I searched the group and was reading some interesting posts about my "loud" engine. After some searching, I have come to believe that my exhaust manifold is cracked. I removed the heat shield that sits over the exhaust manifold and noticed several cracks on a metal piece that sits between the exhaust manifold and my engine (I am assuming this would be the exaust manifold gasket).
How serious is this issue? I have driven the vehicle for about 3,000 miles with the crack and haven't noticed any severe issues. My primary reason for repairing this is that I am not exactly a fan of the lawnmower ripper-sound coming from my engine compartment.
I live in Michigan. Does anyone have an approximate idea on how much a shop may charge me to have the work done?
The car probably will not pass an emissions test with an exhaust leak before the catalytic converter.
There is some dange of the exhaust fumes being sucked into the passenger compartment.
If you are capable of removing the heat shield, you are capable of removing the exhaust manifold and replacing the gasket. The job should cost under $100 if you pay someone.
In theory, the process is just unbolting the old one, replacing the gasket, and bolting the new one back on.
Real world, everything will be rusted, difficult to remove, and bolts may snap off.
I am not sure if the if the manifold is attached to studs in the block and held in place with nuts or if it is just bolted in. Hopefully, it is just bolted on. When you go to get the new gasket, get new bolts.
For tools, you may need a screw/bolt extractor and a drill if the bolt head snaps off. A stud remover would also help. Besides the proper wrenches, you will need a gasket scraper. If you do not have an impact wrench, you will probably need a very long-handled wrench or a pipe to slip over the ratchet handle to give you some leverage.
Spray a liberal amount of rust penetrant on the bolts and tap with a hammer, let it sit overnight. Do this several times before you attempt to remove the bolts.
I can NOT emphasize enough what Ray says - Ignore at your own risk. You can do this yourself - but you MUST know when to stop and get more help. Or you will be forced to.
The exhaust manifold bolts/studs to the heads and the exhaust collector downpipes are the number one rust magnets because they get red hot on every run cycle.
When removing the nuts do NOT just start cranking on them like a gorilla, or you WILL snap off a stud. Sometimes you have to rock them loose - but first drench them in a good commercial penetrant like Kroil.
Or mix a batch of "Ed's Red" penetrant, dirt cheap yet effective:
1 Part Dexron Automatic Transmission Fluid
1 Part Deodorized 1K Kerosene
1 Part Stoddard Solvent AKA 'White Spirits' or 'Aliphatic Mineral Spirits Type I'. Get it at your favorite petroleum distributor. (I'd leave out the 1 Part Acetone and 1 Part Lanolin for this use.)
CAUTION: Stoddard Solvent flash point ~100F, and 1K Kerosene not much higher - No Smoking! No Open Flames! No Kidding.
Then you tighten a quarter turn, loosen a quarter turn, tighten, loosen... Eventually they'll loosen one turn for each half turn tighter, then they'll get out onto clean threads and zip the rest of the way off.
If you sense there are one or two nuts that simply aren't going to let go, before they break get a nut-cracker or a "Hot Wrench" (Oxygen/Acetylene or Plasma cutting torch) in there (After the penetrant evaporates...) and cut/split the nut off the stud. After you get the manifold off and out of the way and have working room, then you can either clean up the threads or replace the stud.
MUCH easier to get the old stud out when it isn't broken off flush with the head. That is the ultimate bad news - then you get into difficult tricks like welding a nut onto what's left of the stud sticking out to act as a bolt head, or taking the head off the engine to have the stud extracted in a machine shop or burned out with a Wire EDM Machine.
And when you put it back together use anti-seize compound on the threads - don't slop it on, just a little dab will do wonders. A thin coating of nickel or copper based paste that will keep them from rusting together quite so bad next time.
This is very true on this engine, specifically on the non-head side of the manifold.
Studs into the head, held on with pinched-tip nuts. Careful, tend to undo the stud from the head and then its fairly easy to strip a head thread (ive done it lol) the nuts dont rust for some reason, seem to be some sort of non-corrosive metal and the studs are in ok condition in mine.
This is KEY to success. You really cant skip this at all, soak them, soak them every half hour for a few hours and leave it with a heavy coating overnight. Then use a shock tactic to undo them, it helps to 'break the seal' so to speak.
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