Exhaust leak --> Blown CT26 --> GTurbo + intercooler (1 Viewer)

[relaxedcruiser]

You most likely don't need a new manifold. The surface can be machined by a engine rebuilder.

As the cast iron is relativly soft you even can do it by yourself.
Glue some sanding paper of the right grit to a perfectly flat surface and sand the surface until no high or low spots are visible anymore. Rotate manifold after every stroke or two to make sure that you are grinding even. If you can find a machine shop, let them do the job !

 

[Br3ntfire]

You most likely don't need a new manifold. The surface can be machined by a engine rebuilder.

As the cast iron is relativly soft you even can do it by yourself.
Glue some sanding paper of the right grit to a perfectly flat surface and sand the surface until no high or low spots are visible anymore. Rotate manifold after every stroke or two to make sure that you are grinding even. If you can find a machine shop, let them do the job !

The problem is the wait, apparently lead times are insane around here at the moment.

 

[DanS HJ-45]

The problem is the wait, apparently lead times are insane around here at the moment.

Start by measuring how out of flat it is. If it's not 1/16" or so, you can take a piece of glass, with a large piece of sandpaper and true it up yourself.

As to the rest, I'd replace the water pump as cheap insurance, because they definitely can leak even if you don't measure excessive play.

I wish I had some time, but I'm pretty much spoken for through October otherwise I'd offer to go give it a look and listen.

Dan

 

[Br3ntfire]

Lil' photo dump & update: Turbo's off the truck now. Took some doing, mainly this lil' bas——d, which was both difficult to get leverage on AND one of the more stubborn bolts I messed with. It had just accumulated a TON of crud around it—I went from thinking it was a 16 to realizing it was a 14 by the time I managed to scrape all the gunk off it, most of which ended up on my face.

Before removal. I really need to clean out all this nasty insulation and replace it...but one step at a time.

Had to ratchet strap down the exhaust to one of the crossmembers to gain the clearance to slip the turbo assembly out. I expected heavy, but whoof, it was HEAVY.

I managed to (with surprisingly light torque) crack most of the manifold nuts loose. One's still recalcitrant, but I'm taking these slow, more broken studs is the opposite of what I want. Unfortunately, the other stud on cylinder 1 is also broken—I'm beginning to suspect that the manifold is VERY warped.

The ol' CT26 leaking the rest of its oil onto a floormat instead of onto the table in my garage.

 

[Br3ntfire]

There have only been 2 truly difficult bolts so far during this process, which I'm undyingly grateful for on what was previously a very rusty truck. I'm not sure how the frame and body were so rusty, but nearly every bolt in the engine bay is in great shape. This one took several heat cycles with MAP gas to break free.

Unfortunately, this stud and the one above it in the picture have fairly well corrosion-welded themselves into becoming one piece with the dump pipe. I've been soaking it in P'Blaster, but have been super busy with work this week so I haven't had the time to properly work at it. Hopefully the soak is doing good in the background, so I can measure tolerances this weekend.

The absolute least I'm going to do at this stage is send the turbo off to be rebuilt and get a new 3" dump pipe either made or sent over from AUS.

I'm leaning GTurbo green wheel, which I'd keep at the lower end of boost. I don't plan on touching the fuel screw as I still need to pass emissions and technically it's illegal to put any aftermarket performance mods here in CO.

If I can land some more work soon so my budget allows, I'd go ahead and do the PDI intercooler kit too just to bulletproof and give myself as much of a safety margin as possible. I'd love to do a full rebuild @roma042987 -style, but would prefer to do it on my own timeline once my budget and shop space allow instead of forcing it by getting too excited about mad power gainz.

I'll pull injectors and have them cleaned/whatever needs to be done and check compression first as well.

 

[Br3ntfire]

Forgot to say—if anyone has recommendations on a good shop with CT26 rebuild experience, I'd love the advice. I know a few of the questions to ask, but if I'm being honest I know little enough it'd be fairly easy to scam me.

 

[Br3ntfire]

With the help of a friend to help keep things held down + a plastic deadblow hammer and some strong whacks, we were able to get the turbine outlet elbow off the turbo. I measured axial shaft play at 0.178 mm, so it's definitely time to make the decision: rebuild or GTurbo.

Radial play was impossible to measure, as I couldn't fit my dial indicator setup in the oil inlet to get the measurement, but it hardly matters as axial play is what kills turbos, and this one is well out of spec. I'm also pretty sure that when i put radial pressure on the impeller, i can juuuust hear it scrape the sides. It might not happen with oil pressure, which keeps the turbine shaft floating - but from what I've read, if you can get it to touch at all it's definitely time to replace - but the axial play told me that already.

 

[Br3ntfire]

A few OEM NOM NOM treats came in from the UAE today. A MUCH larger package from Japan is on its way.
My ritual when parts come in is to get in EPC and immediately label them for ease of installation later—it's saved my butt a bunch of times, especially with a ton of similar but different parts like nuts & bolts.

I've also officially decided to go GTurbo w/ the PDI intercooler setup. Things are getting exciting around here...

 

[Br3ntfire]

I'm back from vacation and working on this today. Bit of a -show, and it's looking more and more like someone who either didn't know wtf they were doing, or gave precisely zero f's had pulled and reinstalled the manifold sometime in the past - only three of the studs didn't pull with the nuts, and at a crazy low torque. I wasn't even trying with an un-extended 12mm box end.

In addition, looks like the manifold has been warped for some time, there are multiple gaskets piled up underneath different exhaust ports. One had five, a few had three and the rest had either one or two, all behind two three-wide gaskets. Crazy that they torqued everything so low, they must have snapped the first two and then given up.

Unfortunately, both studs on cylinder 1 are snapped beneath the head, so I'm going to have to extract those. Currently soaking in penetrant.

I'm cleaning up the rest of the block which is disgustingly dirty with soot and grime, which aren't surprising to see considering how loose all the studs were. It must've been a fairly massive exhaust leak the entire time I've owned the truck that just got bad enough to start whistling. Between multiple rounds of oven cleaner and brakleen I'm starting to see some factory blue down there!

 

[Br3ntfire]

Sooo we're 0.0845" out of flat (almost 3/32"). This is on my CNC spoilboard right after a flattening pass, so not perfectly flat but d—n close.

 

[Br3ntfire]

Spent 3 hours today cleaning most of the last 36 years of grime off the side of the engine block with degreaser, a steam cleaner and elbow grease. Still some more to go but that's all the time I have today.

Do I need to worry about how flat the exhaust manifold mating surface is? I'm worried the pitting from the poorly torqued studs on cylinders 1&2 may have done some damage.

 

[Br3ntfire]

All small parts are in, and the GTurbo is scheduled for delivery today! Here's my labeled hardware pile:

 

[Br3ntfire]

Look what's here! The fit and finish of both are incredible

 

[Br3ntfire]

I did some reverse engineering to make a guide plate to perfectly center my drill bits to get the broken exhaust studs out of my block without ruining the threads.

First i scanned both a single and the half gasket set, then busted out the micrometer and took a bunch of measurements while drawing in fusion 360. Note that these dimensions aren't final.

Machined out a negative on my CNC to test the measurements. The full gasket fit well too.

Here you can see how my template works. I'll drive the studs for cyl 2 through the right side for alignment and holding, then I can use drill bushings to center the bits and keep my drill straight and centered on the studs even though they're snapped off at an angle.

I made the final out of 3/4" plywood, but forgot to take a pic. I screwed all the studs in to make sure everything was aligned properly. It took a few tries to get everything perfect, but once everything threaded easily, i went for the drill.

Again, forgot to take any pics of the finished product, but everything went perfectly, and (after a chase with a tap) everything looks fantastic.

 

[bcsteel]

That is really cool. Can you make more?

 

[Br3ntfire]

That is really cool. Can you make more?

Thanks! I could, but if I were to do it again, I'd want to do it in aluminum. The plywood wasn't quite rigid enough to keep things as tight as I'd want if someone else were risking their engine with my product. More work with tolerances too to make sure it works "as advertised" every time

 

[bcsteel]

Yeah fair enough I can see that. Were you able to accurately drill out the broken studs?

 

[Br3ntfire]

Yeah fair enough I can see that. Were you able to accurately drill out the broken studs?

Yeah, sure did! One was perfectly on center, the other was off a little bit, but not enough to hit any threads. Not sure if that was a measurement error or because it was more angled and the bit wandered or if it was a result of tolerance stacking...or just plain ol' user error.