Engine noise - 425 in a 64 Riviera

[Chewbacca]

Hi

 

The 425 in my Riviera sounds very ‘tappety’. I’ll be honest that this is this is the only nailhead I have ever heard in real life (I’m in the UK). Is this a feature of this engine or should I be investigating further? From the front of the car you can’t hear anything else.

 

Odometer shows 55k but the rest of the car indicates that this is at least 155k. There is no history with the car.

 

if you think this is unusual, is there any short term fix before I pull the cash together for a rebuild?

[RivNut]

An old mechanics trick that my dad used back in the era was to change oil and filter but use 4 quarts of oil and 1 quart of ATF (automatic transmission fluid) and run that for a while.  The ATF has a high detergent quality and may wash some crud out of the lifters. This is NOT something to do if you put any kind of strain on the engine. Just drive it around gently.  Loke i said this is n old trickused to help clean oil passages.  I imagine there will bevothers who say "no way" and/or offer other suggestions.  If I were you, I might try that then run some 15W-50 fully synthetic Mobil 1 oil. The synthetic oil also has some detergent qualities.

 

Addendum.  Please excuse tis Android's tendency to add letters to words or make up alternative spellings. ?

Edited October 10, 2018 by RivNut
Addendum (see edit history)

[65VerdeGS]

Hi Chewy,

 

"Tappety" sounds can come from the valve lifters.  This can be caused by a low oil level - did you check that first?  Sometimes a valve lifter can 'stick' due to internal engine deposits, causing the tapping noise because the push rod is not in continuous contact with the lifter.  Sometimes these will loosen up after a good long drive, but if not, try the following.

 

First,  try to find out exactly where the noise is coming from.  Best tool for this is an automotive stethoscope. Otherwise, use a long-shanked screwdriver.  Put your ear to the handle and place the tip on various engine parts of your running engine while listening for unusual noises.  Be careful around the fan and belts!    

 

If the noise is coming from the valve covers, then it's likely one or more stuck valve lifters.  What to do?  An oil change will probably help.  Also, using one of the additives recommended in this web article:  https://carpassionate.com/best-oil-additives-for-lifter-noise/ might help quell the tappet noise.

 

Hope this helps,

 

[Chewbacca]

Thanks for the advice. I'll try the oil additive when I next change the oil.

 

Cheers

 

[60FlatTop]

As a precaution to avoid misdiagnosis, pull a rocker arm shaft off the noisy side and check for wear on the bottom of the shaft where the arms ride.

 

[jrbartlett]

Two other things I experienced with a 425 in a 1966 Riviera back in the day. A rocker arm broke one time when the car had about 70,000 miles on it, creating a tapping sound. I pulled the rocker arm shaft off and replaced the broken rocker. Also, back when we were running leaded gasoline, the 425 had a tendency to "carbon up," as we used to call it. It would develop pre-ignition, and occasionally a piece of carbon would break loose and create a tapping noise. The solution was to pour a thin stream of Marvel Mystery Oil down the carburetor while applying enough throttle to keep the car running. Then let the car sit overnight to allow the Mystery Oil to soak the carbon buildup on the backside of the valves. Next morning, start it up and take it out on the highway and "blow it out" by running at high speed. It worked several times like an instant tune-up, curing both the pre-ignition and the tapping noise. I don't know that this is necessary anymore given our lead-free gasoline containing ethanol, which serves as a cleaning agent.

[arnulfo de l.a.]

Used to have tappet noise every morning at start up. Went away once motor was at operating temp.  At the time was using 50 wt . Changed to 10-40 and  noise went away. Good luck

[RivNut]

In a previous post, James discussed using Marvel Mystery oil for cleaning up the intake system.   It can also be used in the crankcase.  You might feel more comfortable using it rather than ATF as I mentioned earlier.

[60FlatTop]

At a minimum you should pull the valve covers and look for sludge buildup in the engine. If it is cruddy do you really want to run solvent through the system so it gets distributed everywhere? It could plug up oil passages or oil returns, maybe even the oil pump screen. It is a risk those old timers did with cars that were pretty well clapped out.

 

Think about the 60 years and 150,000 miles. The average of 3,000 miles per year doesn't sound bad, but it is likely it didn't happen that way. Maybe 10K or less the first 5 or 6 years, then 45 years of extended oil changes or just adding a quart. Some periods of unprepared idle sitting. "Life ain't easy for an old used car" to paraphrase Johnny Cash.

 

If it is light noises you might be better off just to live with it until you are ready to dig deeper (one way or the other). Everything has aged equally and formed its own balance. Disturbing that balance is what is kept quiet. Stop by sometime. I have a secret drawer with broken stuff in it.

Bernie

[lrlforfun]

OK Riviera People:  If it ain't broke.....don't fix it.  Clean oil, a filter  and Marvels is by far the best solution.   If you are able to,  overhaul the carb and get it running excellent so hopefully not a lotta gas gets in the crankcase. If the engine explodes you can still get value for the carb plus there's a very good  chance it could add to the driving enjoyment. Drop the pan and clean out the sludge?  Well you are inviting a can of worms with an engraved invitation.  These things are 55 years old. Mitch

[RivNut]

Be advised. "Dropping" the pan on a first generation Riviera involves jacking up the engine to get the pan off.  "It just don't drop!" There's stuff in the way.

[60FlatTop]

If you ever do drop the pan be sure to remove the fan shroud and the distributor cap. The four pan bolts above the crossmember are best removed with a 1/4" drive socket set.

 

I only did it once in the car, just to scoop up the piston pieces.

 

That led to a little more work.

 

I always figure, once you drain the oil out, all those tin things bolted on are inspection covers. I have to admit I inspect a lot of stuff that isn't broken, actually I inspect more than I fix. Or at least do smaller fixes.

This morning I stopped by the NAPA store and ordered a couple hundred dollars of parts for an engine, transmission, and rearend that are very expensive to fix and ain't broke. I know I'll be a little obsessive about this upcoming job, but its my hobby.

 

BTW, my Daughter had her fingers on the key and her foot on the gas when the piston disintegrated. She still remembers how calm I was about it.

Bernie

Edited October 12, 2018 by 60FlatTop (see edit history)

[rapom]

My 64 Riviera always has exhibited a deep knock on startup that goes away as it warms up. It lasts about 1 minute.  Oil pressure is about 35psi.   (You would think it would be the opposite.)  This has gone on for over 10,000 miles since I bought it.  I think it has 122,000 or 222,000 miles.  It's not a light tapping sound,  It sounds like a rod knock.  Anyway, it hasn't gotten any worst so I keep driving it.  Engine is tired but runs great.  

[petelempert]

While you are trying out potions to stop the clatter, consider Rislone. It's an old school zinc additive. Back when I first got my 63, it had been sitting for years and made lot of tappet noise once I got it running. The Rislone actually did seem to quiet my old clapped out motor. Not even sure why. Maybe it was just the motor getting loose again and there Rislone had nothing to do with it. Regardless, I heard about it years ago from an old mechanic named Bill who taught me some good and bad habits. I think a lot of these additives are worth a try only because you are probably living on borrowed time on your motor anyway. I would have tried pouring bourbon in the motor if I thought it might help. I poured bourbon in myself instead and that definitely helped. On a brighter note, you might actually have an exhaust leak at the manifold. Lots of times, a small leak will trick you into thinking its a bad lifter. Same habit of ticking or being noisy at start up then quieting down after a few minutes. With a cracked/leaking manifold, you'll have similar noise until the metal expands and essentially closes the leak enough to conceal the sound. PRL
 

[KongaMan]

In general: unless you were going to do a rebuild anyway, don't do one to solve this problem until you've got a good idea of what it is.

 

I'd concur with the MMO treatment.  Change the oil (including a quart of MMO), run a few tanks of gas through it (don't just putz around town; take it on the motorway and wind it out), and see what happens.  None of this stuff is Jesus Juice; it won't fix something that's worn or broken.  However, it may help something that's plugged, stuck, or otherwise gummed up.  That's what you're banking on here.

 

If you must tear something apart, I'd also concur that it wouldn't hurt to pull a valve cover to see what's hiding beneath.  It might not tell you anything definitive, but you may get some insight into how well it was maintained.

[RivNut]

In a post above, Pete refers to an exhaust leak.  It's not uncommon for the plug in the bottom of the intake manifold to be corroded to the point where it developes a hole in it.  An exhaust leak will sound like a tappet.  Here's a picture of where the plug is in the bottom of the intake manifold.  These plugs can be obtained from Russ Martin in Centerville, CA

 

[Riviera63]

46 minutes ago, petelempert said:

While you are trying out potions to stop the clatter, consider Rislone. It's an old school zinc additive. Back when I first got my 63, it had been sitting for years and made lot of tappet noise once I got it running. The Rislone actually did seem to quiet my old clapped out motor. Not even sure why. Maybe it was just the motor getting loose again and there Rislone had nothing to do with it. Regardless, I heard about it years ago from an old mechanic named Bill who taught me some good and bad habits. I think a lot of these additives are worth a try only because you are probably living on borrowed time on your motor anyway. I would have tried pouring bourbon in the motor if I thought it might help. I poured bourbon in myself instead and that definitely helped. On a brighter note, you might actually have an exhaust leak at the manifold. Lots of times, a small leak will trick you into thinking its a bad lifter. Same habit of ticking or being noisy at start up then quieting down after a few minutes. With a cracked/leaking manifold, you'll have similar noise until the metal expands and essentially closes the leak enough to conceal the sound. PRL
 

 

Pete has a good point about the manifold leak possibly being the culprit. I had this happen to me a couple of years ago. I thought I had a bad lifter. It turned out that I had an exhaust leak around the shaft in the heat riser. Since I don't drive in the winter they positioned the flap in the open position and welded those gaps around the shaft closed. Problem solved, ticking noise gone. This year I had a similar noise start and that quickly got worse. This time a cracked manifold.

 

Bill

[1965rivgs]

Chewbacca,

  Check the oil pressure with a mechanical gauge before you move on to additives, etc

Tom Mooney

[lrlforfun]

OK Rapom: Your describing a piston noise, very common in Nailheads and as long as you don't drive the crap out of it it  might hold for another 10K miles and 10 years.  The plug underneath the manifold? I've seen burn through  it on some 2 barrel units but not on a  4 barrel. Removing the intake is fast, easy and will reveal everything in a nano second.

 

OK Pete: Risolone was formulated for cars.....for example, that had no oil filter and didn't use detergent oil. It is great for breaking up sludge but....it needs to be buffered or it could easily dredge up caca that could clog the oil pump screen. It could also wash out engine bearings.

 

My solution of 4 quarts of 30 detergent, a fresh filter and a quart of marvels with a tight carb is the best of both worlds. It also partially addresses the manifold making noise as it's a piece of cake to remove.   Mitch

[moran75]

17 hours ago, 1965rivgs said:

Chewbacca,

  Check the oil pressure with a mechanical gauge before you move on to additives, etc

Tom Mooney

Hi Tom

can you expand on that for the uninitiated?

kev 

[Chewbacca]

On 10/12/2018 at 1:30 AM, lrlforfun said:

OK Riviera People:  If it ain't broke.....don't fix it.  Clean oil, a filter  and Marvels is by far the best solution.   If you are able to,  overhaul the carb and get it running excellent so hopefully not a lotta gas gets in the crankcase. If the engine explodes you can still get value for the carb plus there's a very good  chance it could add to the driving enjoyment. Drop the pan and clean out the sludge?  Well you are inviting a can of worms with an engraved invitation.  These things are 55 years old. Mitch

 

The carb will be for sale shortly as I am fitting a Holley Sniper EFI unit this winter.

 

I will be going down the oil/filter change and a treatment of additive fr now to see how it goes.

[1965rivgs]

23 hours ago, moran75 said:

Hi Tom

can you expand on that for the uninitiated?

kev 

Hi Kev,

  If oil pressure is too low due to miles/wear (or low oil level in the pan) the valve train/lifters will often provide the first indication by making noise. Since the Riv only has a low oil pressure switch which is appropriately connected to an idiot light, IF IT WERE MY CAR, or if I was servicing the car for a customer, I would want to know how much oil pressure the engine had before I started assuming there was a problem with a lifter and following up that assumption by diluting the oil with an additive, especially if there are excessive clearances in the engine. Just my opinion...

Tom

[lrlforfun]

OK Chewbacca: You really can't go wrong with the oil/filter/Marvels combo.  When I had the car lot I'd do all that PLUS....I'd put a couple of cans of Berrymans B-12 in the tank. The EFI? Sounds good. I don't know much about those units.  Instant start (with electronic ignition) better mileage and performance,  What's the cost?  Personally,  I'd just do the oil and carb thing and forget it.  If that engine is old it's gonna detonate with too much poop. Rebuild? Yeah, I'd definitely consider it.  I have re-built 3 425'z all .30 over and so far so good.  It's just getting very expensive now.   Mitch

[60FlatTop]

Did you get a chance to look at the rocker arm shafts? Only costs a little time and a set of cover gaskets. I have been working on Buicks since my early teens so it is based on reliable experience.

Bernie

[Chewbacca]

15 hours ago, lrlforfun said:

OK Chewbacca: You really can't go wrong with the oil/filter/Marvels combo.  When I had the car lot I'd do all that PLUS....I'd put a couple of cans of Berrymans B-12 in the tank. The EFI? Sounds good. I don't know much about those units.  Instant start (with electronic ignition) better mileage and performance,  What's the cost?  Personally,  I'd just do the oil and carb thing and forget it.  If that engine is old it's gonna detonate with too much poop. Rebuild? Yeah, I'd definitely consider it.  I have re-built 3 425'z all .30 over and so far so good.  It's just getting very expensive now.   Mitch

 

The EFI decision is based on the experience of a friend who did the swap on his Mustang. He saw a 20% improvement in gas mileage which at $11 a gallon is something we always have to consider in the UK. At a cost of $1250 for a full kit with fuel pump and hi pressure lines it won’t take too long to get my money back.

 

it’s not the original carb and has run badly since the day I got it. I know for some fettling a carb is a source of joy but not for me. I’m more of a fan of driving it. The EFI may be overkill but I want reliable starting as well as the mileage improvement. I’ll report out on how successful it is. As the car is poorly restored and by no means original (changed colour inside and out) I’m happy to go down a slight restomod route. No bodywork modifications though. That can’t be improved!

[Chewbacca]

6 hours ago, 60FlatTop said:

Did you get a chance to look at the rocker arm shafts? Only costs a little time and a set of cover gaskets. I have been working on Buicks since my early teens so it is based on reliable experience.

Bernie

 

This will be looked at when it is in the shop for the EFI swap in a week or two.

[rapom]

IrIforfun,  thanks for the info.  I should have known the problem since it happened to me before in a chevy 350.  Lasted about 2 years on that engine until there was to much blowby from the damaged cyl. wall or piston.