Author Topic: Exhaust Valve not sealing  (Read 676 times)

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  • Posts: 79
  • au Australia
    Perth
Exhaust Valve not sealing
« November 26, 2018, 05:26:39 »
Hi all, After 94000Kms my cylinder head will need to come off and have the valves and seats checked. Cylinder number 4 has thrown a code P0304 (misfire) and the exhaust pipe sometimes sucks air back, indicating the valve is not sealed. The spark plugs are good the leads and coils are good and the injectors are good. It is definitely low compression misfire. It is a 2010 trophy 2.0l petrol engine.  My questions  are these, has anyone had a cylinder head removed, either by mobile mechanic or workshop? How long does it take? how much did it cost you?

Thanks



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  • Posts: 3,750
  • au Australia
    Ipswich
Re: Exhaust Valve not sealing
« Reply #1 : November 26, 2018, 05:55:54 »
Hi all, After 94000Kms my cylinder head will need to come off and have the valves and seats checked. Cylinder number 4 has thrown a code P0304 (misfire) and the exhaust pipe sometimes sucks air back, indicating the valve is not sealed. The spark plugs are good the leads and coils are good and the injectors are good. It is definitely low compression misfire. It is a 2010 trophy 2.0l petrol engine.  My questions  are these, has anyone had a cylinder head removed, either by mobile mechanic or workshop? How long does it take? how much did it cost you?

Thanks
Gotta ask the obvious, Has an actual compression test been done? Not a lot of k's either. can't comment exactly other than generic experience. in line 4 probably not too hard but things to think about.

Is this manual or auto out of curiosity.

Is timing belt done or due

Do you replace all idlers and tensioners whilst there?

Are the head bolts torqued to yield and will need to be replaced as part of the job?

Will all other valves be removed and checked, reseated etc

Or do you consider a lower K motor swapout from a wreck?

It is a how long is apiece of string scenario.

Do you replace the valve stem seals

I could see a $1000 getting chewed up quickly and maybe more
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

Re: Exhaust Valve not sealing
« Reply #2 : November 26, 2018, 06:47:04 »
Hello,  The car is a  manual, no compression test done yet, but air sucking back into exhaust pipe leans me toward burnt/sticking exhaust valve, Timing belt is due to be done, and going this deep into the engine is an excellent time for it, new head bolts will be used.  If it is just one valve I would consider just getting that done, as long as the shop thinks the others are all ok, but it would make sense to replace to replace valve stem seals.  A low k wrecker motor could just be someone else's problem waiting to happen. Hope that makes sense

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  • Posts: 3,750
  • au Australia
    Ipswich
Re: Exhaust Valve not sealing
« Reply #3 : November 26, 2018, 07:26:16 »
Yep it does. Really interested  in how the exhaust flow was used to diagnosed.  Is that with a gauge?  Last time I did a valve was in 85. Burnt out dropping a cylinder
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

Re: Exhaust Valve not sealing
« Reply #4 : November 26, 2018, 07:46:47 »
Father In-law held a slip of paper near the exhaust, most of the time it pushed the paper away, but when it stuttered it drew the paper back inwards. Very clever trick. He is old school.

Re: Exhaust Valve not sealing
« Reply #5 : November 27, 2018, 00:27:39 »
Now I'm going to stat this post by saying I am about 80% idiot, but 100% in the wrong. Yes the car gave up P0304 code, I remembered the last time it gave a similar code it was P0303, It turns out it must have been P0302. I was scrutinising the wrong lead and plug. 1 is closest to the timing belt 4 is near the transmission. The old school paper trick must be confused by the lack of explosion in cyl 4 and easily misread as being drawn back into the exhaust.  For all those wondering the cost of a cyl head remove and repair , everywhere between $2500 an $4000, and most centres mentioned timing belt done at the same time. Most shops were surprised at the low mileage and a possible head exchange, which bodes well, as it must not be very common. I am thankful that I wont have the major expense of a new head and will get new plugs and leads, and a timing belt replaced very soon. I saw a worst case scenario, probably due to a similar experience with my hyundai lantra. But that was a mitsubishi engine under licence to hyundai.

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  • Posts: 3,750
  • au Australia
    Ipswich
Re: Exhaust Valve not sealing
« Reply #6 : November 27, 2018, 02:45:00 »
Now I'm going to stat this post by saying I am about 80% idiot, but 100% in the wrong. Yes the car gave up P0304 code, I remembered the last time it gave a similar code it was P0303, It turns out it must have been P0302. I was scrutinising the wrong lead and plug. 1 is closest to the timing belt 4 is near the transmission. The old school paper trick must be confused by the lack of explosion in cyl 4 and easily misread as being drawn back into the exhaust.  For all those wondering the cost of a cyl head remove and repair , everywhere between $2500 an $4000, and most centres mentioned timing belt done at the same time. Most shops were surprised at the low mileage and a possible head exchange, which bodes well, as it must not be very common. I am thankful that I wont have the major expense of a new head and will get new plugs and leads, and a timing belt replaced very soon. I saw a worst case scenario, probably due to a similar experience with my hyundai lantra. But that was a mitsubishi engine under licence to hyundai.
I'm reading this and taking it that it's a misdiagnosis and you don't need a head. Those prices are laughable, my God. You could do a complete powertrain swap for that.

  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

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  • Posts: 3,235
  • au Australia
    Samford Valley
Re: Exhaust Valve not sealing
« Reply #7 : November 27, 2018, 02:49:14 »
Hello,  The car is a  manual, no compression test done yet, but air sucking back into exhaust pipe leans me toward burnt/sticking exhaust valve, Timing belt is due to be done, and going this deep into the engine is an excellent time for it, new head bolts will be used.  If it is just one valve I would consider just getting that done, as long as the shop thinks the others are all ok, but it would make sense to replace to replace valve stem seals.  A low k wrecker motor could just be someone else's problem waiting to happen. Hope that makes sense

No, not really.   :wacko: Many (potentially majority) of these engines are at 250,000km and still going strong.

You are making assumptions without doing a compression test.

The codes relate to misfires which is a broad brush diagnosis. \

Worse case scenario, a wrecker motor will be  more cost effective.

  • Every FD model; BMW Z3 M; Mitzi Magna(mobile office)

Re: Exhaust Valve not sealing
« Reply #8 : November 27, 2018, 05:46:34 »
You are right nzenigma, I made an assumption. I originally was going to replace each lead and plug, in turn, to see if it would make the small misfire go away, then the computer gave a code. I mistakenly remembered that the last time it gave the code it was on cyl 3 (it was actually on cyl 2). With the transverse engine layout, I then looked at cyl 1, thinking it was 4, for plug, lead and coil faults. When I couldn't find any I looked at fuel the injector and couldn't find a problem. This leaves ecu or compression.  I assumed the father in-laws test was accurate and started to price replacements. All mechanics pretty much said they had never heard of a I30 head going bad, and so I double checked everything. I pulled the old original leads and looked again at the coil packs. Then the penny dropped the cylinder numbers are written on the coils. I looked down cyl 4 with my borescope, and swapped out the lead and plug, and the engine runs smooth again.

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  • Posts: 3,750
  • au Australia
    Ipswich
Re: Exhaust Valve not sealing
« Reply #9 : November 27, 2018, 05:54:18 »
You are right nzenigma, I made an assumption. I originally was going to replace each lead and plug, in turn, to see if it would make the small misfire go away, then the computer gave a code. I mistakenly remembered that the last time it gave the code it was on cyl 3 (it was actually on cyl 2). With the transverse engine layout, I then looked at cyl 1, thinking it was 4, for plug, lead and coil faults. When I couldn't find any I looked at fuel the injector and couldn't find a problem. This leaves ecu or compression.  I assumed the father in-laws test was accurate and started to price replacements. All mechanics pretty much said they had never heard of a I30 head going bad, and so I double checked everything. I pulled the old original leads and looked again at the coil packs. Then the penny dropped the cylinder numbers are written on the coils. I looked down cyl 4 with my borescope, and swapped out the lead and plug, and the engine runs smooth again.
:faint:
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

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  • Posts: 2,973
  • au Australia
    Tura Beach ( Deep Deep South Coast) NSW
Re: Exhaust Valve not sealing
« Reply #10 : November 27, 2018, 18:14:57 »
So lucky you decided to go back and recheck everything.
Go a buy a bottle of something to contemplate and celebrate your thought process.   :victory:
  • (09/16 Active X 5dr 1.8 6sp A) 02/18 DM5 Santa Fe H/lander 2.2 6sp white

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  • Posts: 735
  • au Australia
Re: Exhaust Valve not sealing
« Reply #11 : December 07, 2018, 00:04:03 »
You are right nzenigma, I made an assumption. I originally was going to replace each lead and plug, in turn, to see if it would make the small misfire go away, then the computer gave a code. I mistakenly remembered that the last time it gave the code it was on cyl 3 (it was actually on cyl 2). With the transverse engine layout, I then looked at cyl 1, thinking it was 4, for plug, lead and coil faults. When I couldn't find any I looked at fuel the injector and couldn't find a problem. This leaves ecu or compression.  I assumed the father in-laws test was accurate and started to price replacements. All mechanics pretty much said they had never heard of a I30 head going bad, and so I double checked everything. I pulled the old original leads and looked again at the coil packs. Then the penny dropped the cylinder numbers are written on the coils. I looked down cyl 4 with my borescope, and swapped out the lead and plug, and the engine runs smooth again.

Great outcome!
Thanks for letting us know..