6.5L Turbo Diesel Blazer Project

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Here are 3 photos we took on a camping trip about a month ago.



The above photo shows the Blazer on the road to a pair of lakes here in Montana's Bitterroot Valley called "Twin Lakes", elevation about 6500'. It's a 20 mile drive from US-93 to the lakes, about 15 of it on gravel. This mountain valley was formed via glacial action during the last ice age. Lotsa granite boulders... Those BFG's really did improve the appearance of the Blazer...



The above shows the lower of the two lakes. The fish were biting! Cutthroat Trout... Access was not that great, forcing boaters to scramble across the boulders to put in. Not a lot of "scrambling" at my age... Just over the hill beyond the lake is the border with Idaho - and the roadless Bitterroot-Selway Wilderness.



Here's the Blazer at the camp site we chose. Lots of vacant sites to choose from. The CG had 12 sites in total, but just 3 were occupied. Our site's fire-ring and nice picnic table are just out of sight behind the Blazer. The well kept FS outhouse is just a stone's throw away to the left.

The 270 degree Oztent awning was deployed here. On the way out we stopped to pick wild berries (Oregon Grape and what looked/tasted like Blueberries - actually Service Berries). Didn't see any bears... Fun Trip! The 6.5TD did a great job! Sarah drove both ways.

[a5150nut]

I remember as a kid camping sights like that in Califurnika. Now mostly paved with 3 year advance reservations. Florance lake was a great one. Primitive camping spaces and piles of obsidian where you could find broken and imperfect arrowheads. Had to have been 1959 / 1960. Or near June Lake a place called Skunk Meadows. And a hike to Little Tahquitz Valley known now as the top of Palm Springs Tram'

[Robyn]

Thank you for sharing the great pics.
So glad y'all had a great time....

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Introduction: This "Murdered Out" 1994 6.5L Turbo Diesel Chevy Blazer was brought "Back from the Dead" after the engine sat in a thousand pieces for over 11 years. Here, we solve the problems caused by a melted piston, a gouged crankshaft, and cracked cylinder heads that were unrepairable. The Blazer has been back on the road now since the fall of 2021. This YouTube video will show you how well this GM 6.5 diesel currently runs and performs, and what we think of the Fluidampr harmonic damper replacement. Segments of this video put you in the driver's seat, so you can experience what a proper 6.5L Turbo Diesel is supposed to be like on the highway.

Had fun with this one! Check it out. There are some new video clips that haven't been shown here before... including at the very end.

Jim

[DieselDavy]

Great Video Jim,
I watched the whole thing.
Good Content!
d

[Robyn]

Absolutely wonderful presentation.
The excitement in your daughters voice says it all.

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Thanks Dave and Robyn!

Sarah also shot some of the video and stills used in this YouTube video. She had 100% confidence in the end result as we worked through the project. She still thinks her dad is so amazing... I can find no disagreement. Failure was not an option... No pressure! I'm still amazed by the end result...

[Robyn]

This sort of project having been a hands on for Sarah is such a plus.
Reading about it or watching a video about doing stuff is just eclipsed many times over by getting your hands dirty and actually doing it real time....

A wonderful experience for you both to be able to work together on this.....
A father daughter car project is not usually considered the norm for sure....

Sweeeeeeeeeeeeeeeeeet....

[a5150nut]

And kids that have sweat equity in a vehicle tend to take better care and have more appreciation for them.

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Sarah's been driving her Blazer in the city off and on this summer, and reports that she gets quite a few approving "looks" from some of the town folk, and she tells me that it's a new driving experience when compared to her lil Malibu - while navigating through town traffic (people tend not to pull out in front of her, for example).

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Sarah chose the "skelly" spare tire cover shown here... sorta goes with the Blazer's theme...

This shot almost shows the spare tire mount we settled on. As I recall it was pretty inexpensive. We made a few minor mods to it to produce a stable mount that didn't wobble, and fit as close to the back of the Blazer as it could, yet still allow the upper rear window to open. There's a pin that keeps it more upright - with the pin removed, the spare tire assembly folds rearward enough to allow the rear gate to open without interference. I hope to get a video soon that shows its operation and design.



This shows how the spare tire carrier folds rearward - far enough to clear the lowered tailgate. Sarah uses a ratchet strap to lock the carrier into position so it doesn't wobble while driving. There's always a little clearance built-into these 2" receiver hitches to allow easy use. This slop produces more movement than we like. The strap eliminates any slop, stays tight while in use, and hasn't deteriorated after having been used for a year.

We bought it on Amazon, but it's currently unavailable.... But, the link will show you more photos of what it looks like...
https://www.amazon.com/dp/B092DNTMBS...p_mob_ap_share

Incidentally... this Blazer has an excellent sounding exhaust system that produces a nice low rumble under acceleration. This sweet sound can be heard in the video when using headphones, but my computer speakers apparently don't reproduce the lower frequency sounds. The fairly short 3-1/2" in 3-1/2" out muffler was a Kennedy product back in the early 2000's. Let me know what you think... Jim

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This next photo is one I used in the video, showing a faint line around the #8 cylinder's deck, which indicates the close fitting cylinder sleeve - nicely installed. Notice the "M033" block date code on the "599" block used in Sarah's 6.5L diesel...



The close fitting cylinder sleeve in the #8 hole can also be seen from below - in this next photo.



The other 7 cylinders were still within std spec (even after 187k miles), needing just a glaze break for the new rings. By using a sleeve that was bored to std, we were able to install a matching set of eight standard size pistons, which were acquired as new "take-out" pistons. One of our members had recently upgraded a brand new 6.5 engine by replacing the original pistons with lower compression 18:1 pistons, and sold us the "like new" original (20.3:1 compression ratio) piston set for a really good price.

A few of the original pistons may have been OK to re-use. Aside from the destroyed #8, a couple of other pistons showed degrees of scuffing and heat damage. If on a tighter budget, I might have re-used the few remaining pistons that looked OK (assuming they also mic'ed OK), just replacing the ones that looked/measured bad. But, they all had near spotless crowns, having been burned clean by high/excessive EGT - kinda like how I prepare my BBQ grate. - It was best to replace them all - glad I did.

This last photo shows the cam bearings that had been installed by the engine shop. Unfortunately, the pictured cam bearing set had to be removed and replaced with another new set. It really wasn't that big a deal. The machinist did a great job otherwise. Just glad I caught it. Why did the bearings have to be replaced???



It's what's not in this photo that illustrates the problem... Some of the oil holes in the cam bearings should have been visible in this photo, but none can be seen here. Oil hole positioning is called out when viewed as though the engine were sitting upright and you're facing the front of the block. This necessitated installing a new set of cam bearings. I didn't want to trust re-using the cam bearings after they had been removed. They go in tight enough that the OD may have been tweaked a bit going in/out. In any case, new Clevite cam bearings were only about $50/set. Seemed like cheap insurance to just replace them. Jim

[Robyn]

Great pics
Glad Sarah is enjoying the rig.

The 599 block OMHO was/is the best block.
The early 506 block with the large squirts were junk and cracked through the squirter holes and up into the lower edges of the cylinders...then water.

The second generation of 506 was better...Smaller oil squirt holes and they had less cracking in the main saddles.....BUTTTTT...THE Best block was/is the AMG casting.....

I put one of the AMG blocks in my 1995 Dually......
A lot more metal in the block.......

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As mentioned earlier in this forum thread, Sarah's 1994 electronic 6.5TD is equipped with an aftermarket mechanical "Turbo-Master" wastegate actuator (shown here), which can be adjusted to manage maximum boost pressure. Currently, the Turbo-Master is adjusted to allow the factory GM-4 turbocharger to produce about 12-psi during a full-pedal run, and that boost pressure is relatively constant throughout the rpm range - assuming a more or less constant full-pedal accelerator position is maintained.

When originally stock, the electronic engine management system controlled boost pressure using the OE vacuum controlled wastegate to produce a boost pressure that varied across the rpm range even with a constant acc pedal position - with boost pressure maxing out at about 2400-rpm with around 7-psi max and then trailing off as engine speed increases above 2400-rpm. Various theories exist for why that's so... I suspect boost pressure, when stock, trails off as engine speed rises above 2400-rpm for a couple of reasons... 1- These electronic DS fuel injection pumps decrease fueling as engine speed increases due to both its inherent mechanical design and the EFI programming being used, thereby reducing the need for more boost pressure as fueling decreases. 2- Reducing engine power/torque as rpm rises helps with emissions control and engine durability.



The above photo was taken by Sarah just last week while cruising on the Interstate at 75-mph - showing 7-psi boost pressure and 550-degrees F exhaust temperature. The EGT pyrometer is located in the crossover pipe a couple of inches below the flange where it connects to the driver's side exhaust manifold.

Not surprisingly, with the current Turbo-Master adjustment, there is almost no smoke produced by the 6.5 - under nearly all driving conditions. It's easy to experiment with boost pressures when using a Turbo-Master, and I'd like to experiment with a lower boost pressure for three reasons - say around a 7-psi max. 1- The current fuel rate doesn't need that much boost pressure to burn clean. For example, a stock Duramax when driven at these speeds/loads only produces about 3-psi boost pressure. 2- These factory GM-series turbochargers are not very efficient above about 7-psi - and it really needs an intercooler at 12-psi boost pressure. 3- The engine may be more fuel efficient when the wastegate is allowed to open more - to reduce turbine drive pressure while in a light load cruise.

Incidentally... with more than 5K miles since the rebuild, the engine oil still darkens at around the usual 3000 mile mark (for a typical 6.5TD), which indicates that a higher than stock boost pressure may not have a lot to do with how soon the engine oil darkens from soot. I thought it would have made more of a difference... I do know that there is no visible blow-by at the oil fill pipe (when the cap is removed) while the engine is idling.

Did I miss anything?

Jim