1G Overhauling exhaust & turbo, several questions

[XC92]

I've finally gotten around to overhauling my Talon's exhaust and turbo, removing both to clean the front of the engine and take everything apart, give them a good cleaning, remove rust, seal minor cracks, where appropriate apply high heat paint (specifically KBS XTC), then put it all back on with new gaskets, crush washers, o-rings and hoses. Standard issue stuff and after 31 years long overdue. I have all the necessary replacement parts.

1 - Thing is, the FSM said to remove the O2 sensor and oil level gauge. Yet I was able to remove the manifold and turbo without removing either. Any reason to still remove them? I actually bought a new o-ring for the gauge but am not sure that it's really necessary. I can test the sensor but if it's ok I don't see why I'd need to remove it.

2 - There are also a few very tiny cracks in the exterior of the manifold, but none that I could see or feel on the interior. Is it ok to apply some high heat metal seal on them and paint over everything? When everything's back on I can check for exhaust leaks.

3 - 4 of the 9 manifold studs snapped off, which itself was a good reason to do all this. I have new OEM studs, washers and nuts (same for all the gaskets and other bolts and studs, all OEM). I was able to remove 3 of them with vise grips but the 4th snapped flush with the head surface so I'll have to drill it out. Hopefully it won't be a problem. It's the top-right one, so I'll have to remove the power steering pump and bracket. I tried to do that but I couldn't release enough tension on the hose to get it out. Is there a technique for it? I removed all three pump bolts. Should I put the 2 driver's side ones back on?

4 - Do I need to clean the manifold's interior of carbonized soot or is it ok to leave as is? It doesn't appear to be too bad.

5 - Is it ok to take the turbo apart to very gently clean the interior and replace the o-ring, or am I taking a big risk there and should either leave it as is or send it to a turbo shop? I've removed the O2 housing but I mean the turbo unit itself. I have no intention of trying to disassemble the cartridge unit, of course.

6 - I put nearly everything in a tub of Rust911 (an Evaporust alternative) to remove as much rust from the exterior and interior. Is that ok?

Anything else to be aware of or do while I'm at it?

 

[steve]

3 - 4 of the 9 manifold studs snapped off, which itself was a good reason to do all this. I have new OEM studs, washers and nuts (same for all the gaskets and other bolts and studs, all OEM). I was able to remove 3 of them with vise grips but the 4th snapped flush with the head surface so I'll have to drill it out. Hopefully it won't be a problem. It's the top-right one, so I'll have to remove the power steering pump and bracket. I tried to do that but I couldn't release enough tension on the hose to get it out. Is there a technique for it? I removed all three pump bolts. Should I put the 2 driver's side ones back on?

If you have a MIG you could try welding a nut on the stud. The heat of doing so can free it up from the head.

It's been a long day, I'm having a hard time visualizing what your asking about the PS pump.

 

[XC92]

If you have a MIG you could try welding a nut on the stud. The heat of doing so can free it up from the head.

It's been a long day, I'm having a hard time visualizing what your asking about the PS pump.

Never mind about the PS pump, I got it off by loosening the alt and removing the WP pulley. Maybe there's an easier way but I couldn't find it. I had to remove it to drill out one of the snapped manifold studs that broke inside the head.

I was then able to drill a hole in the stud and extract it with a bolt extractor. For good measure I then used a tap to clean out the threads on each bolt hole.

I also verified that the center bottom stud hold is exposed to the oil galley inside the head. This became obvious when I used a motorized air blower to clean out the threads in that hole and oil immediately started to seep out the turbo oil feed banjo bolt hole on the left front top side of the head. Strange, any idea why they'd do this? In any case I'll use some sort of thread sealant or RTV on that stud.

I was able to figure out the answers to most of the other questions. I'm wondering, though, I put some parts in a tub of Rust911, which is an Evaporust alternative, including the wastegate actuator. I mean the bell-shaped thing with a long rod that opens and closes the wastegate in the O2 housing and is controlled by vacuum. Could I have damaged it by putting it in the liquid?

When I took it out the next day, most of the rust was gone but the long rod didn't move in or out, and I could have sworn that it did before. Or will it only move with sufficient vacuum applied? I'm letting it dry now. But it's an exposed part and over the years could easily have gotten splashed when driving over puddles or cleaning the underbody or engine bay, so I'm guessing no damage.

 

[steve]

The wastegate actuator on a DSM is pressure activated.

 

[XC92]

The wastegate actuator on a DSM is pressure activated.

So, it not moving in or out without pressure applied is the norm and it's not jammed, but behaving properly?

 

[steve]

Does it move when you apply boost pressure?
I've never managed to move the rod manually.

 

[XC92]

Does it move when you apply boost pressure?
I've never managed to move the rod manually.

I don't have a vacuum tester but will loan one out today at Autozone to test this and everything else. But for some reason I thought I was able to move it manually prior to dunking it the rust remover.

So I'm probably good, as boost was fine before I took everything apart. Or, at least, there was boost as I could hear, feel and see it on the boost gauge and it didn't stay stuck open or closed. Thanks.

Btw, when installing the new (OEM) exhaust manifold studs, after gently cleaning out the hole threads with a tap (which I've already done and am glad that I did because some of the threads were messed up), is finger tight ok or should I use a tool to tighten them a bit further?

And, for the bottom center stud whose hole is exposed to the oil galley, how to seal it? Is properly installing the stud sufficient, or should I apply something, and if so high temp thread sealant, RTV or nickel anti-seize?

I assume that for all the other studs nickel anti-seize is preferred? Are any of them also exposed to either the oil or coolant galleys? It's a '92 4G63 turbo.

Oh, and in case anyone else is reading this and wondering how to remove studs that snapped off flush with the head, I used a cheap reverse (or left-handed) drill bit set I got at Harbor Freight for under $10 recently, working my way up from the smallest at 1/16" to either a 7/64" or 1/4" bit to make a progressively deeper and wider hole in the center of the stud (after first tapping an indentation into the center of the stud face with a punch), then used a bolt extraction bit to twist the stud out after hitting its other end gently with a small hammer to get it to bite into the drilled-out hole in the stud. Came out w/o a problem. I used the smallest bit in the kit.

Here's the HF reverse drill set:

Left Hand Drill Bit Set, 13 Piece

Amazing deals on this 13Pc Left-Hand Drill Bit Set at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

And here's the extraction set I used:

Pardon Our Interruption

The latter appears to be OOS but I'm sure you can find a similar kit elsewhere. But there are quite a few types of extractor kits so it shouldn't be hard to find one that works. In some cases the reverse drill bits get enough bite to do double duty as extractors themselves.

 

[steve]

I don't have a vacuum tester but will loan one out today at Autozone to test this and everything else.

I assume you have an air compressor and could apply pressure to the WGA to see if it moved. I don't think applying a vacuum will do anything other than find out if the diaphragm is damaged.

The FSM says that the 14b WGA is open at 11.1 psi.

I know there has been discussions about the center bottom stud being open to the oil galley but I don't remember finding it to be so or doing anything special to seal it when I replaced my exhaust manifold and I don't have any oil leaking from there.

 

[XC92]

I assume you have an air compressor and could apply pressure to the WGA to see if it moved. I don't think applying a vacuum will do anything other than find out if the diaphragm is damaged.

The FSM says that the 14b WGA is open at 11.1 psi.

I know there has been discussions about the center bottom stud being open to the oil galley but I don't remember finding it to be so or doing anything special to seal it when I replaced my exhaust manifold and I don't have any oil leaking from there.

No compressor, I live in a 2nd floor walkup with no garage or shed or other storage. No need for one as all my tools are cordless or manual.

But there are vacuum test kits you can loan out for free at auto parts stores so I’ll get one and see.

And, absolutely the bottom center exhaust manifold stud hole is opened to the oil gallery on my 4G63, which I just verified by blowing air into it and seeing oil come out the turbo feed hole in the head (I used a battery powered air blower for that).

I’ll probably dab a little RTV on that stud to seal it, after it’s seated finger tight, in addition to nickel anti-seize on the threads.

So, I’m good on these questions now.

 

[XC92]

I assume you have an air compressor and could apply pressure to the WGA to see if it moved. I don't think applying a vacuum will do anything other than find out if the diaphragm is damaged.

Just to followup, I got a vacuum tester from Autozone, not realizing that it only generates vacuum, not positive pressure.

I was all set to go back and get an actual pressure tester when I realized that I had a decent bike pump with a built-in gauge.

I hooked it up with a special plastic conical adapter that it came with and a short piece of vacuum hose, and what do you know, it worked.

One easy pump (had to be careful to not overdo it as it goes up to 160psi) and the arm moved out, and stayed out till I relieved the pressure.

One more checklist item completed!

And I think that the vacuum tester will actually be useful in testing several other parts while I have them out of the car, e.g. boost valve, EGR valve, etc.

I love it when safe hacks work and save time, effort and money.