt converters do not always get a fresh hub welded on.....If the hub surface is good they get used again.

So it's a crap shoot.

Well done Casey! Glad to read that it is up and running again!

So with the slower spooling of your Hx35w with new converter, do you feel any additional power or loss of power or is it about the same? Any difference with boost levels?

If you want a spare flex plate or starter, I have a few extra ones. Send pm if you do.

6 months after blowing the head gasket, the ol' Tahoe is finally back on the road!

I replaced the defective torque converter, and now FINALLY everything is working like it should! The engine is running great, the torque converter is the correct stall speed, and there are no more vibrations! Hallelujah, praise the Lord!!

To recap:

July 2021 - the original 929 engine blew a head gasket after 378K miles.

I decided to rebuild a spare 506 engine I had pulled from a 1997 C2500 several years ago. That engine had lost compression due to a failed exhaust valve, but otherwise was in great shape.

November 2021 - engine is finally rebuilt and installed; I had decided to rebuild the transmission as well due to the high mileage; new engine ran great, but the transmission shop gave me a high-stall torque converter by mistake; very annoying to drive, so I order the correct torque converter.

December 2021 - after only 900 miles, the new engine lost compression on one cylinder; turns out another exhaust valve failed; apparently this engine had weak valves; engine was removed, and both heads sent back to the shop for all new valves. I used this opportunity to swap in the correct, low-stall torque converter.

January 2022 - the engine is reinstalled and runs great; however now there is a bad vibration that I determine is a faulty torque converter. The converter supplier sends me a replacement converter, and this time I drop the transmission and transfer case to swap the converter. The replacement converter is good, and now everything is running like it should!

So, the engine was removed and reinstalled twice, and the transmission was removed and reinstalled twice. I am so ready for this project to be done! But at least now I should have a long-lasting drivetrain.

Casey

Well done!

SWEEEEEEEEEEEEEEEEEEEEEEEEET.....

So sorry you had to go through such a torturous path to get there.....

The Blazer should be good to go for many years now...

Good job.....And I know how you feel......

I hate it when you are working on something...
And you get so familiar working on it that you recognize individual fasteners,and when the power goes out you just keep on keeping on
Glad you have that behind you and you can enjoy your cool truck for years to come

Thank you all! I'm so glad to finally be at the point where I can enjoy driving it again without worrying about that one thing that still needs remedied.

Quote:

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Originally Posted by Yukon6.2

I hate it when you are working on something...
And you get so familiar working on it that you recognize individual fasteners,and when the power goes out you just keep on keeping on

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So true! I know where every nut and bolt belongs on this rig! I can identify every single fastener now and tell you where it goes...

Casey

Good job Casey... for sticking with it. :cool:

How's that saying go? "A job worth doing is worth doing two (three?) times..."

No... That can't be it... :rolleyes:

Glad to hear that you have it dialed in again. Here's to many miles of open road for you and the Tahoe!

Quote:

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Originally Posted by trbankii

How's that saying go? "A job worth doing is worth doing two (three?) times..."

No... That can't be it... :rolleyes:

Glad to hear that you have it dialed in again. Here's to many miles of open road for you and the Tahoe!

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Ha ha!

Thanks guys! I'm actually getting to enjoy driving it for a change!

Everything is going smoothly (knock on wood). I think I need to figure out a way to set the timing; I suspect it might be a tad retarded. Last time I set the timing, I had a buddy who was a GM tech who brought home a Tech II for me to use, but now he moved to Alabama. I don't know anyone else with the correct tools....

Casey

If the timing is out of spec the computer will start screaming (CHECK ENGINE LIGHT ON)
Whatever it was set to before you did the rebuild will be stored in the computer and come back up and go to work.....

If the actual position of the IP is off so far that the computer can't achieve the desired timing it will set a code...

If the light is not on....you are where you were before.....

What has lead you to believe the timing is off ?????

A lot changed in the engine since you rebuilt it.....Fresh injectors for one.....

Quote:

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Originally Posted by Robyn

What has lead you to believe the timing is off ?????

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The engine doesn't have has much diesel clatter as I would expect, and the idle is just a little rough; not as smooth as I would like. When it's cold and the timing is advanced, it runs more like I think it should.

It's a different engine, with the front timing cover and pump from the original engine. I scribed the pump to the front cover before removal, so it should be pretty close, but I just assumed it's not spot on.

Casey

Hmmmmm

The timing "spot on" is controlled by the computer....Moving the pump physically will not change things unless you go outside what the computer can adjust things....then the SES light will come on due to the timing being "out of range"

Injector POP PRESSURE can have a big effect on "Diesel Rattle" and depending on variations in the POP it can cause slight roughness in the idle as can other injector issues such as the spray pattern....A poor or odd spray can cause roughness too.

Were the injectors new or rebuilt ???

Quote:

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Originally Posted by Robyn

Hmmmmm

Were the injectors new or rebuilt ???

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Brand new Bosch

Stock timing is fairly tame (retarded). Was the TDCO ever optimized (-1.50 to -1.94)? If it was, it may not be, now. You can turn the pump toward advance a little at a time. Stop and back up the tiniest bit when the computer complains.

Quote:

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Originally Posted by DmaxMaverick

Stock timing is fairly tame (retarded). Was the TDCO ever optimized (-1.50 to -1.94)? If it was, it may not be, now. You can turn the pump toward advance a little at a time. Stop and back up the tiniest bit when the computer complains.

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Yes it was, years ago. I wasn't sure if advancing the pump would actually accomplish anything or not without having the computer relearn the new position.

Casey

1mm movement at the pump flange's scribe line equals about a 2 degree change in timing. Sarah's Blazer is a little bit advanced from where it could be. I tried to line up the scribe lines during the install. I may leave it there... I dunno. Or I may have a TDC-Offset performed using the -1.5-1.94 setting Greg mentioned... assuming I can find someone with both a Tech II the skill to do it.

I've also thought about just retarding the pump a smidge at a time (<1/16") till it sounds familiar. I think it'll work that way... without redoing the TDCO. It's easy enough to try. Robyn may be right, but it's been a while since I've studied the process.

I am pretty sure that the actual timing is done by the stepper motor in the DS4 and the computer places the internals of the pump where it needs to be to accomplish the setting.

If you rotate the pump itself and the computer can't get the desired setting then it will complain.......At the factory ....I am told that the IP is placed in a "Given physical location" that will allow enough internal movement for the electronics to achieve the desired settings.

Scribing the pump and the cover will get things close enough so the computer can do it's job and not complain......This will allow the pump to be removed long term during a rebuild and then go back to work without a hitch.

I have never seen the actual fixture used to align the IP on the DS4 with the cover.....but there is one.......

Yes, just rotating the pump won't change the timing. If it seems too advanced, that's where the PCM wants it, and it's probably correct if near OEM position. The PCM compares the crank and cam (pump) sensors, and times accordingly. That is, unless the pump is moved to an extreme the stepper can't compensate past, and the reason TDCO optimization works, by rotating the pump to the advanced extreme either before, or to the limit of compensation (-1.94) window. It can be done by hit/miss moving the pump, or using the learn procedure (scanner not required for OBD-I, but I don't recall the KO/Ko hoops to jump). The PCM will relearn TDCO, itself, over time. Same result, although one is initially virtual, vs. actual. The TDCO is built in to compensate for normal valve train wear. Exceeding -1.94 and associated DTC's are the PCM telling you the pump is broken, or the valve train is worn beyond the computer's ability to compensate.

If you feel the timing is too advanced, TDCO optimization will only increase the advance. Retarding the timing requires programming, or a chip for OBD-I. Who would really want to do that?

Just a whatever it is worth....

I have been through several 6.5 with OBD1 electronics...(94-95 models) and every engine ran and sounded different after the rebuild.

One 94 we had would make an old 7.3 Power Stroke blush on a really cold start.

OMG IT RATTLED.....Ran great though.

That engine ended up with a set of Clearwater heads.

The after market precups in the heads may have been a contributing factor.....?????????????????? Don't know...

The Dahooooley rebuild the first time when we ended up with the block that had been decked too much has a specific sound and feel.

It had a set of 1992 heads on it......Matching cups.

The second time around the block was an AMG block, Scat crank, GM rods, After market pistons and New AMG heads.....

The injectors were fresh rebuilds from Diesel fuel injection service up in PDX (Same parts just swapped them)

DS4 was swapped along with all the rest of the gear.

These two engines were as different as daylight and dark.

Same Heath diesel chip in the ECM

All together different feel and sound.......VERY VERY SMOOTH the last time....

It is hard to compare a used engine with lotsa miles on the clock to a fresh build.....Too many subtle changes that can effect the BUTT DYNO....and what you hear.

Enjoy the fresh power plant ....it's a different little person....