1982 Buick 231 3.8L V-6 Possible Engine Knock Help?

[Tom231]

I'm working on a project and I purchased this rebuilt Buick 231 3.8L V-6 engine 3 years and 11 months ago by a reputable engine rebuilding company. The engine has been sitting in the crate that it came in for most of the 3 years and 11 months and I recently installed it in my project car. Today I finally started it up. After turning the engine over for a few cranks to pick the engine oil pressure, I then hooked up the ignition wire to see if the engine would start up. It did. I have two oil pressure gauges hooked up, one mechanical and one electrical. They both had the same reading when the engine started. If I remember correctly that reading was around 50 psi. The engine starts up on a dime and runs smooth. However, there is a loud noise coming from the engine oil pan area. Sounds like some type of an engine knock. Any suggestions as to identifying what type of knock that may be? Thanks for your support.

[bob k. mando]

the oil pan didn't get dented, did it? could be crank counterweight striking the bottom of the pan.

have also heard of improperly attached torque convertor bolts sounding like a knock.

[Tom231]

You are partly correct. I removed the oil pan yesterday and found two deep groves in the forward shallow end of the oil pan. The first two conrod bearing cap bolts were hitting the oil pan. The oil pan is actually from a 1970 Jeep Commando. These jeeps used the Buick v-6 engines in those years. My engine is from a 1979 to 1982 Buick LaSabre. I needed the front end of the oil pan to be shallow to allow clearance for my rack & pinion assembly. I believe the stroke on the 1979 to 1982 engines must be different. Perhaps that is why the conrod cap bolts hit the oil pan. I have pictures posted at the website listed below if you would like to see just how deep the groves in the oil pan were. I also removed one of the main crankshaft bearing caps to check on the bearing and crankshaft journal conditions. They look ok to me. You can view these pictures and many others from my project at this website:
http://www.ptcruiserlinks.com/forum/...ersion-29.html Thanks for your support and concerns. Let me know what you think about the condition of the bearing and crankshaft journal. Aloha, Tommy.

[bob k. mando]

yeah, i'd agree with the other guys.

see if you can beat the bottom of the pan down enough that you don't have the interference problem any more. be careful of frame rail straightness. when you try to push the material in the bottom of the pan down it's going to want to pull the sides in.

if you're good at welding, it may be a better idea to just patch in a new bottom to the oil pan with enough clearance.

an alternative method is to grind down the heads of the offending rod bolts, although this will change the balance of the rotating assembly.




I believe the stroke on the 1979 to 1982 engines must be different. Perhaps that is why the conrod cap bolts hit the oil pan

no, it's the same stroke. the 225 v6 is based on the Buick 300ci v8 ( 6 / 8 * 300 = 225 ). the difference between the 231 and the 225 is that the 231 shares the same bore diameter as the Buick 350 while the 225 shares bore diameter with the Buick 300 / 340.

and, of course, most 231s have the split throw crank and run a great deal smoother than the 225.

[Tom231]

Hi Bob, I placed a try square across the oil pan rails surface. I then mesured down to the area where the groves were. I had 1-3/8". Using a brass punch, I placed the oil pan on a block of wood, I then pounded out both groved areas until I got a measurement of 1-1/2". This should do the trick. The frame rails did not get affected. I re-installed that one main bearing cap and torqued it to 100 ft lbs. Today I will purchase new engine oil and oil filter. I also need to replace the water pump gasket. It was new when I installed it, however, for what ever reason it is leaking. Do you know if any of the bolts for the water pump is suppose to have some type of sealant on the threads? Once I get these things done, I will restart the engine to see if anything else pops up. Thanks for your support Bob. It is greatly apprecaited. I'll post my findings after I start the engine. Aloha, Tommy.

[Tom231]

Hi Bob, I just removed the water pump to replace the gasket. The gasket looked good when I removed the water pump. I notice alot of coolant came out from two of the bolt holes as I removed the bolts. Why is that? These are the longest bolts in the system. I believe they run through the timing chain cover and to the engine block. If I remember correctly, this is the areas where the leaks were. Do these two bolts require some type of sealant on the threads? Do you know? Aloha, Tommy.

[guyopel]

Yes a gasket sealer will work for the bolts .

John

[Tom231]

Yes a gasket sealer will work for the bolts .

John

I put some RTV gasket sealer on the threads. Hope it doesn't leak. We shall see today what happens when I start up the engine. Thanks John.

[Tom231]

Jon, yes, I used RTV copper sealant on the threads of the long bolts. As you can see the coolant is still leaking from some of the bolts identified by the red arrows. This picture is a view from the bottom of the engine looking up. The fuel pump is at the bottom of the picture. I'm very concerned with the leak at the base of the fuel pump flange. That leak appears to be coming from inside the timing chain cover. That gallery where the fuel pump arm runs through, that's not an area that engine oil circulates in, is it? Any suggestions. Thank you, Tommy.

[Tom231]

I used Avaition Form a gasket #3 on the threads of all the long bolts. So far, no coolant is leaking from any of the bolts. Thanks for your support, Tommy.