Tag Archives: mechanic

Exhaust Gasket Replacement – part one

A few months ago my Saab 9-3 failed smog really badly. I didn’t even know that there was a category below fail, but apparently there is! “Gross Polluter”. After a bit of diagnostic work, including replacing the O2 sensor, my father-in-law and I made a discovery: The exhaust gasket is leaking, causing an excess of oxygen to reach the O2 sensor, causing the ECU to run the car rich, causing massive failures on hydrocarbons. It took a little while to work out that chain! The exhaust gasket was replaced when the head gasket was replaced eighteen months ago, by my typically very reliable mechanic. Unfortunately they massively failed to tighten the nuts holding the exhaust manifold to the head, eventually causing the gasket to fail and leak. The nuts weren’t even hand-tight! Unfortunately cranking them down by hand didn’t solve the problem, so the whole gasket will need to be replaced. Since the faulty work was six months out of warranty, I couldn’t get it fixed for free. The mechanic offered to discount it by several hours, but the bill would still be $600. Surely this can’t be that hard, right? This is a record of my attempt at fixing it myself. My father-in-law, who has taught me most of what I know about mechanicry, is out of town, so I’m going to give it a go myself, and see what happens!

First up, the offending piece. Below is the gasket that’s being replaced. You can see the carbon marks above the middle two cylinders – this is where the leaks happened, and it’s where the gasket has failed.

Image

First step is to remove the heat shield over the exhaust manifold, and then to pull away the top of the airbox. You can also see I’ve stuffed a rag into the turbo inlet, to stop anything from getting in there and damaging it:

Image

Then, in order to gain access to the pulleys on the left side of the engine, the bottom half of the airbox has to come off. In theory, this is so that the power steering pump can be removed, but that’s hard work, so I didn’t bother. The airbox came off easily, though, giving me plenty of room where I didn’t need it:

Image

While fiddling around with this, I dropped the wrench and made a handy discovery! If you have a metal drip-sheet under your car, stuff you drop through the engine will fall onto it, and you can just slide out the pan to collect stuff!

Image

I managed to get all of the studs off using the two-nut trick, except for this one behind the power steering pump:

Image

Eventually got it out by making a lot of very good dexterity rolls:

Image

Once it was out, I looked to be in pretty good shape. However while fiddling around with that last stud I made this discovery… there looks to be a gasket between the turbo and the exhaust manifold! No one told me about this! Once I get the pieces apart I’m going to have a good look at it and figure out what I need to order.

Image

At this point I proceeded to try to yank the exhaust manifold off using a combination of brute strength and a lot of wiggling pieces. If someone else was taking pictures, I’m sure some funny-looking pictures would have resulted. But since it was just me out there, imagining this is left as an exercise for the reader.

Once I’d struggled with the exhaust manifold for a little while, I was getting kind of grumpy, so I wiggled the old gasket out so I could get a look at it. I tore off one of the cylinders while I was getting it out, but here’s what it looks like, next to the new gasket for comparison. Note the huge carbon deposits around cylinders two and three, which were the loosest:

Image

While I was standing around feeling unjustly accomplished, I finally figured out what the guy down by the laundry room was doing. He’s painting his car:

Image

And yes, the top of my car is in desperate need of new clearcoat. That was quoted at $800 – maybe one day!

I went inside at this point, and read up on how to do this without removing the turbo completely, which is what the repair manual wanted me to do. One site recommended detaching the stay connecting the turbo to the engine, as well as the downpipe, I don’t have a jack or jack stands, so this was going to be tricky. Everywhere on the internet was in agreement that the power steering pump needed to be moved, though, so I figured I’d better give that a go.

I got a long ratchet extender wedged into the auxilary drive belt tensioner… hole… thing, and gave it a good pull. This loosened up the belt enough that I was able to slip it off the power steering pump, like so:

Image

Now, to get it detached. This was a real pain in the ass. There are three bolts – one over by the intake manifold, that was a piece of cake to ratchet off. Another one you can see above, right behind the pulley. This one was pretty hard – I managed to get the round end of a 13mm wrench over it, just, and managed to make 1/12th of a turn with every pull. There just wasn’t room for anything more than that, and certainly no room for a ratchet, because of the proximity to the pulley.

The third bolt is below and behind the pulley, and was also one that I could only turn 1/12th of a turn at a time. But this one was also really hard to get positioned, and because it was now holding up the whole pump, it never got hand-loose, so I had to wrench it nearly the whole way off. Oh well, eventually I got it clear, This gave me a couple more inches to work with on the left side of the manifold, as you can see here:

Image

So I got right back to tugging and prodding and leaning on the turbo to try to move it down, but I just couldn’t get the manifold to clear the studs on the top of the turbo. I got lucky when I un-did all of the turbo nuts – one brought a stud with it! This gave me the idea that I could just get the other three studs out, I could slip the manifold right off. I couldn’t use the same two-nut trick I did on the engine block studs, unfortunately, since there just wasn’t enough stud sticking out of the turbo. I tried and tried, but the nuts were almost exactly the same height as the exposed studs. I read about what to do online, and somewhere helpfully advised that I get half-height nuts, which should make it work when you don’t have a lot of exposed studs. Okay, great – where do I get those?

First I called my local auto parts store. They told me that they were out of stock, but that they could order them for Tuesday. I didn’t really want to wait until Tuesday, so I called my next-most-local auto parts store. They didn’t even know what I was talking about. The third-most-local told me I had to go and look through their nuts section myself. Okay, fine. So I jump-start my other car (Which needs a new battery… I should really get on that…), and head on over. I leave the car idling outside, so I don’t have to jump it *again*, and head inside. After a bit of browsing, I finally figure out that the 13mm nut that I needed is what’s known as an M8 nut. However, I don’t know if I need a 1mm or a 1.25mm thread. So I buy both, thinking that they both looked a little shorter than what I’d been using from the turbo, and it must be one of them.

I got home, and found out that yes, they were a bit shorter! Also they’re the 1.25mm thread. So I set to work again, trying to get the studs out. I try and try, and just can’t get it to work – I only have about a turn and a bit on the top nut, and I don’t have any more room to work with. This isn’t going to work. I’m going to need to take the downpipe off the turbo, which the internet says should give me enough wiggle room to get the manifold off.

Okay, so, let’s take the downpipe off. I can get the top two nuts, because they’re on the top, but the underneath one can’t be reached easily, and I have no way to hold the car off the ground to get at it. At this point my back hurts, and I’ve been at it for about five hours, so I think it’s time to call it a day. I’ll have another crack at getting the turbo off tomorrow or Monday – I can probably borrow a jack and stands, so I can get under there and unhook things. Here’s hoping I can get the turbo loose without having to drain my coolant, or worse – my oil!

Tomorrow I’ll probably make a post about hiking, but it probably won’t be very interesting unless one of my friends gets eaten by a bear or something. Which may well happen, because as we all know, there are bears outside.