Jump to content
SAU Community

Recommended Posts

Hello about a year ago i had one of my big bearings go . I had them all replaced and a good condition second hand crank shaft installed . All was fine until a couple of weeks ago when my car started to have a miss when i really put my foot down but it would go back to normal about ten seconds after. But then i was just driving normally oneday and it suddenly started to miss permanantely . i changed spark plugs and it was still there i played with coil packs found out the noise of the engine would stay the same with number 6 plug . so changed front coil with back and it still stayed the same so it wasnt coilpack. At this stage i couldnt figure it out so i took it to a mechanic. He beleives that the piston has hit the spark plug and thinks its a big end bearing gone again. The cars oil pressure was fine and had no knock from the motor or flashing dash lights like last time . So im just wondering if anyone has had a similar problem. or has a better idea of what could be going on?

If it is another bearing there must be something wrong with my motor . im only running stock boost . Mechanicsaid i either get a second hand bottom end or just get new bearings. rb30 bottom end could be an idea too?

Link to comment
https://www.sau.com.au/forums/topic/440753-piston-hit-number-6-spark-plug/
Share on other sites

Why not try unplugging number 6 injector? That would be the obvious next step for me.

I don't understand how the rod could stretch that much to hit the plug. Even if it did, the problem would not have been intermittent in the first place.

I have seen pistons hit the head, and it was making a fair noise by that stage. To hit the plug you would have to be running a longer plug than recommended. My suggestion, try another mechanic.

could be hundreds of things before that mate.

coil parck harness could be stuffed on no 6.

soark plug could be cross threaded

head gasket broken, rings gone, head cracked.

a missfire can pe a pita to diagnose.

but if the piston had hit the plug youd know about it....

Yes but BCPR6ES or BKR6EYA or XYZ123AB-C???

And funnily enough all the other letters mean something also. But no one cares....

http://www.ngk.de/fileadmin/templates/Dokumente/EN/downloads_not_used_in_download_area/ngk_zuendkerzen_code_en.pdf

Pull the plug, use a bore scope and have a look around inside.

IF you used the correct length plugs there is no way the piston would close the plug gap, the sides of the piston would hit the head first and you would hear that from a mile away.

Im wondering if you dropped a valve guide in there.....bore scope will soon find out....

Something hit your plug to close it and i highly doubt it was a piston.

There is always a possibility that the last person to fit the plug dropped it off the socket as they were fitting the plug down the hole and it closed the gap considerably, these things can happen when people are careless, ive seen this in the past on a number of engines where they didnt have the rubber sleeve to hold the plug into the socket in good condition and the plug just slides off and drops down into the head closing the gap.

Anyone who has this happen should get the plug out and recheck the gap before putting it back in.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers) Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose). Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom. For the pan, the workshop manual states the following order: Again, the torque is 8Nm only.
×
×
  • Create New...