LS1 fresh cam/head swap intermittent pop/clank
04-23-2017, 09:04 AM
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LS1 fresh cam/head swap intermittent pop/clank I'm finishing up my ls1/t56 swap on '92 BMW 318is. The donor LS1 came out of a '01 Trans Am. I put 243 heads, a BTR stage 2 cam, stronger valve springs and push rods, and almost all new gaskets on it from its stock form.
The first couple start ups, although it wasn't on for more than a few seconds, didn't make the noise in the video. Now, it does it intermittently (as in it does not do it every revolution) every time. Cylinder 8 is also not firing, but I'm guessing that's a separate issue (bad plug, coil, or injector probably).
I only had a couple hours to troubleshoot but I did the following:
When I get more time I'm going to pull the passenger side valve cover to see what I can find. I've searched for the past week around the internet and can't find anything, so I'm hoping someone here has also had this issue before!
Here's the video. The noise I am talking about is a clanking noise, it sounds like a pop in the video. There's 3 right at the start, 2 at 11 seconds, then 3 or 4 at 13 seconds, and finally a couple more before it shuts off.
Any help would be hugely appreciated.
The first couple start ups, although it wasn't on for more than a few seconds, didn't make the noise in the video. Now, it does it intermittently (as in it does not do it every revolution) every time. Cylinder 8 is also not firing, but I'm guessing that's a separate issue (bad plug, coil, or injector probably).
I only had a couple hours to troubleshoot but I did the following:
- inspected under the driver's side valve cover for a loose lifter or something
- started without the belt briefly to confirm it wasn't an accessory
- removed the intake to inspect all around, check intake valves too
- checked for codes, which there are none
When I get more time I'm going to pull the passenger side valve cover to see what I can find. I've searched for the past week around the internet and can't find anything, so I'm hoping someone here has also had this issue before!
Here's the video. The noise I am talking about is a clanking noise, it sounds like a pop in the video. There's 3 right at the start, 2 at 11 seconds, then 3 or 4 at 13 seconds, and finally a couple more before it shuts off.
Any help would be hugely appreciated.
04-23-2017, 10:28 AM
#2
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Engine Noise Hi, very heard to tell if it is a "back fire" OR a Sticking Valve.
Connect a MAP gauge to the intake, look for a pulse.
The exhaust valve would be more common to stick, if so less pulse.
Did you purge the coolant system for air ?
Lance
Connect a MAP gauge to the intake, look for a pulse.
The exhaust valve would be more common to stick, if so less pulse.
Did you purge the coolant system for air ?
Lance
04-23-2017, 11:15 AM
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I have yet to properly purge the coolant system for air. I also started it up without the radiator for <10 seconds to make sure it would actually start before I tore making everything for the cooling system, and it still made the noise then.
Thanks for the other info, I will check the exhaust valves as soon as I get back home.
Thanks for the other info, I will check the exhaust valves as soon as I get back home.
04-27-2017, 09:03 PM
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Figured I should update out of fairness, and in hopes that it can help someone with the same issue.
Cylinder 8 not firing and the noise turned out to be the same issue. it was not firing due to a loose rocker on the intake valve. I believe the popping was either due to the air/fuel firing in the intake, or the push rod flapping around. Once I tightened it back down to 22 ft lbs it was fine and cylinder 8 began firing correctly.
Cylinder 8 not firing and the noise turned out to be the same issue. it was not firing due to a loose rocker on the intake valve. I believe the popping was either due to the air/fuel firing in the intake, or the push rod flapping around. Once I tightened it back down to 22 ft lbs it was fine and cylinder 8 began firing correctly.