BB72

I have a 496 that I had the bottom end built and the top end by me. I was changing the oil pan for clearance for the steering linkage and found out the oil filter had not a lick of oil through it. It did about ten dyno runs with no issues. Any clues as to why? I missed something for sure.

BlackC3vette

Sounds like the oil bypass was stuck open, not allowing oil to pass thru the filter. Did you check or replace that bypass adapter when the engine was built?

7T1vette

The bypass in the oil filter opens if the differential pressure across the filter is too high. Do you have a high pressure/high flow oil pump? You need to research which oil filter brands/types are compatible with your oil pump.

You can put another filter on it to test that theory, but I would bet that the next filter (same brand/type as the last one) will do the same thing. It is still probably a good test to run.

If that is the problem, the filters you are using are NOT filtering the oil!! They are merely bypassing it.

Fingers crossed...it was just a bad filter. [Was it a FRAM?]

427Hotrod

Is this a Mark IV or Gen5 block?

JIM

BB72

It is a IV Jim.

427Hotrod

The oil goes right from the cap to the filter...have you tried probing the feed hole?

Filter was bone dry?

What sort of oil filter adapter/by pass is on it?

The rear main would get fed....not much else...

http://www.grumpysperformance.com/BBCoilingCustom.jpg


JIM

BB72

Yup, I could send a pic of a bone dry filter but trust me. The input to the filter was also dry. The thing is there's oil everywhere, you remember the pulls on the dyno, you don't get that with no oil. I'll check in the morning if the previous owner bypassed that.

BB72

Thanks for the pics Jim, they really help.

427Hotrod

Gotta be something with the adapter that's routing oil internally and bypassing filter. It doesn't have one of those add on oil cooler adapters or anything does it?

The oil should enter the filter in the "little" holes and come out of it through the center back to the engine. So somehow it's getting from that diagonal hole from the pump/cap directly to the filter outlet path.... without going through the filter. Would be weird......maybe aftermarket adapter with a hole that must be installed in correct position?

Pics would be good.



JIM

PAmotorman

does it have a spring loaded check valve in the block inside the oil filter area ??

SteveG75

You can buy oil filter adapters that don't have the bypass. Just change the filter regularly.

PAmotorman

I thought it was a mark V sorry

BB72

Ok, here's some pics. I'll never buy another Fram filter, you wouldn't believe the dirt and dust inside this brand new filter. Imagine that getting into your motor. The picture of the block is not wiped down at all. That's exactly how I saw it when I took it off, there's no oil even getting to the filter.

Jebbysan

I just do not see how that is possible.......like Jim said it goes straight through the rear main cap and across to the filter boss.......
I would get a bucket of oil and submerge the pump while a helper spins the shaft with a primer/drill.......and investigate if what you are seeing is really what you are seeing.......I believe you when you say it is dry, but sometimes what things seem are not what they seem.......at least you can verify oil flow.

BTW.....OEM style Fram filters are garbage I agree.....but the HP series is not even made by them.....and I recommend them highly as it has the highest flow of any other filter.....I also block the spring loaded bypass off with a 1/4" pipe plug........

It takes exactly one second of oil loss at 6000 RPM to cook a bearing.....you are getting oil from somewhere....maybe the oil fairy

Let us know what you find.....

Jebby

BB72

I think I may have figured it out. What if the shop cut open the filter used on the dyno to check for metal and put a new filter on the motor.

Jebbysan

Yep....that is what we did after a few pulls....new Filter and drain oil as you usually ship engines sans oil to save money.

Jebby

HeadsU.P.

What does a "Anti-Drainback Valve" do? I see some brands list that as a option on their filters. H-m-m-m-m-m-m. I wonder if . . . . . Nahhhh.

GOSFAST

Based on what I see at the rear section of that rear main shell (with minor scuffing) I suspect a balance issue at the rear section of the crank. Not in the engine but outside!!

May be a flywheel, flex-plate, or convertor issue, but have seen that "look" over the years. One specific build we got into had an "out-of-balance" convertor.

Thanks, Gary in N.Y.

P.S. With respect to the bad "rap" about Fram filters, we haven't had a single issue/complaint and we use them on almost every dynoed piece we do! Once off the dyno we don't care what filter the customer chooses, it's up to them??

lionelhutz

That's the only thing that would make sense. Oil must reach the filter on a stock setup if their is oil being pumped throughout the engine.

I wouldn't use the cheap Fram filter, but the high mileage and synthetic versions of their filters are a quality build. I haven't seen the inside of the HP series but it could easily be a quality build too.

71VetteLover

I would guess you forgot to install the oil pump drive shaft when you assembled the short block.