Sticky bucket? Only 600 miles on engine.

[berniek]

Hi again.

After about 600 breakin miles on a '91T (refreshed JDM; mods follow) with decent dino oil I noticed that about 20 seconds after startup, a sharp intermittent rapping sound starts. So far, it has all the earmarks of a sticky valve or bucket. It will rap once or twice every few seconds at odd intervals from 20 seconds after start until it starts to warm up. So far I have only run it in the garage after it really became noticable, since we also have bad weather here in NJ. When doing the head work I did interchange buckets from other heads here to complement getting the right clearance in combination with shims on hand. As long as the buckets were aligned squarely with the head bore, they all went into the head bore and appeared to move freely.

I doubt highly if a valve is sticking unless at 17 PSI boost, the exhaust port pressure is enough to force exhaust gas and soot (runs rich under boost) past the garter spring valve seals.

Any ideas about this problem would be appreciated. Mods are: 550cc injectors, Lex, Walbro, adjustable FPR, Lipp, 3" Random Tech and HKS single cat exhast, 57 trim CT26, Raptor BOV (recirculated to accordion hose), '98 mounts. Stock pistons were used, fitted loose. There is some piston slap during warmup, which then disappears at full temperature.

A bottle of ValveMedic seemed to help somewhat at first, but is not a cure.

Looking forward to some wisdom. Thanks.

BernieK

 

[supraslo]

When I first put mine together, I had a similar noise. My noise sounded like it was coming from the head (valve noise or other). I was enraged when I first heard the noise and feared having to tear the engine back down. So in my anger, I turned the boost up to 20psi and tore up the road like a bat out of hell. I never heard the noise again.

I am not advising you do this unless you are willing to pay the consequences if the noise is something vital. I am just referencing that it fixed my problem. Like the old saying goes...."it is either going to fix it or F%#K it up!"

 

[quake]

Hi again.

After about 600 breakin miles on a '91T (refreshed JDM; mods follow) with decent dino oil I noticed that about 20 seconds after startup, a sharp intermittent rapping sound starts. So far, it has all the earmarks of a sticky valve or bucket. It will rap once or twice every few seconds at odd intervals from 20 seconds after start until it starts to warm up. So far I have only run it in the garage after it really became noticable, since we also have bad weather here in NJ. When doing the head work I did interchange buckets from other heads here to complement getting the right clearance in combination with shims on hand. As long as the buckets were aligned squarely with the head bore, they all went into the head bore and appeared to move freely.

I doubt highly if a valve is sticking unless at 17 PSI boost, the exhaust port pressure is enough to force exhaust gas and soot (runs rich under boost) past the garter spring valve seals.

Any ideas about this problem would be appreciated. Mods are: 550cc injectors, Lex, Walbro, adjustable FPR, Lipp, 3" Random Tech and HKS single cat exhast, 57 trim CT26, Raptor BOV (recirculated to accordion hose), '98 mounts. Stock pistons were used, fitted loose. There is some piston slap during warmup, which then disappears at full temperature.

A bottle of ValveMedic seemed to help somewhat at first, but is not a cure.

Looking forward to some wisdom. Thanks.

BernieK

first off drain the mechanic in a bottle shot you a pm

 

[Nick M]

first off drain the mechanic in a bottle shot you a pm

+1 for the tech....