The Stovebolt Site Forums The Shop Area Engine Shop 216 engine shudder

Hi Folks. I have a 51 GMC 1/2t pickup with a 216 engine (original I believe). It had sat in the grove for 15 years waiting for a 235 replacement engine. That didn't happen so I decided to use the existing engine. It seemed to run fine (after fuel pump, carburetor rebuild, plugs, points, condenser, etc.). After a few hours of running the clutch finally went. The only real problem I had with that operation was driving the new pilot bearing in place. I had to drive it pretty hard to seat it but no apparent damage. Everything else when pretty smooth. The engine now has a shudder (vibration?, engine miss?) which I really don't know the cause. It happens just above idle then smooths out then comes back at higher rpm. It seems like a miss (listening to the exhaust I can hear it load up and then clear) but it could be some sort of out of balance situation. I just don't know. I had the flywheel resurfaced and replaced the entire clutch pack. Compression is 95, 100, 95, 104, 91, and 120. Vacuum is 19 at idle and steady with appropriate response at accel and decel. The engine hesitates when pressing the accelerator. Any ideas?

Tannin,

It doesn't sound like you have a misfire condition; the compression is all right for that engine- not ideal, but all right. Since you say the shudder started after the clutch work, I would suspect a clutch, pressure plate or flywheel matter. Was the flywheel balanced with the resurfacing? Also, from your description, it sounds like you notice the vibration when the truck is standing still. Is that correct? If the vibration occurs when driving, does it change with engine speed or with vehicle speed? See if there is any change in the condition if you put the transmission in gear, set he parking brake, hold the clutch depressed and run the engine through the speed range where you would notice the vibration. If the vibration exists, I suspect you have a clutch/flywheel matter to deal with. If the vibration does not exist with that check, it sounds like a transmission matter- clutch shaft and bearing and/or the cluster gear and bearings.

Your acceleration matter sounds like the accelerator pump is not working properly. Possibilities there are the pump itself is leaking or the outlet check ball is not seating fully or the pump seal is leaking- the check ball would be the first suspect- sometimes the wrong ball is installed, or the ball is left out completely. Before dealing with the carburetor, make sure there are no vacuum leaks, and check/set the initial timing. You should also disconnect and plug the vacuum advance line, then see if the hesitation is gone. If so, you have a vacuum advance issue- probably the diaphragm is leaking, and the vacuum advance control needs to be replaced. You can check the vacuum advance chamber if you have a vacuum pump to apply vacuum to the chamber and see if it will hold vacuum. A quick check on the vacuum advance is to have the engine idling and quickly crack the throttle from idle to about one quarter (1000-1500 RPM) and back to idle. You should see the distributor rotate some (counter-clockwise) and go back to the idle position as the throttle opens and closes.

Hope this helps.

Harvester

Harvester,

Thanks for the methodical approach, I was kinda bouncing off several walls and not getting anywhere. To your questions: Vibration occurs when truck is standing still. Clutch not engaged in/out of gear doesn't make a difference. I think I can rule out transmission and beyond at this point. I did not have the flywheel balanced after resurfacing but I need to check with the maching shop to make sure.

Vacuum advance appears to work but I'll pursue your thought process when I get back to it. I do have a vacuum pump/gage to see if the mechanism is leaking, good idea.

What a time I had rebuilding the carburetor. You are right, I even found a ball in a place where one doesn't go. When I finally understood how the accelerator pump actually works, I was able to get springs, balls, and things in the right place. I verified operation of the accel pump after I rebuilt it but will check that again as well.

I put a dial indicator on the flywheel trying to detect if something is bent/warped. If I kept tension forward on the flywheel while slowly turning it, the readings varied less than 20 ten-thousands (.0020) at the outer part of the flywheel. I thought that was pretty good. However, at one location in the rotation, the dial indicator took a dive and I actually heard a klunk (more like a thud) from the lower end of the engine. That was repeatable. I suppose it's time to pull the pan and see what that is. Do you concur?

So let me ask your advice about moving to the 235 I have sitting behind the shed. It's from a 59 Chevy and should bolt right up after a rebuild. I'm into this clutch/flywheel (new ring gear too) thing for about $300. If I thought I could get a smooth (I understand the technology is not 21st century) running 216 I'd put my time and money into it but I'd probably have an easier time rebuilding the 235 and I could still drive the 216 until that was finished. I'm just thinking out loud but would like your take on it.

Tannin,

It sounds like it is time to take off the oil pan- you shouldn't hear any clunks or thuds when you turn the engine by hand. Before you get into removing the oil pan, see if you can push/pull the flywheel back and forth, fore and aft. If it moves perceptibly, there is a thrust bearing matter to resolve. The thrust bearing is the third main bearing from the front. You can skip the flywheel check if you want to, and take the pan off- you will have to take the pan off anyway to see what is going on.

The 235 engine might be a better alternative to the 216, mainly because the 235 of that year has a full-pressure oiling system, insert bearings for the connecting rods, and aluminum pistons, all of which make the 235 easier and cheaper to rebuild than the 216. The 216 is a nice engine, but it has a splash-feed oiling system for the connecting rods, which means troughs and pipes in the oil pan to direct oil to dippers/scoops on the connecting rods to pick up oil. Also, the connecting rod bearings are babbited bearings, which means the babbit metal (bearing metal) s fused (soldered, so to speak) to the rod. That can be re-done, or you might be able to find babbited rods ready to go, but either they have to be adjusted individually with a time-consuming method, using shims provided with the rods- unless somebody has improved on the technique. I think there are insert-bearing conversions for babbited rods, but I don't know anything about them. Probably someone else here can add to that point.

Also, if the 235 is a passenger-car engine, the front mounts are on the side of the engine, rather than on the front plate. The right-side mounting bracket is near the fuel pump, with three holes in a V pattern (if the bracket is missing from your engine, or if it is a truck engine). Left side is similar. I don't remember if the front plate has the holes for front-mounting as your truck has, but if it is a truck engine, it will have the mount holes; probably someone else here can answer that question. In favor of interchangeability, the '59 and later 235 blocks were made to fit into the older chassis, so the front plate might already have the proper holes for front mounts. It comes to mind that the '59 and later passenger car engines didn't have mount holes in the front plate, but that may be foggy memory...

Hope this helps.

Harvester

Tannin

There is a post nearby regarding painting an engine, with a good picture of a late-model engine in a truck. It shows the front mount arrangement in pretty good detail, and also shows holes in the block for the passenger car side-mount bracket. The bracket holes are between the road draft tube and distributor locations. Good picture- take a look at it.

Harvester

Harvester,

Great picture of the engine. This gives me something to shoot for. The front mount looks just like the one I have on the 235. The engine casting numbers are G132, 3764476 which I believe translates into a 235 in^3 with a date of July 13, 1962. Is luck with me or what?

Back to the 216, I think it's odd but the end play is minimal until I reach that point where I hear the klunk, then the end play is quite perceptable. The pan is coming off this week weather permitting.

I pulled the head on the 235 and found some rust around the valves in cylinder #2. This engine has been sitting under plastic for at least 5 years now and it looks like condensation has done it's job. I'll take the engine to the machine shop to get their opinion and hopefully subsequent machining.

Thanks for the help,

Tannin

Was the GMC built in Canada? I'm not aware of the 51 GMC havcing a stock 216. But some one could have installed on at some point.

I would verify it is a 216 rather than a GMC 228 or 270. The main reason is that the GMC engine is longer than the 216 or 235 Chevy engine.

Roy,

One of the reasons I was excited about GMC was to get the pressurized 228. When I bought the truck (decades ago now)the oil pressure was so low I pulled the pan to see what was going on. To my surprize, it didn't match the 228 repair manual nor did the pan gasket I bought for a 228 match the pan. That's when I found out some GMCs came with 216s or maybe someone replaced it with a 216. At any rate, the serial number of the engine is HBA335252. The HBA indicates it was built in 1950 but I haven't been able to find the 335252 in the lists I've been looking at. If you have any insight in the serial number above, I'd appreciate it.

I haven't had time to pull the pan to see what's going on yet, that wood pile needs attention before winter shows up. Thanks for the information, it's very much appreciated.

HBA335252

HBA = 1950 3100 (216 ci engine)

335252-1000 = 334252th engine out of the Flint, MI plant

http://chevy.oldcarmanualproject.com/chevyresto/5052.htm

Here are locations of other engine...odes let you when those parts were cast.