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View Full Version : How to check/troubleshoot for a collapsed lifter


GregV
03-07-2011, 17:00
Background: I have a 6.5NA replacement engine installed in my '91 GMC V1500 Sub. It has a Banks Sidewinder turbo kit on it, which I installed some time ago from the original 6.2 engine.
This replacement 6.5 engine recently blew a head gasket which put combustion pressure into the cooling system, blowing coolant out of the radiator cap. I tore down the 6.5 in-frame & replaced the head gaskets and also replaced the cyl head assemblies with another good, used pair.
Problem: Now, the 6.5 (with Banks turbo) has a heavy knock in the vicinity of #8 cyl after it has warmed up somewhat. The knock was not there before the head gasket replacement. I suspect a collapsed lifter or a broken valve spring. Also, no more head gasket problems.
Question: Is there way to check/troubleshoot for a collapsed lifter short of major engine dis-assembly?
Note: At this time, I'm in Mexico & plan to trailer the truck back home to WA for further repair. Any info will be greatly appreciated.
Thanks,
GregV
JohnC
03-08-2011, 10:58
Did you loosen the fuel line on the #8 injector? Having the heads off opened the possibility of contamination in the injector which could cause your problem.

If you still suspect the lifter, take the valve cover off and check clearance on the valves. (Should be none).
More Power
03-08-2011, 13:33
I had a lifter failure in my first 6.2L diesel. It made a ticking sound that matched engine speed. A heavier knock is not likely to be lifter/rocker related.

Like John suggested, an injector is more likely. I heard a GM diesel once, in the mid 1990s, that produced a heavy knock. I thought it was due to a rod big-end or main bearing failure. Loosening the injector fuel line fitting made the knock go away, only to return when the line was tightened.

Jim
suburbanK-2500HD
03-08-2011, 13:51
Injector i most likely.

Had the same issue, with a knock that sounds like lifter, rod knock.
But the injector was the problem, i was contaminated....
GregV
03-10-2011, 08:22
Did you loosen the fuel line on the #8 injector? Having the heads off opened the possibility of contamination in the injector which could cause your problem.

If you still suspect the lifter, take the valve cover off and check clearance on the valves. (Should be none).

Hi, John
Thanks for the reply.
I did replace all the injectors with a rebuilt set during the head gasket replacement. Although the "new" injectors had been lying around, with plastic protective caps on them, for about 2 years. No - I have not loosened #8 injector line while running. I will do so.
Taking the valve covers off is a pain, but might be necessary.
Contamination might have been a real problem. I did have my garage available, with the truck half in with the roll-up door half open. The best I could get in the Baja land of thorns, sand & wind.
Thanks again,
Greg
GregV
03-13-2011, 16:24
To All:
Thanks for all the replies & help on this one. It was a bad injector - #6 - after all. I loosened the injector line while it was running, as suggested. Sure enough, loosening #8 still had the knock sound. Then I loosened #6 & the knock went away. I then put an old injector (temporary) into #6 cyl and it is fixed. I'm taking the bad injector back to the states to get it rebuilt again.
Thanks again to all for the help.
GregV
95Burb
03-26-2011, 12:42
Did it sound like this?

http://www.youtube.com/watch?v=3MGD1_jExao&feature=mfu_in_order&list=UL