My 400 burns alot of oil (scratched up cylinder walls I would assume). My question is, can burning a great amount of oil that gets past the rings cause a severe drop of oil pressure at idle. The engine is practically new in regards to cam, main, and rod bearings as well as the oil pump. Pick up was welded on too so it didn't fall off. Also, there isn't anything that I may have forgotten when putting the engine back together that would cause such low oil pressure. I blew the engine up early this year and since I put it back together I have had really low pressure and it smokes a ton. I mean it wants to drop down around 15 pounds while idling. So the only connection I can make is, blown up = scratched up walls = low oil pressure = undrivable car. If anyone has ANY thoughts, please post. Thanks.

 

Also, I have moly rings which just add to the problem. I don't know if I will use them again. It is just hard to seat them. But I couldn't imagine even with moly rings it would smoke like this.

 

Would that be 400 chevy? or 400 pontiac?

 

chevy...sorry about that

 

Exactly what happened when you "blew " your engine?

 

In short, I was running too much compression, not enough octane, too much advance, hot day, humid, drag racing, at about the 1/8, detontation started, and pop. Rings came together and popped the top and ring lands off the 3 and 6 pistons, claimed passenger side head gasket, and after the rebuild it started smoking. Only thing I could think of was the scratches it left on the cylinder walls (which really don't look bad enough to produce this kind of smoke), or possibly, but i would think unlikely, it cracked the block somewhere. It really smokes the most when you give it gas. Sitting and idling isn't that bad but if you look close enough you can see a bit come from under the car. I runs open headers so I couldn't imagine what it would look like out of pipes.

Any other questions just ask, more than happy to share.

 

Ok, So what did you do to fix it?

 

Replaced broken items, honed it lightly, and rebuilt. Like I have said, it didn't look like there was anything wrong other than a few scratches on the walls and I didn't have money for machining.

So do you have any ideas yet, we are starting to go in circles here. I think I have said everything....

So recap.....blew up, totally tore it down, found broken pieces, replaced pistons (all of them) and rings, rebuilt engnie.

 

Well, if I try to give you any help, I need to know all that has happened, and all you have done. I know you must be frustrated after all your work, but that's what happens when you take shortcuts due to lack of funds or experience. Soooo, let's see what we can come up with. First, worst case senario. Did you check the valves? You could have (most likely did) bend a valve head when your pistons came apart. The only way oil get's into the combustion chamber to cause smoke is pass the valves, or pass the rings or sucked in through a bad seal on the intake gasket. None of the above will effect the oil pressure untill the oil level drops from consumption! so you have two problems. 1st, smoke; bent valve head or stem or damaged valve guide or seal.
Are you fowling any plugs? this will help in identifying wich cyl. are
bad. Moly rings take a long time to seal on a fresh engine build, not to mention a lightly honed rebuild. Did you alternate the ring end gaps when you installed them? If end gaps align crank-case pressure will force oil pass the rings. I had this happen to a perfectly good 340 in my duster once and it pumped oil into the cyl. enough to fowl a plug about every 50 mi or so. I got lucky in fixing that problem by removing the plug, disconnecting the coil, and shooting some diesel into the cyl. and cranking it over a bunch. This caused the rings to move around on the piston and re-align in the grooves. Try pulling the plugs find the black one's and do a compression check and compare the cyl's #s. that will tell you alot! I'll bet 3 and 6 are lower than the rest. If your still using the same exaust system you could still have a bunch of oil in it from when you blew it up, in this case, it will burn out eventually! Oil pressure; Any drop in pressure means excesive clearance somewhere. Someone (I can't remember who) had just rebuilt their engine a few weeks ago and posted on this site that they didn't have any pressure worth a dam after it warmed up. I told him to re-check his rod and crank bearings and he found a bolt had backed off even though all had been torqed to 50 lbs. problem solved! Do a compression check on all cyl. and get back to me OK? good luck!

 

check pcv valve and make sure it's working properly and hooked up to the correct port. Also, how many miles have you put on it since rebuild?

 

Alright, first this a brand new set of Dart Pro 1's since the blow up. So its not the heads, it has done this with two sets of heads. Also they gaps were not aligned, the smoke is coming out of both banks I believe, so either I am very unlucky and pistons in both sides of the engine decided to line gaps up at the same time, or it is something else. I don't run pcv valves so scratch that. Plugs aren't really being fouled, of course it pisses me off every time I drive the car so I don't, for that it doesn't get a chance to foul plugs. Next, it's not gaskets, I have replaced heads (thinking originally it was valves, seals, guides problem) and gaskets...still smoke and low pressure. I will test the cylinders again for compression, last time I didn't it was A ok. I have thought of almost every simple explaination, and have done pretty much everything short of pulling the engine...again. So I have resorted to thinking of more non tradtional problems. But nonetheless, it seems the block is going to have to find its way to the machine shop.

Also, I would imagine between 500 and 1000 miles since rebuild. But I don't care moly rings or not, it shouldn't smoke this much durning break in. And the oil in the exhaust, no way, like I said before, just rev it up or put much of a load on it and here comes the smoke. So it is defiantly comeing from combustion and not residue burn off.

I just still have no clue why the burning of oil and the pressure faulted at the same time.

 

Unlucky I guess! Maybe the intake and heads aren't compatable. Sounds like it's sucking oil through the intake gasket! I'm sure there will be some more input on this from other people. Don't get in a hurry, someone has had this problem before! Hang in there, more posts to come.

 

A fresh motor is supposed to blow smoke until the rings seat. If you run the motor hard before they have seated it will continue to blow smoke indefinately. That is what I have been told.

did you allow the motor to break in?

 

The motor had some time to break in, but in the same breath I have to say I didn't drive it around for a 1000 miles under 3k rpms. I don't really buy that whole break in process for rings or they will smoke all the time, I'm not saying your wrong by anymeans, its probably an excellent idea to break a motor in real good before you pound on it, but I would say I have put 500 -1000 miles since the new rings were installed and these were pretty easy miles actaully. Not only that, but when someone builds a fresh motor for dyno testing purposes, or a racing motor, they don't break the drag car in with 1000 miles or whatever before they pound on it, and I have never seen a race car smoke like this, even engines that have over a 1000 passes on them. I tell you guys what, when I make it home for this weekend, I will start it up and get a picture of the amount of smoke we are dealing with, then you will see we aren't just talking about a bit of a worn ring problem. At least I don't think so. But once again, I may be totally wrong about these rings, or the cylinders aren't true anymore, or whatever the case may be it is enough to get on your nerves rather heavily.

But I still don't understand the oil pressure problem. Smoking doesn't hurt anything other than carbon build up and lower octane ratings in the chambers, but this low oil pressure problem will if it sat and idled for very long.