Noisy lifters and other suspicious noises...

[trickyrix]

First of all, you should know that my car is a bone-stock '94 car (as far as I know - I've only had it since October) with about 97K miles on the clock, and I've but about 4K miles on it since I bought it.

I've read up plenty on noisy Miata lifters, and I understand it's kinda one of those "sometimes they do that" things. However, when mine get noisy, I haven't been able to point to any other specific event that happens when they get that way - ie: needing an oil change, hot oil, cold oil, etc etc etc. They seem to get noisy with the phase of the moon. But just today I pinpointed something that might be connected to the lifter noise... and I'm not sure what to make of it, but here goes.

At WOT above 5K RPM, I hear what sounds like whistling or hissing (maybe squealing). If you bring the revs up at less than WOT, it doesn't make any racket. Anyhow, I was out today just cruising around, and the lifters started clicking. It had gone away by the time I got home but, thinking back, I guess I had gotten a little frisky pulling away from a stop light - revving to maybe 5500 RPM at WOT. So I pull into the driveway and bring the revs up gently to 6500 to see if I can hear "the squeal" - no dice. I try again at WOT and get "the squeal" - at which point the lifters start clicking like hell. So now I'm thinking "this doesn't sound too good," and it sorta sounds like a bearing squeal.

Having said all that, I've got good oil pressure (according to the stock gauge), and the engine seems to run just fine - it pulls strong, doesn't overheat, and doesn't exhibit any other funny business. Any thoughts as to what I'm dealing with here? I ran across a thread where someone mentioned main bearings in the same sentence as clicking lifters... but I usually think of a bad main or rod bearing as making a dull knock, not a squeal. Of course, these two noises could be totally unrelated, but it seems otherwise...

At any rate, it sounds like something I need to diagnose and fix before I start bolting on more horsepower.

[icepenguin66]

Hmmm...if it seems to only happen after WOT and high rpms...maybe sounds like an oil pressure issue. High rpm/WOT causing the lifters to starve for oil and once the rpm gets down they get oil back in them to quiet them down again. Just one theory, hopefully not the correct one as that would not be fun for you and your engine.

[johnwag]

Check your timing. I hope you are not referring to detonation.
Check the torque on your valve cover bolts.
Possibly need to replace valve cover gasket. .
What weight of oil are you running?

My 96 used to "zing" at high rpms. It doesn't anymore. I'm using castrol syntec in a 10w40 flavor.

[trickyrix]

Check your timing. I hope you are not referring to detonation.

Definitely not detonation - it's a smooth zing/hiss/squeal and not pinging. If I had a blower, I'd think I had a leak in the intake somewhere.

Check the torque on your valve cover bolts.

Will do... can loose bolts (or tight bolts) cause a racket?

What weight of oil are you running? My 96 used to "zing" at high rpms. It doesn't anymore. I'm using castrol syntec in a 10w40 flavor.

Mobil One 10W-30... would you say your "zing" happened under circumstances similar to mine?

I'll check out the valve cover bolts and report back... thanks for the ideas so far. If you're bored and surfing, please keep 'em coming... this could turn out to be a fine fishing expedition...

[MadMerv]

I know the two don't seem to be related, but the whistle sounds like a vacuum leak. Check the passenger side rear of the block. There is a vacuum line plug there that could have fallen off or deteriorated......

[POS Racing]

I'll check out the valve cover bolts and report back...

Careful with the bolts they tend to break if ya get a bit overzealous!

Miata.net says = Torque bolts to 43 - 78 inch-lbs.

[Titus]

Careful with the bolts they tend to break if ya get a bit overzealous!

Miata.net says = Torque bolts to 43 - 78 inch-lbs.

Yep... I broke one with TC supervising. He said something about how it is important for people to be allowed to make mistakes as it is the only way they learn. Town North didn't stock the bolt and it took them 4 weeks to get them in from Japan. I got a spare.

[trickyrix]

Hmmm...if it seems to only happen after WOT and high rpms...maybe sounds like an oil pressure issue. High rpm/WOT causing the lifters to starve for oil and once the rpm gets down they get oil back in them to quiet them down again.

True... but when they start ticking, it often takes a little bit of time to work itself out (maybe 10-15 min of easy driving). And then everything's fine - often for a couple of weeks straight. It's like they get dry, start clicking, and then it takes a while for the oil to get back up there - and that's what bugs me the most about it... Also, it sounds like it may be one or two that keep sticking since it usually doesn't sound like a whole herd of them clicking at once - it's more of a "tick, tick, tick, tick, tick"...

Ugh.

[trickyrix]

Quick update... I went out and gave 'er the ol' Oklahoma Tune-Up (you know, blow out the carbon, ahem) and I've about decided that the "zing/whoosh/squeal/hiss" sounds like more of an air leak. I checked the vacuum lines that I could find but didn't find anything amiss. Also, in spite of repeated trips to redline, I got no ticky from the lifters. I'm going to go back out and check bolts, scratch my head, and ponder this for a while. Or maybe I'll just beat my toes with a torque wrench. At any rate, whatever breaks can always be fixed...

[johnwag]

Will do... can loose bolts (or tight bolts) cause a racket?

Mobil One 10W-30... would you say your "zing" happened under circumstances similar to mine?

I recently replaced my valve cover gasket and didn't toque my bolts down all the way. I got a ticking noise and a hiss.

I haven't had the "zing" from the valvetrain for 10 months or so. I'm not sure what made it go away, but it did.

[icepenguin66]

I know the two don't seem to be related, but the whistle sounds like a vacuum leak. Check the passenger side rear of the block. There is a vacuum line plug there that could have fallen off or deteriorated......

Whadda ya know, I have to replace that right now! The little plug cracked and started hissing away today.

Oil weight can make a difference, but 10w30 should be fine. Mine made a little noise with the cheap 5w30 break in oil I used the first week I put my engine back in; all quiet gone once I put 10w40 in.

[trickyrix]

Whadda ya know, I have to replace that right now! The little plug cracked and started hissing away today.

Is there one of those lines or endcaps that tends to crack more than the others? I had 3 old RX7s that had the same vacuum line wear out at the back of the carb, but you could tell it because the idle would go to complete crap.

And, BTW, the lifters haven't made a peep all day until just now when I got home and pulled into the driveway!



I'm going to change the oil next week since I'm about due anyhow - but old oil hasn't seemed to affect it... could I (or should I) try the Mobil One 15w50? I've got a few cases of that left from my last car. If that's a bad idea, I may bump up to a 10w40 to see if that changes anything.

[TurboDuane]

Ya, know, with that mileage, you could be having a CAT heading South. When they go bad, they will rattle, and you will notice air noise at high rpm's and high load, which will progressively get worse and will start making more air noise when at any throttle setting.

You should have someone listen to it. Try and make the Friday Lunch.

TD

[icepenguin66]

Is there one of those lines or endcaps that tends to crack more than the others? I had 3 old RX7s that had the same vacuum line wear out at the back of the carb, but you could tell it because the idle would go to complete crap.

And, BTW, the lifters haven't made a peep all day until just now when I got home and pulled into the driveway!



I'm going to change the oil next week since I'm about due anyhow - but old oil hasn't seemed to affect it... could I (or should I) try the Mobil One 15w50? I've got a few cases of that left from my last car. If that's a bad idea, I may bump up to a 10w40 to see if that changes anything.

The one I had just crack was the little vacuum fitting at the back of the intake manifold. I wouldn't think there's a problem with them, just a little black nipple to block it off.

Nothing wrong with 15w50, nice and thick to quiet any problems and make for long engine life under hard conditions or good for high heat applications like turbo or in the Viper's huge ass motor. That's what a friend ran in his 93 Viper, in which the manual states it will loose 1qt oil every 1k miles or something and more under hard driving!

Kinda hard to diagnose a noise from the internet, try to meet up with the guys Friday like said above.

[trickyrix]

Hopefully I can do the lunch thing on Friday, but if not, I'll see if there's anything going on over the weekend.

Thanks again!

[trackdog]

Noisy lifters:

Go to O'Rileys and get a bottle of their cheap Oil Treatment. This looks like motor honey, very thick. Add 1/4 of the bottle which is about 2 ounces or so to the oil at each oil change. We have added this to several noisy Miata lifters with excellent results. The thicker oil gets into the lifters and slows down the pressure lose. Seriously, this works.

What is happening is the tiny check valve in the lifters are worn out and not holding the oil in. This will not hurt the engine, but it will be down on performance. I would not go and replace the lifters, but if you have to do any head work then at that time replace them. Aftermarket lifters are around $15-20 each where the dealer is something like $65 each.

Gary

[MadMerv]

Is there one of those lines or endcaps that tends to crack more than the others? I had 3 old RX7s that had the same vacuum line wear out at the back of the carb, but you could tell it because the idle would go to complete crap.

And, BTW, the lifters haven't made a peep all day until just now when I got home and pulled into the driveway!



I'm going to change the oil next week since I'm about due anyhow - but old oil hasn't seemed to affect it... could I (or should I) try the Mobil One 15w50? I've got a few cases of that left from my last car. If that's a bad idea, I may bump up to a 10w40 to see if that changes anything.

Engines today are built with much tighter tolerences than in the old days, hence the reason for lighter weight oils. I think you're barking up the wrong tree. I would never ever use anything heavier than a 30W.......even in the SM.

TurboDuane has an excellent idea.

[trickyrix]

Well, it would appear that I've got two unrelated problems in the "tick" and the "zing." Sounds like Gary's oil trick is worth worth a shot for the "tick," so that leaves several possibilities for the "zing." I'll monkey with it over the weekend and see what happens... as for TurboDuane's suggestion about the plugged cat, wouldn't that also choke the motor down at higher RPM since it's building higher back pressure?

Anyhow, when I get a chance, I'll get someone to listen in person, but in the meantime I've got some things to try to keep me busy...

Thanks guys!

[MadMerv]

Well, it would appear that I've got two unrelated problems in the "tick" and the "zing." Sounds like Gary's oil trick is worth worth a shot for the "tick," so that leaves several possibilities for the "zing." I'll monkey with it over the weekend and see what happens... as for TurboDuane's suggestion about the plugged cat, wouldn't that also choke the motor down at higher RPM since it's building higher back pressure?

Anyhow, when I get a chance, I'll get someone to listen in person, but in the meantime I've got some things to try to keep me busy...

Thanks guys!

Not necessarily. Sometimes the honeycomb breaks up and rattles but doesn't block the exhaust gases.

[trickyrix]

Not necessarily. Sometimes the honeycomb breaks up and rattles but doesn't block the exhaust gases.

Ah... I see.