Thankfully that stud is very accessible for a repair. I've not done a helicoil with the manifold still in place but I think it could be done?
Exhaust leak --> Blown CT26 --> GTurbo + intercooler (1 Viewer)
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- Thread starter
- #22
I've got to pull the manifold to drill it for my EGT probe anyways so shouldn't be an issue.
Beginning the process of penetrant soaking the rest of them every day until my parts order arrives. Hopefully this is the last stroke of bad luck on this job.
I'd say it's safe to say I figured out where the exhaust leak was. My largest feeler gauge (.889mm) fits in-between the manifold and the head... Now the only question is...was there only ONE exhaust leak
Beginning the process of penetrant soaking the rest of them every day until my parts order arrives. Hopefully this is the last stroke of bad luck on this job.
I'd say it's safe to say I figured out where the exhaust leak was. My largest feeler gauge (.889mm) fits in-between the manifold and the head... Now the only question is...was there only ONE exhaust leak
I've got to pull the manifold to drill it for my EGT probe anyways so shouldn't be an issue.
Beginning the process of penetrant soaking the rest of them every day until my parts order arrives. Hopefully this is the last stroke of bad luck on this job.
I'd say it's safe to say I figured out where the exhaust leak was. My largest feeler gauge (.889mm) fits in-between the manifold and the head... Now the only question is...was there only ONE exhaust leak
It doesnt explain your squeal with all belts off? But a good find!
The studs you want to take the MOST care of are the two rear most (Cyl 6) ones... if they break its impossible to get a drill in there (at least on a 60 series) to do a thread repair.. I had to take my engine off its mounts and bring it forward a little to do a thread repair on a Cyl 6 stud.
- Thread starter
- #24
Is there any possibility that it is the water pump even without excessive play? It probably wouldn't hurt to replace it anyways. Pretty cheap insurance.
I went ahead and pulled the intake and a few other things so I could feel the play in the turbo shaft - upon further reflection it seems like it might have more play than I remember. I'm still unable to feel anything at all axially, but I'd say the radial play is a bit worrying. My guess is at best it's at the very edge of its spec'd tolerance.
I tried to fit my dial gauge in the engine bay to get some actual numbers, but couldn't find an orientation that could reach properly.
Here's a pic of the turbo, if that tells you anything. Looks to my entirely untrained eyes like there might be a tiny bit of metal-to-metal contact right on the edges? I've also been trying to determine how much play is there, so it may just be my grubby fingers rubbing off soot.
I went ahead and pulled the intake and a few other things so I could feel the play in the turbo shaft - upon further reflection it seems like it might have more play than I remember. I'm still unable to feel anything at all axially, but I'd say the radial play is a bit worrying. My guess is at best it's at the very edge of its spec'd tolerance.
I tried to fit my dial gauge in the engine bay to get some actual numbers, but couldn't find an orientation that could reach properly.
Here's a pic of the turbo, if that tells you anything. Looks to my entirely untrained eyes like there might be a tiny bit of metal-to-metal contact right on the edges? I've also been trying to determine how much play is there, so it may just be my grubby fingers rubbing off soot.
With the belt off the alternator.. the water pump wont be turning. So we can rule that out as the source of the squeal.
When you have a second person - a length of garden hose makes a great stethoscope to locate sound, one end to your ear, the other probing around the engine bay. I dont have much experience with turbos so cant comment on your photo.
Is there some metal missing here?
- Thread starter
- #27
Man, i was so focused on the outside, I didn't even look at that... I'll check it out and report back in the morning. But it sure looks like it.
bcsteel
SILVER Star
I would rebuild or replace that turbo.
- Thread starter
- #29
yyyeah, that's not good.
I've been wanting to upgrade to a Gturbo, but I was hoping to put that bill off for another couple years...looks like that's not gonna be in the cards for me.
Adding a "few more" parts to my megazip order now
This is basically every clamp in the engine bay, a few hoses, a few gaskets, and a lot of screws/studs.
Damn.. well, at least its external to the engine.
Is that normal maybe, as I said.. I'm not a turbo guy.. ? I just googled a bit.. that divot seems to be present on a few images?
- Thread starter
- #32
Hmm, definitely a possibility, although mine looks more chipped than machined maybe? Can anyone with more ct26 familiarity chime in? I'm probably going to replace anyways—$2500 on a turbo hurts, but not as much as a $12000 full rebuild would—but it'd be good to know!
- Thread starter
- #34
Thanks for checking! At least I don't need to worry about chunks of metal having been strewn throughout my engine now
Good to know that your problems seems all to be external.
I believe that the cut out on your compressor wheel is actually machined and is done while balancing.
The exhaust leak was quite clearly visible and hearable in your video - and maybe a long shot - but could your mls manifold gasket act like you would whistle on a blade of grass ?
It's quite possible that you get the broken stud out without too much issue. Time is your friend here ! Penetrate as you said - tap in the center with a hammer and small (8mm) punch, be carefull not to damage the threads in the head. clean out the soot which will be present in the threads. Very carefully center punch the exact middle of the broken stud and drill approx 4mm right through - as straight as possible ! this will allow you to get wd40 or similar behind the stud. Drill maybe up to 5mm and punch a torx bit in there, just the size which cuts nice and tight into the stud. Try to undo back and forth but without force as this will break the torx bit. If it does start to move go back and forth ever so slightly and apply more wd40 only turn the stud in the "loose" . If it doesn't turn take more time and tap on the stud after removing the torx bit.
Don't be frustrated and go crazy and try to drill out the whole thing, quite likely you will not drill straight and the tap for heli coil or equivalent will then grab the remaining parts of the stud..... with patience you will get it out in one piece.
Sorry got a bit carried away here - but I actually do like the challenge to get those broken bolts out.
Check if your manifold is actually warped - that would explain the broken bolt, I have seen this before.
Good luck with your repairs - you deserve all sweet running truck now !
I believe that the cut out on your compressor wheel is actually machined and is done while balancing.
The exhaust leak was quite clearly visible and hearable in your video - and maybe a long shot - but could your mls manifold gasket act like you would whistle on a blade of grass ?
It's quite possible that you get the broken stud out without too much issue. Time is your friend here ! Penetrate as you said - tap in the center with a hammer and small (8mm) punch, be carefull not to damage the threads in the head. clean out the soot which will be present in the threads. Very carefully center punch the exact middle of the broken stud and drill approx 4mm right through - as straight as possible ! this will allow you to get wd40 or similar behind the stud. Drill maybe up to 5mm and punch a torx bit in there, just the size which cuts nice and tight into the stud. Try to undo back and forth but without force as this will break the torx bit. If it does start to move go back and forth ever so slightly and apply more wd40 only turn the stud in the "loose" . If it doesn't turn take more time and tap on the stud after removing the torx bit.
Don't be frustrated and go crazy and try to drill out the whole thing, quite likely you will not drill straight and the tap for heli coil or equivalent will then grab the remaining parts of the stud..... with patience you will get it out in one piece.
Sorry got a bit carried away here - but I actually do like the challenge to get those broken bolts out.
Check if your manifold is actually warped - that would explain the broken bolt, I have seen this before.
Good luck with your repairs - you deserve all sweet running truck now !
That's 100% completely normal and I'd be very worried if you didn't have any metal removed from here. You'll also find a similar thing on the other end on the turbine wheel. They are for balancing, material is removed from very specific locations to achieve having all rotating components balanced while spinning at well over 100k RPM.
- Thread starter
- #37
Thanks for the help and advice @relaxedcruiser and @KiwiDingo. I bet the manifold is warped, and it makes total sense that the gasket could be acting like a reed and causing a whistle. Crazy that it could warp enough to just shear a bolt. Although it is a very heat-cycled area which would definitely weaken it over the last 35 years of use. I'm hoping not though, it's easier to get the turbo fixed than find a new manifold, at least in the states.
This week I'm planning on dropping the turbo so I can actually measure the shaft play properly. If it's anywhere near the edge of spec I'll just go ahead and get it rebuilt (at the very least) for peace of mind.
This week I'm planning on dropping the turbo so I can actually measure the shaft play properly. If it's anywhere near the edge of spec I'll just go ahead and get it rebuilt (at the very least) for peace of mind.
Just remember the radial play is measure through the oil drain hole. The specs for the CT26 allowable play is 0.13mm axial and 0.18mm radial or less.
That's how compressor wheels are balanced after machining. Totally normal.
Stop panicking everyone!
Is there an echo in here?
