I have a 1977 Buick 231 V6 (odd-fire) that shares much in common with the small block Buick V8s. More in common than with the pre-1975 or post-1977 V6s actually, which is why I am here on the Buick V8 forum instead of the turbo Buick V6 forum. Long story short....my engine with 6000 miles on it since rebuild just wiped out at least one main bearing. Oil pressure dropped to zero when it happened. Nothing appears to be wrong with the lubrication system so I suspect the bearing wiped out first on its own. The bearing appears to have wiped due to lack of lubrication. This engine used to make 10 psi @ 600 RPM and 30 psi @ 2500 RPM, which is slightly lower than the specifications in the GM service manual. At the same time, excess oil running down the exhaust guides and causing oil burning forced me to install exhaust valve stem seals even though the GM manual specifically says to not install any kind of seal or deflector on the exhaust valve stems. Installing exhaust valve stem seals on an engine that did not originally use them is a Band-Aid fix that doesn't deal with the real problem, but it is what I did none the less. I believe the original Buick lifters flowed less oil topside than these new Melling stock replacement lifters do, which is why Buick did not require exhaust valve stem seals. I believe the new lifters flow more oil topside, forcing the use of exhaust stem seals and also reducing the oiling to the crankshaft which may have contributed to my bearing failure. I need to know definitively what lifters to use, whether I need to use exhaust valve stem seals with those lifters or not, and whether the flow rate of those lifters is sufficiently more to cause crankshaft bearing failure. Many of you here have Buick 340's and 350's which share the same lubrication system and valve train as my 231. Many of your V8s are making two to three times the horsepower my V6 does and your engines don't wipe bearings every other oil change. Surely there are people here who can give me straight answers so I can finally get this cursed engine of mine to both not burn oil and not ruin bearings. If you have a Buick 340 or 350 that has run for tens of thousands of miles without burning oil or wiping bearings, just tell me what manufacturer and part number your lifters are and whether you have exhaust stem seals or not.
While we have gurus especially knowledgeable on this engine, you can't go wrong by visiting this website. taperformance.com They have everything you need to rebuild most of the engines Buick ever produced before 1980. They also have their own branded lifters so you can't go wrong with lifters made by Buick guys for Buick guys.
Read that over again. Its not a lubrication issue but you suspect the bearing failed from lack of lubrication.. Couple things come to mind. First the mains get oil before the rods. So the corresponding rod to that main would have wiped first. Main bearings rarely fail like that. I would guess the block wasn't cleaned properly before assembly, dirt and grit ruined that bearing and journal. That would also cause your dismal oil pressure. Regarding your exhaust valves - yep you shouldn't need valve seals. I'd guess the guides are worn so badly causing excessive clearance. Were they checked during the rebuild? Also did you blueprint the oil pump or slam it together? I'd wager the engine went together dirty and caused bearing failure and low oil pressure or the oil pump wasn't built properly causing low oil pressure. Maybe both.
I realize dropping oil pressure and wiping out bearings are a "chicken and the egg" situation since either one can cause the other. I did not build this engine. A man who has built several engines for me built it. He is very clean and meticulous about his work but makes mistakes like any other. He was particularly careful on building this engine because it is actually the second time he had to do it. He used the wrong head gaskets the first time which did not seal off the oil passage in the block deck on either side that was used to supply oil to the rocker arms on the earlier engines, but is unused on my engine since mine oils through the pushrods. It bled off the oil into the lifter valley and caused most of the lower end bearings to wipe. Ruined the crankshaft too. He built it a second time, free of charge, with a new crank and bearings all rebalanced. That build burned oil past the exhaust guides, so I pulled the heads off and sent them back to him. He had already installed new steel guides and valves and said the stem to guide clearance was good. I asked him to install stem seals on the exhaust valves and he agreed since he couldn't think of any other reason for it to burn oil past the guides. I reinstalled the heads and that completely solved the oil burning. The engine did great until it wiped out its bearings again. He and I paid a lot of attention to the oil pump. I used to work in the shop that built more AMC engines than anybody else, and AMC engines use the same basic oil pump design. I am very used to this type of oil pump. All clearances in the oil pump were blueprinted and a steel thrust plate installed. It was a standard volume pump. I am actually on vacation with this car right now. I drove it 1000 miles from Arizona to Kansas for a car show. I only brought minimal tools with me and I am working in my friend's garage so I cannot fully tear into this engine and diagnose what went wrong until I tow it back home with a U-Haul. I also don't want to get too far into the engine yet because I want it to briefly run for long enough to push itself up onto the tow dolly. I did pull off the one main bearing cap and I did disassemble the oil pump. The oil pump was perfectly fine inside but the bearing certainly was not. I will post a picture of the bearing for you. Right now, without being able to fully tear into the engine, I suspect two things contributed to this. One, the aftermarket lifters flowed too much oil topside which caused the oil burning and bled off oil from the bearings. Two, my dad installed the engine and failed to tighten the bolts holding the engine and transmission together. 6000 miles of running with that misalignment cracked the flex plate and may have overloaded the engine bearings. I will know more when I get it back home and tear it apart. Right now, I am just planning and gathering information. I am going to build this engine myself this time. It will be the third time this engine has been built in 6000 miles. There will not be a forth time.
No more crush. Definitely getting ready to spin. It's a bad sign any time you pull the bearing cap off and the bearing stays on the crank. That used to be a Clevite 77 P-series bearing. Babbitt overlay is completely gone. Most of the copper backing is gone. It is mostly into the steel of the bearing shell itself now. That ridge on the left edge of the bearing is where the crank doesn't ride on it and is an unworn section of the bearing. That shows you how much of that bearing is wiped away. I have coppery glitter in the oil pan. Crank may live to fight another day. The original crank was trashed beyond recovery the first rebuild. This is already the second crank. I'd hate for there to be a third. There will be no forth. Does it seem weird to any of you that the crank journal is not centered on the bearing? It is leaving that little section of the bearing on the left edge hanging out into the open. I have not checked the crankshaft thrust bearing yet but I think I will do that. It may have ruined the thrust bearing.
Maybe get a sbb 350 and put the $$ into that instead of trying to make the v6 work? It would be WAY funner to drive. Anyway, Welcome from SE Michigan!
So I can have an even bigger engine running on the same tiny oil pump? I hear you though. I've thought about that several times. I checked the crank thrust. .040". That was probably the dull knocking I heard. I pulled the bearing (#2) and it was completely destroyed on the rear thrust face but the front thrust face was untouched. The non-thrust surface was also wiped into the copper all the way, but not into the steel like #3 bearing was. Looks like the bearings get worse towards the back. I'd hate to see what #4 looks like... Here is the funny thing though. The rear face of the thrust bearing (#2) is wiped, so that means the crankshaft was thrusting forward with quite a lot of force and not enough lubrication to chew into that bearing. However, the ridge at the edge of the #3 bearing I posted above shows that the crank was thrusting rearward as it chewed into that bearing. I operated this engine for 6000 miles with misalignment to the transmission, which may have caused excessive forward thrust force on the crank and destroyed that side of the thrust bearing. Then I fixed the misalignment and drove 30 miles, which is when the oil pressure disappeared and the knocking started. Perhaps the thrust bearing failure caused by the transmission misalignment led to the failure of the other bearings after the cause of the excessive thrust was fixed.
This makes sense. When you realigned it, you opened up either the oil holes or part of the destroyed thrust bearing( by mere thousandths), and oil just hemorrhaged from that main while #4 lost pressure completely. You're right that it will probably look ugly.
Welcome from west Michigan. Transmission being loose could have allowed some converter movement, thus contributing to the thrust bearing issue.
Wouldn't a loose trans/flexplate also allow thrust? On the timing cover ensure you have the correct gasket. There are different ones for the 225 V6. Not sure on the 231's. I have a whole 66--225 V6 motor if the crank will work. Might also look on the 225 Dauntless forums. They used a lot of buick 225 v6's in jeeps Todd
The loose trans would not hurt the thrust bearing. If the engine and trans were separating the converter would be pulling away from the engine not towards it. The converter could never get closer than when the trans was tight.
I was thinking of the back and forth movement, sort of pounding on the flexplate and crankshaft, that may have contributed to the problem. I would like to know what the crank endplay was.
My trans wasn't just separating from the engine. It was sagging downward and creating an angle between the engine and trans that the flex plate had to act like a universal joint to make up for. As I unbolted the flex plate from the TC, I noted the TC pushing the flex plate forward about 3/16" at the top, and pulling it out about 3/16" at the bottom. That misalignment had to be putting extra loads on bearings. All I can tell you is I have a thrust bearing that failed while the crank was being pushed to the front, but every other main bearing failed while the crank was being pushed to the rear. That suggests there were two separate events of bearing failure here. The front face of the thrust bearing is completely untouched, not even a single sign of regular wear. The rear face of the thrust bearing is completely trashed. There is .035" of material missing entirely from the face of that bearing. I did not pry the crank front to back to check the axial thrust while the engine and trans were misaligned, so I have no idea if the misalignment was causing excessive axial thrust on the crank or not. What I do know is the crank was completely free to shift axially after I replaced the flex plate and bolted everything together straight. Nothing should have been loading that thrust bearing any more than usual after the misalignment was remedied.
