Ok so I had a 400 built .40 over, H beam rods, KB pistons, big valve heads, HV oil pump, COMP Big Motha Thumper cam, Joe Gibbs break in oil. Everything brand new but the block. Ok I prime the pump got 40psi with a my drill. Start the engine and everything look great. Oil is at 40psi at idle, and 60psi under load. 5 miles into test drive 0psi. Took the motor back to the motor shop and found a press fit wrist pin dug a trench into the cylinder. Well found the reason the bearing are shot, fuel in the oil. So the engine is completely rebuilt, new rods, rings pistons, bearings, and JG BR30 At start up the oil pressure is back to 50psi when cold start idle. Once a heat cycle through the engine, we shot it down changed the filter to get all the ***embly lube. New filter and another quart of JG BR30. On 5 mile test drive oil pressure drops again. WTF!!! So when the motor is cold pressure is 40psi at idle, And when warm it drops to around 7psi and another set of bearings gone I'm thinking their is a crack in an oil p***age that when warm let's the oil pressure drop, or something I've never seen a bad oil pump. Please post your thoughts, or your experience of the issue. The motor shop is taking care of the rebuild again as they are very unhappy of the issue as well.
Look closely at the cam bearings and journals. Excessive clearances are usually the culprit on sbc oil pressure problems. Good luck. peace
How big is your oil pan? Most engine builders don't use HV pumps because with a 4 quart pan the oil will all be in the top end and the pump suction will be dry above about 3500RPM. Standard process when you prepare a SBC for rebuild is to take a grinder to all of the oil return holes to get rid of the casting flash and help the oil get back to the pan faster, especially the drain holes in the cylinder heads. Make sure the builder remembered to replace the small oil gallery plug under the rear main bearing cap next to the bolt. Without it no oil goes to the filter.
S****, let's go over some basics. First I'm glad that the engine shop seeems to be standing behind their work- almost. You don't have to change a filter to get out engine ***embly lube first off as long as it was genuine engine ***embly lube. The second problem here is the f****n H/V oil pump, why????????????. If the engine builder can give me a concrete reason WHY, I would like to know. What was done about the cylinder that the pin gouged? These simple questions, and the ones to follow answer for me the quality/knowledge of work by this shop. Now, were ALL of the oil galley plugs removed and the cam bearings knocked out, and the block either blasted or hot tanked? Was the align hone or main housing bores checked? Are you sure they are H-Beam rods and pressed fit pins? I doubt there is a crack in the oil p***age somewhere, and YES there are such things as bad and new oil pumps. I'm not trying to be disrespectful here, but you need to find a different shop, or there is someone on the HAMB in your area that can come by and take a look and report back.
BTW, if fuel in the oil caused the bearings to wipe out, you would certainly show some cylinder wear/scuffing from having washed down the cylinders as well. I don't think that was your bearing problem at all. By what I have read from your opening post, I hope the builder has properly set the ring end gap on those KB pistons if they are the Hyperuetectic ones. If not, you are going to have another serious issue and possibly a rebuild again. All the best, TR
I have a question about the HV pump over oiling the top end.The oil gets to the head through the lifters with some sort of oil metering. And then up pushrods.The oil hole in the rocker arm appears to line up with the pushrod about 1/2 of the time because of the rocker action. So the HV pump can push that much more oil through a metered top end oil system to empty the pan???
Trucked, for the record, whenever I bring up my dislike for the over abuse of H/V oil pumps, it's never about them draining the oil pan. It's about the abuse by people and company's claiming to be engine builders, and using the H/V oil pump to cover up their lack of knowledge, lack of proper machining, and most importantly- not setting up clearances properly and to spec. The same old scenario day after day, " having trouble with my new engine rebuild- all new parts, reputable shop, machined everything correctly, and a new H/V oil pump........................" If anyone wants to dispute that claim, please acknowledge the 50 billion cars out on the road everyday that DON'T have H/V oil pumps. All the best, TR
X2 FROM TR; I was in the business for 8 years in the 70's and I see that the same ol misconceptions still seem to be as they were in the past, if you had a pin come out of the rod someone is NOT using the measuring device called a Mic, go find a shop that will! Sorry for your misfortune!
LOL, no buddy, just a cheap insurance policy. Even if you don't have a dial bore gauge, at least plasti-gauge and check and verify your clearances. If your block needs to be align honed, do it. Don't cover it up with a H/V pump. Same with old rods, spend the $ on new bolts, and have them resized. I hate to see these threads when guy's have their pride and joy and have a rebuilt engine and it's in the toilet worse than when they started. I feel bad for them.
The block was sleeved after the gouging of the wrist pin. The pump is a high volume not a high pressure pump. The pan is a 7 quart Miladon. I was at the shop for the entire rebuild, all plugs removed, and p***ages cleaned with long brushes then everything hot tanked. The crank was polished, mic and new bearing bought. They used plastic gauge on all mains, and rods journals. We had 2 thou clearances. We reused the cam as it and the lifters looked good. All lifters were taken apart and cleaned. The engine builder is a well known reputable builder that has built many of my past motors.
20 thou clearance? There isn't a oil pump in the world with enough volume for that, not one that will fit in a oil pan anyway. Better check again. If you understood how strange just the story alone is about the pressed pin coming out, you wouldn't be defending this guy. I knew this thread was a mistake when I started it, thanks for the confirmation. I wish you both all the best.
I have had the same thing happen to me on a 400. The engine was fine until it warmed up and the pressure would go to zero. I tried for months to fix it, and I never could. I replaced the block with another one and solved the problem. I then read an old article in Hot Rod magazine about how there was a problem with 400 sbc blocks as the cam bore journals were never machined correctly from the factory. G.M. Fixed the problem with specially made cam bearings and all was good, until Joe Gear Drive rebuilds the engine and knocks out the cam bearings, and then he has the oil pressure problem. I believe that Speed-O-Motive had machinery that could fix the problem.
I have seen some of the 400 blocks that had cracks along the cam boss down through the center of the engine. The crack did not show up untill after the hot tank cleaning but I would guess thay would have seen it. Mabe thay could run the oil pump with the intake off and and look for internal oil leek.
"Simply knocking out the old bearings and installing fresh ones with little regard to bearing selection, sizing, or alignment is a big mistake," says Jeff Schaerer, Engine Bearing Product Development manager at Clevite Engine Parts. "For example, ill-fitting cam bearings can result in too little or too much oil clearance, which can damage both the camshaft and/or main and rod bearings. If excessive cam bearing clearance exists, a severe reduction in oil pressure can result in insufficient oil delivery to the rest of the motor."
Some stuff here is right on and some not. First no more HV pumps for street. The Z28 pump in the way to go. When a new build has good pressure at idle, but drops when RPMs come up, it's the mains, almost all the time. If the old 400 block has been thrashed, there might be a crack on top of the main web, close to the cam...I've built over 300 SBCs and here's the deal..The guys building missed something. If it makes it through the burnout the builder has done his job.If not he screwed up....If it was cam bearings the pressure would be off right away...also NO Fram filters....Happy Motoring....
Stay with it...400's are awsome. I had a similar experience with my 400 block... First rebuild ran fine but oil pressure faded after a few days but was still about 20psi so I didnt worry. It turns out then my fuel mixture was way too rich and / or my gapless rings didnt seal and the oil thinned out from the un-burned fuel. When I drained the motor oil, it ran like water. Bores were mirror like so rings may not have sealed. Out comes the motor. Everything was wiped out. A quick 5 thousands hone new piston, new pistons, crank, bearings etc. I fixed my fuel mixture issue with a wide band O2....the motor lived....made ok power and I was a bit disappointed but it ran...Oil pressure fell off one day... i found water in the oil and grit embedded in bearings as if the oil filter wasn't working. I thought it was the intake seal but it turned out the block cracked in the valley near a head bolt. That block was done! New Block....new h/v oil pump, 7 quart pan, no by-p*** oil filter appliance. traditional rings, Motor lives and runs great. Good oil pressure. 20 psi at idle and 50 at cruise. Oil is clean and smells fresh not fuelish. I'm a believer in the No-byp*** oil filter appliance on a new engine. Filters clog easily and even the cleanest block will have some grit left in it that may clog the filter just enough to open the byp*** when cold. This lets oil and some grit byp*** the filter through the pressure relieve valve and wipes your bearings.
One thing on the filter byp***. I used to block off the byp*** on all SBCs, BBs too. But never again. Fram for one some ACs too, will come apart inside and stop flowing. All Chevys ,oil through the filter first. If the byp*** is blocked and the filter fails, no oil will flow. None.
You're right, I've got a baldwin filter on the way to me. Now that my engine is clean and I've been through two filter I'm considering putting the byp*** appliance back.
Ok so it looks as if all the lower main and rod bearing are gone again. The cam bearing look real good? This is telling me that there is some sort of oil pressure loss to the bottom end only. I am leaning towards a crack in the block somewhere. I will be magna fluxing the block first thing next week.
You'll get it fixed, S****, let us know when you find the problem. I had to junk 2 SB 400s last year because of cracks. Both had been abused real bad, broke crank at high RPM..j
Found a huge issue with the motor today. After a lot of scratching my head and going over the motor and the oiling system I thought maybe the new **** crank is bad. We spun the crank with the engine shops balancer and flywheel and no problems? The motor shop balanced the rotating ***embly with their balancer and a 168 tooth flywheel the first time built. Then i thought could my custom built 153 tooth externally balanced flywheel be out of balance or different from their 168 tooth? I took it down to the motor shop. Well well well look here at what I found. So we put my flywheel and balancer onto the crank and give her a spin. Holy **** if the crank didn't try to jump out of the balancing jig when spun up. It looks as if my custom ground flywheel is Aprox 200 grams off. And yes i ordered an externaly balanced 153 tooth flywheel, So back it goes Monday morning. I figured since the motor is completely tore down again I might as well maga flux the block. Woudnt you know it the f-ing block is also cracked above the rear main. I guess I'm going to get another block and start this process all over. This is a lesson learned for sure, never trust a new flywheel to be balanced..
**** dude. That ****s. I had my 153 tooth flywheel switched to external balance for my 468 bbc. They drilled it to balence it.
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