98 12v

I have always thought my truck had an unusually loud knock coming from the engine. I have asked a couple times on here and i just get the usual answers. Most seem to think its the lift pump which does make some noise. Others tell me that since im new to diesels that im just not use to the noise they make. I also understand that the 7100 is a noisy injection pump too. What makes me question the bearings is the fact that the truck was beat to heck before i bought it. The knock is load sensative also. It doesnt do it if i stand on it and its reasonably quiet if im off the throttle but loud when just cruzin. It kinda comes and goes as im driving down the road and seems to coincide with the t-stat opening and closing. I have also noticed the front seal leaking and have already replaced the rear main seal twice and it still leaks. A friend of mine told me thats a good sign that the bearings may be failing. Im gonna cut apart my last oil filter and look for metal tomorrow. Can this be done with the engine in the truck or would i have to pull it out to replace the bearings if thats the problem. Just figured i would run it past a few more minds before i start to worry.

clutch1

you could do an inframe overhaul, engine just needs to be lifted a little to get the pan loose.

clutch1

Oh yeah have you tried an oil analysis.

mainer

If I were you I would search around for a good bottom end.... and swap that 53 block out... sure its more work ... but it would get rid of the 53 block.


i have a complete motor in garage minus pump that i plan on doing this with someday to get rid of my 53 block but i would consider selling it if your interested, had 190k on it out of a good running truck ( i drove it)

pm me if your interested cheaper than you think

kd460

yes, do an oil analyisis and see whats going on. KD

TIMMY22

Im with the oil test crowd, well worth the $$$. It's amazing what they can pick up on that.

98 12v

Thanks guys. I hadn't given any thought to the oil annalysis. Ill ask around the dealerships tomorrow and see who does it around my area. If nobody does it hear ill be in fargo for a rodeo on friday nite and ill just go straight to the cummins dealer there.

kawi600

Hows your oil pressure? Right around 40psi? yes, if its too high that can mean problems and will pop seals. These motors dont usually destroy crank bearings Id been told.
That noise might be a lifter or a few other things. Maybe do a compression check to rule out anything up top.

kd460

Another thing you might try is running some biodiesel. If things quiet down, then it's noise from your injection pump. It's amazing how much noise the pump makes and how much noise biodiesel eliminates.

If the knock stays the same, then maybe it's what your thinking. The pump noise won't be gone with bio, but greatly reduced.

It's worth a try. KD

John DiMartino

It sounds like you got an injector problem......if you had a bearing going,it wouldnt be quiet under heavy load ,it would hammer.Do the right thing first oil analysis,and take it from there.Guessing could be $$$.

CTD NUT

Main bearings won't make a sound when they wear out....but rod bearings sure will. And the rod bearing knock will be load sensitive. Either way, if rod bearings are worn, it is quite likely that the mains will be too and vice versa. If rods and /or mains are worn excessively, you will definitely see abnormally low oil pressure.

JKM

FWIW , doing an oil analysis now wouldn't really do him alot of good, he needs a couple samples to start comparing and see if anything has changed.

John DiMartino

A sample isnt worthless,it isnt as good as one if hed been sampling,but if his wear metals are off the charts,he needs to get in the engine and find out why.Also fuel dilution/glycol/silicon.You dont need a baseline with them to know there is a problem.

98 12v

Thanks for the help guys. I checked on the oil sampling and i have many places that will do it right in my neighborhood. I will probly do it on my next change since they all suggested taking the sample from the middle of the drain to avoid getting some shavings from the threads. My oil pressure is about 40 at idle and 55 or so cruzin down the road so i guess that is a bit of comfort. Its still getting kinda cold around here so i will try the bio idea in a week or two and see if that helps. I hadnt thought about maybe an injector. I started using Howes Diesel Treat when I bought the truck so it maybe cleaned up things a little and now it lost its gummed up cushin. I may be overreacting a little but if i do have a problem i would like to find it early.

CTD NUT

That amount of oil pressure is too high to even think about bearings being worn so badly that they are knocking. Cut those pressures in half and that would be more likely pressures for badly worn bottom end bearings......assuming of course that the gauge is accurate.