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HELP needed please

V

Vetteracerx

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I just built a big block for my K5. Its TBI. Problem is its pushing oil out of everywhere! even the top of the dipstick tube!! WTF It has a PCV and breather tube in the bottom of the K&N air cleaner. The engine is 9.5 to 1. Zero deck oval port heads, dual plane intake, custom program. no EGR or knock sensors. It makes 15" of steady vacuum at idle. I put a psi guage in the drivers side valve cover and drove it. The PCV was left in place (passenger side cover). I watched it make 5 psi durring a hard acceleration before it blew a breather out. Gotta be blowby right?! This engine was broke in on a dyno using a carb and HEI dist. 400hp 500 ftlbs tq. My engine machinist says keep driving it and see if it stops. Ideas? Thanks guys
 
I know its just been built, but I would do a compression test.
With that much blowby, you might have a ring missing.

Been done before.
 
When you say the pcv is in the bottom of the air cleaner what exactly do you mean?In case you don't know the pcv needs manifold vacuum to operate.
 
I read that as the breather alone was plumbed into the air cleaner, but it reads your way too.
Then later he says the PVC is in the valve cover, but no mention as to what the hose is hooked to......
 
Fordum said:
I know its just been built, but I would do a compression test.
With that much blowby, you might have a ring missing.

Been done before.
Click to expand...
I will try a comp test. Def. no rings missing. I have heard that break in oil will sometimes affect ring seating?
 
Fordum said:
I read that as the breather alone was plumbed into the air cleaner, but it reads your way too.
Then later he says the PVC is in the valve cover, but no mention as to what the hose is hooked to......
Click to expand...
PCV is in the passenger side valve cover. Breather tube is plumbed into air cleaner base.
 
I just changed to oil to regular (no additives). I tried again to seat the rings by driving 30-50mph lotsa of throttle and using the engine to decelerate. still no luck.
 
I would do a compression test. 15" of vacuum isn't great, unless you've got a bigger cam in it.

I did have a motor that was doing the same thing, and it ran prety well. It had broken rings in two cylinders. If you gave it alot of throttle, it pushed oil out everywhere.

Yours could be rings that were not installed properly.
 
it wont hurt to drive it first i would try most anything first but if it pumpin out oil like you say sumthing aint rite give it a day or 2 i have been in the same sitaition before sounds like you just got the motor in and its acting up but i have had the same stuff happen and it just being sumthing simple so just give it a day or 2 maybe you will get lucky so just wait until tomorrow and start over beleilve me it will help i have done these saturday nights a many a time :whistle:
 
Yep, wait until tomorrow. You never know, the truck might catch on fire, or a meteor might hit it and you won't have it to worry about.......:D

But, if it does not clear up at least a little in the next few miles, I would do a compression test even if you are thinking about pulling it.

That will pinpoint the trouble if you have bad rings, hole in the piston, or whatever so you know which one to look at when you tear it down.

Of course, I suspect you will see which cylinder it is when you pull the plugs.
If one has that bad of blowby, its not going to be firing well either.

Don't suppose you heard a thudding noise when you first cranked it did you?
Local NAPA has a big piston sitting on their counter with the perfect print of a large hex nut in the top.....

Last time I remember seeing one with that much blowby, it had a small hole burned in the top of the piston.
The hole was small enough that it could suck in fuel, and compress it enough to fire.
But when the pressure wave hit, a large part of it went into the crankcase. The faster it ran, the more pressure built up in the case.
 
Well, there's your problem, right there........:waytogo:

Probably not hurt. But you are going to have to tear it down far enough to see whats wrong with that one cylinder.
Assuming it was not bored out .060 and a standard piston and rings put in, then either something knocked a hole in the piston, or you might find a set of rings laying on the workbench......

Depending on what its installed in, you might be able to just pull that head, drop the pan, and slide that piston out.

Unless a foreign object fell into the cylinder, I'm betting on a missing ring. I don't think that forgetting to stagger the gaps would be enough to do that much.

Or, the kit you used might have a wrong size piston in it. At least you know which way to go now.

Let us know what you find.
 
Well, you've got a strong running 7 cylinder. Now you just need to fix the one cylinder and make it a strong running 8 cylinder.:laugh:


It may not take much, but I certainly wouldn't drive it any more. Running a broken engine is never a good thing.

On a positive note- it really could be something simple like rings installed wrong, or a defective piston. Since you've got 92#'s of pressure, it is a small problem creating big issues.

Best of luck.
 
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