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Noise from '31 Model 57's Straight 8


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Hello all,

 

I'm getting a bit of noise from the engine of my '31 Buick.  I'm not entirely sure how to diagnose it...maybe a rod bearing needs to be tightened?  Valve out of adjustment?  If anyone has heard this before and can give some advice on how to diagnose, I'd appreciate it!  The sound can be heard in the videos below:

 

https://www.youtube.com/watch?v=i_2NJ0Mxw6w

 

https://www.youtube.com/watch?v=YegwPOOoZcE

 

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Take a length of hose and put your ear to one end while you place the hose on or near the bottom of the engine block. Then move it to the upper part of the block near the valves. That should help you isolate or locate the noise better. A bearing or crankshaft noise will be at the bottom of the engine. Generally, a main bearing noise shows up more when the engine is under a load, therefore my guess is that this is a valve train noise or upper engine noise, but I'm sure others will disagree.

Pete Phillips, BCA #7338

Leonard, Tx.

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The noise seems to be loudest from about the level of the spark plugs.  But i'll probably have to get a stethoscope to figure it out for sure.

 

I took a video of the valves for fun - they seem to be functioning properly, though there's not a whole lot of oil up there.  I'm used to my other vehicles, where it'll squirt you in the face if you don't have the valve cover on. 

 

The car was only at about 3/4 full of oil, so i filled it up. The oil I'm using is a mix of 30 weight and Lucas Oil Stabilizer - maybe it's too thick?  I'm getting about 30 lbs of oil pressure at idle according to the gauge.

 

 

Edited by envoy_to_the_stars (see edit history)
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I'll go out on a limb and predict that you have an exhaust valve that is broken and jammed in its guide.  It is being hit by the piston.  It's easy enough to take the valve cover off and look, even with it running.  

 

To me, the knock sounds like it is occurring with every rotation, a rate of about 320 knocks per minute.  The cam would turn half that speed and so this might allow you to eliminate that part.  The gen and water pump are turning about engine speed and could have a problem but I would expect you to be able to discern those.

 

Although a video might be worth a thousand words, I'd like to hear more from you regarding the evolution of this noise.  

 

The idea of course is to do the easiest things first.  Those include:. Pete's suggestion on listening, valve cover removal, compression test, and then oil pan removal.

 

Good Luck and hopefully others will chime in.

 

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Hey Joel, thanks for the input - take a look at the video above for a look at the valve operation.  They're all moving up and down, and all the valves are opening and closing as far as I can see, but I'll get in there with a flashlight and double check.

 

The water pump is newly rebuilt and operating perfectly - no noise from there.  The noise doesn't appear to be coming from the generator when i put my ear up next to it.

 

I have only driven the car about 50 miles in the last 5 months, but it was making that noise 5 months ago as well.  That's when I changed the oil to 30 weight.  I can't recall if it changed in volume at that point.

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I moved the car out so I could get over to the driver's side of the engine bay, and found this little surprise:

 

Dck13qL.jpg

 

It didn't appear to be missing from any valves, so I just removed it.....  I went ahead and took a video from the other side as well.  There really doesn't seem to be much oil up there, is that level of flow normal?  Again, the gauge registers 30 lbs of oil pressure.

 

The sound could be in time with the cam - watching the valves move up and down it seems like it's in sync.

 

Here's a video from the driver's side:

 

https://www.youtube.com/watch?v=TlrUV8w0NvE

 

Edited by envoy_to_the_stars (see edit history)
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You gotta wonder where the heck that washer came from!  Also, noise didn't appreciably change when you removed the cover?  

I see periodic drips of oil but it is less than half of what I would expect see.  Also, engine seems to be firing on all 8.  

 

I'm stumped at the moment.

 

 

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There are periodic drips, but to your point, not exactly what I'd expect.  It's full of half Lucas Oil Stabilizer (really thick stuff) and half 30 Weight Rotella right now - maybe it's too thick??

 

Yes, it is firing on all 8 cylinders...it has an occasional misfire when it's cold, but nothing major.  Noise doesn't change in volume when the valve cover is off.

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37 minutes ago, DonMicheletti said:

One way to check if it is valves is to slip a feeler gage under each rocker and see if the sound changes. If so do a valve adjustment.

I dont think the noise is "hollow" enough to ne a rod or main

 

I think Mark Shaw adjusted them shortly before I bought it, but I'll double check.  I'm sure it says it in the adjustments manual, but do you recall what the gap should be?  I'll warm it up tonight and give it a check.

 

 

I'd expect if it was rod knock, it would get louder if I revved the engine or put a little load on it.....but it doesn't really change noticeably.  The noise is very consistent in volume and occurrence.  I'll try pulling the spark plug wires and see if that cuts it out...I assume it's rod bearing related if that's the case.

Edited by envoy_to_the_stars (see edit history)
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Occasionally an adjusting screw  locking nut will come loose and the screw will back out - a long shot.

It has been too long since I owned a '31 for me to remember the valve clearances. The'38 valve lash is .015", but it is a flat tappet cam and I'm pretty sure the '31 has roller followers. There might be a difference

 

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I second Ben, see if that isolates it to a cylinder. Have you put a vacuum gauge on it? If so, does it drop a little periodically in sync with the noise? If so, you can use the gauge, a timing lite, and a small box to isolate it to a cylinder. Cut holes in the box so the vac gauge can be placed in it, a hole to point the light at the gauge, and a hole to look at the gauge. Then move the inductive pickup down thru the cylinders while looking a the gauge and it will be clear which one it is.

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18 hours ago, envoy_to_the_stars said:

The noise seems to be loudest from about the level of the spark plugs.  But i'll probably have to get a stethoscope to figure it out for sure.

 

I took a video of the valves for fun - they seem to be functioning properly, though there's not a whole lot of oil up there.  I'm used to my other vehicles, where it'll squirt you in the face if you don't have the valve cover on. 

 

The car was only at about 3/4 full of oil, so i filled it up. The oil I'm using is a mix of 30 weight and Lucas Oil Stabilizer - maybe it's too thick?  I'm getting about 30 lbs of oil pressure at idle according to the gauge.

 

 

 

If you watch a rocker arm, the sound seems to be in perfect time with it.  Would that mean it's a lifter issue?

 

I don't know about 8 cylinders, the sixes seem to have more oil splashing around up there.

 

I had a small block chevy engine that had 1/2 of a valve spring keeper get loose off the valve stem.  The spring was still retained to the valve with 1/2 keeper that was left wedged in the valve stem.  It made a similar sound, but not as loud. 

 

I wonder if this is somehow valve geometry related...

 

 

 

 

 

Edited by 27donb (see edit history)
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13 minutes ago, 27donb said:

 

If you watch a rocker arm, the sound seems to be in perfect time with it.  Would that mean it's a lifter issue?

 

I don't know about 8 cylinders, the sixes seem to have more oil splashing around up there.

 

I had a small block chevy engine that had 1/2 of a valve spring keeper get loose off the valve stem.  The spring was still retained to the valve with 1/2 keeper that was left wedged in the valve stem.  It made a similar sound, but not as loud. 

 

I wonder if this is somehow valve geometry related...

 

 

 

 

 

 

A local antique shop said that they think it may be a dead lifter as well. Not sure how to further diagnose that though. 

 

Im concerned about oil flow up there as well...it's not dry, but there's not

much up there. What could cause low flow to the top end even with 30 pounds of oil pressure? 

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The oil passage holes in the rocker arm shaft get plugged up especially if the car has sat for a long time. Remove the oil tube at the back of the rocker shaft and verify that oil is coming out of that when the engine runs.

Pete Phillips

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The valve adjustment should be on the valve cover. no less that .008 when engine is hot. also this engine has roller style lifter set up. you can see these if you remove the two engine side covers on the passenger side. has two big flat head screws holding them on.. . you may be able to run the engine with these covers off and see if oil flow is better off of cam.. also may let you hear if noise is in the lifter set up.   IF you take the lifter assy out to inspect be careful. there are springs, small clips and retainers in there and the whole assy will fall apart...  Let us know what you find out.

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1 hour ago, envoy_to_the_stars said:

 

Im concerned about oil flow up there as well...it's not dry, but there's not

much up there. What could cause low flow to the top end even with 30 pounds of oil pressure? 

 

On the 27's, the oil pressure reading came from the fitting coming out of the block.  The oil filter system was after the oil pressure fitting, so if the filter was clogged it would reduce pressure and flow to the rocker arm shaft, but the pressure reading would not show it.  There was a fitting on top of the oil filter with a petcock that could be opened while the engine was running.  If oil flowed out of the valve, the filter was NOT clogged.

 

Your '31 set up looks quite different, but you could check the flow after the filter to the rocker arm shaft by loosening or removing a line (temporarily) to check for oil flow out of the filter.  If there is a clog or low flow out of the filter, that might explain why the oil pressure is good on the gauge but the upper end is somewhat dry.

 

Also, filling an oil squirter can with engine oil and manually lubricating the rocker arms where they contact the valves while the engine is idling and see if the noise changes might indicate if this is a lubrication problem or not.

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Hey Envoy, can't help with your engine knock issue but looks like you have lots of help already.

 

however, I have a '31 8-57 as well and am struggling with the Marvel updraft carb.  Have you had carb issues?  Do you know anyone who can rebuild these carbs?

 

wish you the best!!  I'm new to prewar cars but really enjoy even the problems and reading the great advice!!

 

blessings,. Jerry

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On 4/1/2016 at 0:28 AM, envoy_to_the_stars said:

It's full of half Lucas Oil Stabilizer (really thick stuff) and half 30 Weight Rotella right now - maybe it's too thick??

 

Again I am not familiar with the differences between the sixes and eights...but I run either 50w or 20w-50 with no problems, and that's pretty thick.

 

Absolutely no running in cold weather though, it's all set up for 50+ degree use only!

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The oil flow to the rockers is about normal for these early straight 8s.  These engines were designed to limit oil flow to the top end.  They were more concerned with good oil to the lower end bearings.  30 weight oil is on the light side for these engines.   30 is okay for winter weather, but 40 or 50 weight is preferred in the summer.   This is the recommendation for high speed driving in the early 30's so the high speed driving is closer to our normal driving today.

 

I would replace the oil filter just to be sure it isn't plugged up.  They don't have a bypass in the canister type filters.  That is an after market filter assembly.  Buick was very specific in filtering only the oil going to the rocker arms and they used an 1/8 inch tubing from the filter to the cylinder head to limit the oil flow.  Many times when the filter assembly is converted because the original filters are no longer available, the line size is changed to a larger size.  I would not be overly concerned with the oil flow.  Remember, 10 years earlier, the valve train was open and the rockers had to be manually oiled once in a while.  

 

On the noise you hear, you could have a spring broken at the lower end of the push rod.  This spring was to keep the roller lifter in contact with the cam.

 

Bob Engle

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Hi,

 

Quote

Try , while running, pulling sparkplug wires one at a time.  Does noise change??

 

If you pull the wires off the plugs, you'll quickly learn that that is a bad idea.  Use an insulated plug wired puller to grab them.

 

Been there.

 

--Tomshocked.jpg

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On the oil flow, your oil flow looks normal for cold oil at idle. There is no evidence of oil starvation such as shavings or hot parts. My 29 does the same cold, but take it for a drive, pop the valve cover off then rev the engine with hot oil and oil goes everywhere.

My 29 engine has almost the same sound at idle for as long as I can remember. I have adjusted valves with no luck. May be piston slap or wrist pin. Possibly in the accessories. I don't fear engine failure at all. I also inspected cam and followers last time pan was off, all looked great . Check what you can to safeguard , then run it.

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On ‎4‎/‎2‎/‎2016 at 7:52 PM, Jerry Smith said:

Hey Envoy, can't help with your engine knock issue but looks like you have lots of help already.

 

however, I have a '31 8-57 as well and am struggling with the Marvel updraft carb.  Have you had carb issues?  Do you know anyone who can rebuild these carbs?

 

wish you the best!!  I'm new to prewar cars but really enjoy even the problems and reading the great advice!!

 

blessings,. Jerry

 

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Jerry smith. the marvel carb on the 31-57 is very simple. rebuild it yourself. you can get a kit for it from bobs automobilia.. they now offer a plastic or brass float to replace the cork one that is stock and comes with the rebuild kit. I recommend buying one. if not dip the cork float in some kind of fuel tank sealant. you can also get a book from bobs that has the specifications and adjustments for the 31. I also advise you GET ONE...  Hope this helps

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3 minutes ago, my31buick said:
On 4/2/2016 at 8:52 PM, Jerry Smith said:

Hey Envoy, can't help with your engine knock issue but looks like you have lots of help already.

 

however, I have a '31 8-57 as well and am struggling with the Marvel updraft carb.  Have you had carb issues?  Do you know anyone who can rebuild these carbs?

 

wish you the best!!  I'm new to prewar cars but really enjoy even the problems and reading the great advice!!

 

blessings,. Jerry

 

Perhaps this question should be started in a new thread, in order to keep this existing thread on topic of the engine noise concern.

 

 

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  • 2 weeks later...
  • 4 weeks later...
On 4/3/2016 at 10:32 AM, Mark Shaw said:

I agree with Bob.  This engine was rebuilt about 20 years ago with new roller lifters..

 

Regarding a broken spring at the lower end of the push rod?  

 

I've got some time this weekend to dog in and figure it out.  I'll report back what I find!

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  • 9 months later...

Quick update, everyone.

 

I adjusted the valve clearances on the Buick a few weeks ago, and she's running a lot smoother now!  Several clearances were too loose, and several were too tight.  That took care of some noise by itself.

 

With regard to the other noise - I had the bottom end of the engine dismantled, inspected, and re-assembled by a specialty shop here in Houston (the owner has a Model 90 of his own), and he didn't identify any causes of the noise or any causes for concern.  There's no loss of power, no hesitation, no rod knock, etc.  I'll keep investigating as I find time, but I'm confident there's nothing to worry about.

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