Lost a spark plug - Fuel Economy, Hypermiling, EcoModding News and Forum

travelingaaron · 02-28-2010, 12:31 AM

So my car has been having issues anyway and I recently did a compression test to find out that I had no compression on one cylinder. I don't know if it was me putting everything back together poorly or something else.

My car has been sputtering and dying lately but I thought it was from a gas-additive I put in the tank trying to free up the valve on the bad cylinder. The dying did not start till right after I added the additive. I bought the additive at Auto Zone when I took the compression test kit back so I probably should have considered that it might be something else but nothing looked wrong. I have to add oil frequently due to a leaky oil pan seal (on my to do list with the engine rebuild). I am sure that I would have noticed a spark plug hanging when adding oil, it was the first thing I saw when I popped the hood.

So what causes a spark plug to back itself all the way out? The hole was empty and my spark plug wire was hanging there not attached to a plug. This is a different cylinder than the one that had no compression.

Christ · 02-28-2010, 12:42 AM

It may have blown the threads clean out of the head. I've seen it happen before, usually due to overtightening.

travelingaaron · 02-28-2010, 01:00 AM

Hmmm... That sounds like it will be fun to fix. Maybe I should just ditch this engine. Might be cheaper to just find a 1.0 to put in it and get better mpgs anyway. Going to start looking for engines.

Christ · 02-28-2010, 01:04 AM

The fix involves a $30 Heli-coil kit and about 20 mins of your time. You just tap the head with the included tool, thread a new thread insert in with silicon sealant on it, and then thread the spark plug into the sleeve and all's well again.

That's not necessarily what happened, though. It was just a suggestion. You'll have to check for yourself to see if the threads are damaged.

Frankly, it could have just been not tightened properly, and backed out from vibration.

If you're going to replace your engine w/ a G10, you have to replace the trans/axles, as well. The G13's transmission is mounted/designed slightly differently because of the engine length.

travelingaaron · 02-28-2010, 01:34 AM

Quote:

Originally Posted by Christ

If you're going to replace your engine w/ a G10, you have to replace the trans/axles, as well. The G13's transmission is mounted/designed slightly differently because of the engine length.

I am confused, how is this not the same as the people that have metro's with the G10 swapping in a tranny from my car? I thought I would be a step ahead since I already have the taller gearing.

It is dark now and the car is sitting on the side of the road a few miles from here so I can not look and see for sure if there are any threads left. I see it taking far, far longer than 20 mins though lol. It took me that long just to get the compression test kit screwed in to each spot. Very little room to work with around the spark plugs.

Hopefully when I go to tow it back here tomorrow I will find that the threads are indeed still there.

Christ · 02-28-2010, 08:30 AM

Quote:

Originally Posted by travelingaaron

I am confused, how is this not the same as the people that have metro's with the G10 swapping in a tranny from my car? I thought I would be a step ahead since I already have the taller gearing.

It is dark now and the car is sitting on the side of the road a few miles from here so I can not look and see for sure if there are any threads left. I see it taking far, far longer than 20 mins though lol. It took me that long just to get the compression test kit screwed in to each spot. Very little room to work with around the spark plugs.

Hopefully when I go to tow it back here tomorrow I will find that the threads are indeed still there.

IF you mount the G10 to a G13's transmission, the engine will sit too far to one side, is all. (That I'm aware of)

There are people here that know more about that part than I do.

travelingaaron · 02-28-2010, 09:45 AM

I see. Gonna have to do some research then. There is a 4 door lsi for sale on craigslist for 350. I would then have the springs to lower it and a 3 cyl engine if I can do it. Thanks again.

thatguitarguy · 02-28-2010, 10:49 AM

You don't have to closely examine the threads - just try to screw in a spark plug and see if it tightens.

The helicoil is a good quick fix. Be careful in the future to tighten, but not over tighten anything, especially when screwing into aluminum.

MetroMPG · 02-28-2010, 11:19 AM

The 3 cyl engine will fit in the 4-cyl car without messing with the transmission/axles, but it'll sit further to the driver's side than it did in the 3-cyl car, so you may have to mod the motor mounts.

It's going the other way that is more of a problem (4 cyl engine into 3 cyl car).

gone-ot · 02-28-2010, 12:35 PM

...aircraft radial engines were notorious for "blowing" spark plugs.

...the R-3350 turbo-compound engines with PRT's on our Lockheed EC-121 "Warning Star" aircraft would typically loose either a "plug" or a "jug" about once or twice a year...of course, that's after running continuously for 16-20 hours at a time during each flight.