Valve knock medium throttle under load?

[afterburn 549]

Thanx for chiming in. He needs some serious help .

[Packy]

Maybe you guys already mentioned this, but did you check your chain tensioners?

turn it over by hand and see what valve is hitting. If you can remove the rocker arm from that valve, do it and then try and turn it over again. Check your chain tensioners to see if they are too squishy or if the cam got out of timing. maybe your skipped a tooth. If you can turn over the engine without the rocker pushing the valve into the piston then you know it's a timing/cam/valve thing. If you get a bad leak down on that cylinder and it's not coming out of the intake or exhaust, then you have more serious problems like a broken ring.

[E Sully]

I gave a quick read on you rebuild thread. Did you install the collars again on the tensioners? When my tensioner failed I had bent the exhaust valves on that side. If yours had skipped and bent the valves, you would hear the air in the exhaust, not the center of the engine.

Originally Posted by sobamaflyer

They are Alusil, my machinist reported to me Friday they are well over spec in every dimension confirming all the previous thoughts of just putting them back as they were.

I am curious what you mean by over spec. If the rings were worn, or the top ring land was too large it could lead to broken rings. Also, did you ever determine for sure if they were Alucil or Nikacil? Unfortunately, it looks like you will probably need to pull the heads.
How do the spark plugs look?

[eastbay]

You say you adjusted the valves and now have big leakdown numbers. I think you might want to go back and set your valves just a little bit looser. It's free to try.

[sobamaflyer]

thanks all, I got busy with work for a few days.

Walt: My help has come from several sources on this board but largely from Howard Freeman. I'm going to repeat my test Saturday after opening the valve covers, checking the valve clearance and the cam timing & the head torque. I did listen at the intake and had an ear in the tailpipe and didn't hear hissing there, but I could hear it well under the engine and with an ear at the fan shroud.

Oddly it really doesn't smoke at all past the first minute or so, I keep a shiny metal pan under the engine and while there is oil on it there isn't a pronounced spot. I have some "moistness" under the engine but no real spots of an obvious drip.

E Sully: I did install the collars, the tensioners were actually rebuilt by Howard (as you may have read in that thread). I probably should have said I was told they were well over the MINIMUM specifications in his reference materials. It's been a year and a half and I've slept so now I'm having trouble remembering which pistons I had but I want to say after showing the markings under them to this board they were told to be the ones that could be refinished without destroying the coating. (I didn't do that even, just cleaned and reused).

The plugs looked really good in color on all 6. I had a questionable trace of oil on plugs 1 and 6, it didn't coat the electrode but could be seen on the base and the base of the electrode a little whereas the rest didn't have any.

____________________

Again, thank you all, I'm considering dropping the engine Saturday morning so I can check into all this easier/more thoroughly. If something's really broken I'll have to have it out and apart anyway right? I may take the covers off to have a harder look and check the head studs first but after that...?

[sobamaflyer]

So here is where I am:

-I opened up the valve covers, I double checked the valve adjustment on #1 & #2. I have sat and studied the springs as best I can for a good long while and don't "see" anything wrong with them.

-I realized I never went back and retorqued my head nuts, they were all needing a little tightening to get to the 23.5 ft/lb.

-I put the dial gauge on cyl #1 at TDC and set it to "0", I spun the engine 720° and it read 0.033 (which if I remember correctly was right in the middle of where it was supposed to be and is in the middle of the indicators on the gauge from last time?)

-I redid the leak-down on #1 and #2, I am now getting 24% loss on #1 and 12% loss on number 2. I can hear absolutely no hiss in the intake or the exhaust, I can FEEL the air coming out of the now exposed oil return tubes. This time I set my compressor to 80lbs and set my gauge to 50psi, I got the numbers above by doubling what I saw below 50psi on the 2nd gauge.

________________

Is there something different I need to do/read from the dial indicator to indicate the question of jumped cam tooth? Wouldn't it run really weird if that was the case?

Is what I report enough that I really do need to go ahead and drop it and at least tear open the top end to see what is faulty?

Sorry for the book, thank you for any advice offered.

Travis

[afterburn 549]

If the air is coming out of crankcase then its a piston ring or cylinder problem.
If its all of them , I would hazard a guess rings installed wrong , upside dwn, or all just plain wore out.

[sobamaflyer]

The patient's heart is out of her body and on the stand, I'll report what I find this week as I proceed to tear it back apart

[sobamaflyer]

I've taken the left head and #1 & #3 pistons off. I've studied the head for an hour and can't find anything that looks wrong at all with it, all the valves seat well, all the springs look fine.

I confirmed I do have Nikasil Pistons, I took my micrometer to them using the engine rebuild book's spec section as a guide and checking my #3 piston & cyl. (which I got bad #s on) I come up with it completely within the spec for "0" size. The inside of the barrel looks just as it did when I put it in there (shiny with a light cross hatch) The rings look exactly the same, none of them on #1 or #3 are broken.

I'm pretty befuddled, I'm beginning to believe my bad leak-down test numbers may be operator error of some kind or another? I still can't explain the noise that sounds like valve clatter from bad gas either.

Do I button her back up and go about my happy life and believe these things just talk to you in different ways at different times?

Leak Down - I have a cheap Home Depot compressor - I've set the hose side gauge to 100psi. I have an OTC leakage tester. Today I put it on the other side of the engine (on the stand), backed completely off the 2 rocker adjusters to ensure I was checking for just the cylinder. I set the input gauge to 80psi, this time I read a stead 76psi on the other gauge.

[afterburn 549]

Were your heads loose?
If thats a fresh engine looks like leaky heads to me. (look at cyl edge too )
and that valve looks sunk.
are the rings on upside dwn?
Where is the sealing gasket?
Pix are pix, but from here........

[sobamaflyer]

Heads were a tad loose yes
Valve I believe is an optical illusion in the picture (looks odd on here to me too but not in person)
Rings upside down, got me?! I never took them out the first time for fear of breaking them and lack of necessity.

[cgarr]

could a leaking head seal cause a sound like you hear? both the head and cylinder sealing surface do not look good to me:

[sobamaflyer]

I had the same impression about the sealing surfaces, I put new copper gaskets on at the bases when I rebuilt but maybe I should replace them and the head gaskets too?

None were bad but I did have to tighten a bit to get them all to the 24.5lb

[cgarr]

that would make sense because you said it only gets loud under a load bet it was the top sealing surface starting to fail..

[sobamaflyer]

I did/do see signs of combustion around the cylinders that shouldn't be there, makes sense what I report I could have been hearing as a "leak". Is that too much to hope for, get some new seals and properly torque and it's all good?

[afterburn 549]

Last i knew 30 pounds torq with steel studs was the "right" number.
Rings can be up side dwn, not sure what the "last" guy did.
How many hours miles on this sense last taken apart ?
It does not "look" near clean enough.!
Were the ring gaps in the correct place when installed?
you say fresh overhaul right? ( how many miles or hours with this pictures"
Yes you need to use NEW sealing gaskets everywhere..no skimping !
looking the bottom pic i am sure that is a loose head for what ever reason . (so I am sure they are all headed that way)
There are a LOT of vertical FOD (scuff) marks on pistons and cyl. ( they will not seal)
you need to take rings off and measure gaps in cylinders. (wore out)
Sorry for the discrepancies .

[sobamaflyer]

-I had a little to go to get them to 24.5 so if 30 is right they were a good bit off.
-There is about 4k miles since I had this all shiny and clean and put together.
-I made it a point to put the gaps opposed to each other when I assembled but I forgot to note where they were when I pulled the cylinder back off.
-FWIW there isn't nearly the vertical marks evident in the light of day.
-I used new seals when putting it together, I'll order another new set today.

[afterburn 549]

.The pic shows lots of vertical marks..maybe a a opticle confusion..?
You did have a huge leak dwn problem right?
Looks from pic like lots of blow by for 4K..(unless things were not clean on assembly)
oil gap up fire rings 120 apart
use NEW steel cyl studs
pour some gas or solvents in ports of vavlves and see how long it takes B4 it leaks or "shadows" out.
what cam(s) do you have?
where did you set the cam timing at ?
Hyd ten. ok?

[Ronnie's.930]

In post #29, second pic from the top, is that a Dilivar headstud with the coating scratched off (or a painted steel stud)? I ask, because if it is Dilivar, then that is a break waiting to happen.

[afterburn 549]

We all want you to succeed. so dont take anything as a flame please.
I think you need as a very min new rings, a expert to look at the cyl wall as it looks like lots of vertcle scratches to me in the pic.
The can be re chromed if necessary.
There looks like a lot of gas oil passing the fire ring .(top ring)
also pretty sure I can see damage to top rings.
Things need to be near purrfect to work.