Engine noise 49 Super

[gdmn852]

Hello tracking down engine noise in my 49 Super, changed out hydraulic lifters and also replaced pushrods, most were bent this did quiet it down a lot however a knock still remained, disconnected Spark plugs one by one until noise stopped.discovered that cylinder 8  caused the knock, assumed that connecting rod is loose.Next step will be drop oil pan check and measure bearing. I imagine someone has done this before, any tips or suggestions? Thank you Gary 

[Aaron65]

Dropping the pan in a straight 8 Buick isn't bad because the engineers thought of the mechanics having to work on them.  Your car should have four holes drilled in the front crossmember so you can easily remove the front four oil pan bolts.  Other than that, you may have to turn the crankshaft so the counterweights don't get in the way of the front of the pan as you slide it out.  It's been a while since I removed the pan from my '53 Special in the car, but I had to do something to the oil pump, and I believe I finished the job in an hour or two.  Make sure you have a manual on hand for torque specs and things like that.  Good luck - let us know what you find!  

[gdmn852]

Hello thanks for the reply I have all the manuals as you mentioned like to study them thoroughly before starting a project on the Buick ,lots of information, steering  cross Shaft also has to be detached also. I don’t know the history of the car with having to change hydraulic lifters and pushrods rods it may have been run low on oil and not maintained.hoping the journals on shaft are good if not will have to plan on removing engine for overhaul.Rear seal leaking also good time to fix it too.Always a reason why things fail . Thanks again for the reply,Gary 

[Aaron65]

No problem...I don't remember pulling any steering linkages on mine, so you may want to try removing the pan without disconnecting the steering first.  If it doesn't work out, you can always disconnect some stuff then.  Good luck!

[raydurr]

Start by inspecting your camshaft lobes closely. Engine use with bent pushrods can damage the hardface on the camshaft. Piston pin wear and piston slap can all cause noises. These noises can change with a change in engine temperature. How good was your oil pressure ? Now would be a good time to service you oil pump. If pressure had been low before , you may consider raising the oil pressure with a shim in the relief valve spring area. As long as rod and main clearances are not extreme you can use your car for many miles with it making a little noise. You can easily spend thousands on a correct engine rebuild. Many just run a heavier oil and drive.

[BuickBob49]

I recall my mechanic telling me that he loosened up the front motor mounts on my 1949 Super to push up the front of the engine a bit to get the pan out. Could that be correct?

[gdmn852]

I had it down before and disconnected the steering link also the crankshaft has to be in the right position to allow the pan down. I was wondering how much clearance does bearings have to have before they start knocking,oil pressure on very good when primeing oil for lifters change pressure built up quickly.

[Guest]

The standard seems to be .001" per inch of bearing diameter if not otherwise stated.  If you were building a racing engine it would be more, perhaps .002" or .0025".

[Ben Bruce aka First Born]

10 hours ago, BuickBob49 said:

I recall my mechanic telling me that he loosened up the front motor mounts on my 1949 Super to push up the front of the engine a bit to get the pan out. Could that be correct?

 

 For SOME mechanics, perhaps.

 

  Ben

[Guest]

7 hours ago, Ben Bruce aka First Born said:

18 hours ago, BuickBob49 said:

I recall my mechanic telling me that he loosened up the front motor mounts on my 1949 Super to push up the front of the engine a bit to get the pan out. Could that be correct?

 

 For SOME mechanics, perhaps.

Or perhaps he did not have a putty knife to clean the grease and dirt from the cross member to be able to see the holes.

[neil morse]

19 hours ago, BuickBob49 said:

I recall my mechanic telling me that he loosened up the front motor mounts on my 1949 Super to push up the front of the engine a bit to get the pan out. Could that be correct?

 

On pan removal, of course the '41 may differ from the '49, but here's a thread that discusses what I had to do to get the pan off my '41:

 

 

[gdmn852]

Hello thanks for the link and reply’s my “master plan “ is drop pan and check the bearings journals if they Aren’t damaged then check diameters if the are still good then replaced the bearing inserts, if not I will be pulling engine for rebuilding.Not something I am looking forward to.

[raydurr]

How has your oil pressure been? Especially at hot idle?

[neil morse]

Sorry, I just realized that the link I posted only covered the removal of the oil pan.  When it came to putting it back on, I had to resolve the issue of getting the pan to clear the tie rod with the oil pump installed.  Here's the rest of the story from my "Me and My Buick" thread.  Click on the arrow in the upper right-hand corner.

 

It was pretty easy once I figured out how to jack it up so the tie rod dropped low enough.  Again, as I said, I don't know if the '49 is the same, but this is what worked for me.

 

 

[gdmn852]

Hello, the oil pressure has always been good. I don’t know the history of the car other than it was restored in 2008 but I think it sat in storage for some time after that.The “restoration “really I think consisted of paint and upholstery don’t think much was done to the engine. I would like to at least pull the head and perhaps new rings if I can repair the bearing in the car if not the engine will have to come out for rebuilding. I think I will have to do a lot of removing of front end parts to pull the engine,at least the core support.When these were everyday drivers, bearing and re ringing of cars appearently was a somewhat common repair talking to the few remaining old time mechanics.

[raydurr]

Many Buick cars had really good owners in terms of good maintenance and little abuse. There are 80 year old cars with engines that have not been rebuilt that still perform well. They tend to leak a little but perform well. In many ways I would prefer an unmolested engine to one that has been rebuilt by someone with no expertise in that series engine. Chances are if your car has good hot oil pressure that your oil clearances are acceptable. It would not hurt to inspect all the bearings but small imperfections don't mean an overhaul. Rings would certainly help. A cylinder head rebuild could possibly yield better performance.

[gdmn852]

I agree with you about finding someone today that could do a competent job rebuilding a Buick straight 8 ,from previous experience on a Porsche engine rebuilt that was a lot grief . The condition of the bearing journals will be a determining factor.As it does burn oil a ring and valve job would worth while . I think I might be able to hone the cylinders with engine still in the car I recall an old timer honeing a 47 Buick that way but once again that will depend on condition of cylinder walls.It shows 60 thousand miles but don’t know how accurate that is. The bearing knock really isn’t that loud so hopefully can fix it ,assuming it’s not the wrist pin .

[gdmn852]

Hello finally got a chance to work on Buick, dropped pan and checked bearing and journal , both are good ,clearance at .001 crank has been ground-.020 under.So noise must be either wrist pin or piston.As all the auto machine shops are busy right now, plan to reassemble engine to get it back on road and pull head for valve job and repair piston problem towards end of September. Thanks for all the replies.Gary

[Robby120113]

On 8/6/2020 at 6:59 AM, gdmn852 said:

Hello tracking down engine noise in my 49 Super, changed out hydraulic lifters and also replaced pushrods, most were bent this did quiet it down a lot however a knock still remained, disconnected Spark plugs one by one until noise stopped.discovered that cylinder 8  caused the knock, assumed that connecting rod is loose.Next step will be drop oil pan check and measure bearing. I imagine someone has done this before, any tips or suggestions? Thank you Gary 

Why the knock will stop if you disconect the sparkplug wire? So there are no extra forces on that piston? I have also a small knock when cold. Did the pushrods already. Dont know if the solid lifters can cause it?

[gdmn852]

Hello, right the noise stopped when disconnecting spark plugs due to less force on piston . My car has hydraulic lifters that were changed and reset .Have run a compression check and found all are low ,when rechecking with oil in cylinder, number 8 the knocking cylinder, compression was up 15 pounds, must be from piston slap due to loose fit in cylinder. Plan to disassemble engine this winter for valve and ring work and possibly have to rebore is cylinders are bad. On this car noise gets worse when engine is at operating temperature and at low rpms .Hose this information can help you with your car .Good luck ,Gary 

[gdmn852]

Finally got engine apart, cylinder walls are scored up will have to rebore ,they measure around 3.100 so must be standard bore will need it abc hope it will clean up at .04 over.Now to find a machine shop.

[Ben Bruce aka First Born]

If boring all eight and buying pistons, might as well go as large as available pistons. More cube and more compression as the Combustion will not change.

 

  Ben

[Ronnie]

9 minutes ago, Ben Bruce aka First Born said:

If boring all eight and buying pistons, might as well go as large as available pistons. More cube and more compression as the Combustion will not change.

 

  Ben

The engine shop where I worked discouraged people who wanted to do that. The power gain is minimal and you lose the ability to bore the block again in the future if needed.

[Ben Bruce aka First Born]

2 hours ago, Ronnie said:

The engine shop where I worked discouraged people who wanted to do that. The power gain is minimal and you lose the ability to bore the block again in the future if needed.

 

 Yeah, sure, like some one may want to bore it in another 71 years.LOL.  

 

  Ben

[gdmn852]

Hello, all cylinders are scored, engine may have been run low on oil or maybe seized up at one time , I don’t know the history of the car before I bought it ,scoring is quite deep,will have to find a good engine shop for rebore.The engine was rebuilt sometime in the past as the connecting rods are numbered and crankshaft is undersized, was hoping to avoid the rebore but now have no choice.Hope to pull engine later next week and strip it down further,probably find more unwanted surprises 😎

[Ronnie]

1 hour ago, gdmn852 said:

The engine was rebuilt sometime in the past as the connecting rods are numbered and crankshaft is undersized, was hoping to avoid the rebore but now have no choice.

Be glad the person who rebuilt the engine the last time didn't bore the cylinders out the maximum amount to get a little more compression.

[gdmn852]

Got engine apart ,found cause of noise, piston slap . Enclosed a picture of piston, engine must have froze up from sitting or run low on oil,this also helps explain why I found bent pushrods also .Curious what I will find out on connecting rods.