Can oil leak from the bottom of the heads on a 4.3?

[brsox88]

So my new 4.3l engine (new block and heads from rapidomarine.com) with the vortec valve covers is leaking oil around the bottom of the head at the rear starboard. Atleast it seems from there since that's where I see the most oil buildup. Seems to increase leaking/spray when at full throttle.

1. Can heads leak oil at the bottom between the head and block? I thought that at the bottom of the head is where the tops of the pistons were, so no oil should be coming from there right?

2. If it is leaking at the head, whats the next step? Buy a new head and gasket, mark the positions of the valves and replace? I'm worried they gave me a bad head.

3. Is it ok to run if I am leaking about a half a quart of oil on a full day out?

 

[wellcraft-classic210]

Could be your intake manifold gasket -- They can squeeze out of place if silicone is used along the rail -- High rpm's will splash oil out and any blow by helps it along.


Easy to see if your watching while someone is driving or can inspect along the edge // Camera's and mirrors can be helpful in tight locations.

 

[harleyman1975]

My thought too intake is more likely the culprit.

 

[brsox88]

I should have mentioned its leaking at the exhaust side of the head/valve cover. Intake uses the proper gaskets and no leaking is happening there. But again, why would oil be at the top of the pistons/valves then to even leak there??

 

[Bt Doctur]

It would leak from that area if the bottom of the valve cover has rotted out. Doubtful if a head gasket issue.Either valve cover of intake rails

 

[brsox88]

So basically its not possible for it to leak oil from the bottom of the heads because no oil goes through there? And if it were leaking there wouldn't the engine run rough since there would be low compression? The valve covers are vortec ones which are plastic, so they can't rot out? Not sure how it could leak around the intake either if there is no oil that runs through there, its just air and water in the intake correct?

 

[Bt Doctur]

Plastic can split and crack . so remove them for inspection . If the crankcase develops positive pressure oil mist will leak from the front and/or rear sealing rails and also the dist base basket

 

[brsox88]

Pressure is at 40psi constant, only place I thought oil mist would come from is the vent hoses on the valve covers. I can replace the valve cover as its only a $35 part but does anyone know the answer to my questions? Is it even possible for the heads to leak at the bottom? Is it possible its cracked since they are just refurbished heads anyways?

 

[GA_Boater]

By bottom do you mean the joint between the head and block? No, it can't leak oil there. If the head is cracked above the joint and below the valve cover lip on the head, very doubtful unless the lip itself is cracked.

Most likely it's the valve cover gasket, then the valve cover. Over tightening valve covers cause many oil leaks.

 

[Rick Stephens]

That's a lot of leak. I can't see it likely to come from a blown head gasket.

As suggested, pull the valve cover. I don't think you can over tighten the plastic Vortec valve cover bolts as they are a shoulder bolt that seats tight in the head at the thread end of the bolt. However, have seen a number of plastic valve cover gaskets that were rolled or pinched because weren't installed correctly.

There is no difference at all between valve cover vent blowby and the pressure that exists at the intake end rails. A leak at the intake will get exactly the same pressure waves and may get more oil since it is closer/lower to actual oil flow.

 

[brsox88]

I'll replace the valve cover, but I don't get why you guys think it could be a leak at the intake/intake gasket rail? There is no oil that runs through there, and if it were a leak there I would see it either at the front or rear of the intake rail or on the top of the intake that meets the head. Maybe I should provide a picture incase you guys are thinking of something else?

 

[tpenfield]

Aren't rebuild engines great

 

[Bondo]

2. If it is leaking at the head, whats the next step?

Ayuh,.... It's NOT leakin' from the bottom of the head,.... There's no oil there,....
There's water on the other side of that partin' line 'tween the head, 'n block,....

The next step is to Look Higher,....
Oil, like water, flows downhill,....
Above the point yer seein' the oil is, the valve cover, the intake gasket, the distributor gasket, 'n the oil pressure port right next to the distributor,...

Where ever ya See oil,... Look Higher, til ya don't See oil anymore,... The leak is 'bout right in front of yer nose at that point,.....

 

[Scott Danforth]

common leak points

valve covers
non-sealed intake manifold bolts
loose oil fittings

I find that UV dye and the UV light and glasses works wonders in following the yellow brick road

https://www.amazon.com/FJC-4972-Fluo...ection+glasses

 

[Lou C]

Agreed, valve cover damaged or not tight, gasket not fitted into cover flange right, rear of intake not properly sealed with silicone, oil pressure sending unit not tight or needs sealer on threads....
The front and rear edges of the intake on these get a 3/16ths bead of silicone sealer..

 

[brsox88]

No Title

RTV red was heavily applied at the rear and front of the intake manifold when built, I already took the valve cover off and it looked fine but going to replace it in case there is a crack I don't see. Still not sure how it would leak that much since its not like it fills up with oil. Also, how can a head not leak oil, how does the oil get to the valve train then?

The reason I thought it was the head is because it seems to spray oil onto the side of my bilge by the engine mount, only way it could spray there seems to be from the bottom of the head. Check out the pictures.

 

[Bt Doctur]

Where is the dip stick on that motor?

 

[brsox88]

Dipstick is on the right side in that picture with the power steering below/next to it. Does anyone know the answers to my previous questions?

 

[Bt Doctur]

so the dipstick goes into the side of the oil pan on the right side facing the motor?

 

[Bt Doctur]

I`m trying to get info thats neded because most gm engines go THRU the engine block on the left side facing the motor. If there is no plug in that hole it will squirt oil right where your seeing it.