98 V70 exhaust manifold - Whats a good part?

[erikv11]

There are tons of aftermarket manifolds yes, stainless and for your NA they are relatively cheap and many people have used them with no issue. You may need to hit the search button and dig, I haven't bought one myself.

[98v70dad]

There are tons of aftermarket manifolds yes, stainless and for your NA they are relatively cheap and many people have used them with no issue. You may need to hit the search button and dig, I haven't bought one myself.

I have found tons of aftermarket parts. Its not difficult to do. Finding something that people have had good service experience with is another matter. I've searched this webite and found literally nothing. I spent a good bit of time on it too. Maybe I need better searching skills. I'm not ready to dive into the exhaust manifold replacement project with an aftermarket part of unknown service experience.

[98v70dad]

There are tons of aftermarket manifolds yes, stainless and for your NA they are relatively cheap and many people have used them with no issue. You may need to hit the search button and dig, I haven't bought one myself.

I have found tons of aftermarket parts. Its not difficult to do. Finding something that people have had good service experience with is another matter. I've searched this website and found literally nothing. I spent a good bit of time on it too. Maybe I need better searching skills. I'm not ready to dive into the exhaust manifold replacement project with an aftermarket part of unknown service experience.

I can generally look at a part and tell if its of decent quality, but buying on the internet doesnt give you that advantage.

[98v70dad]

We discussed this issue about 5 years ago.
See the thread below, you may want to ask the people who use OBX to see what they say in terms of long-term reliability.

viewtopic.php?t=45649

Thanks. That's helpful. I spent a good deal of time searching and didn't find that thread.

[98v70dad]

I have used a piece of tissue around the manifold to discover leaks. The tissue will flap when encountering a leak. On two cars the exhaust manifold gasket failed between cylinder 2 and 3 on the bottom. Use the tissue from the flex joint going up the the manifold.

So tonight I tried the tissue test (I've been too busy to do it any sooner). I took an 18 inch piece of full width TP and draped it over the manifold. There is so much air moving that the piece lifts up and floats horizontally right at the top of the manifold. This is without even removing the heat shield.

I am unable to determine where the leak is (if there is one) but there is definitely a good bit of air moving. The effect is the strongest in the middle of the manifold. The cooling fan was never on. If there isn't a leak I don't know what else under the hood in the engine compartment would be stirring up that much air. I'm going to remove the heat shield (if I can get the fasteners loose) and try again to see if I can learn anything more.

Does this sound like what you found? Do you have any other thoughts that might be helpful to me?

[kahl]

I strongly suspect your exhaust manifold gasket has failed. Glue a 2"x2" piece of tissue on a paint stirrer stick and go around the edges of the manifold. Your goal is to find out where the gasket has failed. With a lighted mirror you should see carbon marks on the block where exhaust gases has stained the area. If you want to chat about this fun filled wonderful job PM me with your number and a time to call.

[scot850]

Manifolds can also crack so you may have to look around and under the manifold too.

Neil

[98v70dad]

Manifolds can also crack so you may have to look around and under the manifold too.

Neil

Thanks. I spent a good hour under the car with a strong flashlight and a mirror looking for manifold cracks from below and didn't see anything obvious. Of course if there's a crack between the manifold tubes or on the top side I wouldn't have been able to see it.

I did notice that the volutes behind the braided wire were not uniform in diamter. I used a short piece of coat hanger wire to probe where I could and it seems as if that section is collapsed on one side, although I couldn't feel any cracks or "holes" catching on the wire. I wanted to check the manifold area with the TP from below but was not brave enough to do that with the engine running and the car up on ramps. I don't believe I'll do that test.

I haven't taken the heat shield off because I'm afraid I'll break a fastener since they are heavily corroded. Also, the volvo is my daily driver. It takes the car two hours to cool down and by the time its cool enough there isn't time to complete the mission and have the car back in service for the next day. Maybe a Saturday job but to date I've had more pressing issues on other project that require attention.

[98v70dad]

I strongly suspect your exhaust manifold gasket has failed. Glue a 2"x2" piece of tissue on a paint stirrer stick and go around the edges of the manifold. Your goal is to find out where the gasket has failed. With a lighted mirror you should see carbon marks on the block where exhaust gases has stained the area. If you want to chat about this fun filled wonderful job PM me with your number and a time to call.

Thanks. I spent an hour beneath the car with a strong flashlight and an inspection mirror and don't remember seeing any carbon tracks but I wasn't specifically looking for that.

I didn't look visually from the top because I haven't removed the heat shield yet. I'm a little afraid to try to remove that because all the fasteners are heavily corroded. I had a coolant leak for a time and at least one of the fasteners is even more corroded than the others due to the coolant bath over time.

I appreciate your offer to help and I may take you up on it when I've collected more info. I'm assuming that you're talking about the gasket replacement rather than the TP leak probing as being a fun filled wonderful job. I'm very very hesitant to try to do the gasket replacement myself due to the need to have a working vehicle. If I break off a stud I have no resources (and will to continue) to fix it. However, I managed to pull off everything else I've tried-so I'll consider doing it.

Your comment about the failed gasket may explain the droning, buzzy vibration that I get when putting the engine inder load (accelerating) . I would describe the drone as like a low frequency vibrating reed. A failed gasket could possibly vibrate like a reed between the head and manifold as the gas escapes past it.