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#89982 - 08/28/02 10:07 PM
School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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1st series.
Everybody please take your seats. Get out your repair manuals, owner's manuals, an early copy of the Dyke's Encyclopedia, the Motor's Factory Shop Manual (That's the green covered one), the Motor's Auto Repair Manual (That's the blue one), all the copies of the Chevrolet books titled "What Every Chevrolet Mechanic Should Know" (That's the green one) and any answer sheets that go with that type book. Although not required, any parts books can be of value. Best you bring a 'sack lunch' as the sessions may go longer than expected. (Would someone ask the student in the right rear of the classroom to please refrain from throwing 'spit balls').
I had planned to watch TV tonight but nothing interesting was on. Decided to go to the shop and work. The project is a 1928 with an unknown history other than numerous pieces of paper that verify several parts were purchased. The engine ran well but had a peculiar noise best described as a 'scraping' noise. Several days ago the the pan was dropped and some shims taken out here and there. It was noted that the back wall of number 3 cylinder had scrape(?) marks on it. Assumption was made that a ring had broken and was scratching the wall. Buttoned it up at that time for later investigation.
Tonight I dropped the pan again after draining the oil, drained the water, and proceeded to remove the head. Removed the cap from number 3 rod (making notes as to the location and number of shims) in preparation to remove it. After the head was removed the piston was lowered, rag stuffed in the cylinder, and the tough job of removing the carbon was started. Had to use transmission oil, steel wool and about a quart of 'elbo grease'. Finally was ready to push the piston up very slowly so I could catch each ring and prevent it from 'snapping" and possibly breaking it. Removed the piston and made the following observations: Approximately 1/3 of the rear side of the piston was 'scarred' from the top to the bottom. All rings were intact. Piston pin was not protruding on either side. The piston was marked .020 and FRONT. When the rod was held in my hand and with the piston pin parallel to the floor, as was the rod, the piston DID NOT MOVE.
Class dismissed. Your assignment is to evaluate the above information, and present your theory as to the nature of the problem.
We will continue this as it develops in the shop.
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#89983 - 08/29/02 06:06 AM
Re: School is in session
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Chev Nut
Registered: 01/08/02
Posts: 9622
Loc: West Allis,Wi.
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#89987 - 08/29/02 08:48 AM
Re: School is in session
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RustyFender
Backyard Mechanic
Registered: 12/15/01
Posts: 220
Loc: San Jose, CA
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RustyFender raising his hand. Check the dippers on the rod caps to make sure the splash depth is correct. Possibly the recent rebuild employed a new cork pan gasket which could lower the pan enough to reduce splash and cause the wrist pin to almost sieze from lack of proper lubrication. This in turn would cause the piston skirt to dig into the cylinder wall. I would also check for proper oiling provisions on the piston wrist pin and that the piston was installed in the correct direction. 
-R
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#89988 - 08/29/02 09:01 AM
Re: School is in session
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CHEVY
Registered: 12/30/01
Posts: 1461
Loc: ORTING,WASHINGTON
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#89990 - 08/29/02 09:19 AM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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Congratulations students. It is obvious you have been attentive. At this point no additional work has been accomplished so these answers are based on the initial inspection as presented.
Chev Nut : I can't discount your corrision theory at this point, although it doesn't appear to apply. Your second post about the 'ridge' is true. Very little ridge, and as indicated, engine doesn't appear to have many hours on it. I should have pointed out also that the buildup of carbon at the top of the piston travel is 'normal'. If you plan to reassemble with the same parts it is important to remove this carbon before removing the piston through it. In severe cases of wear it will also be necessary to use the ridge reamer.
MrMack : From the evidence so far it appears that all the components are compatable; ie, piston and rings were replaced at the same time. Other indicators as I disassembled the engine indicate that it was done by 'professionals(?) and something went sour.
ChevyChip : Good questions. My reference to the 'back side' of the piston was that opposite the side marked 'front' or firewall side. You may be on to something when you mention 'camside'. I should have mentioned that the pistons are 'aftermarket', are aluminum and appear to be very 'crude'. At this point I don't know if they are 'round' or 'camground'. Something to check out. When holding the rod in my hand I would have expected the piston to 'tip' as I held it horizontal. It didn't. This is obviously not a scientific test, but a quick check to see if the piston pin was seized or too tight.
At this point in the investigation my attention will be upon the possibility of piston pin problems, bent rod, or defective piston. Will also try to identify the manufacturer of the pistons, although I already have my suspicions based upon the simularity to known pistons.
Okay class. Recess, while the instructor works on the next lesson plan.
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#89991 - 08/29/02 02:44 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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Everyone please take your seats and knock OFF THE NOISE. Class is again in session.
First: Q&A
Rusty Fender : Clarification on the dippers. 1928 does not have 'dippers' but instead has 'protrusions' on the rod cap that hit in the oil and SPLASH it all over the area. (At least I know you were paying attention and not looking out the window and dreaming of driving your old Chevy). I have not checked the depth yet but will during reassembly. Pan gasket was normal thickness. Piston was installed correctly and from all appearances oil was making the trip up inside the piston to the piston pin.
CHEVY : I WILL ANSWER YOUR QUESTION IN AN EVASIVE MANNER. PISTON INSTALLATION CLEARANCE IS DICTATED BY THE PISTON MANUFACTURER. IT DEPENDS ON TYPE OF GRIND, COMPOSITION, AND OTHER VARIABLES. AS A RULE I FOLLOW THE MANUFACTURERS RECOMMENDATION WITH THE EXCEPTION OF THE 53/54 PG ENGINES. DUE TO THE HARD STARTING CHARACTERISTICS OF THESE ENGINES I ALLOW MORE CLEARANCE. EVEN THEN OCCASIONALLY I HAVE TO LOAN THE CUSTOMER A 4-FIELD STARTER UNTIL THE ENGINE HAS WORN IN AND WILL CONSISTENTLY START WHILE HOT. I THEN REPLACE THE STARTER WITH EITHER A HD OR STANDARD STARTER. PLEASE NOTE THAT FIGURES PRESENTED IN PRIOR POSTS WERE FROM OLD REPAIR MANUALS AND APPLY TO OEM PISTONS AND NOT NORS PISTONS. (WOULD YOU PLEASE REMAIN AFTER CLASS AND WE WILL DISCUSS HOW TO TYPE WITHOUT USING THE 'CAPS LOCK' BUTTON)
d2d2 : Your question is very logical. Follow the discussion and you will be surprised at the apparent conclusion.
Okay class, here is the latest information.
Took the piston and rod out to one of my trusted machine shops for their inspection and opinion. Upon close inspection in good light it was evident that the piston pin/piston was to blame for the problem. The pin was very tight in the piston and could not be slid from side to side. Brought the unit back to the shop and started to remove the piston pin. It moved some but refused to be extracted. Was able to get a look inside the damaged side and it was evident that the boss on the damaged side had completely disintegrated and particles of the piston were impregnated into the pin and would not let it be removed. (Students I hate to admit this, but in attempting to remove the pin, in my frustration, I managed to break the oil ring). Now I am faced with an addition problem. Because only one side, the backside, of the piston failed, it caused the most damage to the rear of the piston. There were wear marks on the front side that indicated the piston was in a bind, but not near the damage as to the rear.
In view of my next actions it appears we will have to suspend class for a while. I called the apparent manufacturer, discussed the problem, and then shipped it out to them for their examination. Now we wait.
Please keep your books handy as we will continue the class when we get an update.
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#89993 - 08/29/02 07:13 PM
Re: School is in session
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CHEVY
Registered: 12/30/01
Posts: 1461
Loc: ORTING,WASHINGTON
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#89996 - 08/29/02 08:19 PM
Re: School is in session
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chevguroo
Backyard Mechanic
Registered: 01/13/02
Posts: 332
Loc: Sydney, Australia
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Hi, this is Chevguroo, away at boarding school, receiving snail mail after class is out.
In my 28 years of mucking around with Chev 4's I have seen many symtoms of engine problems. 2 of the most common are bent crankshaft and bent push rod. The bent crankshafts I have measured have been up to 9 thou, and I have heard of a lot worse in 29's.
The bent crank usually results in excessive centre main wear, and possibly would have little affect on the piston.
Bent rods are hard to measure and special equipment is needed. I have a device that is used for straightening bent Chev 4 rods, that was used with a jig back in the good old days.
However if your rod had a bend towards the back, this would force the piston towards the back of the cylinder, and hence the wear/scrapping as described.
My bet will be on a bent rod.
Do I get an early mark?, as it is Friday arvo down hear and I'm taking the 28 2 door out for a run tomorrow
Chris
PS the original radiator has sprung a leak, does anyone one know whether the warranty was for 70 years or 80 years?
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#89997 - 08/29/02 09:38 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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Okay class, heads up.
Q&A
MrMack : You and Chipper can go outside, however return to your seats promptly when the bell rings.
CHEVY : At this time I don't want to name the manufacturer of the pistons as I am only 99.99% certain who did it. Besides, it would serve no purpose. Congratulations, I see you discovered how to release the 'Caps Lock' button.
MrMack : No, the name of the manufacturer is not on the pistons, however by a process of reasoning I am 99.99% sure who did them. Location where the engine was initally rebuilt, familiarity with the product, and other key indicators. No, I have not purchased parts from J C Whitney for years. Around 1972 when I did my '41 numerous parts were purchased from them. Shipping costs are a big deterrent now.
Chev Nut : See above. I do not question their parts, it's just that I am too far away and shipping adds too much to the cost.
chevguroo : You are correct in your findings with the Chevrolet 4-cylinder engine. The straightness of the components is very important and are measured very carefully. At this point I don't suspect a bent rod but rather a defective piston/piston pin. My new purchase, the '28 Roadster, still sports it's original radiator core and performed flawlessly on the last two tours at Crater Lake, OR and Lassen Park, CA. I assume my warranty is still good.
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#89999 - 08/31/02 07:27 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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We'll take a vacation until the piston, rod, and pin are investigated by the manufacturer. What, with holiday, slow shipping, reluctance to make a decision, ect, it may be several days till we start school again. Don't worry, we will continue untill the case is solved. Now go out and play in the schoolyard, but be CAREFUL. (AND CONTINUE TO WORK WITHOUT THE CAPS). 
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#90000 - 09/11/02 10:07 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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ATTENTION everyone. School is back in session. Gather up all those kids out in the school yard and take your seats.
When we last dismissed the class we had shipped the piston, rod and pin off for identification and evaluation. That mission has been accomplished. Go to this location for the identification of the manufacturer and return to your seat.
http://www.vccacolumbiariverregion.org/chatimages/chatray4.jpg
I think that is a firm indicator of the manufacturer.
This next picture is a view of the piston pin boss nearest the firewall. Note that the casting appears to have 'sponged' in this boss. The other side of the piston reveals normal wear and no damage. Material in the damaged boss has transferred to the piston pin and attempted to 'freeze' the pin, however that never did happen. Go take a look and return.
http://www.vccacolumbiariverregion.org/chatimages/chatray1.jpg
This next picture is of the end of the pin that received the damage. Note the buildup of material on the pin. Go look and return.
http://www.vccacolumbiariverregion.org/chatimages/chatray6.jpg
This last picture is the side of the piston facing the firewall and the side of the piston that had the damaged boss. Go look and return.
http://www.vccacolumbiariverregion.org/chatimages/chatray2.jpg
The rear (firewall side) of the cylinder was scratched. This area was honed out and would be considered servicable.
As noted in another post I contacted the piston manufacturer to obtain a single piston and set of rings. Short version: They won't make a single piston. They will do a set: $600.00, rings are ONLY $80.00, time frame, about the same as the construction period for the Golden Gate Bridge.
At this stage of the game the engine is coming out of the car. It will be totally disassembled, hot tanked, and thoroughly inspected. While the engine is out the engine compartment will be detailed, a new wiring harness installed, and adjustments made as to body and radiator shell fit.
Depending upon the results of the detailed inspection of the engine it will receive new pistons, with cylinders bored out and fitted to each new piston. Rods most likely will be inserted. Other work will be done as necessary.
This will conclude the 'school'. Progress on the rebuilding will be posted only if there is an interest in it.
Final grades will be posted in the hallway within one week. Suggest you retain your notes for future reference. Have a great vacation.
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#90001 - 09/11/02 11:43 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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A great big THANKS to 32 confederate for staying up late and assisting in the posting of the pictures in my last post. Couldn't have done it without him.
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#90003 - 09/12/02 12:54 PM
Re: School is in session
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CHEVY
Registered: 12/30/01
Posts: 1461
Loc: ORTING,WASHINGTON
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#90004 - 09/12/02 02:11 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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CHEVY
"Depending upon the results of the detailed inspection of the engine it will receive new pistons, with cylinders bored out and fitted to each new piston. Rods most likely will be inserted. Other work will be done as necessary."
Pistons will be aluminum and will be purchased from my local parts house. Clearance will be as specified by the manufacturer.
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#90005 - 09/13/02 06:56 PM
Re: School is in session
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CHEVY
Registered: 12/30/01
Posts: 1461
Loc: ORTING,WASHINGTON
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#90006 - 09/13/02 07:25 PM
Re: School is in session
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AntiqueMechanic
Technical Advisor
Registered: 12/02/01
Posts: 4722
Loc: Vancouver, WA
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I always use aluminum pistons in all rebuilds. Modern pistons as a rule do not cause any undue problems.
The engine will be totally rebuilt with replacement parts as necessary and will employ several upgrading methods.
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From observation of A.T. fluid and steelwool used I would say there was some corrision between the cyl. wall and piston.Engine may have been "stuck" at one time or had a coolant leak on that cylinder also causing wrist pin to also corrode to the piston.Corrosion broke loose or was broken loose allowing it to run,scarring piston (and cyl. wall???)with rings making noise scraping over rough cylinder wall. 
