It’s cold outside but I decided to try to check my compression Chevy IL 6. After pulling the plugs & removing the valve cover I realized I find have any way to turn the motor. The flywheel up front does not have a nut on it so I can’t go that way. I’ll get a remote starter & try that. I think the # 2 cylinder is at TDC & the rockers are loose so I assume this is where I should do the test.? It holds no pressure but I can’t tell where it’s going. Help!
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
That engine most likely has hydraulic lifters. Loose rockers indicate something is stuck, (like valve stems in the guides) or the rockers are way out of adjustment. Even with both valves fully closed, there shouldn't be any looseness between the rockers and the valve stems. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
A cylinder leakage test. I’m just trying to find out if the rings are bad or the head has a problem. It blows smoke when I release the gas after revving & it uses oil.
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
That engine most likely has hydraulic lifters. Loose rockers indicate something is stuck, (like valve stems in the guides) or the rockers are way out of adjustment. Even with both valves fully closed, there shouldn't be any looseness between the rockers and the valve stems. Jerry
I did adjust the valves myself after I put the head on the motor. Right now the #2 appears to be on compression stroke & the cylinder is up. The rockers are up & I can jiggle them, so they are loose. Problem is that I can’t turn the motor by hand.
Last edited by klhansen; 02/02/202610:59 PM. Reason: removed unnecessary quote
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
With all the spark plugs out and transmission in neutral, you should be able to turn the engine using the fan blade. What year engine do you have? Those rockers look like the ones used on the SBC V-8's that get adjusted at the rocker studs. I don't know when GM went to that style rockers on the 6 cylinders. Likely after 1958 as I had a 235 with rocker shafts.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
The 235 with rockers mounted on a shaft was used through the 1962 models. In 63 the engine was a 230 cubic inch model that used the individually mounted rockers.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Put the transmission in high gear and slowly roll the truck forward. Set the parking brake firmly before pressurizing a cylinder. Search the forum archives for "companion cylinder valve adjustment" to get each cylinder on TDC of its compression stroke. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I believe this is a 1972 ish model. I think the Nova & Camaro used it. I did the simple valve lashing technique when the motor was out. The harmonic balancer has 3 threaded holes in it that I used bolts to turned the motor using a pry bar. It’s a bit tighter being in the truck but hopefully I can do that. My memory is coming back now. So now I only want to do the pressure test then go from there.
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
Oh, the fan belt is not tight enough to be able to use it to turn the motor.
Tighten that sucker up a bit. A v-belt will grip pretty well if tight enough. Readjust the belt tension after you're done.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Nothing is simple to do. I had to remove the alternator to remove the brace. I had to cut the hole in it longer in order to tighten the belt. After tightening it I could turn the motor with the fan but not good. Still not tight enough I guess. I neglected to remove the battery cable & grounded the alternator (big spark). Ruined it! I did adjust two valves used that lashing technique again. So while checking cylinder compression m, air leaks out pretty bad somewhere. It must be in the head, I don’t feel air from the oil dip stick. Just to see if a valve was not closed fully I released the rockers fully so the valves should be closed. It still leaked down but not as loud. Is there anything I can do other than take the head in for service?? Thanks
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
Listen at the carburetor and the tailpipe. It's possible you've got a burned valve or a carboned-up valve seat. Have you considered installing a slightly shorter belt instead of metal butchering? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I have no idea what belt that is Jerry? That head was serviced before I put it on. Best I remember he didn’t do anything special to it. I just remember it had fresh grease in contact points at the rockers & rods. I have about 700 miles on it & I ran ethanol free gas most of the time. I honestly could not tell where the leak sound came from. The motor runs great.
Last edited by Phak1; 02/04/20261:30 PM. Reason: Typo
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
As Jerry suggested, change the belt. Pull the old one and take it to your auto parts house and they should be able to measure and replace it. I would get two belts, one the same size and one the next smaller size. Your present belt is probably stretched and worn and the same size is probably the correct one. If you are lucky, the part number may still be visible on the belt.
Last edited by 1955 1 Series; 02/04/20264:36 PM. Reason: clarity
As Jerry suggested, change the belt. Pull the old one and take it to your auto parts house and they should be able to measure and replace it. I would get two belts, one the same size and one the next smaller size. Your present belt is probably stretched and worn and the same size is probably the correct one. If you are lucky, the part number may still be visible on the belt.
I have to replace the alternator anyway so replacing the belt is no problem.thanks.
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
My opinion is if the engine runs well, plugs are not fouling with oil, and it only smokes while decelerating, it probably is a valve stem/seal/guide issue.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
My opinion is if the engine runs well, plugs are not fouling with oil, and it only smokes while decelerating, it probably is a valve stem/seal/guide issue.
Great! Tell me more good news. On this head, can I replace them myself or will I have to pull the head or have someone do it for me? Does Rislone valve seal repair oil work??
Last edited by glennj3; 02/09/20264:22 PM.
1953 Chevy 153A 3/4-ton Working on my project since 2015 Follow along in my DITY
