OK, this is the LZ9 in my MG and I have had a problem from the beginning with valve lash noise. Like an air cooled VW needing maintenance. This motor has roller lifters and no provision for any adjustment, have to buy new custom lifters. My theory right now is an aftermarket cam was used and the PO didn't get longer pushrods. The noise is minor but annoying to those who know engines. I pulled the valve covers and can measure lash, like a solid lifter motor. I measured a range of 0.004 to 0.030 and was rather shocked with that range so a week later rechecked everything and now I have a bunch of lifters that are soft. Can't measure lash on them because the pushrod is collapsing the lifter. Is this possible, after a week of winter temps or should I add new lifters to the shopping list? And if any of you have a similar motor needing custom pushrods is a variance in length for a no lash condition over 0.020?
did you run the engine between checks? as you rotate the engine, valve spring pressure will bleed down the lifters and they'll be soft until they're fed pressure again. At least, that's been my experience. I suppose it is possible that if the pushrods are truly too short, you could have hammered some of the valvetrain bits that are not designed to operate with lash. I don't know why you would need longer lifters if you can get longer pushrods.
My bad, meant longer pushrods. The bleed down you mention is spot on. I am waiting for an adjustable pushrod so I can spec the length but the range of lash had me concerned, hence the rechecking. There is no visual damage on the cam lobes or anything else, will pull some oil today for analysis.
I have seen this with bucket type lifters too, they can bleed down if they sit. Get some oil pressure in it and recheck.
I also have a somewhat clattery lz9.
Haven't found a reason for it and I don't know how to solve it.
I haven't even looked into figuring out how to check lash on a hydraulic lifter (figured they would just bleed down and give an erroneous result).
In reply to wvumtnbkr :
Mine held pressure for a while, did compression testing and the next day checked lash. A week later they had bled down. The FB group 60degreeV6 is pretty good for support on this motor.
stock pushrods per Ben at WOT-TECH
5.879 intake
6.168 exhaust
lifter .156 travel, preload .075 but .090 to .050 are the recommended limits
I had a terrible time getting TDC, no mark on the balancer and it has a trigger wheel but it isn't marked. Ended up using a chopstick in the spark plug hole, ballparked the middle of crank travel and put a dot on the trigger wheel. Then every 120 degrees another piston came to TDC
Ben's theory is the PO put an aftermarket cam in the motor and didn't get custom pushrods to match. I have no idea, and PO has ghosted me. Wish the motor had lash adjusters, but all I want is for it to sound like a hydraulic lifter motor not an air cooled VW needing maintenance.
When I rebuilt a Dodge 360, one of 16 valves had to be taken down more than the others. I bought an adjustable push rod. Worked out fine. This is one of many examples.
This is supposedly a low mileage motor. Based on the condition inside and compression it has never been opened up. Got a new cam because the VVT had to be removed for the new standalone
They can take time to pump up, you might want to raise rpm to 2500 so you are getting full oil pressure. I had a new lifter not want to pump up on my Harley, they make a racket.
All hydraulic lifters can bleed down with time and/or load. However, hyd lifters have a spring inside that returns the plunger to full-up so there should never be real lash at TDC while you're checking unless the lifter is damaged or the pushrods are wrong (assuming factory-condition heads and non-adjustable setup). Checking cam timing accurately in a hydraulic motor requires the use of "checking" valvesprings that are lighter that the lifter springs for this reason. Are you seeing lash as a true air gap, or just able to cram in feeler gauges and compress the lifter springs?
The comments about pumping up are valid as well, but not applicable to a non-running check. Many GM lifters from that time had trouble staying pumped-up while running...different story.
I'd be pulling a couple lifters to check wheel & axle condition, especially if the lash range is that large. It's possible the new cam needs longer pushrods because the base circle is smaller (I'm reading it as non-stock), but that's still quite a large range of lash.
In reply to Nockenwelle :
It is real lash. I can rock the rocker and the measurement is based on slight drag of the feeler. The second time I could see the pushrod move so I knew the lifter had bled down. I found a place that sells performance stuff for GM V6s and he is the one who told me that I most likely have an aftermarket cam and they require custom length pushrods. An adjustable one is due here any day now and then I will learn what length rods to order. When I redid the lash there were several valves with lifters that held oil. The measurements were the same or a thousandth off so I am comfortable with the first set of numbers.
I pulled one side of lifters and the roller looked perfect on every one. The cam looked fine too, no sign of any wear. Starting the motor up to get all lifters working is not possible, the intake is off and headers out getting coated. On the plus side the rockers are 1.6 ratio so the range is not as big as measured.
As nice as this car is there are several things that were done poorly. Not going into details as we all have made boo boos and I am sure people who worked on some of my cars cursed me too!
