Oil behind intake

str8stang036

str8stang036

New Member
Dec 28, 2002
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Miami
#1
I have been having a throttle blip/buck from idle and stopped position. I haven't been able to tune it out yet, but today I discovered oil puddles on the block behind the intake. I assume this is a vacuum leak, am I correct?

Jose
 
#3
Oh, forgot to talk about the PCV. It is completely covered. I have the Edelbrock Super Victor EFI intake, no port for the PCV. I have one breather on each cover.

Its enough oil to cook a small steak. LOL
 
#4
You need to get some positive crank ventilation. Breathers alone aren't enough. Your motor is going to rott without some clean air circulating through it. You should be running a PCV vale to one of your valve covers. Odds are, the pressure built up in the engine and created a leak in your intake gasket.

Kurt
 
#6
Ok, there is definately some misinformation in that last thread, I skimmed through it. The oil in the back of the intake is not a vacuum leak. If you don't have a PCV valve hooked up there is no vacuum involved. the issue has to do with exhaust gasses. The main reason to have positive crank case ventilation is to circulate out those exhaust gasses. All engines have a little blow by. The exhaust gasses get down into the crank case and they contain gasses that contaminate the oil, and cause corosion to the metal in the engine. The PCV system recirculates these gasses into your intake system so they don't build up in the engine. It is perfectly ok to run a PCV valve along with a breather. The stock engine comes with a tube that goes to your inlet pipe, essentially using your air filter as a breather. It's the same thing as using an independent breather. However, your oil leak is completely unrelated. Sounds like just a leaky intake gasket.

Kurt
 
#8
It's not uncommon for the gasket between the intake and block to leak. There is a lot of gap between the block and the bottom of intake, so that gasket has a tendancy to leak. It wasn't my intention to insinuate that your engine was stock, just using an example of how it is set up from the factory.

Kurt
 
#11
Im really sure this has been mentioned before somewhere and excuse me if im telling you stuff you already know.

Buuuut i have had leaks in the oil valley seal from reputable Mustang performance shops. With that said Cleanliness is next to Godliness. When putting an intake in the surfaces must be super clean!!!! That rail on a 302 block in the rear is thin, 351 too but not as bad. Personally after scraping the old gasket material off i use sandpaper or a brillo pad the etch the metal a little. This helps the gasket maker and/or gaskets from moving. Then after I wipe clean with a alcohol based cleaner (Pre Cleaner). Some folks like not using the cork/rubber gasket on the front/ rear (i believe companies like trickflow tell you not to use them). I use them and also put a thin layer of black gasket maker on both sides of the gasket making sure i put extra in the corners. Also Tourque sequence is important. Use a torque sequence.....don't just randomly torque the bolts snug & do use a torque wrench!!! Usually they want you to do something like 16/ 20/ 25 pounds and repeat 3 times gradually. Im anal so ill torque it 5 times gradually so everything seats properly. Using ARP studs helps too. Also lightly oil the threads to get proper torque Readings. Let it sit long enough for the gasket sealer to fully cure. (overnight if possible).

I have installed everything from stock 302-351 to Trickflow street heat/ Trickflow R and Box R.
The reason for the thorough explanation is because its leaking....so its going to have to be taken apart. Figured i would give the DIY tips on leak free installation. Also not having Crank case ventilation is bad!!! These gases WILL destroy gaskets like mentioned by someone else here. I tried blocking the PCV valve some years ago and noticed the motor started running like crap and i was getting oil threw the valve cover breather tube. Bottom line is no matter how modified the motor you DO need Positive Crank case Ventilation!!! I have a Trickflow box intake 90mm and even that is vented.

Sorry about being long winded but i HATE doing intake gaskets and im sure im not the only one!!! Better done right the 1st time.

Chris
 
#12
95Vert383AOD- thanks for the thorough explanation, I appreciate your tips. I am looking into some form of crank case ventilation to add. I like using the rubber gasket on the ends, however I can't seem to find them for a 351w. I prefer rubber over cork that fel-pro has, do you know any place that has them?
 
#13
str8stang036 said:
95Vert383AOD- thanks for the thorough explanation, I appreciate your tips. I am looking into some form of crank case ventilation to add. I like using the rubber gasket on the ends, however I can't seem to find them for a 351w. I prefer rubber over cork that fel-pro has, do you know any place that has them?
Click to expand...

Personally i like the rubber ones myself as well. Seems FelPro only makes the rubber front and back pieces with the 302. Cork works too....but just remember black Gasket Maker is your friend here. Use a Good amount of it.....and give it plenty of time to dry like i said. Some folks feel that 2 valve cover breathers are enough. I feel the more the better. I have 2 valve cover breathers connected with a "Y" fitting between the Mass air meter and throttle body on the intake tube. Also if you want to vent properly then valve covers connect before the throttle body and your PCV valve connects after the throttle body. Using a Super Victor EFI i would say connect the PCV somewhere on the 90 degree Elbow.
 
#15
str8stang036 said:
Even on a turbo setup you recommend what you said above?
Click to expand...

Honestly i haven't done the turbo thing yet. So i couldn't tell ya. I do know that Trickflow recommends the intake i have for boosted applications and it has a PCV valve. I believe people who run turbos tend to connect the valve cover breather hose after air filter and mass air meter where there is no pressure. But im not sure of these gases are good to be vented into the turbo inlet. I'm not a turbo guy YET. :shrug:
 
#17
That looks nice....i would hate to keep having to check that can. Would be nice if the oil catch drained back into the engine threw either the oil pan or dipstick...Crap i should patent that. Personally i like the fact that the vacuum from the intake manifold actually draws the gases out rather then pressure building up to the point it forces itself threw the hole.
 
#19
str8stang036 said:
What do you think about this?Moroso 25900 - Moroso Crankcase Evacuation Systems - summitracing.com
Click to expand...

Honestly for the price you could probably design it yourself with parts from the parts store for alot cheaper that $61.88 + shipping. The easiest way to "Positively Vent Crankcase" gases is threw the crank case. Design something like you would find on a factory oem intake using a PCV valve. If you don't trust yourself use a good machine shop. I tried running my 351 based motor with 2 valve cover breathers and no pcv on the intake......i started building pressure in the valve covers to the point oil was leaking out the valve covers. I connected the PCV on this lower intake to the manifold vacuum and the valve cover pressure and leaking valve covers went away.
 
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