Officially bummed: knocking 92 300D 2.5T

[cscmc1]

On my way to work today, the 300D ('92 2.5T) started faintly knocking. Over the course of the next couple of blocks, and into the parking lot at work, it was knocking loudly and smoking like crazy. Power seemed to be fine, and the knocking decreased a bit as the car coasted into the lot. Under power, the knocking was more pronounced.

I checked the oil, which seems to be OK, and the smoke seemed to be a lighter gray. Didn't smell at all like a head gasket failure; it was burning oil or fuel, I think. Hard for me to tell the difference as it was quite cold and windy this morning. I went back out later and re-strated the car while the engine was still warm. Still knocking and smoking like crazy. Oil pressure looks good.

I am going to try to limp her home at lunchtime (and fumigate the neighborhood) and try cracking injector lines to see if I can hear/see a difference. I have a short lunch, so that's all I'll have time to do. I am also heading out this week for a 5+ week military deployment, so diagnosis time will be virtually nil with the holidays and all. I need to spend time with the wife and family before I head off and miss Christmas and New Years, obviously.

Anyway, any other thoughts on relatively simple diagnosis procedures or things to make note of, in particular? I am hoping GSXR's suggestion (via PM) that it *could* be a stuck injector might be right. Boy, that would make me happy. I had planned to send them all off to CSeanWatts when I got back anyway as there has been a slight miss at cold idle once in a while (with accompanying little puffs of white smoke) and nailing.

Any thoughts/suggestions/prayers would be appreciated!

[awsrock]

EEk! Never a good thing to hear after working with your suspension so much! I hope it isn't anything serious. How many miles do you have again? If I was more experienced and had a garage, I'd say you should drop it off with me while you're gone! 5 weeks sure is a long time. Best of luck!
I might have a bad injector too..just noticed a significant leak in #2, and I can't imagine that it is the return lines, because those are only a few months old. I'll have to check it out today in the light

[cscmc1]

Thanks... I'm at about 260K on the odometer, and I'm assuming the engine is original to the car. It has been running so well, too. Sigh...

[Motorhead]

With it at idle, loosen one injector line at a time to find out which cylinder is noisy. Pull the offending cylinder's injector and have it checked. You could just have a bad injector. Trade it to another cylinder, start the engine and repeat the cylinder check and see if the same injector in another cylinder acts the same.

[cscmc1]

Thanks, guys. Just got her home (wow, was she smoking/knocking). I'm going to loosen the injector lines one at a time now. FWIW, the exhaust smells like burning plastic (!).

[cscmc1]

Loosening injectors made no difference. The smoke is white/gray, but will alternate in degrees of darkness. It'll puff white, then gray, back to white, and so on. I also noted some smoke at the back of the head/block near the firewall in occasional puffs. It was coming up and out near the oil filter housing, and smelled exactly like the exhaust out the back.

No real blowby, for what it's worth, and oil pressure held steady on the trip home (only about a mile).

When I cracked the injectors, the fuel seemed to smell more solvent-like than I am used to. Not sure how to describe it, but diesel fuel usually has a tame odor; this was quite sharp.

Anyway, what a downer, and what timing.

[rrgrassi]

I noticed the ULSD smelled different when I filled the car up this week.

Burning plastic smell sounds like the beginnings of coolant burning, based on the white smoke.

[cscmc1]

Originally Posted by rrgrassi

I noticed the ULSD smelled different when I filled the car up this week.

Burning plastic smell sounds like the beginnings of coolant burning, based on the white smoke.

Hmmm... does a bad head gasket in a diesel smell much different than one one in a gasser? I know that smell well (sadly), and this smells different (at least at the moment). Would a bad head gasket knock, too? I mean REALLY knock? This this is NOISY.

Thanks for the advice, by the way. I can use all I can get at the moment.

[larry perkins]

better check the oil level,if its the l head seal gone, you could gets lots of oil out the exhaust.
larrp perkins

[cscmc1]

Originally Posted by larry perkins

better check the oil level,if its the l head seal gone, you could gets lots of oil out the exhaust.
larrp perkins

Thanks, Larry. Oil level is still OK on the dip stick, but I have only driven it about 1.5 miles in this condition. Not sure how quickly oil loss will show up. So far, no oil in the coolant or milky-ness to the oil, so I'm not sure (yet) that the fluids are mixing.

[rrgrassi]

Does the cooling system hold pressure over night?

I do not know if there is a difference in smell in a blown head gasket on a gasser vs diesel. I'm sure there would be since diesel does have a different smell. Either way it smells like a coolant leak on a hot engine mixed w/exhaust to me.

[Motorhead]

Did loosening individual injectors change the knock? Or did you find one particular cylinder that didn't make much difference with the injector line loosened? The smoke might take more than an instant to go away. Chances are that you have residual in the exhaust system. You could have lost a head gasket.

[cscmc1]

None of the injectors made a difference (that I could hear) when loosened. I just loosened them enough that they spit a little fuel out the top; didn't want to smoke the neighbor out if I could help it.

I'll have to check the coolant system pressure; thanks.

[compress ignite]

'Fingers Crossed for you to ward off Evil.

[cscmc1]

Originally Posted by compress ignite

'Fingers Crossed for you to ward off Evil.

Thanks -- I can use all the help I can get!