Engine/Transmission (1998.5 - 2002) Bent valve?

[CumminsAholic]

How would I know if I bent a valve without taking it apart or doing a compression test? Is it possible? I dunno if I'm hearing things or what. I put a PS64 and a head gasket on last weekend. After 25lbs of boost I have almost a surge, shh shh shh shh noise and the boost gauge is pretty erratic. I dunno if it's the turbo or if an intake valve is bent and forcing pressure the wrong way. It didn't do it with the stock turbo and I didn't go over 35 lbs of boost or 3/4 throttle for a week til I did my last retorque. It did this right away after the swap, so I dunno how I could have bent a valve without getting on it. At WOT it has a pretty bad miss with the box on, with it off, not too bad. Could this be because a lack of fuel to the vp? I still only have my stock lp. . I know, I know. . not good. It didn't have this miss before the swap. Maybe a leaky injector line? What should I check? I hate to take the head off... again. I'm going to try to find a compression tester and do that, maybe I just have a lack of fuel, the surge is normal and leaky valve noise is in my head.

Corey

 

[Sea01Cummer]

Possible Boost Leak? I'd check the easy stuff first.



steve

 

[CumminsAholic]

I doubt it's a boost leak, I have a PDR boot kit, I'll check the lines though.

Corey

 

[Graphic man]

is the motor making any funny noises other then you said?



Scott

 

[CumminsAholic]

Not really. Kinda a thump thump thump helicopter sound at cruising speeds. I didn't notice that before. Sounds totally normal at idle. I'd think if it was a valve it'd be really noticable at idle. It's hard to tell with just the downpipe, it's pretty loud once it starts to build boost. The thumping goes away once it starts to build boost. I'm going to call II tomorow. Maybe it's just the comp surge that everyone is talking about. I thought it only did it at a certian rpm range though. If it's comp surge it doesn't bother me, I just don't want to drop a valve, I have a lot of $$ into my head. It's probably all in my imagination. I know that the miss isn't in my head though. It's really pronounced at wot. It's almost like I'm hitting a rev limiter on a gasser. It kinda clears out when it shifts from drive to od, but then comes back again.

Corey

 

[mechanic]

Forgive the question, but when you have been in this business as long as I have you learn to ask the stupid questions as well. Did you readjust the valves after reassembly? If so, did any of them have a substantial increase in clearence? (More then the rest) If one is bent, it would have greater clearence then the others because the head of the valve would be contacting the seat on one side only and not allow the valve to close all the way so the stem height would be shorter causing more clearence. What happened that could have bent a valve? Another thing that I have seen is that a carbon fragment can get between the valve and seat holding it open a little while adjusting the valves, then when you start the engine it blows it out and leaves the valve tight enough to have negative clearence and cause a miss. One way to check for compression balance is to disable the injector pump (Unplug or remove fuse or unplug ecm) and crank the engine and listen for an increase in RPM for one cylinder stroke. We old timers will do that as a first check.

I would recomend rechecking the valve adjustment first, injector leak, or pattern, then go deeper.

Hope this helps.

 

[Jetpilot]

Could be several things... . The shh, shh, shh, sounds I expect is turbo surge. As for the running bad like mentioned did you re-adjust the valves? Also when you installed the head maybe a pushrod wasn't in the lifter right and is bent. I don't think you have a bent valve though. Does the truck run strong? The compressor surge normally occurs around 1800-2000 rpm under moderate throttle.



Doug

 

[JCutter]

Could the miss be the fueling box, bad connection? I have the TST with the hook for the pump wire and after awhile it seems like it isnt piereced anymore and gives me that missing affect. I just rehook it and its good to go.

 

[CumminsAholic]

Thanks for the hints guys. I'm told the shh shh shh is the turbo surge. It does it at any rpm after 25lbs of boost unless I'm at WOT. Yeah I readjusted the valves, no they weren't much different. If I did something I'd have have to been before the head came off. I checked all the pushrods to make sure they were in the tappets right before I put the valves in. Yes the truck runs strong. I can't believe the difference a turbo can make. I haven't over-reved the motor, 45psi max.

Even if I didn't bend a valve I don't understand the (bad) miss I have at wot. I have my pump wire soldered on, so it's not loose. It does it with the box off, worse with it on. I think that somehow that and the surge are related, I just have to figure out how. The only other thing I can think of is fuel starvation... fass is on the way... but why didn't it do it with the stock turbo? It'd pump just as much fuel right?

Corey

 

[CumminsAholic]

Update... I think the surge is turbo, I did a few test runs tonite. The miss starts to happen about 2800 rpm. At 3000 rpm it gets REALLY bad. (Surge is only from about 25 to 35 lbs of boost) If I let the r's get down in od and step on it it goes past the surge and then starts to miss ad the rpm increases. Could my valves be set too tight? I set them at . 009 and . 019 on a cold engine. Before I did those settings on a hot engine, but I read in the book that is was supposed to be on a cold engine so after I did my last retorque I let it sit overnight and did the adjustment. Doug, what do you reccommend I set the valves at? I hit 50 lbs of boost tonight.

Corey

 

[boydo]

Sound like you need more fuel, the stock lp can't move enough fuel to supply the vp44 with big nozzles and a box. The noise is probably your pump dry firing causing your engine to miss. I stroungly recomend a complete fuel system like a FASS or Airdog, even adding a booster pump would barley be adiquate for your fuel demands.



Good Luck



Bret

 

[CumminsAholic]

I have a fass on the way. I don't understand why it didn't do it with the stock turbo though. I need to do a valve adjustment just to make sure. I no longer think it's a valve, it wouldn't fire if it was a valve. It could be... injector line, injector pump, fuel starvation, valve adjustment... what else?

Corey

 

[boydo]

You could pull your injectors and have them pop tested for leakage and spray pattern, pull your connector tubes at the same time and check for damage where they seat on to injector. I think the FASS will solve alot of your trouble, and a be sure to adjust valves everytime you re-torque your head.