Screeching under load

[dpuckett]

My 91 has been making an odd noise under load for a while. 255K, original everything as far as I know. When I get on it, it starts ticking at about 4 psi (right off the line) and then it changes to a screeching noise after about 10 psi, regardless of rpm. Under no load, I can run it to the governor without making the noise. ALternator and turbo are new; no changes after replacing either of them. I had thought maybe a belt? Have yet to replace it. I have noticed some oil seepage along the driver's side of the block, up high, under the intake, and it uses a little water, though it is not mixing with oil or burning out the tailpipe. I was wandering around over at www.dieselinjection.net and they had a section on the bigger Cummins engines, and common complaints. One of them was the noise mine makes ( yeah, apples to oranges, I know) being a blown head gasket. If it was a blown HG, wouldnt I see a major leak, or have mixing of water and oil somewhere? THis is driving me nuts (albeit a short drive it is) trying to figure this out. I dont really have the $$$ to do a head gasket, or rather, get a head with 7mm injector holes, get it ported, and put a thicker HG on, new injectors. I'd be stuck with a stock replacement for now. ANy ideas on what to check? I searched the forums, and found nothing like what my truck is doing. FIgures; I always get the oddball stuff.



Thanks

Daniel

 

[Greenleaf]

Ticking?

A possible exhaust port leak?? Blown-out exhaust gasket?? Check the turbo vane again for play/interference?? Check valve lash??Check all accessories for loose bearings with drive belt removed??Does engine have to be hot or cold to develop this noise??Only while in gear?? What gear??



Someone help me out here... ... ... ... .

 

[dpuckett]

Greenleaf-

No play in turbo vanes- checked yesterday to check on filtering of my K&N (which was doing just fine). Exhaust port leaks could be a possibility- been leaking since I got it; havent got to an ATS 3 peice yet. Will check accessories again in AM ( too many skeeters now). Does it in gear when I get on it hard. ANy gear, hot or cold. Though I may try it now cold.



I cant seem to find where my water is going, but I have to put in about a quart a month (4 mo; put 14K on it). Uses 1 qt oil in 5K; half come out 3 old VC gaskets. Peak boost at 6500ft is still 28 psi, screeching like all get out. OH yeah, it's been doing this for 8K; I just go easy on it most of the time.



Daniel

 

[Greenleaf]

I'd do an oil sample anyway. Had a unit leaking coolant, which I couldn't locate. Also, psi test cooling system. BTW, seen waterpumps leak cold, but not hot.



Sounds like your rig has to be in gear to develop this noise [?] A belt will probably squalk all the time. Double check it only does this when in gear/driving and not parked.



Scott

 

[Greenleaf]

Was thinking about a bus,,,, once, the engine mounts failed on this unit and when she [the driver] really got on it the fan came around to hit the shroud. Checked any drive line components?

 

[dpuckett]

I talked to a few mechanics today, and they all said the same thing- given year, mileage, and symptoms, it is most likely a head gasket. It does the noise when hot or cold; and is strictly load based. Now just have to come up with the money to get it, and then the time to do it. Thanks a lot.



Daniel