Engine/Transmission (1994 - 1998) Got a new 12v truck and has a knock??

[JCurry]

Well after driving about 30 miles, the knock came back. I changed idle to 850 rpm and it runs alot better. Installed a new overflow valve and it didnt seem to help anything, although now i have a spare. I had a leak on my water sensor o ring which was causing my hard starts in the morning. I removed the fuel heater and reinstalled without it after cleaning the screen. I checked injectors and the knock is coming from #6. I think instead of changing 2 of them, i will get a new set just to eliminate that as an issue.
My question is, where can i get a good set of injectors, for a decent price? I dont really care to get more hp, just maybe better mpg? Truck runs great and had some 20* weather today and it started first try. Gotta love these Cummins!
Im gonna try to get a audio clip of it tonight and put it on youtube for you guys to hear.
The other day i was coming home and my wife was behind me, i have never WOT the truck since i bought it but when she went to pass me i did for about 10 seconds. I noticed that after i did that i could barley hear the knock until a few miles down the road again. Makes me think (hope) its an injector issue? If i run it a lil harder than usual, the miss goes away for a few then comes back. Thanks for all the advice TDR!!!

 

[LVJUNIOR]

I have the same issue. Except I just changed the head gasket to fire rings and I know the cylinders have cross hatch in them still. It did not have a knock before I changed the gasket the injectors only have 2000mi on them and I have a very smooth idle and lots of power. There was no metal in the old oil and I have crawled all over this thing with a stethoscope and so has my friend who has worked on 12v's for years and neither of us can hear where the knock is coming from. It is much easier to isolate the sound if you stand 10' away from the door.



I was just about to add a thread myself when I saw this one and it sounds like we have a similar problem

 

[GrantP]

Of course I could complain about the wifes new VW I opened the hood and ... ..... ? Just closed it when I seen they had put the engine in the wrong way.

Now that's funny. :-laf

 

[JCurry]

LVJUNIOR: have you tried cracking the injector lines to see which cylinder your knock is coming from? I ordered injectors and should have em here tuesday, sure hope we can get our issues fixed. Mine has not gotten any worse after driving 3000 miles. I can still hear it all the time but it stays the same, just annoying.

 

[LVJUNIOR]

I have not cracked the injector lines yet and won't be able to until Monday. I did listen to the injectors with my stethoscope and didn't find the noise there.

 

[LVJUNIOR]

did you get your injectors? did it fix the problem

 

[Wingate]

before spending a bunch of $$$$$ on injectors..... If you have isolated it to #6, pull #6 and swap it with another injector. If the noise follows the injector to the new hole, then its the injector. If it stays on #6, new injectors aren't gonna help ya. .

 

[KYOUNG]

Its probably your input shaft in your transmission whipping a bearing out!!!

 

[JCurry]

Swapped injectors and same problem on #6. I brought it to a local diesel shop and they told me i probably have a bad wrist pin. I am still waiting on a price quote for the total repair but have a few questions. Since i have had the truck i have drove it about 5 to 6000 miles. Is it likely i have messed up the crank running it this long? I bought it with the knock and have no idea how long the previous owner drove it like this. It has never gotten louder but i know that doesnt mean it hasnt gotten worse... . Also, am i better off spending $1500 on a 12valve engine with 127k on it and driving this truck til it blows, or have it fixed? I just hate to put alot of $ into it and find out in 5k miles that another wrist pin is broke or running it this long with a problem has messed up something else.
Thanks for the help and advise!!!!

 

[ata]

I'll be really surprized if it's a wrist pin. Cummins just don't have wrist pin problem's. I'm still betting on a piston problem. The engine was either run hot or the oil jet for cooling the piston is plugged from bad oil filters. Either way when they have it down make sure the oiling jets for the pistons are all clear and not broken. But if it was me I would spend the money and get it fixed. With only 127000 it's hardly broke in and the truck is far from wore out.

 

[JCurry]

Whats the average cost to have a piston replaced?

 

[DPashko]

cummins pistons are about $275 a piece. in canada anyways. I dont know how much labour would be. I would call piers and you can get a whole set of 6 mahli pistons for $300 or so, they come with rings and pins. If it was me i would replace all the pistons, bearings and polish the crank just to freshen it up and probably be good for a long long time.

 

[JCurry]

Got the quote today... ... . #@$%! $5300 - 5800 to have it fixed and rebuilt... he said if I remove the engine it would be about $2000 anyone in the Colorado area want a new truck? LOL Not sure what i should do now... . :{

 

[SMorneau]

I am not experienced in building motors. But I do have the equipment necessary to remove the engines and it is not that much work. Something doesn't sound right.

What does the truck look like and how much rust does it have. Maybe I might be interested.

Scott

 

[JCurry]

No rust at all. Its a CO truck. Has a dodge 1500 cab on a 3500 frame/suspension. Send me your email address and i will send pics. Think i will put it on craigslist tomorrow. If it doesnt sell there i will just pull the motor and have it rebuilt. I would rather have 2 trucks but if i can sell it, i can have twins on my 01 :-laf

 

[ata]

Take the truck some place else. With that low of miles I'll bet the other 5 cylinders are just fine and have another 250000 left in them. Cylinder Number 6 is the bad spot for the 5. 9 it will get hurt and the rest are fine. Take the head off and see what you really have wrong. There must be a shop that will do a one hole repair and then run it until it drops.

 

[Texis]

If you have to rebuild the engine, I would suggest you find a donor engine. I see them for 1200-1800. That beats the crap out of 5K.

 

[38flathead]

I'm experiencing the same noise on my 96 12v it preforms fine just has this noise that seems a lot louder than normal thought it was comming from my vaccum pump but don't know. Changed the oil and fuel filter still there hopefully we will find the reason good luck jim

 

[hbowers]

I'll go with ATA, I think it's a scored piston and cyl wall probably in #5 or #6.

determine which cyl. then remove head. if cyl is not too bad you might be able to hone the cyl and replace the scored piston. w/o pulling engine. good luck.

 

[ramdriver15]

Sounds like this YouTube - Cummins knock

yeah that was my truck. I put a new lift pump in the truck and it didnt go away. then i took the truck out and reved it up to 5k rpm and it went away.



I was getting oil in the fuel and im betting that it was jut making it a ping in the ignition of the fuel.