O2 sensor replacement

[Keith7481]

Earlier this summer my 2016 VP 350 with closed cooling was throwing a code for the port bank running lean. I had the code cleared and it didn't come back. Last week I was changing my oil, warmed the engine and found that the port exhaust manifold was much hotter to the touch compared to starboard. I only have about 250 hours on the motor. Am planning to change the O2 sensor and wasn't sure if i should change just the sensor that is precatalytic or both. They are not too expensive, but thought i would ask. TIA

 

[Lou C]

You want to find out why that side of the exhaust is so hot, it could be a lean condition but without a scanner that reads live data it’s hard to tell. Exhaust systems do clog because of how cast iron corrodes (flakes off & clogs passages). You can look at the spark plugs on that bank and see if they look lean. White center electrode insulator would be a cue. Should be tan/brown. Cause might be partly clogged injectors on the side that’s lean. More info on what the code said specifically would help. The upstream sensor regulated fuel mix wheras the downstream checks catalyst efficiency. So it might be the upstream O2 sensor but you could tell much more radio watching live data on the scanner. I had that problem on my old 98 Jeep 4.0 & I diagnosed it with the scanner.

Even with closed cooling for the engine your exhaust is probably raw water cooled and you might be at the point where the exhaust elbow is clogging. If you find that I’d change both.

 

[alldodge]

Last week I was changing my oil, warmed the engine and found that the port exhaust manifold was much hotter to the touch compared to starboard.

I'm assuming open cooling

A motor at idle in most cases does move enough water to fill everything the same as higher RPMs, if it's on a hose even more so. If the port side will not burn you with a touch then it's ok IMO. While you may or may not need a O2 sensor, I wouldn't throw parts at it in this case without testing

 

[Keith7481]

You want to find out why that side of the exhaust is so hot, it could be a lean condition but without a scanner that reads live data it’s hard to tell. Exhaust systems do clog because of how cast iron corrodes (flakes off & clogs passages). You can look at the spark plugs on that bank and see if they look lean. White center electrode insulator would be a cue. Should be tan/brown. Cause might be partly clogged injectors on the side that’s lean. More info on what the code said specifically would help. The upstream sensor regulated fuel mix wheras the downstream checks catalyst efficiency. So it might be the upstream O2 sensor but you could tell much more radio watching live data on the scanner. I had that problem on my old 98 Jeep 4.0 & I diagnosed it with the scanner.

Even with closed cooling for the engine your exhaust is probably raw water cooled and you might be at the point where the exhaust elbow is clogging. If you find that I’d change both.

Thanks, I was think about plug replacement, but that requires a visit to the shop. I thought since I can do the sensor first myself, id throw the part at it and see if that solves it. If not I'll take it in. Appreciate your suggestions.

 

[Keith7481]

I'm assuming open cooling

A motor at idle in most cases does move enough water to fill everything the same as higher RPMs, if it's on a hose even more so. If the port side will not burn you with a touch then it's ok IMO. While you may or may not need a O2 sensor, I wouldn't throw parts at it in this case without testing

Closed cooling,,, idled for 5 minutes, I could touch it, but much hotter than starboard

 

[alldodge]

Closed cooling,,, idled for 5 minutes, I could touch it, but much hotter than starboard

Unless your sitting in the water might be the same, also depends on if raw water goes thru the elbows or just the exit ports. Would need serial number to see how your configured

 

[Lou C]

Actually in my experience spark plugs are easier by far to remove than O2 sensors. Watching fuel trims on the scanner would really help….

 

[Lou C]

If it got that hot in only 5 min either no water is getting fed to that elbow or it’s totally clogged. I have a raw water cooled older OMC/Volvo system on my V6 Cobra and at idle the exhaust on both sides is usually 95-100*F and this system has been used in salt water for 7 seasons, about 8 is how long I will use them before changing all of if due to salt water corrosion.

I would
Disconnect the hose feeding the exhaust on that side and start the engine just for a minute, water should be pumped out of that hose. If not you have to find out why. Don’t know how your system is plumbed but if it’s closed cooled, it’s likely that the exhaust is fed with raw water from the heat exchanger. AFAIK Volvos with closed cooling have a half system with raw water cooled manifolds. Elbows are always raw water cooled. Do this before doing anything with the O2 sensors.

 

[Keith7481]

Unless your sitting in the water might be the same, also depends on if raw water goes thru the elbows or just the exit ports. Would need serial number to see how your configured

40869534

 

[Keith7481]

Actually in my experience spark plugs are easier by far to remove than O2 sensors. Watching fuel trims on the scanner would really help….

I dont have a scanner, was thinking about getting one. To remove the plugs id have to get inside the engine compartment. Im 6 1, 225lbs, no way I could get in their. The local shop hires kids in high school to work on these engines, it's a difficult design. O2 sensor is easy to reach. the sensor is $150, any reason for not putting one in before pulling the hoses as you suggest?

 

[Keith7481]

If it got that hot in only 5 min either no water is getting fed to that elbow or it’s totally clogged. I have a raw water cooled older OMC/Volvo system on my V6 Cobra and at idle the exhaust on both sides is usually 95-100*F and this system has been used in salt water for 7 seasons, about 8 is how long I will use them before changing all of if due to salt water corrosion.

I would
Disconnect the hose feeding the exhaust on that side and start the engine just for a minute, water should be pumped out of that hose. If not you have to find out why. Don’t know how your system is plumbed but if it’s closed cooled, it’s likely that the exhaust is fed with raw water from the heat exchanger. AFAIK Volvos with closed cooling have a half system with raw water cooled manifolds. Elbows are always raw water cooled. Do this before doing anything with the O2 sensors.

Looks like that hose is on the lower side of the engine, down by the plugs?

 

[Keith7481]

If it got that hot in only 5 min either no water is getting fed to that elbow or it’s totally clogged. I have a raw water cooled older OMC/Volvo system on my V6 Cobra and at idle the exhaust on both sides is usually 95-100*F and this system has been used in salt water for 7 seasons, about 8 is how long I will use them before changing all of if due to salt water corrosion.

I would
Disconnect the hose feeding the exhaust on that side and start the engine just for a minute, water should be pumped out of that hose. If not you have to find out why. Don’t know how your system is plumbed but if it’s closed cooled, it’s likely that the exhaust is fed with raw water from the heat exchanger. AFAIK Volvos with closed cooling have a half system with raw water cooled manifolds. Elbows are always raw water cooled. Do this before doing anything with the O2 sensors.

Wouldn't the previous lean code suggest plugs or sensor before plugged exhaust?

 

[alldodge]

40869534

Not able to fully understand the circulating system from the drawings, but it does show items feeding the exhaust elbows. Unable to determine if the elbows are fully closed off from mans but appears so

https://www.volvopenta.com/shop/0/part-sections/54163952?hintPhrase=&hintType=None

 

[Lou C]

You may have 2 separate problems, one the lean code, two the hot exhaust, they may or may not be related. I would first investigate the hot exhaust, that's certainly a common problem on inboard engines.
I really doubt running lean, especially because you're not saying it's misfiring, it going to make your exhaust on one side get that hot in such a short time of idling. I can run my engine on the water hose for an hour and the exhaust on both sides is barely warm to the touch, and this system is only a year or 2 away from being replaced which is typical in salt water regions.
Since you have a cat converter, it is also possible if the cat converter element itself is clogged, that would certainly cause the exhaust to get really hot. When those clog, it is often due to contaminated fuel, misfires (that put raw fuel into the exhaust stream) or an excessively rich fuel mix. This is why a scanner that reads live data would be so helpful. Here I'm just guessing at logical causes.

 

[Lou C]

maybe ping Muc he may know.
in the diagram it looks like one hose feeds the elbow and the other sends water into the stream after the elbow and there is a valve involved as well.
Looks like if there was a problem with part #29 it could affect this. It's some kind of pressure control valve.

 

[Keith7481]

maybe ping Muc he may know.
in the diagram it looks like one hose feeds the elbow and the other sends water into the stream after the elbow and there is a valve involved as well.
Looks like if there was a problem with part #29 it could affect this. It's some kind of pressure control valve.

Thanks very much I'll see if I can reach him, much appreciated!

 

[Fun Times]

port exhaust manifold was much hotter to the touch compared to starboard.

Just to confirm, exhaust manifold or the riser is extra hot? or both?

Seawater System: Heat Exchanger to Exhaust Elbows

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

https://www.volvopenta.com/shop/0/part-sections/54163981?hintPhrase=&hintType=None

Volvo Penta Shop

Find and buy the full Volvo Penta aftermarket assortment for marine and industrial applications. With more than 200.000 genuine parts to support all maintenance and repair you will find all you need. Identify the Volvo Penta engine, shield or drive when looking for spare parts, maintenance...

www.volvopenta.com

Do you have a sea water strainer to check in on?

Seawater Strainer Kit

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

Seawater Filter

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

 

[Lou C]

Sounds good remember it's always better to diagnose before changing parts.

 

[Keith7481]

Sounds good remember it's always better to diagnose before changing parts.

Agreed, but it's very hard to get service, want to do what I can in my own, sensor is about it.

 

[Keith7481]

Just to confirm, exhaust manifold or the riser is extra hot? or both?

Seawater System: Heat Exchanger to Exhaust Elbows

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

https://www.volvopenta.com/shop/0/part-sections/54163981?hintPhrase=&hintType=None

Volvo Penta Shop

Find and buy the full Volvo Penta aftermarket assortment for marine and industrial applications. With more than 200.000 genuine parts to support all maintenance and repair you will find all you need. Identify the Volvo Penta engine, shield or drive when looking for spare parts, maintenance...

www.volvopenta.com

Do you have a sea water strainer to check in on?

Seawater Strainer Kit

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

Seawater Filter

Make sure to keep your Volvo Penta Genuine!

www.volvopenta.com

I only touched the manifold, didn't check the riser, in hindsight, I should have. No strainer.