been a while I posted but I have a issue with a new to us tractor hauler my dad just bought without me looking at. This thing has a knocking sound coming out of the breather box and has no real diesel power. I think the turbo is causing the problem but not sure so I came to my friends here for advise If you have any questions that could help me describe my problem.
- Thread starter Roy in Ga
- Start date
Wisconsin Cowman
Member
Gm 6.5 knocking sound means something bad is going to happen with the experence I had with them. How many miles and what is the year.
Wisconsin Cowman
Member
DK44H is right 6.5’s have not that great on power good fuel mileage like said. I would take of the hose that goes from turbo to air box and check the shaft for any play or the fins didn’t chew the housing up.
rustred
Well-known Member
i have 398,000 km. on my 1995 1/2 ton 6.5 and it has hauled many a heavy tractor and fast trips. not many people pass me on the highway. original glow plugs, injectors and heads not been touched.never did complain about the power. it was a big improvement from the 6.2 that was a real economical engine, getting 27 mpg in my 86 pickup. the 6.5 around 19mpg. now the duramax is a dream to drive, very good truck. ohh that noise may be a bad injector if its a loud knocking.
Probably not going to be good news....
Check the turbo as other mentioned but unless it's going through a lot of oil and slinging it out the exhaust I doubt that's the problem. They don't knock because of the turbo.
Burnt or tight valve will cause a sput, sput, sput through the intake or exhaust, depending on which is burnt. Bad injector will cause a knock as well. You can open each line, one at a time and see if the knock goes away and see if the engine stumbles when you open the line. If it doesn't stumble and the knock stops, you found the bad hole. Then you need to figure out if it's the injector or compression...
Just about everything after that gets worse, right on down to a broken crank; a fate they're not unknown for.
Rod
Check the turbo as other mentioned but unless it's going through a lot of oil and slinging it out the exhaust I doubt that's the problem. They don't knock because of the turbo.
Burnt or tight valve will cause a sput, sput, sput through the intake or exhaust, depending on which is burnt. Bad injector will cause a knock as well. You can open each line, one at a time and see if the knock goes away and see if the engine stumbles when you open the line. If it doesn't stumble and the knock stops, you found the bad hole. Then you need to figure out if it's the injector or compression...
Just about everything after that gets worse, right on down to a broken crank; a fate they're not unknown for.
Rod
this thing is I guess more of a popping because it forces air back with the pop or knock I thought about it for some time last night and figured it might be in the head or something like that it does have a miss so maybe that is the problem I just have to isolate the problem before I tear into it could the injector cause such a violent pop that it sounds like a knock. it has the rhythm of exhaust with the engine so now I am leaning towards a bad head (valves)
Any time I've dealt with a bad injector it made a loud thud much like a bad main bearing. This is on a Ford engine tho... your GM could be different.
If it's really got much pushback into the intake then I'd really look at a valve. That can make a fairly loud pop if it's bad enough.
I'd suggest trying to narrow down which cylinder is the culprit by opening each line and seeing which one doesn't cause more of a miss. That should be the bad one. Then compression test that cylinder or and mabey a couple more for reference and compare that against specs. I don't know what they are for that engine but I'd guess that since it's a prechamber engine it's probably going to push 500 # or so.
If it's got valve or other head issues or piston issues it's probably going to have poor compression...
Or you can just pull the head on the effected bank and see what's happening.
Rod
If it's really got much pushback into the intake then I'd really look at a valve. That can make a fairly loud pop if it's bad enough.
I'd suggest trying to narrow down which cylinder is the culprit by opening each line and seeing which one doesn't cause more of a miss. That should be the bad one. Then compression test that cylinder or and mabey a couple more for reference and compare that against specs. I don't know what they are for that engine but I'd guess that since it's a prechamber engine it's probably going to push 500 # or so.
If it's got valve or other head issues or piston issues it's probably going to have poor compression...
Or you can just pull the head on the effected bank and see what's happening.
Rod
these are things I have been thinking about but as hot as it is here I have a hard time getting motivated to get out in for something that is not really a must and we don't really have the $ to go into it right now so I am trying to research it for known problems so I might have a direction in witch to start in a couple days I thank all who have and that will offer suggestions with this truck I will post an update as I go along for those that are interested.
might pull the valve covers an see what might be in there don't know why I haven't thought to pull them as I suspect a valve and that could tell me what is wrong or where the problem cylinder is. Thanks for waking my brain to pull the covers.Seems building cabinets and ambulances has made me forget the basics LOL!
yea Rod dad just called and said he is trying to get his $ back but if he can't we will have to fix it so I am going to try and figure out where the problem is. I like the truck and he likes my F-150 so we may trade and I fix the truck. The guy lied that sold it to him and said it was the clutch not the engine but on this truck earlier in the month I called and he said there was something wrong with the engine. On a side note I looked up the Kelly Blue Book value and it is double what he paid for it if it were fixed so as far as value he should easily be under that if the engine can be fixed and not replaced
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