Sticking hydraulic lifter

Hi guys,
On first start up on rebuilt chev350 I have a knocking sound.
I think it may be a sticking hydraulic lifter, engine has roller rockers.
What can I do to stop a sticking lifter to see if this is the problem ?
Thanks mike

 

I'm no SBC expert but there's other things it could be other than a faulty lifter.

Something out of alignment,clearance issues,a valve that's too tight, guides missing, etc.

 

Lifters sometimes do that after a rebuild. Once they reach operating temperature and have received enough oil, the sound must disappear. My vintage Porsche rattles like a can of nails when I start it once a year, then gradually the lifters fill up and the engine purrs like a cat.

 

Why solid bump stick followers? If my memory is right, you're not asking enough of this engine to need solid lifters.

The first thing to do is get a 12" - 18" length of wooden dowel, say 1/2" around. Stick one end in your ear (yeah, your ear) and the other on the lifter valley. See if you can isolate the noise, by moving it around. Certain sounds are obvious, but pin it down as best as you can. Next up will be a vacuum gauge which will confirm what you suspect. Pull the valve covers and check heights as you turn the engine by hand.

Before any of this you can try "Marvel Mystery Oil" or my usual concoction adding 20% - 25% automatic transmission fluid to the engine oil. Pull the filter, replace the filter after filling with ATF, them top off the remaining oil with ATF. Run the engine an low to moderate RPM, until you've got a few good solid heat/cool cycles in it. This often will free up a reluctant lifter. Of course change the oil and filter after this run in, with regular motor oil

 

First diagnose the problem. You can isolate the noise by running the engine without the valve cover. Twist the rocker arm with your fingers and the noise will decrease when you grab the problem one.

 

If you have a lifter making noise and they're new hydraulic lifters most likely it just needs adjusting. I would re-set all the lifters one side at a time. First determine which side the lifter that's noisy is on and set that side first. Find the noisy one and tighten it till it just quietens down and then go through all the lifters on that side. One at a time loosen them till they just start making a noise and then tighten them down till the noise just stops and then turn it down another quarter of a turn, some times the motor may miss for a short time until the lifter bleeds down. After setting all lifters on one side at a quarter of a turn past zero lash I always set them down an additional quarter of a turn. It will be messy if you don't have the right equipment such as an old valve cover cut in half and clips to go on the rocker arms.

 

I was going to suggest ATF but noticed it was a rebuilt engine.

I know ATF is for ungumming the engine-freeing up stuck lifters- and cleaning out deposits, but will it help anew one?

 

Being these are new hydraulic lifters I seriously doubt there's a problem with a lifter, most likely if it is a lifter making the noise it probably just needs adjustment. I would definitely re-adjust them first before doing anything else.

 

These are the rocker arm clips. They make setting lifters a much less messy and easier job especially when used with an old valve cover cut in half to catch the oil.

 

you need to make sure that it is indeed a lifter, if there is some other problem you will want to correct that before it causes damage to your new engine.

Noisy lifter will cause no harm, but if it truely a knock, and not a chatter sound (that come from noisy lifters), than you need to find it and correct it. If you have a bearing with incorrect clearance, or a valve hitting a piston, causing the knock, you could do very serious damage to the engine if you run it at all.

Always diagnose the problem BEFORE you try and fix it. As obvious as that sounds, it is not always done, and much time and effort are wasted fixing things that are not broke, and you still have your problem.

If it is a bad bearing, you pull the spark plug wires one at a time and the bearing with too large of clearance will stop making noice when that wire is pulled. If it is from the valve train, it will occur at a rate half the engine rpm, and if you back off the adjustment so that lifter so it is not making contact with the cam, you can isolat which lifter is making the noise. If neither test stops the noise, you have to look for other possible problems that may require dismantling the engine.

good luck,

 

I've used those rocker arm clips once, as has everyone else I know and I think I still have them in a dusty box somewhere. They really don't work that well and just fly off, usually just before you get a splash of hot oil in the eye.

The best thing you can do is buy a used set of rocker covers and cut the top off (as has been mentioned), knowing you'll be tossing some oil around. At least most of it will return to the crank case, with a butchered cover in place.

Agreed with Petros, find the problem, then address the problem. Most engine noises can be ID'd with a vacuum gauge, stethoscope or simply hunting around with a dowel in your ear. Any reasonably skilled mechanic can tell the difference between a click, tap, slap or knock and the probable location within a few minutes. A knocking sound doesn't sound good, but is it really a knock.

 

This is the problem with DIY engine rebuilds.

 

I don't know if it's a problem for DIY builds. There's a lot more to a rebuild than just installing new parts. The unspoken stuff like cleaning threads and chasing out oil galleries, are stand practices for a mechanic, but the DIY'er might skip some of these procedures. I've seen all sorts of stuff over the years, like leaving the freeze plugs, because they looked good, replacement of all the major parts, but skipping to ones that make the engine run like crap, such as the distributor gear, or a good valve lap. We just don't know the level of experience Mike has or his rebuilder. Hell, he might have reused the lifters or has a bent, reused pushrod.

bought a brand new rebuilt 350 four bolt, some years ago. The guy tossed some money at parts and did the job himself, but he "screwed up something" (his words) because it had next to zero oil pressure, in spite of a new pump. Unwilling to tear it down again, I bought it cheap. He apparently cleaned out the oil pan with a red shop rag, which got below the windage tray and left in the pan, when it was bolted back on. A quick fix for me, but I plastigauged the bearings anyway to see what else he missed. The cam had flat spotted a couple of lobes, so I changed it and I replaced the lifters, because I couldn't tell if they were new or not. The engine ran fine in a buddies boat for years afterward. In the same vain, I know a guy that loved his VW bug and he bought a book, tore apart the 1600 duel port and rebuilt it, according to what he read. This engine ran reliably for several years, so a DIY'er can get it done, assuming common sense practices and procedures are followed. This is the part we don't know about this engine.

 

It would be nice to hear from Mike to see if he found the problem. Hopefully it was just a loose rocker arm and he has it fixed. As far as those rocker arm clips the ones I used didn't look exactly like them but I always used them when setting hydraulic lifters as long as the engine was just idling I never had a problem and they sure do make setting valves a lot cleaner. I've rebuilt over a hundred small block chevys in my day. But I have all the equipment and plenty of experience to do it right. Mike has already said these were new hydraulic lifters. I wonder what oil pressure he's getting I know he was having a problem when he was first installing the bearings and pistons.