Lack of oil to rear lifters

[60sIron]

I’ve had a difficult to diagnose valve noise since day one on this engine.  It has a high volume oil pump and has great oil pressure.  This is a hydraulic roller setup with the T&D shaft type rockers which oil through the pushrods.  Part of the difficulty finding this problem is that it seems to work fine when it first starts up, so when I fix something and start it up and the noise is gone, I think I’ve fixed it.  Then it returns at the end of a test drive when the engine is fully hot.  I’ve also had trouble pinpointing if the noise is coming from the left or right bank.

So today I started it up and got it fully hot until the noise returned.  Then I removed the valve cover and started it up.  The front 5 rocker arms appeared to be getting normal amounts of oil.  The rear 3 seemed to be getting a lot less, and the last rocker arm didn’t seem to be getting any oil at all.  So now I’m thinking the noise is lifters starved for oil and not closing up the lash.  Has anyone here encountered a problem with rear lifters losing oil pressure when hot?  The gauge still shows plenty of pressure and the front lifters seem to be working fine.

I fully expect this will require a tear down, but I’m not sure what to look for.  Very much want to avoid a tear down, find nothing, reassemble and same problem situation.

[67xr7cat]

The oil feed passage on an FE is from the back to the front so if there is oil at the front, there is certainly oil at the rear lifters.  What lifters are in there?  I know Morel has an oil spec for their lifters and if you don't follow it they say you may have problems.  I would also check your lifter preload on all the lifters to make sure there is enough. 

[jayb]

I'm guessing you pulled the driver's side valve cover.  On that side the oil comes up from the #2 cam bearing location, and has to go to the back to oil all the rockers.  If there isn't sufficient oil going to the back then it is likely bleeding off somewhere.  Since it happens when the engine warms up, it is likely a clearance opening up with temperature and bleeding off excessive oil.  I would be looking at rocker arm to shaft clearance, a broken or cracked rocker shaft, or a leak around the rocker pedestals.  I doubt the lifters are the problem.

[67xr7cat]

Jay he stated he is oiling thru the pushrods.

[jayb]

Oops    Should have read more carefully...

[60sIron]

These were Howard's Cams lifters, but they have Morel part numbers on them, so I suspect they were made by Morel.

For what it's worth, I have swapped out the lifters and it didn't change the problem.  The oil is 10W30, Pennzoil I think.  Maybe Castrol.  Ordinary motor oil.

I have a video of this, but it is too big and wrong format to post.

[jmlay]

Facebook post with video:

https://www.facebook.com/share/v/15yyKc9Ned/?mibextid=wwXIfr

[427Fastback]

I believe i read a post (think it was Rory's) That morel specs 5/30. Nothing thicker...I could be wrong...

[My427stang]

10w30 is almost always good, it's based on a Kinematic Viscosity rating, and not clear if required for the non-short throw but I have seen SBFs with thick oil and Morel hang up.

FWIW I go .045 to .060 preload on standard travel Morels whether sourced from Morel, Lunati or Howards.

The odd thing is the factory oil gallery to the back down the center, then mostly back to front after it splits, and almost directly feeds the #8 exhaust after the split, so odd the rears would starve, maybe something in there on the rear one as it took the corner or maybe bad preload or worn lifter bores.

Are you in the preload window and are the rocker adjusters where you would see oil coming through?  Wouldn't change the noise, but the oil could be unrelated and just a weak lifter 

[Barry_R]

Is it "only" oiling through pushrods - or does it oil through the shafts? 
Most of my T&D bolt on sets, like you have, are shaft oiled.
I have had shaft oiled systems where the mounting fastener locations were off by enough that the shank of the bolt effectively close off the oil feed through the shaft.
Just a light oversize on the shaft's mounting holes and the problem resolved.
Also be aware that T&D is very particular as to adjuster location relative to the rocker arm body.

[jayb]

I think Barry is onto something.  The T&D adjusters have a relief in the diameter, or "waist", where oil flows out of the pushrods and into the rocker body, through the adjuster.  If the adjuster's "waist" is not lined up with the hole in the rocker body, the oil will be severely restricted or cut off.  On my cylinder head package I specify only a couple turns on the adjuster is permitted, to make sure the waist on the adjuster remains lined up with the oil hole in the rocker body.

To check this, take one of the rockers that is not oiling and note the position of the adjuster.  Then remove it completely, and you will see the waist I'm describing.  Measure down to the oil hole in the rocker body from the top of the rocker, and then do the same with the adjuster to see if the hole is lined up with the waist.  If the adjuster threads are lined up with the rocker body hole, instead of the waist, you have found the problem.

[Rory428]

I believe i read a post (think it was Rory's) That morel specs 5/30. Nothing thicker...I could be wrong...

Yes, at least with the Morel "Hi-Rev" hydraulic roller lifters in my 347 SB Ford, Morel does specify 5/30 or 5/40 oil. So I have been using 5/30 Brad Penn oil in that engine for the 5 years that I have been racing it. Not sure if Morel has the same oil recommendations for "regular" hydraulic rollers.

[60sIron]

Thank you Barry and Jay, that gives me something I can check.

These are all 8.750” pushrods.  If this is a problem would I need a special pushrod a few thousandths different?  Mill down the rocker stands a bit or shim them up a bit?

[blykins]

Thank you Barry and Jay, that gives me something I can check.

These are all 8.750” pushrods.  If this is a problem would I need a special pushrod a few thousandths different?  Mill down the rocker stands a bit or shim them up a bit?

If the adjuster position is the case, you wouldn't need to change the geometry of the rockers, just the pushrod length based off of a new adjuster position.

[XR7]

On the T&D adjusters, they can only be turned in, or down toward the pushrod between zero and 2 full turns. If they are turned more than two turns the oil path is blocked. You don't need to take the rockers off to check, just back off the lock nut on one of the offending rockers, and count the turns backing it up until it stops, if it is more than two turns you need longer pushrods, not by a few thousandths, but by .025 or .050 depending on how deep they are. Usually you can tell just by looking at the adjuster if there are no threads showing and/or below the top of the lock nut they are too deep. I like to try and set them where they are around the 1 full turn mark, then you have plenty of adjustment both directions. If I remember right, I think one turn on the adjuster is around .034 thousandth of pushrod length with 1.75 ratio on the T&D race rocker paired shaft rockers anyway, that is all I have messed with, not street rockers like what you have so that could be slightly different on the adjuster since the pivot length is shorter.  I usually have to buy pushrods in .025 length differences, and on large cams, with the reduced back circle on the intake lobe in particular, most times I have .025 longer pushrods on the intakes versus the exhaust. In a pinch you could mill the rocker stands on the bottom, but that changes the geometry, maybe it would need to go that direction (if your lucky) but maybe not, depending on lift. That is a whole different discussion. Good luck, and let us know what you find.

Thor   aka: XR7  my old membership failed and starting over...