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Please Help with this Popping Noise

A mid-size luxury crossover SUV, the Volvo XC90 made its debut in 2002 at the Detroit Motor Show. Recognized for its safety, practicality, and comfort, the XC90 is a popular vehicle around the world. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America).
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zakmuh
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Please Help with this Popping Noise

Post by zakmuh »

Hi,

I'm getting this strange popping noise coming through the intake manifold in my 2007 XC90 D5 engine. I don't hear this noise when I open the oil filler cap- it only comes though air intake hose. Its really loud in cold start! Please watch these two YT videos.





I'm thinking of taking the block head out and check all the valves and everything. My guess is the head is full of carbon build ups and all sticky...but I'm waiting for someone who would have had a the same issue and take their advice first before getting my hands on the engine

Thanks in advance

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RickHaleParker
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Post by RickHaleParker »

Sounds like leaking Valve or a cylinder getting too much fuel. Disconnect the injectors one at a time to isolate which cylinder.
Once you isolate the cylinder you can check for defective/leaking injectors by swapping the position of two injectors and repeat the test above. If the popping moves to the other cylinder it is the injector.

Have to tried the stethoscope directly on the injectors?


If I recall correctly, the D5 is direct fuel injection.

You could de-carbonize a cylinder including the combustion chamber without removing the head by:
1. Remove injector.
2. Move that cylinder to the top of its compression stroke.
3. Flood the cylinder with Seafoam.
4. Let it sit for a extended time so the Seafoam has time to work.
5. Disconnect all the injectors so it will not start.
6. Crank the engine to push out the Seafoam.
( Put a rag over to catch the Seafoam and a cup to catch fuel if you did not cap the line ).
7. Reinstall injectors and start engine. Run engine until all the carbon get blown out.
⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

zakmuh
Posts: 49
Joined: 10 Jun 2016, 03:27
Year and Model: 2003 XC90 D5
Location: Nottingham - UK
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Post by zakmuh »

Hi Rick. Thanks for your reply. Yup D5 is CRDinjection system. I haven't actually tried the injectors with stethoscope. I'll check it and see.

Sorry I'm a bit confused..3 questions:
1. There are 5 injectors. I'd disconnect injector's power connection one at a time and start the engine and check if the noise stops. If I'm disconnecting one by one, why do I have to swap and test again? If as you say an injector is faulty, wouldn't it show as soon as its disconnected?
2. sorry, my understanding is if an injector is faulty then the engine would judder/vibrate excessively? In my case engine runs smoothly.
3. If it is a leaking valve, then would decarbonising solve it or I'd have to take the head out and do it?

Cheers

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RickHaleParker
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Post by RickHaleParker »

zakmuh wrote: 27 Nov 2021, 11:27 1. There are 5 injectors. I'd disconnect injector's power connection one at a time and start the engine and check if the noise stops. If I'm disconnecting one by one, why do I have to swap and test again? If as you say an injector is faulty, wouldn't it show as soon as its disconnected?
2. sorry, my understanding is if an injector is faulty then the engine would judder/vibrate excessively? In my case engine runs smoothly.
3. If it is a leaking valve, then would decarbonising solve it or I'd have to take the head out and do it?
1.
  • A. Process of emanation. There is more then one thing that can cause the popping. Not all have been listed.
    B. Disconnect and reconnect the injectors when the engine is running. It is not going to shock you.
    C. Swamping the injector will tell you if it is the injector or something else.
    If the popping moves with the injector it is the injector. If the popping stays with the cylinder it is something else.
2. Not necessarily.

3. Decarbon might solve it and it might not but the Seaform treatment is a lot less work and cost less then pulling the head.

Wild speculation is not going to diagnose it. Get some more factual data and start the process of emanation.
Last edited by RickHaleParker on 28 Nov 2021, 02:10, edited 2 times in total.
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1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

zakmuh
Posts: 49
Joined: 10 Jun 2016, 03:27
Year and Model: 2003 XC90 D5
Location: Nottingham - UK
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Post by zakmuh »

Nice one Rick. Thanks for your advice. I'll start with this now and keep you posted as I work through it.

Ta

zakmuh
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Joined: 10 Jun 2016, 03:27
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Post by zakmuh »

Hi mate

Did the test as per your instruction-noise was consistent for each one.

I disconnected the fuel pump and cranked the engine. Then it gave the popping noise from one of the cylinders. Can we confirm its leaking compression? How could I check which cylinder it is from?

Cheers

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RickHaleParker
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Post by RickHaleParker »

zakmuh wrote: 28 Nov 2021, 11:00 Hi mate

Did the test as per your instruction-noise was consistent for each one.

I disconnected the fuel pump and cranked the engine. Then it gave the popping noise from one of the cylinders. Can we confirm its leaking compression? How could I check which cylinder it is from?

Cheers
Looks like we can eliminate injectors.

Compression test. Excessive compression on a cylinder maybe too much for the sealing. Carbon build up would do this.

Leak down test would be next to determine if one or more cylinders is leaking.

Another thing that that can cause popping is a slow exhaust valve. The exhaust valve does not open all the way. At the end of exhaust stroke there is still a little pressure when the exhaust valve closes. This pressure pops out when the intake valve opens.

If a exhaust hydraulic lifter is leaking down it would take longer to pump back up when the oil is stone cold. That would keep a exhaust valve from opening all the way until the lifter get pumped back up. Pops on startup then goes away.

If the lifter never pumps up fully you could get the popping all the time.

Go back to the tail pipe and see if you can detect a weak beat in the rhythm.
⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

zakmuh
Posts: 49
Joined: 10 Jun 2016, 03:27
Year and Model: 2003 XC90 D5
Location: Nottingham - UK
Has thanked: 6 times

Post by zakmuh »

RickHaleParker wrote: 28 Nov 2021, 21:35
If a exhaust hydraulic lifter is leaking down it would take longer to pump back up when the oil is stone cold. That would keep a exhaust valve from opening all the way until the lifter get pumped back up. Pops on startup then goes away.
Brilliant....You've pretty good knowledge on this one and Thank you very much for that.

I just noticed a tiny bit of oil leaking at the bottom side of vacuum pump. Checked the vacuum hoses and no oil in there and no oil is leaking while engine is running. Could this leak be the cause of an issue for lifters?

On that exhaust beat...YES I could hear the popping effect through the exhaust as well- its more like the echo of that popping. This confirms its the exhaust valve issue?

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RickHaleParker
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Post by RickHaleParker »

zakmuh wrote: 29 Nov 2021, 07:06 On that exhaust beat...YES I could hear the popping effect through the exhaust as well- its more like the echo of that popping. This confirms its the exhaust valve issue?
A Oil leak not going to cause it. Really Low Oil could could collapse the lifters but, if it was that low you would have a lot more problems then you do.

I won't call it confirmed. The fact that you can hear the same sound in both the intake and exhaust makes it inconclusive not decisive.

Its the beat, not the sound, you need to listen to. You listen for numbers. Don't sweat if you cannot hear any numbers.
⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙⸙
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

zakmuh
Posts: 49
Joined: 10 Jun 2016, 03:27
Year and Model: 2003 XC90 D5
Location: Nottingham - UK
Has thanked: 6 times

Post by zakmuh »

Hi Rick,

Sorry it took a long while for me to work back on the intake removal.

We've got a serious problem. On the exhaust side, one in the pair of 5th cylinder lifters is broken and it has sheared off the lifter hole - yellow arrow in the pic. Red arrow one is the good one in that pair. So that exhaust valve is closed permanently. So as you've said this closed valve causing the popping by escaping the excess exhaust pressure through inlet valve.

Image

I searched for the broken pieces in the entire area, including intake side but no single piece was found! I have to replace the cylinder head. Oh well!

Cheers
Attachments
xc90 Broken lifter sink.jpeg
Last edited by zakmuh on 09 Dec 2021, 13:09, edited 1 time in total.

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