6.9 Distributor rotors

[WGB]

When my 450 fouls it stays fouled - I would check that there is a spark at those plugs and then replace them.

You can try cleaning them but for a few dollars a couple of plugs is a sound investment.

I have a set of colder plugs in my 450 as all it is doing is idling once a week athough I am back to 7 cylinders at present again.

It is usually no 1 cylinder that fouls first.

Bill

[13B]

Interesting this fouling phenomenen... my 6.9 never fouls plugs but the possibility is always in the back of my mind esp. in peak hr melbourne traffic where I can travel for km at idle speed or just above... so I use the freeway onramps to rev the sucker out in an attempt to burn any crap off the plugs... don't know if its needed but it can't be a bad thing.

As for my 450SE, with its loose old engine and rich D-jet setup its easy to foul plugs.  In fact I won't even start the car unless I'm prepared to warm it up fully and take it for a short 5-10min drive before switching it off.  The plugs which foul are in this order: 1, 2, 6 and 7.  The others were not fouled when I bought the car and have never fouled.  There is a big power descrepancy when even 1 plug fouls, and the engine sounds rough and unhappy.  Glad 3&4 don't foul because they are so hard to remove.

I.

[oscar]

Hmm,  I drove the 350 to work this morning and Number 1 isn't firing again after I cleaned the plug and cleaned the inside of the suppressor to get it firing again a couple of days ago.  I'm adamant the spark is leaking around the plug.  The only thing common between the d-jets and k-jets including the 6.9 about number 1 cylinder is the rocker cover cap is located in the same spot.  If yours are like mine, I could do with a new seal in the cap since oil leaks down the cover, possible over the rocker gasket then to where number 1 plug is.  The leak is not much but it's there.  I'm wondering if the oil causes a caplillary like action into the suppressor and causes the spark to travel on the outside of the plug to the block.  Wild theory but something's not right.

It'd be interesting to know TJ if your number 2 suppressor is oily inside or the area around the spark plug hole is oily.  Maybe your rocker cover gasket is slightly wet too from oil and leaking down.

[TJ 450]

There is a small amount of oil at the base of the plughole at no.2, but it's completely dry everywhere else. The inside of the suppressors are clean, as they're new. However, when the old leads were on there it was a different story as there was oil everywhere. When my 450 had the miss, it was putrid around that spark plug as well... I think it's quite probable.

Tim

[oscar]

Firstly, I forgot about the 6.9 having a dry sump so there's no cap on the right cover, so that's why I added the strikethrough in my post above.

Anyway, maybe the oil around number 2 is just coming from the rocker cover gasket.  When you get a chance TJ, slowly remove the ignition wire from number 2 plug whilst it's running.  Slowly remove it and slowly put it back on.  I just did that to my number 1 plug and took a video of me doing it.  You can see that when the suppressor is half way on the plug, the engine picks up revs.  When I advance the supressor all the way or take it off further, the misfire occurs again.  For some reason the spark is leaking to the block when the supressor is seated all the way on the plug.  I've tried this out at night but can't see any flashes as to where the spark is earthing when the misfire occurs.

I probably wont be able to upload the video till much later but I'll post a link as soon as I do.

[WGB]

The M116/117 motor has a rubber gasket on the cam-cover(until the K-Jet engine frequent valve clearances were needed) while the M100 has a composite gasket.

If you put on a new gasket on a 6.9 motor and torque in the corect order at the correct 15nm it will be totally oil tight. What happened with my old gasket is that it slowly crept out from under the cover at about the point of the No 2 sparkplug until it ceases to seal and the oil starts to drip.

Can be temporarily fixed with gasket sealer like Permatex but new gaskets are best bet - quite cheap from AutohausAZ, nearly $200 each from local agent.

Bill

[oscar]

my old gasket is that it slowly crept out from under the cover

Is the gasket for a 6.9 "U" shaped in cross section.  I know you guys have studs rather than bolts but I thought the shape of the gasket might be the same and would stop it from bulging out so to speak.  Welcome back from HK too BTW.   hope you guys enjoyed yourselves.

Hope I haven't thrown your thread off course TJ but here's that video.  You might have to watch it a few times to here the increase and decrease in revs.  It's seems so obvious when you do it yourself.  You'll also hear the spark as I remove the suppressor but generally, as soon as the supressor is properly seated, the cylinder doesn't fire and the revs drop. 

http://www.youtube.com/watch?v=aSxTxlHkjWI

[WGB]

The gasket on 116/117 motors is a u-section shaped rubber one.

The 6.9 motor has a flat composite one like a thin head gasket with shaped holes for the seven studs that hold it on.

It is re-usable but is really designed to be changed each time.

Bill

[oscar]

The gasket on 116/117 motors is a u-section shaped rubber one.

The 6.9 motor has a flat composite one like a thin head gasket

Sorry Bill, I misread your other post as though you said M110, not M100 since the M110 has a flat composite gasket too.  My mistake.

[TJ 450]

No worries Oscar. It's all quite relevant, even for my 450 as well. I got a set of BP6ES's tonight, but I have removed the suspension fluid reservoir and pressure regulator/dist. valve for cleaning. As a result I won't be able to start the car until Saturday afternoon, when I have it back together with fresh hydro fluid and filter. When it's running, I'll see what happens.
By the way, how much does your engine move when it's missfiring? Does it rock the entire car from side to side when in drive at idle? I'll upload a video on YouTube that I filmed when I first got the 6.9 running without Nathan pouring fuel down the intake  Bear in mind that this was a few months ago.

Tim

[oscar]

By the way, how much does your engine move when it's missfiring? Does it rock the entire car from side to side when in drive at idle?

I just had a look at my video again and I admit it looks like an earthquake is happening the whole time.  The rev changes are there and the engine wobble does disappear when all eight fire.  The problem with the vid is that I used my phone cam and my elbow resting on the battery, the wobbles are accentuated especially since the frame rate isn't crash hot.

But, when just one cylinder misses, the chassis shakes at idle and is noticeable, putting it in drive and dropping the revs a bit further it's worse again, but I reckon it would be even more noticeable in a 6.9 just due to its size.  At about 1200rpms the shake isn't that noticeable but the power loss is and so is the exhaust note under load.  It's weird but with one cylinder missing, the exhaust sounds more like a bigger V8 with a wop wop wop wop happening.

[TJ 450]

It actually looked quite smooth compared to what I'm used to  I know what you mean about the exhaust note, my 450 was like that as well. This 6.9 really generates some serious seismic waves 

Tim

[TJ 450]

Here's the video of how the car was running a few months ago.

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</YOUTUBE>

Tim

[Big_Richard]

young TJ,

I am available saturday afternoon / perhaps sunday, if you want to organise a nathan and PB visit for some unprofessional opinions.

[oscar]

Holy crap TJ, what are the other wheels parked around the 6.9?

The video is amazing.  Even though the engine is running like a dog, it sounded like a supercharged locomotive when you slowly press the accelerator.  I couldn't see the wobble in the vision sorry.  This work computer is too slow and it just appeared jumpy, but the misfiring is obvious.  I thought it sounds like a bad knock when you start it up.  Why did it take a couple of attempts for the starter to kick in?  Was it just the gear selector in the wrong posi?

BTW, I've tried to embed videos too and I only ever get the link, not the image of the video.  What's doing there?