A customer brings me his car that has a substantial engine oil leak from the rear of the engine oil pan/ rear main seal area. The engine is a 1975 Pontiac 400 Cu In. It has a chrome oil pan on it that’s probably made in Indonesia. The customer purchased the car the way it is and does not really know what has been done or not done to the engine. The engine ran fine with no noise or knocks and had good oil pressure, just leaked oil. So I remove the oil pan to repair the leak, which ended up being from the rear oil pan seal around the main bearing cap being rolled and torn. The big problem is I find two rather big pieces of either cast iron or cast steel in the bottom of the pan as pictured. The oil was fairly clean with a normal amount of engine wear in the bottom of the pan. The two pieces appear to match each other and are machined on three sides and appear to have a radius. The two pieces together measure about 1” long and about .250” thick that tapers down on the OD to about .220” thick. The ID radius machining appears to be straight across. The OD radius appears to be machined straight across then tapers down. The side appears to be machined also with a bevel at the ID. I have been unable to identify where these broken pieces came from in the engine. The pieces are too wide to be from the bottom of a rod or rod cap and I have looked at all 8 rods at the top above the wrist pin with a mirror and the tops of the rods are machined flat and not broken. The crankshaft and oil pump has nothing machined like that and the bottom of the lifter and cylinder bores don’t look like that either. The engine also has stamped steel rocker arms. The owner of the car brought the two pieces to and engine rebuilder and he was unable to identify the pieces also. I find it hard to believe that some Bozo that put the chrome oil pan on and screwed it up, I might ad, put the broken pieces in the pan to FU## with the next guy that had to fix what he screwed up. I don’t want to take this engine apart to find the broken pieces did not come from it and were put there. I can’t believe someone would do that, but if I or someone else can’t identify where they came from in this engine, I will have to assume that is what happened and put the pan back on and hope for the best. The owner is fully aware that if I do put it back together, it could be a potential time bomb. I do understand the owners side of it, that he does not want to spend money taking the engine apart to find that the pieces didn't come from it, but on the other hand, from my side of it, if they did come from the engine, it isnt destroyed yet and can be repaired. Please ignore the gnarly fingers in the one photo!! This one has me stumped! Any of you guys have any ideas what these pieces could be from? Bill
The distributor that is in the engine is a aluminum GM HEI and I would doubt it ever had a cast steel distrbutor as the engine is in a 75 Trans Am. I realize that the car is really too new for this forum but a Pontiac engine is a Pontiac engine no matter what its in and I need some help. Bill
that car is old enough to have countless number of intakes/distributors/carbs swapped into/off of it. I'm thinking these pieces are from the bottom of a distributor also. The factory ones are pretty much "stuck", and could have easily been broken while pulling, beating, and twisting to remove the one, now gone, that left these tidbits of curiosity. I can't think of anything else that it could be from, not an "Expert", but i've tore apart a LOT of Pontiac engines over the years.... (FWIW)
i googled "first gm hei distributors" and came up with this info that just happens to show a picture of the first style pontiac distributor. kinda looks like cast iron to me. http://www.ebay.com/gds/HEI-Ignitions-A-primer-/10000000002053885/g.html
I will agree that the apparent OD of the pieces could be about the same as a distributor but the ID appears way too large. Most distributors that I have seen have roughly a .500" diameter shaft and even the ones that have a bronze bushing for the shaft are quite thin. It seems to me the ID is way bigger than that? Bill
I have a 66 Pontiac 421 motor fresh from the machine shop and everything new in there boxes ready for assembly. I just took the time to look at every single piece there. Absolutely noting I have for that motor looks to have any machine work like your broken pieces. Wish I could have helped shed some light on your mystery. The Wizzard
They're pieces that have broken off of the harmonic balancer snout. I'd bet if you remove the balancer you'll find out that it's junk. Here's a new earlier-style balancer ('67 and older) but the snout looks the same.
Well you guys steered me in the right direction. I removed the balancer yesterday and although it was not broken, the broken pieces are a spot on match to the balancer snout. It must have been replaced somewhere between the chrome oil pan install and the current owner. The balancer looks like it was replaced with an OE used one with the machining on the snout exactly the same as the broken pieces. Now I don't have to worry about the engine coming apart on the road test! The owner is relieved also. Thanks guys for the help and insight on the mystery pieces in the pan. Bill
Those engines usually loose the stock plastic cam gear at about 70 or 80 K and if someone was a bit heavy handed like my former coworker in the dealership I worked in in Texas I can see the damper snout being broken.
I imagine what he means is when the timing set was changed , the guy that drove the hub back on w/ a BFH probably cracked it [the hub] ... dave
OP, Cornhusker lotion will help remove the cracks in your fingers. That sure looks like the bottom of a cast iron Pontiac distributor. I remember back using a three foot pry bar to remove those distributors.
This is something similar, and involved a Pontiac V-8 also. My younger sister had a Firebird with a 326 in it. She called me one day to help her out, she was dead on the side of a road, and did't know what was wrong. I get there, pop the hood, and the distributor is about 6 inches out of the block (???). The hood kept it from being launched further out of the block. On teardown, I found a cast iron loop of metal broken; it apparently helps to guide/retain the oil pump drive from the distributor. How and why it got broken is anyones guess, but the block was junk. I'm guessing the broken part let the distributor shaft wobble enough that a crank counterweight struck it, driving it up. We bought a Bonneville for the 400, 2 barrel engine, and swapped that in. I've actually forgotten what became of the car after that, but I do remember it would smoke the tires as long as you'd let it. I am Butch/56sedandelivery.
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