divil

I am tracking down various running issues...what do these plugs tell you? I pulled them a few days ago, and #4 was more like #1, but after some WOT driving yesterday, I pulled them again today and now #4 is a bit cleaner. The big outlier is #2...the difference between #2 and #3 is a little more noticeable in real life than in the pics. #2 looks squeaky clean.

Sometimes I got lucky with the camera focus, other times not so much...couldn't tell until I zoomed in later:

Cylinder #1:










Cylinder #2:










Cylinder #3:









Cylinder #4:








There was also a white or light grey residue on the #2 piston, that I could just about see with a flashlight, but I couldn't get a picture of it. It kind of looks like dried up antifreeze.

Tom M'Guinn

Line them up together and take a picture of them all from 1 to 4 so we can compare in same light, etc. Hard to tell from those pictures what is lighting and what's real etc., but I when one is clean and three look normal, that can be a worry (HG leaks steam-clean the plugs). What gap are you running -- it looks huge, but suspect that's just the close up pictures making it look like that?

divil

Those pics were all taken in identical light within minutes of each other - all from exactly the same spot and same angle, on a bright sunny day with no clouds. The contrast in real life is at least what you see there, maybe even a little more. I could probably get better resolution on #2, but the colours are about right.

The gap is just under .030".

I went for a short drive after I took those, and I just pulled #2 again, and now it's much darker. I suppose that's from the cold enrichment? Whatever it was taking another pic now isn't going to show how it looked earlier. But I've pulled it a few times lately and it's always been very clean & white. I will go for a long drive and photograph them all later.

divil

OK this is weird...I went for a long drive with a few WOT runs. This is what I did yesterday so I wanted to make sure the next pics of the plugs would be in a similar situation.

I noted earlier that after a short drive, the #2 plug was suddenly much less white than it was this morning when I took the pics. Well, it's still like that now. Now, I have pulled these plugs 3 times over the last week, and #2 has been clean and white every time. Today, after a 30-45 minute drive, it's suddenly much darker. I thought the car was driving a little better than normal today too.

#1 felt a little reluctant to come out, the block might be still too hot, so I'll leave the rest of them for now and get the pics later, or maybe tomorrow.

One other odd thing...I can hear the sound of air and/or liquid being squeezed through a small leak. I narrowed it down to the electric water pump. That pump probably has a bad o-ring, so no surprise there. But then I held the overflow hose up to my hear, and there is the sound of air from that too. Over an hour after I parked the car. Is that normal?

Voith

#1 is burning some oil, when oil is burning, ash is forming on the plugs..

divil

Yeah I'm definitely burning some oil in there. The last set I took out had been there for a year or so and there was a lot of ash built up on those. Which makes me wonder, could it be that all cylinders are seeing the same AFR but they are different colours solely due to different rates of oil burning?

grumpyf14d

Here's a link to help out reading plugs but one thing to keep in mind is that in order to really read a plug you have to be able to look at the base of the porcelain.

http://ngksparkplugs.com/tech_suppor...qs/faqread.asp

mtnman82

My guess would be it looks like #1 is burning a little oil, but maybe like a valve guide leak. #2 looks like a head gasket leak (steam cleaning). Have you run compression or leak down tests? Or tried to pressurize the cooling system?

divil

I did a leak down test a few days ago. 1, 3 and 4 were all pretty much exactly the same, around 3.5%, but 2 was marginally higher. I mean, it was still less than 4%, so we are talking a very small difference, but I could see it on the gauge. I didn't open the cooling system at the time to check for bubbles as it was still a little hot.

I have a chemical block/headgasket test kit that uses a special fluid that's supposed to change colour if there are combustion gasses in the coolant. I tried that today and I can't get it to change colour. But I don't know how definitive that test is.

I haven't tried to pressurize the coolant lately, so that is something I can check again.

mtnman82

I've used the gas tester on a V8 Dodge and the 944, both had very minor head gasket problems (I had caught just the beginning) and neither registered with the gas tester. I also pressurized the coolant tank and it would hold pressure for a good 15 minutes. But I was loosing water with no apparent leaks (very, very slowly) and had a plug that looked steam cleaned on each.

What really set me off with the 944 if I recall correctly was a few times after I had shut down the car, ~10-15 minutes later it would belch like a quart of coolant.

Dave W.

Those chemical coolant testers only work if exhaust is actively pushed into the cooling system while testing. If the headgasket was that bad, you'd see bubbles constantly pushing up through the expansion tank.

Tom M'Guinn

No.

If you are getting lots of pressure in the coolant, and have one steam cleaned plug, those would make me look into the HG... See my head gasket R&R linked below for tests and signs for bad HG.

Tom M'Guinn

+1 Often the coolant will look all bubbly/foamy in the tank...

divil

I've read the link...great info there thanks. I have some of those symptoms but not others. For as long as I can remember, I've never been able to keep air out of my cooling system. It doesn't matter how I bleed it, the heater is always erratic. If I rev the engine the heater works better for a few minutes. Coolant temp always goes up at idle and down again either if I rev it, or when I drive away. But, it never overheats, and I never get a drop of coolant out of the overflow hose (this is something I've been checking regularly for years).

Really the car is not doing anything that it hasn't always done, as long as I've had it. I've never seen any spark plug quite as clean as the #2 looked lately, but looking back at old photos, I see that 2 was always a bit whiter than the others, with 3 close behind - here's a similar thread of mine from a few years back. (But, for clarification, the #2 from that thread is nowhere near as clean as the current one was earlier today).

On the other hand, I just went through the pain of changing my rod bearings so the last thing I want is to contaminate my oil with coolant and have to change the bearings all over again. So I will have to keep a close eye on it. I've always wondered how long my car will go without the head coming off - I suspect it's never been off before, and I'm at 196K miles now.

Tom M'Guinn

At 196k, you're overdue for a valve job anyway. But in the meantime, have you checked the reservoir cap to make sure it holds pressure and have you pressure tested the system? If you have an external leak, a pressure test will show it quickly. Any place that coolant comes out, air gets in...