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i have a 78' ford f150 with a 400m engine and i had a cam go flat in my truck, so i replaced it with a 252-h compcamsand lfter set, i also replaced the timing chain with a non-retarded one.when i got the motor fired up, i had no oil pressure and the lifters wouldnot pump up, so i went to the parts store and bought ahi-volume/hi-pressure pump, my friend told me to check my main bearingswhile i had the pan dropped. i did and found the crank was severly scored.i had a friend that was parting out his 78' bronco, and i bought the 400mfrom him. it was completely stock and he drove it into the shop before wepulled the motor. i got it home and installed the rebuilt heads off myprevious motor, the new cam, lifters, timing chain, and hi-volume oilpump. i went to fire it up and no oil pressure, i have replaced the oilpump intermidiate drive shaft, and distributor. i have an electric and amechanical gauge installed, i pulled the oil sending unit out and startedthe motor and the oil just bubbles out. i am at my wits end and am aboutto burn this thing to the ground! please help!!!!</PRE></TD></TR><TR><TD> </TD></TR></TBODY></TABLE></P>

 

You may have the oil pump pickup tube gasket problem or a small crack or hole in the pick up tube. If the oil pickup tube is sucking air for any reason then the bubbles are the result, usually. Also, one of the internal oil plugs may have popped out. If an internal oil plug has popped out then the oil will not build much if any pressure.

I'll go with the pickup tube being the source of the problem. Put the oil pressure sending unit back in. Over-fill the oil pan to a point where the entire oil pump pick up tube is submerged in oil and try priming the oil pump with a drill in reverse using an adapter. The oil pump should build up enough pressure that the drill will be working hard. Don't give up to quickly, because it may take a few tries to get the oil pump primed.

Anyway, If this helps then you'll be taking the oil pan back off and taking the oil pump pick up tube off. Let us know what happens. By all means don't start the engine with this much oil in it!

 

come to think of it the pump didnt have a gasket with it, i used silicone, i did try the drill in reverse to try and prime the pump and my brother was inside watching the mechanical gauge, he said it read nothing. this is the 2nd motor that had oil pressure before i worked on it now it has none, the only common factor between the 2 is the cam and lifters, how does the oil supply route through the 400m? could i have a faulty camshaft??? i have never heard of one but could it be a possibility? is there anything else i should check before buying a new cam? thanks

 

The oil galley plugs are threaded, so the possibilites of a plug poping out is out. As a last resort, we have taken the oil pan off and with a big catch pan, ran a hose to the oil pump and sucked oil out of a can using the electric drill. Then you can see where all the oil is going. I have seen a reground crankshaft with the wrong bearings (loose of course) and oil just pours out the rod area.

 

they are the same bearings that were in it when i got it, i keep going back to the camshaft, is there any way it could b causing this????

 

theres an easy well to tell. Just pull the distro and use the ol' drill method to turn the oil pump shaft. I wouldn't think that the cam being misinstalled or the cam bearings being mis installed would cause you to lose 100% of your oil pressure but perhaps i'm wrong.

 

ok i did the cam in reverse thing, i think i burned up my drill, it was laboring pretty hard, i pulled the sending unit out of the back of the block and it just gurgles out, this is a hi-volume oil pump shouldnt it be shooting out of the back of the block?

 

Here is a diagram of the oiling in a 335 series motor.



It sounds to me like the cam is installed incorrectly or it is the wrong size. Did the cam slide in easily?

Are you sure that you replaced all the lifters?

You need to find out where the oil is going when you turn the pump.

Did you knock out a cam bearing?

 

The engine had good oil pressure before the cam went flat, correct?

 

ok so everyone is straight here, the orignal motor in the truck had the cam that went flat, it had oil pressure but it was not the greatest-20lbs, i installed the new cam (compcams 252h-10 anad lifter set) got the thing back together, fired up and no oil pressure, i went and bought a new oil pump and at that time i dropped the main bearing to check and discovered the crank was toast. i bought a 2nd motor out of a buddys bronco that had great oil pressure, i re-gasketed it, and installed the new cam i had bought and installed in the 1st motor, since the 2nd motor had the original cam in it, i also installed a new timing chain and the hi-volume/hi-pressure pump, i get it fired up and no pressure. come to think of it now the drivers side lifters are the only ones making noise, i guess i should put the oil pan back on and pull the valve covers to see how much oil is coming out of the pushrods. or is there a way i can do it without the pan on? i never pulled the valve covers because both of my oil pressure gauges read zero. i have installed probably a dozen camshafts in both chevy and ford motors, and this one is the first that has given me any problems, the cam went in nice and smooth there is no way i knocked out a cam bearing, this is the 2nd motor that i have had the same problem with and both have had oil pressure before. this is a brand new compcams, is there anyway i might be able to get this replaced or warrantied?

 

The lifters on the drivers side get oil last. (See diagram).
The oil sender is after the passenger side lifters and main bearings and cam bearings, but before the drivers side lifters.
Bad cam bearings are the usual culprit for low oil pressure in these motors.

You could mic. the cam to be sure that it is in spec. You should give Comp Cams a call to see what they suggest.

 

The reason I asked is it does sound like you have the wrong cam. Monday at work I want to check some specs, but I have gotten a cam from Comp Cams that was mis-boxed. I am thinking if the cam journals are a little smaller on a different cam, it would fit but be to loose. I want to check the specs of a SBF cam, if the journals are slightly smaller, than you might have a missed boxed cam also. If it is wrong, Comp will take care of it.

 

how can it be bad cam bearings if the motor had awesome oil pressure before the cam swap???? i will have to check the journal sizes tomorrow

 

Since you mentioned that you didn't use a gasket for the oil pump, I would be very suspicious of that area. Just perform the oil overfill test and eleminate the oil pump pickup. I don't see how air bubbles could still be coming out at this point unless your oil pump is pumping air mixed with the oil.

 

there were never any air bubbles coming out it just gurgles out of the sending unit hole, there are no air bubles