V6 Exhaust Manifold Gaskets

[mlhansen]

I’ve known I had a slight exhaust manifold leak for a while. I’ve been putting off doing anything about it but it has gotten especially bad lately. Anyone have any experience replacing the gaskets on a V6? There seems to be all kinds of threads about V8 manifolds, but I’m struggling to find any info on the V6.

I’m pretty tempted to just throw some new gaskets at it and see if it fixes the issue. I just worry that the manifolds are warped and will become an issue. Just looking for some advice and see if anyone has done this and what issues that had or didn’t have. Thanks.

 

[djpope09]

I replaced the exhaust manifold gaskets while doing the headgaskets in my 04 V6. I didn't have any leaks before, so I didn't bother checking if they were warped.

I'm guessing you could use a straight edge from corner to corner (top left to bottom right, top right to bottom left) and a thickness gauge to see if they have any significant gaps. Might be hard based on the shape and you may have to fully remove the manifolds.

If gaskets are cheap I would do that first. Taking them off is pretty easy, unless your manifold nuts have rust-welded to the studs like the passenger side of mine did. Here is how I would do it *note that there I may be missing some steps since I didn't do it exactly this way*:

* Before buying any parts, examine all 12 exhaust manifold nuts (6 on each side) and figure out if they will actually come off. One side of mine had so much rust that I couldn't get the nuts off. The manifold, stud, and nut were all rusted together and there wasn't enough room in the engine bay to do anything about it.

* If you think you can get them off, start a few days early and spray down all the nuts with penetrating fluid every day. Driving may warm up the manifolds and help the fluid get in, but I've heard that exhaust leaks can also damage the manifold so that may be something to consider.

* Start by removing the manifold nuts. This is pretty straight forward.

* Then unclip the 02 sensors on each side. These are just downstream of the manifolds at the back of the engine and can be hard to reach.

* Find the bracket near the end of the manifold pipe, but before the connection to the intermediate pipe. I think it's connected to the body on both sides. Unbolt the bracket so you can move the manifold off the studs. I don't recall, but you may also have to unbolt the manifold where it meets the intermediate pipe. There is two bolts on each side and a donut gasket on each side that will have to be replaced if you do this part.

* Pull the manifolds off the studs and remove the old gaskets. You may want to try to clean the mating surface on the cylinder head before installing the new gaskets. I would use carb cleaner and a razor blade if necessary.

* Put everything back together.

If you need to fully remove the manifolds you will probably have to remove some things to get them out. On the passenger side you will need to unbolt the trans fluid dipstick (and probably the oil dipstick) at the cylinder head. Worst case, you may also need to remove the power steering pump. On the drivers side you will have to move the wiring harness and maybe the generator or A/C compressor.

Hopefully this helps you.

 

[nyc4runnin]

I replaced the exhaust manifold gaskets while doing the headgaskets in my 04 V6. I didn't have any leaks before, so I didn't bother checking if they were warped.

I'm guessing you could use a straight edge from corner to corner (top left to bottom right, top right to bottom left) and a thickness gauge to see if they have any significant gaps. Might be hard based on the shape and you may have to fully remove the manifolds.

If gaskets are cheap I would do that first. Taking them off is pretty easy, unless your manifold nuts have rust-welded to the studs like the passenger side of mine did. Here is how I would do it *note that there I may be missing some steps since I didn't do it exactly this way*:

* Before buying any parts, examine all 12 exhaust manifold nuts (6 on each side) and figure out if they will actually come off. One side of mine had so much rust that I couldn't get the nuts off. The manifold, stud, and nut were all rusted together and there wasn't enough room in the engine bay to do anything about it.

* If you think you can get them off, start a few days early and spray down all the nuts with penetrating fluid every day. Driving may warm up the manifolds and help the fluid get in, but I've heard that exhaust leaks can also damage the manifold so that may be something to consider.

* Start by removing the manifold nuts. This is pretty straight forward.

* Then unclip the 02 sensors on each side. These are just downstream of the manifolds at the back of the engine and can be hard to reach.

* Find the bracket near the end of the manifold pipe, but before the connection to the intermediate pipe. I think it's connected to the body on both sides. Unbolt the bracket so you can move the manifold off the studs. I don't recall, but you may also have to unbolt the manifold where it meets the intermediate pipe. There is two bolts on each side and a donut gasket on each side that will have to be replaced if you do this part.

* Pull the manifolds off the studs and remove the old gaskets. You may want to try to clean the mating surface on the cylinder head before installing the new gaskets. I would use carb cleaner and a razor blade if necessary.

* Put everything back together.

If you need to fully remove the manifolds you will probably have to remove some things to get them out. On the passenger side you will need to unbolt the trans fluid dipstick (and probably the oil dipstick) at the cylinder head. Worst case, you may also need to remove the power steering pump. On the drivers side you will have to move the wiring harness and maybe the generator or A/C compressor.

Hopefully this helps you.

For the rusted nuts, how did u get them off? Cut them off? Im attempting the head gasket myself and this is the part im most worried about...

 

[radlynx]

all my manifold nuts and bolts look rusted. im planning on just replacing the stud and nuts. where did you get the parts? whats the part number? im afraid i will break the bolt if i do this and get more headache.

Sent from my SM-G930T using Tapatalk

 

[djpope09]

For the rusted nuts, how did u get them off? Cut them off? Im attempting the head gasket myself and this is the part im most worried about...

I left them on and pulled the cylinder head out with the exhaust manifold still attached. I did it by myself with the engine in the vehicle and the hood/front bumper still on. Not super easy, but there's plenty of room. You may want to have another person help you guide them out.

I took the heads to a machine shop to be cleaned up and they cut the old nuts off for me. I think I had to replace most of the studs as a result. You can get the nuts and studs from your local Toyota dealership. They aren't very expensive. Or you can go to Ace Hardware and find similar studs and nuts.

 

[djpope09]

all my manifold nuts and bolts look rusted. im planning on just replacing the stud and nuts. where did you get the parts? whats the part number? im afraid i will break the bolt if i do this and get more headache.

Sent from my SM-G930T using Tapatalk

I don't recall the part number, but your local Toyota dealership will know. Maybe start on the driver's side if it looks better and then you can use the studs/nuts from that side and take them to Ace to find a similar replacement. If you want to do it right, just get them from Toyota and pay a little more.

The nuts on mine basically crumbled and the studs were mostly fine. I had to replace them though since the machine shop cut them off for me.

I guess you need to know your limits though. If you think you will make it worse by trying to do it yourself just find a local mechanic who can do it. I would say the worst case scenario would be having to remove the cylinder head with the manifold attached so you can take it to a shop to have the studs cut off. In that case your manifold job becomes a more expensive head gasket job.

 

[jacobswetsuit]

I'm curious if anyone has replaced the front exhaust assembly/exhaust manifold at home? I'm wondering what all is involved in the process, if I have to lift my engine, etc. My bank 2 cat went bad and I'm looking at a pretty exorbitant repair price, but if I could do it myself I'd be a whole lot better off.

 

[gaber6]

When I did my HG job, the driver side was a pain. My cat bolts or the hanger bolts are seized and no way to turn them. Either way, I had to wrestle the manifold with just barely slack to get it over the exhaust studs. Would be easiest if all the studs could come out, so you don't have to pull the manifold away from the engine more than the width of the gasket.

 

[MikeinNH67]

I replaced the passenger side exhaust manifold as it was longer sealing well to the engine. Getting the nuts off was a bear but I live in the rust belt. I don't recall anything else being that tough to remove and certainly did not have to lift the engine. Driver's side would be way harder.

 

[jgravlin]

I am getting ready to start removing the passenger side exhaust manifold on Friday. Mine is badly cracked and getting worse. I have been soaking the bolts and nuts with penetrating lubricant for a couple days. I don't live in the rust belt but the nuts look nice and rusted I will let ya'll know how the job is going.

 

[MikeinNH67]

I am getting ready to start removing the passenger side exhaust manifold on Friday. Mine is badly cracked and getting worse. I have been soaking the bolts and nuts with penetrating lubricant for a couple days. I don't live in the rust belt but the nuts look nice and rusted I will let ya'll know how the job is going.

I ended up whittling away at what was left of the nuts with a plasma cutter. Once the manifold was off I chased the threads with a die. I had to replace one or 2 studs because I went a bit too deep with the cutter.

 

[jgravlin]

I got to the manifold a day early all 6 studs came loose from the block which I am fine with. The 2 studs on the lower connection point also came loose easy peezy. The hanger bolt did not come free, I sprayed more penetrating oil on it if it does not come loose I am going to just cut it off. I am replacing all the hardware anyway. There is very little room to work had to use a bunch of different size extensions. Tomorrow I hopefully will get everything cleaned up and install new manifold.