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Help With Engine


Dan850T5

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Hi all,

My car started firing on 4 again for the second time in two weeks (replaced the plugs first time and that solved it temporarily). Anyway it happened again earlier, so i blasted the plugs out and plug 4 was completely focked already!

I had a look into the block through where the plug sits and there is a pool of oil within the block in cylinder 4! every other plug apears to be ok.

Can anyone advise as i believe this could be a piston ring?

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What plugs are you using? And what gap?

+2

you should be running champion coppers or at least some sort of coppers or OEM plugs. if they are platinum or iridium your just wasting money,

and re-size your sig pic please

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Apologies for sig, removed for time being.

The gap on the plugs is 0.7mm, as specified in my Haynes Manual, i was advised from another forum and through my local motor parts company that platinum tipped plugs were required, so i am running NGK platinum tipped plugs.

I will try to explain in more detail what i am seeing. All the plugs, bar plug 4 are in good condition, as you would expect seeing as they are only 2 weeks old, plug 4 when i removed it last night was covered in a black grimey substance, which doesn't smell like fuel. if you look into the block where plug 4 sits, there is a "pool" of liquid, which i believe to be oil. If you look into the block through all the other plug locations, it is dry and no problems.

What i believe to be happening is the oil or whatever is in the block on plug 4 is being transferred onto the plug itself and preventing it from sparking, hence it firing on 4

My beliefs are either piston ring or head gasket, but i'm not a mechanically minded person naturally so i'm lookin for advise. I've got it booked in with my mechanic on monday/tuesday but any ideas on what i may be dealing with will be a big help

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try the plugs first, go spend 10 bucks and get some champion coppers, try those first, let me go find the gap.. its suppsed to be .025 - .027 standard if i recall correctly..

the stuf on the plug may be un burnt fuel.. soo a change in plugs may help.

brb with actual #'s

actual gap found

where are you from if you dont mind me asking also..

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What i believe to be happening is the oil or whatever is in the block on plug 4 is being transferred onto the plug itself and preventing it from sparking, hence it firing on 4

My beliefs are either piston ring or head gasket, but i'm not a mechanically minded person naturally so i'm lookin for advise. I've got it booked in with my mechanic on monday/tuesday but any ideas on what i may be dealing with will be a big help

Hello,

That pool of oil in the plug well is caused by a leaking valve cover seal. The valve cover gasket is liquid, not a standard rubber or cork gasket. There is also an o-ring that seals each spark plug well. You will need to remove the entire valve cover to repair and reseal. Not too bad of a job, but it does usually involve removing the timing belt. When that oil leaks into the plug wells, it can contaminate the plug wire boots and cause arcing. That is likely where your misfire is originating. If left this way too long, it will soak into the rubber of the plug boot and it will then disintegrate. Therefore, you may need to replace the plug wires also. Let me know if I can help any further.

Good luck to you,

Joe - Volvo Master Technician

2000 S70 AWD, 1995 850 Turbo

P.S. - As Aaron has stated, only use OEM plugs. Factory gap spec is .028"-.032"...

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Joe, thank you very much for the help there! I will pass this on to my mechanic. As for the gap, 0.028" works out at approximately 0.71 millimeters (i'm in the uk by the way) which is the gap im running in these new plugs, but you are saying that platinum tipped are a bad idea?

It seems the everywhere i look, i.e motor shops and in the haynes manual says platinum tipped are the correct choice, i've just spent £35 on this new set.

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Hello,

That pool of oil in the plug well is caused by a leaking valve cover seal. The valve cover gasket is liquid, not a standard rubber or cork gasket. There is also an o-ring that seals each spark plug well. You will need to remove the entire valve cover to repair and reseal. Not too bad of a job, but it does usually involve removing the timing belt. When that oil leaks into the plug wells, it can contaminate the plug wire boots and cause arcing. That is likely where your misfire is originating. If left this way too long, it will soak into the rubber of the plug boot and it will then disintegrate. Therefore, you may need to replace the plug wires also. Let me know if I can help any further.

Joe, could it be a bad valve stem seal on the cylinder, rather than the whole valve cover? Or is that what you mean by the o-ring? Because I thought the head has to come off for the valve stem seals.

yeah I know some people say you can do valve stem seals with the head in the car ...

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Joe, could it be a bad valve stem seal on the cylinder, rather than the whole valve cover? Or is that what you mean by the o-ring? Because I thought the head has to come off for the valve stem seals.

yeah I know some people say you can do valve stem seals with the head in the car ...

Hello all,

As far as using platinum tipped plugs, I believe the OEM turbo plugs are platinum tipped (on both the electrode and ground). OEM plugs for the NA engines are not. I would try to remedy the valve cover leak first (and possibly the plug wires), then see how the plugs work.

As for the valve stem seals, they will leak oil into the combustion chamber, not into the plug well. That will cause the engine to smoke, but not misfire (unless extreme). As for replacing them with the head on, it can usually be done. You would need to put an "air hold" on the cylinder. This involves pumping the culinder full of compressed air (through the plug hole). This air keeps the valves from falling into the cylinder when the keepers are removed. Make sense?

Hope this was helpful,

Joe - Volvo Master Technician

2000 S70 AWD, 1995 850 Turbo

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Hello all,

As far as using platinum tipped plugs, I believe the OEM turbo plugs are platinum tipped (on both the electrode and ground). OEM plugs for the NA engines are not. I would try to remedy the valve cover leak first (and possibly the plug wires), then see how the plugs work.

As for the valve stem seals, they will leak oil into the combustion chamber, not into the plug well. That will cause the engine to smoke, but not misfire (unless extreme). As for replacing them with the head on, it can usually be done. You would need to put an "air hold" on the cylinder. This involves pumping the culinder full of compressed air (through the plug hole). This air keeps the valves from falling into the cylinder when the keepers are removed. Make sense?

Hope this was helpful,

Joe - Volvo Master Technician

2000 S70 AWD, 1995 850 Turbo

from what i read of the OP's posts, the oil is in the combustion chamber, so my guess is the valve stem seals. and wouldnt the "air hold" only work if your valve seals perfectly and the piston rings are perfect? seems a bit risky to me...

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from what i read of the OP's posts, the oil is in the combustion chamber, so my guess is the valve stem seals. and wouldnt the "air hold" only work if your valve seals perfectly and the piston rings are perfect? seems a bit risky to me...

This is not Joe, but I think everything he said is correct. I changed the valve stem seals in a Dodge Dynasty (we called it the Die-Nasty), and used compressed air as he said. It seems tricky but if you take your time, it can be done. I had the black smoke situation, and after putting in new valve stem seals the black smoke immediately went away. I don't think it's seals though.

The easier thing to do is remove the valve cover and replace the spark plug tube o rings.

I don't think it's related to the spark plugs, but putting in coppers is cheap and easy. I have done both (plats and coppers) in my NA and it ran fine with either.

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Hello all,

As far as using platinum tipped plugs, I believe the OEM turbo plugs are platinum tipped (on both the electrode and ground). OEM plugs for the NA engines are not. I would try to remedy the valve cover leak first (and possibly the plug wires), then see how the plugs work.

As for the valve stem seals, they will leak oil into the combustion chamber, not into the plug well. That will cause the engine to smoke, but not misfire (unless extreme). As for replacing them with the head on, it can usually be done. You would need to put an "air hold" on the cylinder. This involves pumping the culinder full of compressed air (through the plug hole). This air keeps the valves from falling into the cylinder when the keepers are removed. Make sense?

Hope this was helpful,

Joe - Volvo Master Technician

2000 S70 AWD, 1995 850 Turbo

This is not Joe, but I think everything he said is correct. I changed the valve stem seals in a Dodge Dynasty (we called it the Die-Nasty), and used compressed air as he said. It seems tricky but if you take your time, it can be done. I had the black smoke situation, and after putting in new valve stem seals the black smoke immediately went away. I don't think it's seals though.

The easier thing to do is remove the valve cover and replace the spark plug tube o rings.

I don't think it's related to the spark plugs, but putting in coppers is cheap and easy. I have done both (plats and coppers) in my NA and it ran fine with either.

If the valve stem seals are leaking, which sounds probable Joe is correct. The compressed air WILL hold the valve up. The seal is above the combustion chamber and in the head. When you put compressed air into the cylinder it is through the spark plug hole and into the cylinder. It would only leak if the valve is not full closed or BENT. Is there oil in the spark plug well? If there is no oil pooled up in the plugs well on that cylinder then the seals aren't leaking. This is just for knowledge, since if the valve stems are leaking you would change these seals for the plugs anyway. The spark plug seals under the cam carrier which has to be removed to replace the stem seals.

Platinum plugs are original to Volvo turbo cars. Bosch and Champion are the only 2 that I know of that burn at a different heat index so they don't give off the powerful spark at the correct temp. Yes Bosch makes the plug for Volvo but at their index. I can't remember the temp tight now. I'll find it.

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Ok, to clarify the oil is leaking into the area where the electrode points into (So you taker the plug out and its the area you can see into,sorry for describing it so crudely)and it's only on plug 4.

So i'm looking at either valve stem seals or the valve cover seal leaking?

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