bryanwheat
DSM Wiseman
- 7,110
- 199
- Aug 16, 2004
-
Columbia,
Missouri
Did either of these machine shops actually do a vacuum test on the valves?
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Did either of these machine shops actually do a vacuum test on the valves?
It shouldn't' be leaking at all from the valves if this is a freshly rebuilt head. You should only be leaking at the rings. I would still pull it and have the valves and seats done properly.
Yea, I mean obviously I'm sure it works for some people but I personally don't know anyone who doesn't spray their metal HG.
I agree and that is what I'm going to do but is there ever a "perfect" seal? Like should I be able to spray brake clean in the ports and not be able to see or hear any bubbling going on? Or will there always be a bit of air making it through?
There will always be "some" leakage, but it should be so small as to be practically unnoticeable if everything is done properly.
*****
My bet is on the valve seats not being cut perpendicular to the guides, or the valve grinds not sealing against the seats.
BTW - Have you verified the valve stem and guide dimensions?
The head is going back to the original shop on Thursday morning ... <snip> ... I feel if there was an issue that would make one part not compatible with another that is their job to figure out.
Take your cams out and perform the same test.
-Jafro
Well just when I thought I had it kinda figured out, the car threw me another curve ball. Was tearing everything apart in preparation to remove the head and decided to leak it down before I loosen the head bolts. This was with both manifolds off, and nothing but the valves and springs in the head. Wouldn't you know it the numbers improved pretty remarkably.
Cyl #1; 100 psi in...94 psi out, leak from intake and exh. valves, slight CC
Cyl #2; 100 psi in...84 psi out, leak from in. and exh. valves. Rings are worst on this cylinder.
Cyl #3; 100psi in...90 psi out, Mainly intake valves, slight exh, slight CC
Cyl #4; 100psi in...94 psi out, Mainly intake valves, slight exh, slight CC
Was going to say that valves might be bent (from a previous timing belt mishap, or something similar) but it sounds like valves are new, so that theory is out of the question.
I may have missed it, but did you or the shop check the valve springs, seats, shims, and retainers in relation to the valve stem height? In other words, are you sure the valves were fully seating? Did someone accidentally try to install some Honda springs or something?
Did they measure the seat pressure (always a good idea, especially if you are running big cams).
A fresh valve job should seal 100%. No leakage at all past the valves.
Our engines, before being started up will only have 4% leakage when cold and that's leaking past the ring gaps.
On the theory that's out of the question, can you explain to me how replacing the same sized valves and cutting new valve seats brings them back up to the correct install height?
Edit: Oops, wrong guy.
edged1g: I read this whole thread and missed that one sentence. Having never seen the car, and only referencing the use of Kelford 272's, I stand by my diagnosis. I may not be spot-on for the exact cause, but in my head I feel I'm in the 97% range. 3% chance the lifters aren't bleeding down.
Have all of the lifters been purged?
That's not good man hope you figure it out, did you trust the shop, to go through it, I always talk to my shop and we stay in touch about everything in detail. I hate doing things twice.
I feel that I'm extremely patient and most others in my shoes would have hung them out to dry by now...
Well didn't hear from them like I thought I would today. I'm speechless...
Finally got around to getting the motor all back together yesterday. Went to fire it up and wasn't really getting anything. But I could smell fuel and lots of it. So I hooked up the laptop to try and see what the car was doing. My map sensor was reading 38 psi all the time, thus dumping ridiculous amounts of fuel. Disconnected the map and programmed the ecu to run a stock maf and she fired right up.
Finally got around to getting the motor all back together yesterday. Went to fire it up and wasn't really getting anything. But I could smell fuel and lots of it. So I hooked up the laptop to try and see what the car was doing. My map sensor was reading 38 psi all the time, thus dumping ridiculous amounts of fuel. Disconnected the map and programmed the ecu to run a stock maf and she fired right up.