Engine/Transmission (1994 - 1998) Major missing/knocking

[CAROLINA CUMMINS]

Howdy,



I'm working on a 97 12v here at the house, and it has a bad miss/knock.

My friend said he was pulling his trailer w/tractor on it up a pretty good hill, engine temp about 190deg or so in 4th gear 45 mph. he said it all of a sudden started missing bad and he pulled over real quick and stopped.

When he pushed the clutch in it cut off, and he said the coolant temp went out of sight(?).



He brought it to me, and I checked the oil and coolant, oil a little low, maybe a quart at most, not much. Radiator is full, but resevoiris empty. Neither seem to be cross contaminated.



I cracked the injector lines one by one and all seemed the cause a noticeable miss; seperate from the other one(does that make any sense??). When I cracked the number five line it seemed to smooth out alot, but still miss from the lack of fuel. It did make a noticeable difference in the severity of the knock/miss, almost went away.



The fuel has been turned up in this truck, not much at all. I slid the plate forward a smidge a while back. truck has about 180,000 miles on it, and lived a pretty rough life before my friend bought it 6 months ago.



Sorry for the long post, but I would like ya'lls input. Neither of us can afford to just swap parts until we find the problem. Hope I made sense explaining the problem. I'm thinking I'll at least be pulling the head to check the piston and such, I checked the pushrods on #5 and they seemed straight, hard to tell while it's still hot.





Thanks, Steven

 

[Murphy67]

Sounds like the Fuel Shutoff is not fully on or off. This creates a lean condition, engine starving for fuel. It however would not explain the coolant temperature spike.

 

[PKemp]

Before you go pulling the cylinder head, pull the injectors and check compression.

 

[JAmos]

I'm taking a couple shots in the dark here but could it be a head gasket problem or an injection pump problem?





Jordan

 

[CAROLINA CUMMINS]

Well,



I checked the fuel shutoff solenoid, no dice there, it sounds alot like one cylinder anyway. Good suggestion though



I have a compression checker on the way, hope to get it about Tues-Wed



Something else I think might help with diagnosis a little bit. When I started it up to pull it in the garage, it took me a little bit to get it to idle any at all. I had to hold the pedal down to get it to crank, and had to hold it above 1000 rpm for it to stay running about 2 or 3 minutes before it would idle.

I'm still curious about #5, it seems to be the culprit; would a toasted piston still knock if you loosened the injector nut??

Hopefully it's not something that serious, but the conditions when it occurred got me thinking toasted piston or the like.



This week I'm going to pull the valve covers and check the pushrods, valve adj, pump timing, and compression test when I get that. Maybe by the time I get all this done I'll have found it.



This truck lived a very hard life with the previous owner. I fixed the KDP cracked timing case a few months ago, and the PO had driven around for years; maybe, with it cracked, there is a 1/4" film of oil/dirt completely covering the underside of this truck. Dunno how many times it was run low on oil.



Thanks for the help



Steven

 

[ata]

45 MPH in 4th gear pulling a hill with a load with the plate slid forward. I Vote for toasted piston.

 

[Evan A. Beck]

Does it sound like someone tapping on an anvil with a 32 oz ball peen hammer?

 

[HLEschenko]

What's the condition of the fuel filter, strainer, and flexible fuel lines? Sounds like a problem in the fuel delivery system to the injector pump.

 

[PSchwering]

As Much as I hate to say it, it sounds to me like a rod bearing. I would pull the lube oil filter, & cut it open. If you spun a bearing, there should be a lot of chips in the filter.



I Sure Hope I am wrong... ... ... ..... P.

 

[PKemp]

Sure sounds like a rod bearing. A bad injector (broken tip) would have stopped knocking when you cracked the high pressure fuel line. A bad fuel supply problem would affect all or most of the injectors unless it was a single colapsed delivery valve in the pump (but that doesnt explain the knock). A toasted piston would see fuel in the oil from the injector washing down the cylinder and the knock would almost be gone (unless the toasted piston ate the wrist pin) A bad rod bearing would knock like he!! because the piston would still hold some compression putting pressure on the bad bearing journal on each stroke. Sounds like a ball peen hammer on a piece of heavy plate steel. A compression check will tell you wether its a toasted piston or a bad bearing. Cross your fingers, turn around three times and throw salt over yer left shoulder (then quaf a six pack), but it doesn't sound good. If you know someone who has one of those laser thermometers, just point it at the cylinder block, each cylinder "area" in turn on the passenger side below the exhaust manifold. The cold(er) reading is the bad piston hole..... P. S. run it as little as possible until you uncover the culprit... .

 

[CAROLINA CUMMINS]

Well fellas,



Here's some stuff I found tonight while working on it.



This thing is insanely loud underneath the truck/oilpan area .



PKemp, the knock quietens considerably when I crack the #5 line



I took all the valve covers off and cranked the truck to check the valvetrain for any problems such as bent pushrods etc... . I got to noticing alot of white smoke around top of the engine, at first I thought it was a very bad exhaust leak, but I paid real close attention; and it was coming from around the pushrods



I then crawled under the truck to check the blowby and it had some but not alot, because it was coming out the top of the engine duh?! So I put the valve covers on and check the blowby again.

There isn't alot of smoke, because engine is cold, but you can see some w/flashlight. I can also feel the firing pulse from one cylinder(it seems) almost to the ground(4x4). Now, that could be normal, I haven't paid alot of attention on a good running engine before; but I seriously doubt it.



I tried the infrared thermometer, but couldn't get consistent readings. And the compression checker I ordered is on backorder :-{}



Thanks



Steven

 

[Vaughn MacKenzie]

A bad rod bearing will be quieter if you disconnect that injector line, probably the same deal with a bad piston. If you got pulsing blowby you probably have a bad piston. My blowby is a light steady vapor streaming out of the tube, not that much and not that fast. No pulsation.



Vaughn

 

[PSchwering]

Just to Clarify, The Knock gets BETTER when you loosen #5 injector line, & gets Worse when you tighten it back up, Correct? All the symptoms point to a Mechanical problem in the #5 Power Cylinder It could be : Spun rod bearing, Cracked/Broken Rod, Broken Piston Pin, or maybe even a broken piston. I suppose even a Broken Crankshaft would cause the symptoms, but these cranks are tough.



Again, I hope I am way off track, But it's the best advice I have, Pat

 

[CAROLINA CUMMINS]

Yes, the knock gets better; as in almost completely quits, when I loosen the line to the #5 injector.



Thanks for all the advice guys, ya'll are a big help. I'm going to get started pulling the head this evening.



Steven

 

[cojhl2]

Oh my,, shouldn't you pull the injector first,, to make sure it is not causing some kinda detonation.



If there were a hole in the piston it would not fire when the injector is hooked up.



Since there is no discernable miss and the noise changes when you disable the injector it means it is burning,, doesn't it?



I dunno,, but Im subscribed to see how this turns out.

 

[PSchwering]

Oh my,, shouldn't you pull the injector first,, to make sure it is not causing some kinda detonation.



If there were a hole in the piston it would not fire when the injector is hooked up.



Since there is no discernable miss and the noise changes when you disable the injector it 9means it is burning,, doesn't it?



I dunno,, but Im subscribed to see how this turns out.

Yes! The cylinder is firing when the Fuel line is tight. When you loose the fuel line, the firing stops. the Load on the rod goes way down - Since there is only compression - and not combustion loads.



I too am Very interested in where this ends. Keep us informed. P.

 

[CAROLINA CUMMINS]

Okay guys,



I finally got the head pulled, it took me about 4-5 hours. not too bad in itself. The oilpan is another story .



The #5 cylinder doesn't look all that bad, the piston looks pretty good from the top; but the cylinder walls are scored a little. All the other cylinders still have the crosshatching visible



Injectors look OK, as does the head.



I'll get a chance to pull the oilpan and the pistons probably Thurs.



Thanks



Steven

 

[Vaughn MacKenzie]

If the cylinder wall is tweaked, then likely the piston has been damaged.

 

[BPonci]

What do you concider scored? (scratches?) If you can take a pic and post it. That would help.

 

[CAROLINA CUMMINS]

Well, I can feel the scratches with my fingernail, but they are not real bad; I don't think. I will try to get some pics tonight or tomorrow.



Steven