Just how critical is a clacking lifter?

[HondaDustR]

Hey guys, quick question...

I'm finally going to have some time off of school to go home this weekend, which means I have some free wrenching time. I need to check and re-tension the cam/balance belt, but I am debating on whether to pull the cam tower again and swap some lifters. I have one, maybe two, that like to randomly go totally flat, clacking loudly. Usually they'll straighten out at least enough to go quiet if I rev past 3000 for a few seconds, but it's kind of annoying, and by the obvious workings of hydraulic lifters in general, it probably compromises valve lift on the affected valve at least when it does go flat.

So the question is, what sort of harm could come from leaving it in there versus swapping different used lifters to try to eliminate the problem, since it would end up being either the 3rd or 4th different lifter my cam has run on, depending on the lobe. Any metal part that makes that sound can't be good for the long term, and the German case hardenning has proved itself well with the last 3 or so mixups. I know in a perfect world the entire cam and all lifters would be replaced all at once at the onset of any problem, but the world ain't always perfect...

It's not a question of time, since I can have the cam tower off and back on during the belt job in less than an hour, but more a question of severity of the problem and risk. I wouldn't care if the cam disintegrated except that it would probably ruin the rest of the motor, as the cam has in excess of 160K on it and who knows how "in spec" it still is. It is the original from my old motor. Either leave it as is until I can find a lower mileage late cam, housing, and lifters in good shape (could be next summer, or as long as 3 years down the road), or swap lifters to quiet it down until I can find a better valvetrain. The late cams seem to have been a bit harder to find lately. They have a slightly better profile than the early part.

Any thoughts?

[89-944NA]

Other than the obvious noise, if the lifter fails completely, you can have one hell of a noisy engine, and I believe you can also bend a valve.

[88Silver924S]

Years ago I had a Mazda with a noisy lifter and poured in some Gunk brand Valve Medic or something like that as a first try before a "surgical" solution. It worked that time, the lifter quieted down and never misbehaved again; no tear-down required. Something like that might be a first try. If it works, great, if not no harm done. If it was me I would change the oil between 400 to 800 miles to get clean oil back in the engine after some treatment like that . Good luck.

[rmcdonnell]

I'm in the same boat, except I haven't done the cam tower before, and I'm cautious about doing the job when I don't have to.. (so I flushed and replaced oil instead, again, and the noisy one is now quieter, but still clacks a bit).

I had the perfect weekend last week, and bottled it. I decided to wait for spring, as I can't afford for the car to end up with down time, and I don't want to rush the belt job. Might as well do the head then, there's not much more risk.

But I'd like to know how much damage the noisy lifter can do in the longer term, and I'm very interested in opinions. My guess so far is, not that much, which is why I decided to put the job off.

R

[Pettybird]

what oil filter are you using? cheap ones allow the oil to drain back into the pan and are hard on engines for start-ups. how long has this been going on?

[rmcdonnell]

I'm on a new Euro Porsche supplied filter, (I think HondaDustR was on K&N, but he will know for sure!), so I don't think these are just start-up probs. I don't know if the later cam profiles are more aggressive on the lifters?
R

[HondaDustR]

Definitely K&N. Running Brad Penn 20W-50 at the moment. It's seldom loud at startup, it just likes to occasionally go flat.

How long it's been going on is a complicated story, so I'll try to get just the relevant details. It is the original cam, housing, and about half of the lifters from my old motor that I killed at 150K. Shortly before the thing died, I had the cam housing off to replace valve stem seals, since I was using close to 1qt every 250 miles with no obvious smoke and no leaks. I had not really had any significant problems with the original lifters, but a couple sounded a little soft, so I swapped a couple from a good used set while I was in there. Well, the seal replacement job did not end well at all, and I was crawling around the garage looking for lifters so I could have a car to drive...swapped the worst from the used spare bunch in place of an unuseable and a lost one and threw the thing back together complete with whatever crap and grit was stuck to the parts at the time (learning experience ,but I have never been so at the car before or since...). She started up and ran fine, and made it to Kentucky and back a week later with no lifter noise (brought 6 qts of oil just to be sure...all of them were gone by the time I got home!...and having only 6 old valve stem seals instead of 8 made absolutely no difference). After that, I went back in 2 weeks later for take 2 on the stem seals and successfully replaced them. The cam and bearings were fine, a few of the lifter bores were scratched...one somewhat deeply from the road rash on the lifter running in it for 2K miles, but they all still fit nice and tightly. Swapped a couple of the damaged lifters out and had everything ready to go back together...and it starts raining (I can just about predict the weather by what my car repair plans are, I swear...). It's getting dark, so I wrap it up and save the final cam installation for tomorrow. I get everything together the next day, completely forgetting the shop towels in the head. Sparing the gorey details, from just the lifter's perspective they ran with no oil pressure at around 5000 rpm for about 30 sec. They were kept in order and re-used along with the cam and housing, since the bottom end didn't start destroying itself until oil pressure was lost and the crap wasn't able to circulate. The top end stayed pretty clean. The cam, housing, and lifters went on the rebuild and have generally worked fine, except for the random collapsing of what sounds like only one in the 3 or 4th cylinder area. I don't remember the first time I noticed it, but it wasn't right away as soon as I started driving it again.

Damn I said I'd keep it short...oh well. I like a dramatic story. I may have answered my own question and really should just replace the entire cam assembly, and I eventually plan to, but may continue the musical lifters game until I can buy a good used one.

I'm really not sure I could bring myself to put anything other than oil and maybe seafoam into my motor now. It's been rebuilt down to every last seal and o-ring and is nearly pristine with only 14K on it. If it had more like 150K on it, I would probably give one of the magic elixers a try.

[rmcdonnell]

I'm not clear about what goes wrong with the lifters anyway... I can understand that Seafoam might clear gunk out of them that stops them pumping up, and there is a non-return ball valve that is part of the central piston area, that maybe starts returning more than it ought to, but what gets worn or broken that turns a good one bad? Are they always blocked oilways, or soft or broken ball return springs, or bad ball valve seats or what.

I'd prefer to fix or measure the problem, rather than buying shed loads of lifters that by some accounts will need replacing before they are 10,000 miles old. The only spare lifter I have is rock hard, as far as I can see, the piston doesn't move. Is it pumped up to a max pressure and height that seals solidly and doesn't allow more oil in or out? Or do I just need to overcome the internal pressure by pressurising oil

How is the central piston fitted in position? Is it held in the central lifter chamber, and a large washer forced down the lifter bore that seals onto internal chambers, limits the piston movement, and seal around the lifters edge, cause it all looks like one bit to me.

If you have a soft lifter could the central piston be jammed or welded in place making a solid lifter? At this moment in time, I don't see why not...

R

[John_AZ]

Originally Posted by rmcdonnell

If you have a soft lifter could the central piston be jammed or welded in place making a solid lifter? At this moment in time, I don't see why not...R

Very good recent post may explain:
Dissecting 944S lifters

John

[HondaDustR]

Well, I went ahead and pulled the cam housing. My initial listenning diagnosis was dead on. The 3rd cyl intake lifter was flat as a pancake. All the rest were holding oil and were nice and hard. The cam still looks good, but it's definitely showing some use. It's got 165K on it and I like to rev it hard when I can, and it had 90K when I got the car. She's smooth as glass now. No clicking or rattling, and it sounds alot more controlled up in the top end of the revs. I think it gained a little bit of power, especially up past 6000, but that could be compounded by the colder weather. Personally, I'd rather make valve lash adjustments every now and then than dealing with these things. They're freaking heavy when they are full of oil!

[rmcdonnell]

Brilliant, excellent work just diving in and getting it sorted. Experience is everything, when you have done it before, you have all the right tools, nothing is going to be ridiculously tight, or snap off, but it still takes a bit of determination to confront the problem.

Do you reckon the bad lifter has a seized central piston assembly? Also John's pointer was for 944'S lifters on a 16V motor, and the central piston appeared slightly different from my N/A type, though they may work the same way.

cheers
R

[HondaDustR]

...and I didn't want to dump oil all over my still clean motor.

No, it wasn't seized, just wouldn't hold pressure. I guess the piston/bore wears after awhile or the check ball doesn't seal any more...or air gets hopelessly trapped inside. Once full of oil, they should feel very hard. The point is, they fill to take up the exact clearance of each individual valve, removing any need to adjust or measure anything. The 8v lifters are nearly identical to the 16v parts only bigger.