Help where to start looking

Cnrenner

New member
Feb 17, 2018
6
0
0
Ok i have 2012 was driving home yesturday got into the gas ran rpms up to about 3200 before shifting but drove fine after that. stopped shut it off for awhile get back in it start driving get about 8 miles come to stop n it sounds like someone is beating on a drum under my hood. So i drove to next gravel pulled off n shut it down sitting on trailer still. No check engine light on. Any suggestions would be great.
 

Cnrenner

New member
Feb 17, 2018
6
0
0
The truck used lightly car trailers n boats. Mileage 124k head gasket done 1/2/17 by dealership. Has all delets done and a 30hp tune done. The thumping sound is coming from the air box and the engine has a tick but its had to tell which side tick is coming from cuz of the thumping in the air box
 

Cnrenner

New member
Feb 17, 2018
6
0
0
Sorry for some of the miss information replacing injector took care of have one out of balance but did not fix the thumping noise checked compression all within 5lbs of each other checked valve lash all right at .120 did leak down test on a few cylinders they were at 3-4%. So we are still scratching our heads. Any more help or suggestions would b great.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
1,729
0
36
Neenah, Wisconsin
Sorry for some of the miss information replacing injector took care of have one out of balance but did not fix the thumping noise checked compression all within 5lbs of each other checked valve lash all right at .120 did leak down test on a few cylinders they were at 3-4%. So we are still scratching our heads. Any more help or suggestions would b great.
Is your valve lash 0.120" or 0.012"? There is a huge difference between them. One is proper and the other is 10x what it should be.

Proper valve lash is 0.012"
 

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
4,595
0
36
At Da Beach
Torque converter come apart? Might be transferring sound thru crank to front of motor. Or I hate to say it, broken crank? Is the crank balancer wobbling?
 

Cnrenner

New member
Feb 17, 2018
6
0
0
Idk about the crank but the converter is still good cuz i drove it up on a trailer no problem. If u put ur hand on airbox u can feel it there n hear it put hand on motor feels like running motor no stutters.
 

JoshH

Daggum farm truck
Vendor/Sponsor
Feb 14, 2007
12,905
2
38
Texas!!!
Sounds like a valve is not opening or not sealing properly causing it to blow back through the intake, but this should have shown up on a compression test. What was the compression? The only other thing I can think of is if the cam pin sheared and threw cam timing out of whack.
 

CHEZELTINE

New member
Dec 16, 2013
50
0
0
BOISE, ID
What did you end up finding? My lb7 did the same thing, ended up being a broken exhaust push rod on the pass. side.

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