Bought my 1994 a few weeks ago and the engine has had some serious lumpy idle issues. Sounds and feels like its running on less than 6 cylinders, Well I thought I would start with the easy stuff and replace the spark plugs, all the plugs except for number 3 appeared normal. I've included a picture of 3. It lacks power and idles like a big block with a serious cam. It has 219,000 miles. Any suggestions are greatly welcomed, otherwise enjoy the really ugly spark plug.
Steve
And despite the sickly motor its nice to be back behind the wheel of a 4x4 toyota

 

Have you done a compression test?

 

Normally that would be the first thing I'd do, but I've never seen a plug this bad.
I've got a decent compression tester, I'll do it day after Christmas and post the results.

 

have you pulled any codes, yet. To be honest, I've had 3 other 3.0's, all over 200K, and I have NEVER seen a plug like this. In 1 of the stickies on the top of this page, there is an 800 number for Toyota. Call them give them your VIN, and see if your rig falls under the HG recall. I KNOW they honored it til then, as my NEW current '94 3.0 rig was built in July of '94, and my rig had the recall done. Just some thoughts.....

 

Oh my dear god

Thanks for sharing the pic! Gruesome and amazing.

That looks like google images when you type in any kind of ailment, you get the worst possible result. And that, without a doubt, looks like it belongs right in that image search for sickly spark plugs. Incredible

I can only imagine what the combustion chamber looks like for cyl 3?? Yowza

What do you think guys? HG? Bad piston ring causing oil blowback? I guess a compression test would help. If it comes back normal maybe a leakdown test?

 

Looks like oil to me. But when you do the compression test, you'll have to pull the plug. If it's as bad as I suspect, the plug will already be oily.

Most likely cause is a bad ring, which should show up as low compression. A bad valve guide will also admit oil (which is characterized by blue smoke on start up that quickly disappears), but may not be as obvious on compression.

 

Hi All
I got the truck to operating temperature and did a compression test on cylinder #3 this evening, 50psi. Then I pulled the tester and squirted some 30 weight oil and did the test again, still 50psi. I suppose I need to pull the valve cover and see if the valves are properly adjusted. I'm getting no CEL or any codes. The spark plug that came out of cylinder 3 has about 20 miles on it and has appears to be OK.
Need to call Toyota and check to see if recalls have been performed.
I'm kind of intimidated by the complexity of the engine compartment as I have been driving and maintaining a 1981 VW diesel rabbit for the past 20 years. I do like a challenge and apparently I've got one, on the plus side, the deeper I get into it, the more I'll know about it and I'd rather not start learning on a dirt road 20 miles from a highway.

Thank you to everyone for the support!

Steve

 

I think a 3.4 swap is in order

 

But for now, I've got to pull the head.

 

Just taking a shot in the dark here, but i think you've got a ring issue, mainly the oil control ring… Thats a bunch of caked on oil on that plug for it just to be a valve. How did the compression test look on the rest of the cylinders?

 

I'm being a slacker and haven't done the other cylinders. It took me most of yesterday to find my gasoline tuneup tools, haven't used them in a number of years. I put a couple of squirts of oil in the cylinder for the second test, and it did nothing to improve the compression. That said, it is an awful lot of oil for a bad valve guide seal. Please forgive me, if I'm asking a bonehead question, if I pull the head can I drop the oil pan and push out #3 piston to inspect the rings and cylinder walls?

 

I am having the exact same issues with my #5 cylinder...I tested it 2 days ago and its at 30psi while the rest are between 150-158psi! I also get a strong exhaust smell coming into my truck. After i cleaned up the plug it started to fire again and it runs smooth but i know im still not getting compression. Im now stuck between rebuilding my heads or getting a nice rebuilt 3VZE to drop in and parting out my existing motor.

See my plug looks identical:

 

I've seen a plug that bad on a chevy V8 with a bent valve (stuck permanently open). Once the cylinder stops firing due to low compression, the plug will foul really badly quite quickly. On the chevy, I cleaned up the plug and it was back to looking the same way after 50 miles of driving.

Do a leakdown test to see where the air is exiting. Then pull the valve cover and check the valve lash. Don't assume you have to tear apart the bottom end until you've eliminated the top end possibilites, which are generally easier to check out. Unfortunately, #3 cylinder is on the passenger side, which means in this case you'll have to pull the plenum to get to the valve cover.

Oh, and if you do decide to get into the bottom end, I'd plan on pulling the engine. To get the oil pan off without pulling the engine, you'll have to drop the front diff. At that point I think it becomes easier just to pull whole engine and work on it out in the open.

 

A bent valve was just what I was thinking or a valve with no clearance. I'm thinking after i check valve clearances, I'm going to a u pull it and look for a head with clean plugs replace the head and call it good while I save for a rebuilt motor. If I have to drop the front differential then I'm far enough in to justify pulling the motor.