To test this feature, visit your live site.

Bent pushrod

2013 GMC Sierra 1500. Currently at the dealership:

SCAN AND FOUND P0304. CHECK AND FOUND IGNITION COIL FIRING. CHECK AND FOUND NO COMPRESSION ON #4. REMOVED VALVE COVER AND FOUND BENT INTAKE PUSH ROD. RECOMMEND ENGINE TEAR DOWN AND INSPECTION FOR LIFTER/CAMSHAFT DAMAGE. $800

Unfortunately, misfire happened on the way to work, so it's probably done 50 miles since it started misfiring.

So I'm going to take it home 5 miles and try the lifter release method. Perhaps AFM delete if it comes to that.

Would it be better to drive it the 5 miles with:

New pushrod
Bent pushrod
Removed pushrod?

Thanks,

Bob

5 comments

5 Comments

Crazed Performance Repair

Apr 23

•

The floppy rocker would have to be checked with a good pushrod installed. That doesn't sound like the rocker is loose from collapsed lifter though. That's a very subtle tick at most from the device I'm listening on. At most it might be a bad spot on the lifter roller but incredibly hard to say based on that video. If you have it in a shop for diagnostic what have they said so far? Doesn't even look like it's misfiring actively. At least not badly. I see a little bit of a shake there.

Bob

Apr 23

Replying to

Dealer troubleshooting per original post, the bit in capitals:

I'm not going to get them to tear down the engine. They won't do if an AFM delete if need be and the truck will be stuck.

Symptoms are rough idle, laggy acceleration.

I'm wondering if there is any conventional troubleshooting they could do that would be helpful as part of their engine diagnostic before giving it back. Eg leak down test, running compression test etc.

Crazed Performance Repair

Apr 24

•

Replying to

You could have them check for a spunlifter. Below is my FAQ response for such a situation.

The lifter could also be spun, using the starter relay with the key off, spin the engine over. Make sure not to jump the wrong terminals as it could damage the ECM. Vlom Must be on for this test. While it is spinning watch the suspected rocker move. Make sure that it rocks at least 6 to 7 times before you let up on the starter. If the one rocker stops moving before then, it is getting fed oil pressure and is likely spun. However, if two rockers stop moving then you likely have a leaking VLOM. You can determine a spun lifter by looking at the side of the lifter. To see the side of the lifter you need to pull the VLOM and clean out the oil tower of the suspected lifter with cleaner and shop air. Once cleaned you can look down the oil tower and if you see a hole in the lifter it is not spun. If however you see only shiny metal or a flat surface then the lifter has spun due to a bad plastic lifter guide. When this happens you will need to replace the camshaft and all lifters. This would be a good time to do a full AFM/DOD delete where you remove all AFM components and replace them with non AFM components.

I do now offer AFM delete kits for select models. Be sure to check my website for your engine.

https://www.crazedperformancerepair.com/afm-delete-kits

Crazed Performance Repair

Apr 23

•

Best to drive removed pushrod on both intake and exhaust. But you will also want to unplug the fuel injector. I recommend verifying the lifter is collapsed and not damaged prior to the lifter release attempt.

Bob

Apr 23

Replying to

Thanks for that. I recall from your videos that the check for collapsed lifter is by observing rocker play at the pushrod. How to check the lifter is damaged?

Any other troubleshooting that I should ask the dealer as part of the engine diagnostics they are billing me for?

Leak down test?

Running compression test?

Video attached of how it sounds. Wasn't loud, but ticking more apparent on bank 2.