Losing oil

[Bob Podstawski]

For years my 340 HP ran super after a full rebuild. Offenhauser with 2-4s. Decided to go Fueltec injection which required a 4 BBl intake which my shop got from Edelbrock. All done tuned up and running amazing!. Take my first long trip (100 mi) cruising about 70. Notice when I floor it to pass, I got smoke. Then off the throttle...OK. I get to my destination and I'm 3.5 quarts low!! Refill and go easy on the way home...3 qts low! The next morning I look at the garage floor and I've got a 2 ft round oil stain.Back to the shop. They replace the VC gaskets (which frankly were not leaking), clean up underneath and go out for a ride. Up on the lift they see oil coming down the back of the block at the rear of each head. Mechanic says head gasket? Sounds like BS to me. What I'm wondering is could this be a PCV valve issue? Pressurized Crankcase? At a loss....HELP!!

 

[El Rat]

Change mechanics!

 

[61belairbubbletop]

Do you have a PVC valve at rear of distributor , or road draft tube ?
Valve cover breathers ?

 

[61belairbubbletop]

Yeah, what E R said above !

 

[Don Jacks]

Sounds like an intake manifold that isn't sealed at the back of the engine.

 

[Carmine]

I think Don is correct. It ran well with no oil loss before you changed the induction system/manifold. That's where I would be looking, Carmine.

 

[sp6t1348]

Geometry change; new intake does not port match. Seasoned block; probably decked and line bored, then heads resurfaced. No oil loss until new intake on...Intake is the culprit. They can be machined... need to check it; oil from the lifter valley could be getting sucked into the intake runners, especially at that rate.

 

[IMBVSUR?]

Good luck. Hopefully you will get it resolved quickly. Haven't seen too may cars that were estimated by the quarts per mile.

 

[bwell]

I agree with Don, had the same problem when changed to hilborn injection manifold. Didn’t have enough silicone sealer at rear of manifold, leaked like crazy.

 

[Carmine]

I guess that might be one of the disadvantages to using silicone sealer and not that rubber gasket; not using enough of it and then you have leaks. I know alot of people and shops use strictly silicone now. I often wondered how that held up over time. I never mind using the rubber gasket although it could move around on you, Carmine.

 

[El Rat]

Set the manifold on the motor without gaskets. My guess is the problem will be obvious. I never liked anything over 3/16 or so at the end rails. In addition the angle on the intake should match the intake side of the heads. At some point I made end rail “spacers” that I screwed to the back and front of the block...used counter sunk 1/8” screws

 

[El Rat]

I have used RTV since 1965 without a failure. After 1st trying silicone grease (duh!) what a dumbass!

 

[Don Jacks]

RTV can make up for minor fittment issues better than the rubber parts ever could.I like to let it "skim over" before I put the manifold on. Using the right type for what you're doing will help,as not all silicon sealers are the same.

 

[425/409ER]

I would spend the money on a set of intake gaskets to see if it's sucking oil on the bottom of the intake manifold especially after the crap I went through with edelbrock and the intake I bought. It was machined wrong and had I not caught it I am sure it would have sucked oil. I have a dual quad Vortec edelbrock intake that I finally found was sucking oil. Switched it to my Vortec race intake and the oil burning stopped completely.

 

[Carmine]

Just wondering, has anyone ever had concern about using too much silicone which gets squeezed off the inside edges and into the lifter valley, ends up moving around inside the engine. I guess this is possible. I think something like that contributed to the oil return passages in my 409 heads, becoming clogged, Carmine.

 

[El Rat]

RTV is your friend

 

[Bob Podstawski]

Thanks for all the info boyz...changed intake set...matched port angles with original GM intake...dead on. Replaced VC and distributor base gaskets.
Will idle all day dry as a bone. 30 mph...no problems. Get on the interstate and she'll blow out a quart every half hour. Back on the lift and the rear of the engine is oily wet between the block and the heads more on the right than the left. This engine overheated a few times over the last few years..is it possible I have a head gasket issue or warped heads? HELP!!

 

[Don Jacks]

Head gaskets don't usually leak oil on these engines.Are you using a PCV set up or the road draft tube?

 

[Bob Podstawski]

The Edelbrock intake doesn't have the casting for the road draft tube. Instead, has a boss just to the left front of the distributor in which we drilled and tapped a 5/8" fitting. Rubber hose to PCV and trans modulator then to the Fuel-Tec vacuum port. The oil fill tube will pull a paper towel to it when the engine is running.

 

[Jim Sullivan]

If you put a pcv valve in the port in the Edelbrock intake, thay could be one cause of your oil consumption. At least on the older version I have, it was. Mine has a terrible baffle that doesn't deflect any oil.