Please look at my plugs

ianc · 01-02-2006, 08:32 PM

Ugh, this is really sucking. Please take a look at this shot:

I just bought this car about two months ago. I did a compression test on it then and all was good. Should have done a leakdown on it... It's run good up until about a week ago at the start of the heavy rains. I figured it was something to do with the dampness; some intermittent connection.

Tonite when I started it to go do some errands, it was running extra poorly. The occasional pop in the exhaust and a rough idle. When I got home I resolved to look into it further. I pulled the injector wires and looked for a drop in RPM's. I disconnected the ISV first. I got a small drop on each of 4-6, but very small or next to none on 1 and 2. I pulled plugs 1-3 and they're what you see above, with 2 being the black one. I retested the compression on all three, and they're all 170 lbs. The engine was warm. The wires, cap and rotor are all new.

No. 2 looks black, but not wet black like you'd expect from an oil fouled plug, but I can't think what else it could be. The plugs are not that old though...

I guess I'll do a leakdown tomorrow at the shop, but I have a bad feeling I'm going to be pulling heads on that side. Any comments?

Arghh...

ianc

Charlie V · Charlie V's Garage

looks oil wet to me.

Wil Ferch · 01-03-2006, 04:47 AM

Hard to tell if it is solely oil wet or is there a "fuel wet" issue lurking there too. Before we all go over the deep end...check to see if you're getting spark on that cylinder...maybe ( just maybe) it's a bad plug wire or something along those lines.

Wil

Icemaster · Icemaster's Garage

What Wil said...almost looks like that center plug isnt' firing...?

ianc · 01-03-2006, 08:40 AM

Well, I'm hoping it's fuel, and that injector is just stuck open or leaking. I'm still doing a leakdown on it this eve and will report back.

I find it hard to believe that cylinder would still have decent compression but oil foul a plug. I suppose if the guides were bad enough, but...

ianc

Steve@Rennsport · 01-03-2006, 08:50 AM

You didn't mention how many miles are on the motor, nor what your oil consumption has been.

I would do that leakdown regardless, but thats not conclusive for guide wear.

I would make sure that the ignition lead for that cylinder has the same resistance as all the others and check that injector for leaking.

Last,......One should remove the valve covers and have an experienced and competant person check the guides for lateral movement; thats the best indication of guide wear.

ianc · 01-03-2006, 09:07 AM

Hi Steve,

Thanks for the response. The engine has about 130K on it and hasn't been apart as far as I can tell.

I changed the plug wires out for new Bosches a couple of weeks ago, but I can check the resistance certainly. I changed them because they were the originals and the problem at first seemed intermittent, so I reckoned the wires were a good bet.

Oil consumption is tough to guess at because I have not had the car for long, and when I got it, it was leaking rather badly from the thermostat o-ring, which I just fixed last week.

Does checking for lateral movement involve removing the valve springs, or is just rocking it back and forth and comparing with the others OK?

I'm just wondering if a bad guide could allow enough oil into the cylinder to cause that even if the rings are OK. Seems funny too that only that one head would have a guide problem. I know of the Carrera guide problems, but would think that all of the heads would be affected equally?

ianc

911mot · 911mot's Garage

With the compression you've got I'd plump for a spark problem. Have you checked No 2 is sparking? Plug the fouled plug into the lead, pull fuel pump fuse, and get someone to crank while you check it. If no spark try one of the other plugs. Then start checking leads etc...

pmajka · 01-03-2006, 09:55 AM

what is bad oil consumption?

i dropped a quart in 4000 miles.

center bottom of motor is wet.

floor under engine gets slippery when i step in it.

Steve@Rennsport · 01-03-2006, 11:28 AM

Quote:

Originally posted by ianc
Hi Steve,

Thanks for the response. The engine has about 130K on it and hasn't been apart as far as I can tell.

I changed the plug wires out for new Bosches a couple of weeks ago, but I can check the resistance certainly. I changed them because they were the originals and the problem at first seemed intermittent, so I reckoned the wires were a good bet.

Oil consumption is tough to guess at because I have not had the car for long, and when I got it, it was leaking rather badly from the thermostat o-ring, which I just fixed last week.

Does checking for lateral movement involve removing the valve springs, or is just rocking it back and forth and comparing with the others OK?

I'm just wondering if a bad guide could allow enough oil into the cylinder to cause that even if the rings are OK. Seems funny too that only that one head would have a guide problem. I know of the Carrera guide problems, but would think that all of the heads would be affected equally?

ianc

Hi Ian:

My pleasure, sir,..

Check the plug wires and connectors for continuity. Those horrible Beru connectors are well known for being POS.

One checks guide wear by moving the whole valve assembly (installed, as-is) laterally. Its an "experience" thing.

You are right; generally speaking, if one guide is bad then most of the others are, too.

My first impression is that of an ignition problem and after that, its internal. The leakdown will tell you if you have a ring problem or not. Leaky injectors that will not close can do the same thing.

Time for some serious detective work,.....

ianc · 03-13-2006, 10:46 PM

See here in case this was turned up in a search:

Testimonial for Techron

ianc

jevvy · 03-13-2006, 11:09 PM

Hi Ian

I went through a similar experience about a year ago with my 3.2 with 130k on it:

I tried all the suggestions above apart from the valve wiggle and came to the conclusions I had worn valve guides with 1 bad one in particular. I also like you had good compression results but I was burning a bit of oil. I looked at rebuild options amd how much of it I could do myself and ended up going for a 3.6 transplant with a 45k motor I found.

I sold the 3.2 to a guy on here (1972_911T) for his transplant into an earlier car. He was well aware of the motors condition and was going to rebuild it anyway. What did he find, well maybe you should ask him for more detail however a few of the pics he sent me showed the internal parts to be quite coked up, he said the guides were worn and needed new rings - other than that all was cool.

And this is my old 3.2 in its new home:

stlrj · 03-14-2006, 02:50 AM

Did you replace the old wires with new Beru's?

Joe

Paulporsche · 03-14-2006, 04:31 AM

pmajka,

Bad oil consumption would be something like 1 qt per 800 mi. You probably have a small leak, possibly a valve cover, pressure sender, or return tubes.