oil pressure and crankcase pressure

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superbee79

superbee79

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when i put my 318 together it had way too much oil pressure and i don't know why, it blew the oil filter completely off of the motor. I changed the pump and pick up and relocated the filter after running a piece of coat hanger down where the oil goes back in from filter didn't see any dirt or anything come out or fall down in. never seen this happen before. then the relocation kit from jegs isn't really long enough so i need a longer one to get filter where i want it to be. has anyone else had any problems with too much oil pressure i think there might be a crankcase pressure issue too because when i rev it up it pushes the dipstick out.
 
did you have a machine shop clean block ? did they remove (all) oil plugs some say they do an dont .... theres a pressure relief spring in the block of oil pump trash most likely got in there a stuck it shut not letting the valve open or did you use the old one ? (oil pump/pick up tube)
as far as your jeggs thats on you
 
Even if the block passages are plugged somewhere, the relief should dump pressure directly back into the pan. I vote for screwed up relief.

By the way, how much is "too much"? My old 340 used to run "too much" I.E. routinely pegged a 100 psi SW gauge. I never perceived any problems, and never blew out a filter. I do realise this was a few years ago, filters "may" have been a little better then. Wix. Always, Wix.
 
every screwed up relief I have ever had the misfortune of running into would lose pressure, not gain it.

if you put the rocker shafts on backwards you could be restricting oil there and increasing psi.just a guess
 
Oil pressure and crankcase pressure are 2 different animals. A sticking relief/ by-pass could cause high pressure. Cylinder blow-by (ring seal) can cause excessive crank case pressure, especially when the engine is under load (full cylinder pressure).
 
ganggreen said:
Oil pressure and crankcase pressure are 2 different animals. A sticking relief/ by-pass could cause high pressure. Cylinder blow-by (ring seal) can cause excessive crank case pressure, especially when the engine is under load (full cylinder pressure).
Click to expand...
thats what the AND means i know they are two different things when i put it together it had some blow by AND i had an oil pressure issue where it blew filter off
 
what kind of breather system is on the car?? pcv or just an element on one valve cover.... try two breathers if no pcv. my car has one breather and after a full throttle pass down the track it will push the dipstick up a .5 inch.

fram filter??
 
1wild&crazyguy said:
every screwed up relief I have ever had the misfortune of running into would lose pressure, not gain it.

if you put the rocker shafts on backwards you could be restricting oil there and increasing psi.just a guess
Click to expand...
what do you mean by backwards? Rockers only go one way pushrods go in the little cups at the end of them. Did you mean on the opposite side they came off of when you said backwards?:read2:
 
What wild&crazy is talking about is the rocker shafts themselves. The part the rockers swivel on. Factory shafts have a notch in the end of the shaft that should face down toward the head when installed.
 
Doesn't the oil pump itself have the pressure relief valve built-in?? I would probably drop the pan and remove/disassemble the pump the check it out. You didn't mention the pressure you saw (got a gauge on it?) but I'm sure it'd peg over 100 psi if it blew the filter off the motor anyway, huh?

Any chance that the oil pump got any moisture in it before installing it on the 318? Maybe a small amount of rust on that valve is sticking it closed.

I don't think any restriction anywhere in the motor's oiling system is responsible.
 
just a note
the notch on the rocker shaft goes down and towards the front on the left (drivers)side
and down and towards the back on the right ( pass side)
..the shaft oiling hole is larger on the bottom second hole from the notch(right next to the long head bolt)
if it was different,i believe it would clatter do to lack of lubrication thru the shaft
 
If your oil pressure is too high, look into your oil pump. The oil pump has the pressure releif valve and spring that sets the pressure for the engine. The stiffer the spring for the relief valve, the higher the oil pressure that the engine will run. The relief valve bleeds off any pressure excess of what the spring is designed for. I have run the MP high volume pump with the high pressure spring and typically run 75 - 100 lbs with no problems.

I had a bad experience with a TRW oil pump 30 years ago. The pressure relief valve stuck between open and close and had no oil pressure. TRW rebuilt the pump for free, but did not compensate me for my engine damage. I sold the pump to someone for $25 and warned them what happened and to this day do not run TRW parts. Their "lab" analysis for my failure from TRW was and I quote:

"Small tiny minute particles small enough to fit through a stock oil pump pick up screen" had gotten wedged between the valve and valve bore and caused the valve to stick. I say if it can't handle what the pickup screen filters out, it is junk. I have run MP and Mellings pumps ever since with no problems. This was on a very clean 50k mile 70 340 that was disassembled and readdembled with a new cam and TRW pump. I changed the oil three times within 500 miles because the car sat in a body shop for a while and I did not want body dust in the oil.

So basically, the spring sets the pressure, and the valve blows off the excess above what the spring is calibrated for.
 
Dartman has a point about the oil plugs in the block. I had an engine where the machine shop forgot to put a couple in and it took me 5 engine pulls before I found the problem. They left the two that go behind the camshaft thrust plate out and I could only get 25 psi cold on startup and went down to 10-15 warm. I can't remember where all of the plugs go at this time without looking at a bare block, but find out where they are all supposed to be and double check that they are all reinstalled before putting the block back together. Remember it is YOUR engine, not theirs. Don't let their mistake cost you engine damage.

Now what about the engine bearings. Are all of the oil holes properly aligned in the engine??? Misaligned oil feed holes can cause high pressure.

The main bearing shells have holes for the halves that go into the block for the crankshaft. Do not put the shell without the oil hole in the block. The shell WITHOUT the hole goes in the MAIN BEARING CAP.

Same goes for the conecting rod bearings, if they have oil holes to oil the cylinder bores, they must go into the rod, not the cap. The SHELL FOR THE CAP DOES NOT HAVE A HOLE IN IT. THE SHELL OPPOSITE THE CAP MUST HAVE THE HOLE, (or the one that goes into the rod gets the hole).

Also verify that the machine shop properly installed the cam bearings. Each cam bearing has holes for oiling that must be aligned with the holes in the block. Before assembling the short block, get a wire hanger and straighten it out. Stick the wire in each of the holes in the block for the main bearing shells and make sure that you can see the tip pass through the cam bearing into the cam bore (gently so as not to scratch your cam bearings). This will make sure that none of the oil feed holes from the crank to the cam are not blocked/obstructed. A general rule is that the holes should not be covered/overlapped by more than 50%. Or the hole should have at least 50% alignment or better. Next take the wire hanger and roll the block over and stick the wire into the oil feed holes on the head face of the block and check that the holes are properly aligned and not blocked. Over half of the hole should not be blocked, or reset the cam bearings for proper alignment.

I know it might be a little late to check these if your engine is assembled. This should always be checked before assembling the short block. ALWAYS CHECK YOUR OIL PLUGS AND BEARING HOLE ALIGHNMENT BEFORE/WHILE ASSEMBLING THE SHORT BLOCK! Just make this mistake ONCE, and you will never repeat it... Believe me..
 
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