Boost Bleeding Off = Bent Intake Valve?
07-10-2009, 11:00 AM
#41
The valve lapping was a good idea. I didn't even think about that. Last stuff I used was blue dye and you rubbed it on the valve itself. You have to make sure that it remains at 90* to the seat and rotate it. If the valve/seat checks out it should be a solid line all the way around. You will have to find out what to use for the gate though since you don't really have a way to use the valve. I hope you get this sorted out Hummer!
07-10-2009, 11:10 AM
#42
That doesn't make much sense to me since the wastegate should close when you're below the threshold regardless of its size. If it's like the gates I used in the past, it's not an open closed thing. There are varying degrees of open relative to gate settings and boost.
As for the spooling, that's all relative to engine size, turbo size, system design quality, exhaust back pressure and turbine size. Who's to say it wouldn't spool even more quickly with a fully closed wastegate? It is possible that you have never felt this thing truly spool properly and therefore have no frame of reference.
I am hoping we're right and when you get this resolved and feel that turbo spool better, you find your denture cream no longer works.
As for the spooling, that's all relative to engine size, turbo size, system design quality, exhaust back pressure and turbine size. Who's to say it wouldn't spool even more quickly with a fully closed wastegate? It is possible that you have never felt this thing truly spool properly and therefore have no frame of reference.
I am hoping we're right and when you get this resolved and feel that turbo spool better, you find your denture cream no longer works.
07-10-2009, 11:46 AM
#43
The valve lapping was a good idea. I didn't even think about that. Last stuff I used was blue dye and you rubbed it on the valve itself. You have to make sure that it remains at 90* to the seat and rotate it. If the valve/seat checks out it should be a solid line all the way around. You will have to find out what to use for the gate though since you don't really have a way to use the valve. I hope you get this sorted out Hummer!
07-11-2009, 03:04 PM
#44
OK, just pulled the wastegate off and it looks like the v-band flange between the merge and the wastegate was leaking. I never heard a leak or saw a soot stain on the outside of the connection but when I pulled the gate out and looked at the V-band flange mating surfaces there were soot stains. Guess I'll put a little copper high temp silicone on it and give it a try. I lnow that has worked for me in the past whe my DP v band flange was leaking.
07-11-2009, 05:49 PM
#50
Middle of this coming week to next weekend. I'm waiting on the replacement o-ring that I ordered for the bottom of the wastegate hat. I bought mine second hand but it was still new, unfortunately its an early design and the engineer James @ JGS said its a common thing for that O-ring to tear anytime you pull off or put on the hat. You can tell that the o-ring was twisted up a time or two by the way it was broken so I honestly think it was done when the hat was installed & this is the first time I've ever had the hat off. I'll def post some results.
09-28-2009, 03:24 PM
#52
Well a month ago I yanked the heads off and found that 7 intake valves had contacted the pistons. I took the opportunity to swap to some 317 heads & patriot extreme dual valve springs. I put them on and it still bleeds off by 2psi every gear. Yesterday I decided since my wastegate was hard to get in position due to me plumbing the dump back into the down pipe and not using a flex joint, to go ahead and change that and take a closer look at the wastegate itself. Upon close inspection I think that the sleve that the WG valve seats into may have been cocked sideways a little not letting the wastegate close all the way, I talked to some diesel truck guys that said they had the same exact problem with all the same symptoms.
My solution is to block off the WG dump to the DP and just let it dump to atmosphere. It was pretty much impossible to get the WG and the DP v-band flanges to line up and seal perfect, this way all I have to worry about is getting the WG inlet with the sleeve/valve seat lined up.
I should know something by this weekend & I'll post the results good or bad.
My solution is to block off the WG dump to the DP and just let it dump to atmosphere. It was pretty much impossible to get the WG and the DP v-band flanges to line up and seal perfect, this way all I have to worry about is getting the WG inlet with the sleeve/valve seat lined up.
I should know something by this weekend & I'll post the results good or bad.
