Piston Inspection

[james curl]

Does anyone remember if the piston skirts can be view for cracks with the oil pan off and each piston brought down to bottom dead center? The loud clicking that my engine makes when cold and at idle has gotten much louder in my opinion since I put the 4600 mile trip on it. The clicking becomes much quiter once the enging warms up. I have removed each and every sparkplug wire and the noise does not change. I do not want to remove the head if I do not have to for the engine has 135# compression on all 6 cylinders. If it is a cracked piston skirt then I will pull the head and replace the piston. I have installed a second new oil pump, a different distrubtor, another new fuel pump and a new water pump. The noise remains no matter what I do. If under the car with the engine running you can hear the click in the rear of the oilpan around # 4,5&6 cylinders. We, beings all of my friends and myself have listened with a stethoscope and no one can pin point the problem. You can hear it in the area of the oil filter in the oil galley and some at the oil pressure relief valve. I have replaced the old oil pressure relief valve with a kit that has a new improved oil pressure relief valve and spring that I got from Terrell Machine. The kit says that the piston hunts its own center, they must have had a problem with early , pre 46 engines with the oil pressure valve clicking for aftermarket people to marker a kit. My engine came out of a 41 dodge.

[Jerry Roberts]

You didn't mention the obvious valve tappet . When checking those just slip a feeler guage in the gap and listen .

[james curl]

I spent the better part of a day adjusting the valves, first I drove 50 miles to get the oil up to temperature then started, already had the access panel off before I started. I have a split manifold which slows the process up, had to start the car and let it run about 30 minutes after the first round of adjusting, then checked all valves again. If it was a valve it would have to have .100" clearance to be this loud and it would no quiten down when the engine warms up. You cannot distinguish the click when the RPM's are above 1200-1500.

[Don Coatney]

James;

Have you tried to retard your ignition timing? Although it may be set "by the book" try and retard it and see if the noise subsides. You have nothing to lose. It is easy to set the timing back to where it is if there is no change in the noise. A simple timing adjustment cured my engine knock.

[blueskies]

James;

Have you tried to retard your ignition timing? Although it may be set "by the book" try and retard it and see if the noise subsides. You have nothing to lose. It is easy to set the timing back to where it is if there is no change in the noise. A simple timing adjustment cured my engine knock.

Don-

I listened to James' noise on the salt, and it didn't sound like a timing noise to me. It is more of a clattering rattle type noise, a stummper for sure.

James-

With the pan off, you should be able to see all of the piston skirts very clearly. These pics of my engine's guts were taken with the engine in the car, up on jack stands.

You will also be able to see the cylinder walls when the pistons are up, to find any evidence of scoring from a bad wrist pin keeper or such.

And if you look very carefully you should be able to see the wrist pins too. Here's what I overlooked when I was searching for the noise in my engine, circled in this pic- the crack in the wrist pin bushing.

I feel your pain, having been through this myself... I'm glad your car made it back home, the noise sounded pretty severe to me.

Pete

[james curl]

For Don C. I have set the timing every way that will allow the engine to start and run.

For Pete Thank you for the pictures, I can now feel comfortable about pulling the oil pan. I have the car up on eight jack stands, four to the side and can remove the pan without any problems I hope. If I do have a cracked piston as I am beginning to supect the hard part will be pulling the head while the car is as high as it is. We started off driving the car 55-60 mph and ended up on I-10 in El Paso coming east and the speed limit is 80 mph. Drove 70-75 all the way across west Texas. The noise is much louder now than when you heard it.

[grey beard]

Your description certainly sounds like a wrist pin bushing. Remember Blueskiies and his elusive noise? Seems like even veteran engine buiders who get everything else perfect can sometimes overlook this little item. Even when replacing pistons, the pins push through with only hand pressure - no press fit on anything - so it's easily overlooked. I had to replace one wrist pin bushing - just switched rods with a spare engine - on number six hole when I rebuilt mine - also changed all pistons. Didn't knock before I took it apart, but I could feel the play in this one rod with the new pin installed.

Good luck finding the problem.

[james curl]

After viewing Pete Andersons pictures today I removed the oil pan and started looking. What I found just by rocking the flywheel back and forth was that #6 wristpin bushing would move up and down in the rod bushing as well a move side to side at top dead center. #4 rod wristpin would also move up and down in the rod bushing. Started pulling the rods and pistons out starting with #6, the rod bearings have all of the white metal worn off of the center of the bearing, both upper and lower halfs, this is true for all six rod bearings. When #6 rod and piston were removed the top ping was broken into two halves. The # 5 piston also had the top ring broken but was two pieces about 3/4" long, rest remains on the piston. The rod bearings were probably damaged when the oil pressure valve relief spring broke into four pieces about 25 miles from home and I reduced speed and drove home with 25 lbs of oil pressure. I will check the conditions of the mains tomorrow after I attend a retirement party for a former workmate. My oldtime manual says to take a penney and drag across each bearing surface, if it is smouth and does not chatter it is ok. If it chatters and leaves copper in the ridges then it might polish up or will have to be turned. Hope for an easy repair, new rings, rod and main bearings,new bushings for the wristpins plus a gasket set. About another $200.00.

[Normspeed]

James, how many miles on that engine?

[james curl]

8704 miles on total rebuild. First time that I have ever had a failure in an engine that I rebuilt. Also first time that I reused the oil pressure relief valve spring. First non-chevrolet that I have ever done and may be the last. Say what you want about cheverlot but I have over 100000.00 miles on the 235 I-6 that I rebuilt 28 years ago and still uses very little oil.

[james curl]

Well all hopes of easy repair are dashed, the mains were all ok, no problems with lubrication there. The rod bearing surfaces on all six throws did not pass the penny test and should be turned. I am going to tear down the original engine that came in the car and see if I can piece together one good engine out of two. Hope to do so for less than 1000.00 dollars by using the .040 over pistons in the original block after boring and as many of the good parts from the bad engine. Was told by a friend that his brother in laws neighbor was given a 60 1/2 ton pick up with a six cylinder in it and he wants to install a V-8 in it, I do not know what year the trucks went to the slant six, would be nice if it were a 230 flat head six. Might get it cheap enough to justify rebuilding with machine work and new parts. The man at our old car junk yard wants $700.00 for either a Chrysler or De Sota flat six that would require a total rebuild if it is salvagable after sitting in the weather for 40 or more years. Don't want to go with the dreaded SBC if I can help it but am getting tired of throwing money into the pit (flat head six).

[builtfercomfort]

I feel bad for you - can't be fun. You can often get a complete old 'pulled running' motor for much less than $700. I've seem motors on the HAMB for $50 - guys were pulling them and putting in V8s. If you have a little patience, you can ask around, check craigslist, etc. and maybe get a deal.

But the economics of a modern V8 are hard to beat. Luckily this forum will help you out whichever way you want to go.

[Young Ed]

60 was the crossover year for trucks. flathead and slant 6 were both available.